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  Subjects -> BUSINESS AND ECONOMICS (Total: 3075 journals)
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BUSINESS AND ECONOMICS (1154 journals)                  1 2 3 4 5 6 | Last

Showing 1 - 200 of 1566 Journals sorted alphabetically
4OR: A Quarterly Journal of Operations Research     Hybrid Journal   (Followers: 9)
Abacus     Hybrid Journal   (Followers: 11)
Accounting Forum     Hybrid Journal   (Followers: 22)
Acta Amazonica     Open Access   (Followers: 3)
Acta Commercii     Open Access   (Followers: 2)
Acta Oeconomica     Full-text available via subscription   (Followers: 2)
Acta Scientiarum. Human and Social Sciences     Open Access   (Followers: 4)
Acta Universitatis Danubius. Œconomica     Open Access  
Acta Universitatis Nicolai Copernici Zarządzanie     Open Access   (Followers: 3)
AD-minister     Open Access   (Followers: 2)
ADR Bulletin     Open Access   (Followers: 5)
Advances in Developing Human Resources     Hybrid Journal   (Followers: 21)
Advances in Economics and Business     Open Access   (Followers: 12)
AfricaGrowth Agenda     Full-text available via subscription   (Followers: 1)
African Affairs     Hybrid Journal   (Followers: 57)
African Development Review     Hybrid Journal   (Followers: 34)
African Journal of Business and Economic Research     Full-text available via subscription   (Followers: 1)
African Journal of Business Ethics     Open Access   (Followers: 7)
African Review of Economics and Finance     Open Access   (Followers: 3)
Afro-Asian Journal of Finance and Accounting     Hybrid Journal   (Followers: 6)
Afyon Kocatepe Üniversitesi İktisadi ve İdari Bilimler Fakültesi Dergisi     Open Access   (Followers: 3)
Agronomy     Open Access   (Followers: 11)
Akademika : Journal of Southeast Asia Social Sciences and Humanities     Open Access   (Followers: 4)
Alphanumeric Journal : The Journal of Operations Research, Statistics, Econometrics and Management Information Systems     Open Access   (Followers: 4)
American Economic Journal : Applied Economics     Full-text available via subscription   (Followers: 124)
American Economic Journal : Economic Policy     Full-text available via subscription   (Followers: 94)
American Journal of Business     Hybrid Journal   (Followers: 14)
American Journal of Business and Management     Open Access   (Followers: 50)
American Journal of Business Education     Open Access   (Followers: 10)
American Journal of Economics and Business Administration     Open Access   (Followers: 22)
American Journal of Economics and Sociology     Hybrid Journal   (Followers: 27)
American Journal of Evaluation     Hybrid Journal   (Followers: 12)
American Journal of Finance and Accounting     Hybrid Journal   (Followers: 16)
American Journal of Health Economics     Full-text available via subscription   (Followers: 12)
American Journal of Industrial and Business Management     Open Access   (Followers: 23)
American Journal of Medical Quality     Hybrid Journal   (Followers: 7)
American Law and Economics Review     Hybrid Journal   (Followers: 26)
ANALES de la Universidad Central del Ecuador     Open Access   (Followers: 1)
Annales de l'Institut Henri Poincare (C) Non Linear Analysis     Full-text available via subscription   (Followers: 1)
Annals in Social Responsibility     Full-text available via subscription  
Annals of Finance     Hybrid Journal   (Followers: 26)
Annals of Operations Research     Hybrid Journal   (Followers: 8)
Annual Review of Economics     Full-text available via subscription   (Followers: 29)
Applied Developmental Science     Hybrid Journal   (Followers: 4)
Applied Economics     Hybrid Journal   (Followers: 44)
Applied Economics Letters     Hybrid Journal   (Followers: 28)
Applied Economics Quarterly     Full-text available via subscription   (Followers: 10)
Applied Financial Economics     Hybrid Journal   (Followers: 21)
Applied Mathematical Finance     Hybrid Journal   (Followers: 6)
Applied Stochastic Models in Business and Industry     Hybrid Journal   (Followers: 5)
Apuntes Universitarios     Open Access   (Followers: 1)
Arab Economic and Business Journal     Open Access   (Followers: 3)
Archives of Business Research     Open Access   (Followers: 4)
Arena Journal     Full-text available via subscription   (Followers: 1)
Argomenti. Rivista di economia, cultura e ricerca sociale     Open Access   (Followers: 2)
ASEAN Economic Bulletin     Full-text available via subscription   (Followers: 5)
Asia Pacific Business Review     Hybrid Journal   (Followers: 5)
Asia Pacific Journal of Human Resources     Hybrid Journal   (Followers: 309)
Asia Pacific Viewpoint     Hybrid Journal  
Asia-Pacific Journal of Business Administration     Hybrid Journal   (Followers: 3)
Asia-Pacific Journal of Operational Research     Hybrid Journal   (Followers: 3)
Asian Business Review     Open Access   (Followers: 2)
Asian Case Research Journal     Hybrid Journal   (Followers: 1)
Asian Development Review     Open Access   (Followers: 14)
Asian Economic Journal     Hybrid Journal   (Followers: 6)
Asian Economic Papers     Hybrid Journal   (Followers: 7)
Asian Economic Policy Review     Hybrid Journal   (Followers: 3)
Asian Journal of Accounting and Governance     Open Access   (Followers: 3)
Asian Journal of Business Ethics     Hybrid Journal   (Followers: 7)
Asian Journal of Social Sciences and Management Studies     Open Access   (Followers: 6)
Asian Journal of Technology Innovation     Hybrid Journal   (Followers: 9)
Asian-pacific Economic Literature     Hybrid Journal   (Followers: 5)
AStA Wirtschafts- und Sozialstatistisches Archiv     Hybrid Journal   (Followers: 5)
Atlantic Economic Journal     Hybrid Journal   (Followers: 14)
Australasian Journal of Regional Studies, The     Full-text available via subscription   (Followers: 2)
Australian Cottongrower, The     Full-text available via subscription   (Followers: 1)
Australian Economic Papers     Hybrid Journal   (Followers: 16)
Australian Economic Review     Hybrid Journal   (Followers: 7)
Australian Journal of Maritime and Ocean Affairs     Hybrid Journal   (Followers: 11)
Balkan Region Conference on Engineering and Business Education     Open Access   (Followers: 1)
Baltic Journal of Real Estate Economics and Construction Management     Open Access   (Followers: 1)
Banks in Insurance Report     Hybrid Journal   (Followers: 1)
BBR - Brazilian Business Review     Open Access   (Followers: 5)
Benchmarking : An International Journal     Hybrid Journal   (Followers: 11)
BER : Consumer Confidence Survey     Full-text available via subscription   (Followers: 4)
BER : Economic Prospects : An Executive Summary     Full-text available via subscription  
BER : Economic Prospects : Full Survey     Full-text available via subscription   (Followers: 2)
BER : Intermediate Goods Industries Survey     Full-text available via subscription   (Followers: 1)
BER : Manufacturing Survey : Full Survey     Full-text available via subscription   (Followers: 2)
BER : Motor Trade Survey     Full-text available via subscription   (Followers: 1)
BER : Retail Sector Survey     Full-text available via subscription   (Followers: 2)
BER : Retail Survey : Full Survey     Full-text available via subscription   (Followers: 2)
BER : Survey of Business Conditions in Building and Construction : An Executive Summary     Full-text available via subscription   (Followers: 4)
BER : Survey of Business Conditions in Manufacturing : An Executive Summary     Full-text available via subscription   (Followers: 3)
BER : Survey of Business Conditions in Retail : An Executive Summary     Full-text available via subscription   (Followers: 3)
BER : Trends : Full Survey     Full-text available via subscription   (Followers: 2)
BER : Wholesale Sector Survey     Full-text available via subscription   (Followers: 1)
Berkeley Business Law Journal     Free   (Followers: 11)
Bio-based and Applied Economics     Open Access   (Followers: 1)
Biodegradation     Hybrid Journal   (Followers: 1)
Biology Direct     Open Access   (Followers: 7)
Black Enterprise     Full-text available via subscription  
Board & Administrator for Administrators only     Hybrid Journal  
Border Crossing : Transnational Working Papers     Open Access   (Followers: 2)
Briefings in Real Estate Finance     Hybrid Journal   (Followers: 5)
British Journal of Industrial Relations     Hybrid Journal   (Followers: 30)
Brookings Papers on Economic Activity     Open Access   (Followers: 46)
Brookings Trade Forum     Full-text available via subscription   (Followers: 3)
BRQ Business Research Quarterly     Open Access   (Followers: 2)
Building Sustainable Legacies : The New Frontier Of Societal Value Co-Creation     Full-text available via subscription   (Followers: 1)
Bulletin of Economic Research     Hybrid Journal   (Followers: 16)
Bulletin of Geography. Socio-economic Series     Open Access   (Followers: 6)
Bulletin of Indonesian Economic Studies     Hybrid Journal   (Followers: 3)
Bulletin of the Dnipropetrovsk University. Series : Management of Innovations     Open Access   (Followers: 1)
Business & Entrepreneurship Journal     Open Access   (Followers: 15)
Business & Information Systems Engineering     Hybrid Journal   (Followers: 5)
Business & Society     Hybrid Journal   (Followers: 9)
Business : Theory and Practice / Verslas : Teorija ir Praktika     Open Access   (Followers: 1)
Business and Economic Horizons     Open Access   (Followers: 2)
Business and Economic Research     Open Access   (Followers: 5)
Business and Management Horizons     Open Access   (Followers: 11)
Business and Management Research     Open Access   (Followers: 16)
Business and Management Studies     Open Access   (Followers: 7)
Business and Politics     Hybrid Journal   (Followers: 6)
Business and Professional Communication Quarterly     Hybrid Journal   (Followers: 7)
Business and Society Review     Hybrid Journal   (Followers: 5)
Business Economics     Hybrid Journal   (Followers: 6)
Business Ethics: A European Review     Hybrid Journal   (Followers: 16)
Business Horizons     Hybrid Journal   (Followers: 9)
Business Information Review     Hybrid Journal   (Followers: 13)
Business Management and Strategy     Open Access   (Followers: 39)
Business Research     Hybrid Journal   (Followers: 1)
Business Strategy and the Environment     Hybrid Journal   (Followers: 11)
Business Strategy Review     Hybrid Journal   (Followers: 6)
Business Strategy Series     Hybrid Journal   (Followers: 5)
Business Systems & Economics     Open Access   (Followers: 1)
Business Systems Research Journal     Open Access   (Followers: 4)
Business, Management and Education     Open Access   (Followers: 16)
Business, Peace and Sustainable Development     Full-text available via subscription   (Followers: 3)
Bustan     Hybrid Journal   (Followers: 1)
Cadernos EBAPE.BR     Open Access   (Followers: 1)
Cambridge Journal of Economics     Hybrid Journal   (Followers: 55)
Cambridge Journal of Regions, Economy and Society     Hybrid Journal   (Followers: 9)
Canadian Journal of Administrative Sciences / Revue Canadienne des Sciences de l Administration     Hybrid Journal   (Followers: 1)
Canadian Journal of Economics/Revue Canadienne d`Economique     Hybrid Journal   (Followers: 25)
Canadian journal of nonprofit and social economy research     Open Access   (Followers: 2)
Capitalism and Society     Hybrid Journal   (Followers: 2)
Capitalism Nature Socialism     Hybrid Journal   (Followers: 11)
Case Studies in Business and Management     Open Access   (Followers: 8)
CBU International Conference Proceedings     Open Access   (Followers: 1)
Central European Business Review     Open Access   (Followers: 1)
Central European Journal of Operations Research     Hybrid Journal   (Followers: 5)
Central European Journal of Public Policy     Open Access   (Followers: 1)
CESifo Economic Studies     Hybrid Journal   (Followers: 15)
Chain Reaction     Full-text available via subscription   (Followers: 1)
Challenge     Full-text available via subscription   (Followers: 4)
China & World Economy     Hybrid Journal   (Followers: 15)
China : An International Journal     Full-text available via subscription   (Followers: 17)
China Economic Journal: The Official Journal of the China Center for Economic Research (CCER) at Peking University     Hybrid Journal   (Followers: 10)
China Economic Review     Hybrid Journal   (Followers: 10)
China Finance Review International     Hybrid Journal   (Followers: 5)
China Nonprofit Review     Hybrid Journal   (Followers: 3)
China perspectives     Open Access   (Followers: 11)
Chinese Economy     Full-text available via subscription  
Ciência & Saúde Coletiva     Open Access   (Followers: 2)
CLIO América     Open Access   (Followers: 1)
Cliometrica     Hybrid Journal   (Followers: 1)
COEPTUM     Open Access  
Community Development Journal     Hybrid Journal   (Followers: 23)
Compensation & Benefits Review     Hybrid Journal   (Followers: 6)
Competition & Change     Hybrid Journal   (Followers: 10)
Competitive Intelligence Review     Hybrid Journal   (Followers: 2)
Competitiveness Review : An International Business Journal incorporating Journal of Global Competitiveness     Hybrid Journal   (Followers: 5)
Computational Economics     Hybrid Journal   (Followers: 9)
Computational Mathematics and Modeling     Hybrid Journal   (Followers: 8)
Computer Law & Security Report     Hybrid Journal   (Followers: 15)
Computers & Operations Research     Hybrid Journal   (Followers: 10)
Construction Innovation: Information, Process, Management     Hybrid Journal   (Followers: 14)
Contemporary Wales     Full-text available via subscription   (Followers: 3)
Contextus - Revista Contemporânea de Economia e Gestão     Open Access   (Followers: 1)
Contributions to Political Economy     Hybrid Journal   (Followers: 6)
Corporate Communications An International Journal     Hybrid Journal   (Followers: 4)
Corporate Philanthropy Report     Hybrid Journal   (Followers: 2)
Corporate Reputation Review     Hybrid Journal   (Followers: 5)
Creative and Knowledge Society     Open Access   (Followers: 10)
Creative Industries Journal     Hybrid Journal   (Followers: 8)
CRIS - Bulletin of the Centre for Research and Interdisciplinary Study     Open Access   (Followers: 1)
Crossing the Border : International Journal of Interdisciplinary Studies     Open Access   (Followers: 4)
Cuadernos de Administración (Universidad del Valle)     Open Access   (Followers: 1)
Cuadernos de Economía     Open Access   (Followers: 1)
Cuadernos de Economia - Latin American Journal of Economics     Open Access   (Followers: 1)
Cuadernos de Estudios Empresariales     Open Access   (Followers: 1)
Current Opinion in Creativity, Innovation and Entrepreneurship     Open Access   (Followers: 8)
De Economist     Hybrid Journal   (Followers: 12)
Decision Analysis     Full-text available via subscription   (Followers: 8)
Decision Sciences     Hybrid Journal   (Followers: 15)
Decision Support Systems     Hybrid Journal   (Followers: 15)
Defence and Peace Economics     Hybrid Journal   (Followers: 16)
der markt     Hybrid Journal   (Followers: 1)
Desenvolvimento em Questão     Open Access  

        1 2 3 4 5 6 | Last

Journal Cover Agronomy
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  This is an Open Access Journal Open Access journal
   ISSN (Print) 2073-4395
   Published by MDPI Homepage  [148 journals]
  • Agronomy, Vol. 7, Pages 1: The Current Status, Problems, and Prospects of
           Alfalfa (Medicago sativa L.) Breeding in China

    • Authors: Shangli Shi, Lili Nan, Kevin Smith
      First page: 1
      Abstract: This paper reviews the current status, methodology, achievements, and prospects of alfalfa (Medicago sativa L.) breeding in China. There are 77 cultivars that have been registered in the country, these include 36 cultivars bred through breeding programs, 17 introduced from overseas, 5 domesticated from wild ecotypes, and 19 through regional collection/breeding programs. Cultivars have been selected for cold resistance, disease resistance, salt tolerance, grazing tolerance, high yield, and early maturity. Most of these cultivars have been developed through conventional breeding techniques, such as selective and cross breeding, and some are now being evaluated that have been developed through the application of transgenic technology. The major problems for alfalfa breeding in China include low success rate, slow progress to breed resistant varieties, lack of breeding materials and their systematic collection, storage and evaluation, lack of advanced breeding techniques, and low adoption rate of new cultivars. There are gaps in alfalfa breeding between China and the developed world. Improvement of alfalfa breeding techniques, development of cultivars with adaptations to different regions within China, and the protection and utilization of alfalfa germplasm resources have been identified as major strategies to improve the efficiency of alfalfa breeding in China.
      PubDate: 2017-01-01
      DOI: 10.3390/agronomy7010001
      Issue No: Vol. 7, No. 1 (2017)
       
  • Agronomy, Vol. 7, Pages 2: Improvement of Faba Bean Yield Using
           Rhizobium/Agrobacterium Inoculant in Low-Fertility Sandy Soil

    • Authors: Sameh Youseif, Fayrouz Abd El-Megeed, Saleh Saleh
      First page: 2
      Abstract: Soil fertility is one of the major limiting factors for crop’s productivity in Egypt and the world in general. Biological nitrogen fixation (BNF) has a great importance as a non-polluting and a cost-effective way to improve soil fertility through supplying N to different agricultural systems. Faba bean (Vicia faba L.) is one of the most efficient nitrogen-fixing legumes that can meet all of their N needs through BNF. Therefore, understanding the impact of rhizobial inoculation and contrasting soil rhizobia on nodulation and N2 fixation in faba bean is crucial to optimize the crop yield, particularly under low fertility soil conditions. This study investigated the symbiotic effectiveness of 17 Rhizobium/Agrobacterium strains previously isolated from different Egyptian governorates in improving the nodulation and N2 fixation in faba bean cv. Giza 843 under controlled greenhouse conditions. Five strains that had a high nitrogen-fixing capacity under greenhouse conditions were subsequently tested in field trials as faba bean inoculants at Ismaillia Governorate in northeast Egypt in comparison with the chemical N-fertilization treatment (96 kg N·ha−1). A starter N-dose (48 kg N·ha−1) was applied in combination with different Rhizobium inoculants. The field experiments were established at sites without a background of inoculation under low fertility sandy soil conditions over two successive winter growing seasons, 2012/2013 and 2013/2014. Under greenhouse conditions, inoculated plants produced significantly higher nodules dry weight, plant biomass, and shoot N-uptake than non-inoculated ones. In the first season (2012/2013), inoculation of field-grown faba bean showed significant improvements in seed yield (3.73–4.36 ton·ha−1) and seed N-yield (138–153 Kg N·ha−1), which were higher than the uninoculated control (48 kg N·ha−1) that produced 2.97 Kg·ha−1 and 95 kg N·ha−1, respectively. Similarly, in the second season (2013/2014), inoculation significantly improved seed yield (3.16–4.68 ton·ha−1) and seed N-yield (98–155 Kg N·ha−1) relative to the uninoculated control (48 kg N·ha−1), which recorded 2.58 Kg·ha−1 and 80 kg N·ha−1, respectively. Interestingly, faba bean inoculated with strain Rlv NGB-FR 126 showed significant increments in seed yield (35%–48%) and seed N-yield (34%–49%) compared to the inorganic N fertilizers treatment (96 kg N·ha−1) over the two cropping seasons, respectively. These results indicate that inoculation of faba bean with effective rhizobial strains can reduce the need for inorganic N fertilization to achieve higher crop yield under low fertility soil conditions.
      PubDate: 2017-01-01
      DOI: 10.3390/agronomy7010002
      Issue No: Vol. 7, No. 1 (2017)
       
  • Agronomy, Vol. 7, Pages 3: Development and Testing of Cool-Season Grass
           Species, Varieties and Hybrids for Biomass Feedstock Production in Western
           North America

    • Authors: Steven Larson, Calvin Pearson, Kevin Jensen, Thomas Jones, Ivan Mott, Matthew Robbins, Jack Staub, Blair Waldron
      First page: 3
      Abstract: Breeding of native cool-season grasses has the potential to improve forage production and expand the range of bioenergy feedstocks throughout western North America. Basin wildrye (Leymus cinereus) and creeping wildrye (Leymus triticoides) rank among the tallest and most rhizomatous grasses of this region, respectively. The objectives of this study were to develop interspecific creeping wildrye (CWR) × basin wildrye (BWR) hybrids and evaluate their biomass yield relative to tetraploid ‘Trailhead’, octoploid ‘Magnar’ and interploidy-hybrid ‘Continental’ BWR cultivars in comparison with other perennial grasses across diverse single-harvest dryland range sites and a two-harvest irrigated production system. Two half-sib hybrid populations were produced by harvesting seed from the tetraploid self-incompatible Acc:641.T CWR genet, which was clonally propagated by rhizomes into isolated hybridization blocks with two tetraploid BWR pollen parents: Acc:636 and ‘Trailhead’. Full-sib hybrid seed was also produced from a controlled cross of tetraploid ‘Rio’ CWR and ‘Trailhead’ BWR plants. In space-planted range plots, the ‘Rio’ CWR × ‘Trailhead’ BWR and Acc:641.T CWR × Acc:636 BWR hybrids displayed high-parent heterosis with 75% and 36% yield advantages, respectively, but the Acc:641.T CWR × ‘Trailhead’ BWR hybrid yielded significantly less than its BWR high-parent in this evaluation. Half-sib CWR × BWR hybrids of Acc:636 and ‘Trailhead’ both yielded as good as or better than available BWR cultivars, with yields similar to switchgrass (Panicum virgatum), in the irrigated sward plots. These results elucidate opportunity to harness genetic variation among native grass species for the development of forage and bioenergy feedstocks in western North America.
      PubDate: 2017-01-01
      DOI: 10.3390/agronomy7010003
      Issue No: Vol. 7, No. 1 (2017)
       
  • Agronomy, Vol. 7, Pages 4: A Short Non-Saline Sprinkling Increases the
           Tuber Weights of Saline Sprinkler Irrigated Potatoes

    • Authors: Rob Stevens, Joanne Pech, Gary Grigson
      First page: 4
      Abstract: Previous work has shown that a short non-saline sprinkling, following saline sprinkling, increased crop growth. We incorporated this finding into an investigation of two approaches to the conjunctive use of saline and non-saline water sources for sprinkler irrigation of potatoes viz., (i) mixing waters prior to application, and (ii) keeping waters temporally separate, that is commencing each irrigation with saline water and finishing it with non-saline sprinkling. The latter approach delayed canopy senescence and increased tuber weight by at least 150%. Under both approaches, soil salinities and leaf and tuber concentrations of Na+ and Cl− were similar. Thus, the advantages of a non-saline sprinkling cannot be explained in terms of its effect on either soil osmotic potential or bulk tissue concentrations of putatively toxic ions Na+ and Cl−. We propose that the positive effect of finishing irrigations with a non-saline sprinkling may be attributed to either dilution, and hence increase in osmotic potential, of the water film that remains on the leaf after each irrigation or its effect on the distribution of the putatively toxic ions Na+ and Cl− within tissue.
      PubDate: 2017-01-03
      DOI: 10.3390/agronomy7010004
      Issue No: Vol. 7, No. 1 (2017)
       
  • Agronomy, Vol. 7, Pages 5: QTL Analysis for Drought Tolerance in Wheat:
           Present Status and Future Possibilities

    • Authors: Pushpendra Gupta, Harindra Balyan, Vijay Gahlaut
      First page: 5
      Abstract: In recent years, with climate change, drought stress has been witnessed in many parts of the world. In many irrigated regions also, shortage of water supply allows only limited irrigation. These conditions have an adverse effect on the productivity of many crops including cereals such as wheat. Therefore, genetics of drought/water stress tolerance in different crops has become a priority area of research. This research mainly involves use of quantitative trait locus (QTL) analysis (involving both interval mapping and association mapping) for traits that are related to water-use efficiency. In this article, we briefly review the available literature on QTL analyses in wheat for traits, which respond to drought/water stress. The outlook for future research in this area and the possible approaches for utilizing the available information on genetics of drought tolerance for wheat breeding are also discussed.
      PubDate: 2017-01-04
      DOI: 10.3390/agronomy7010005
      Issue No: Vol. 7, No. 1 (2017)
       
  • Agronomy, Vol. 7, Pages 6: Biochar for Horticultural Rooting Media
           Improvement: Evaluation of Biochar from Gasification and Slow Pyrolysis

    • Authors: Chris Blok, Caroline van der Salm, Jantineke Hofland-Zijlstra, Marta Streminska, Barbara Eveleens, Inge Regelink, Lydia Fryda, Rianne Visser
      First page: 6
      Abstract: Peat is used as rooting medium in greenhouse horticulture. Biochar is a sustainable alternative for the use of peat, which will reduce peat derived carbon dioxide emissions. Biochar in potting soil mixtures allegedly increases water storage, nutrient supply, microbial life and disease suppression but this depends on feedstock and the production process. The aim of this paper is to find combinations of feedstock and production circumstances which will deliver biochars with value for the horticultural end user. Low-temperature (600 °C–750 °C) gasification was used for combined energy and biochar generation. Biochars produced were screened in laboratory tests and selected biochars were used in plant experiments. Tests included dry bulk density, total pore space, specific surface area, phytotoxicity, pH, EC, moisture characteristics and microbial stability. We conclude that biochars from nutrient-rich feedstocks are too saline and too alkaline to be applied in horticultural rooting media. Biochars from less nutrient-rich feedstocks can be conveniently neutralized by mixing with acid peat. The influence of production parameters on specific surface area, pH, total pore space and toxicity is discussed. Biochar mildly improved the survival of beneficial micro-organisms in a mix with peat. Overall, wood biochar can replace at least 20% v/v of peat in potting soils without affecting plant growth.
      PubDate: 2017-01-07
      DOI: 10.3390/agronomy7010006
      Issue No: Vol. 7, No. 1 (2017)
       
  • Agronomy, Vol. 7, Pages 7: Acknowledgement to Reviewers of Agronomy in
           2016

    • Authors: Agronomy Editorial Office
      First page: 7
      Abstract: n/a
      PubDate: 2017-01-11
      DOI: 10.3390/agronomy7010007
      Issue No: Vol. 7, No. 1 (2017)
       
  • Agronomy, Vol. 7, Pages 8: Molecular Characterizations of Kenyan
           Brachiaria Grass Ecotypes with Microsatellite (SSR) Markers

    • Authors: Naftali Ondabu, Solomon Maina, Wilson Kimani, Donald Njarui, Appolinaire Djikeng, Sita Ghimire
      First page: 8
      Abstract: Brachiaria grass is an emerging forage option for livestock production in Kenya. Kenya lies within the center of diversity for Brachiaria species, thus a high genetic variation in natural populations of Brachiaria is expected. Overgrazing and clearing of natural vegetation for crop production and nonagricultural uses and climate change continue to threaten the natural biodiversity. In this study, we collected 79 Brachiaria ecotypes from different parts of Kenya and examined them for genetic variations and their relatedness with 8 commercial varieties. A total of 120 different alleles were detected by 22 markers in the 79 ecotypes. Markers were highly informative in differentiating ecotypes with average diversity and polymorphic information content of 0.623 and 0.583, respectively. Five subpopulations: International Livestock Research Institute (ILRI), Kitui, Kisii, Alupe, and Kiminini differed in sample size, number of alleles, number of private alleles, diversity index, and percentage polymorphic loci. The contribution of within‐the‐individual difference to total genetic variation of Kenyan ecotype population was 81%, and the fixation index (FST = 0.021) and number of migrant per generation (Nm = 11.58) showed low genetic differentiation among the populations. The genetic distance was highest between Alupe and Kisii populations (0.510) and the lowest between ILRI and Kiminini populations (0.307). The unweighted neighborjoining (NJ) tree showed test ecotypes grouped into three major clusters: ILRI ecotypes were present in all clusters; Kisii and Alupe ecotypes and improved varieties grouped in clusters I and II; and ecotypes from Kitui and Kiminini grouped in cluster I. This study confirms higher genetic diversity in Kenyan ecotypes than eight commercial varieties (Basilisk, Humidicola, Llanero, Marandú, MG4, Mulato II, Piatá and Xaraés) that represent three species and one three‐way cross‐hybrid Mulato II. There is a need for further collection of local ecotypes and their morphological, agronomical, and genetic characterizations to support Brachiaria grass breeding and conservation programs.
      PubDate: 2017-02-09
      DOI: 10.3390/agronomy7010008
      Issue No: Vol. 7, No. 1 (2017)
       
  • Agronomy, Vol. 7, Pages 9: Chemical-Free Cotton Defoliation by;
           Mechanical, Flame and Laser Girdling

    • Authors: Mathew Pelletier, John Wanjura, Greg Holt
      First page: 9
      Abstract: A novel new way to achieve chemical-free defoliation of cotton is discussed. The research found that by severing the phloem tissue on the main stalk, via a girdling operation, the operation stimulated the cotton plant to alter its growth into an early senescence pathway that resulted in the plant shedding its leaves and opening up all its bolls, leaving the plant in the perfect state for machine harvesting. Even with follow-up rains, zero regrowth occurred in the treated plants, unlike the untreated control plots where significant regrowth did occur. This report compares the results of greenhouse and field trials where the girdling operation was performed by hand, flame, mechanical and via a CO2 laser to achieve phloem tissue severance. Design parameters for a prototype laser girdling system are also provided. Results suggest that for deficit irrigated cotton, girdling can provide an alternative means to defoliate cotton.
      PubDate: 2017-01-25
      DOI: 10.3390/agronomy7010009
      Issue No: Vol. 7, No. 1 (2017)
       
  • Agronomy, Vol. 7, Pages 10: Round-Bale Silage Harvesting and Processing
           Effects on Overwintering Ability, Dry Matter Yield, Fermentation Quality,
           and Palatability of Dwarf Napiergrass (Pennisetum purpureum Schumach)

    • Authors: Satoru Fukagawa, Kenichi Kataoka, Yasuyuki Ishii
      First page: 10
      Abstract: Round-bale silage harvesting and processing methods were assessed to evaluate overwintering ability and dry matter (DM) yield, fermentation quality and palatability of overwintered dwarf Napiergrass (Pennisetum purpureum Schumach) in the two years following establishment in Nagasaki, Japan, in May 2013 using rooted tillers with a density of 2 plants/m2. In 2014, harvesting methods under no-wilting treatment were compared for flail-type harvesting with a round-baler (Flail/baler plot) and mower conditioning with a round-baler (Mower/baler plot), which is common for beef-calf–producing farmers in the region. In 2015, the effect of ensilage with wilting was investigated only in the Mower/baler plot. Dwarf Napiergrass was cut twice, in early August (summer) and late November (late autumn), each year. The winter survival rate was greater than 96% in May both years. The DM yield in the Mower/baler plot did not differ significantly for the first summer cutting or the annual total from the Flail/baler plot, but did show inferior yield for the second cutting. The fermentation quality of the second-cut plants, estimated using the V2-score, was higher in the Flail/baler plot than in the Mower/baler plot, possibly because of higher air-tightness, and the second-cut silage tended to have better fermentation quality than the first-cut silage in both harvesting plots. Wilting improved the fermentation quality of dwarf Napiergrass silage in summer, but not in autumn. The palatability of the silage, as estimated by alternative and voluntary intake trials using Japanese Black beef cattle, did not differ significantly between plots. The results suggest that dwarf Napiergrass can be better harvested using a mower conditioner with processing by a round-baler, an approach common to beef-calf–producing farmers, than with the flail/baler system, without reducing the persistence, yield, or palatability of the silage. Moreover, wilting treatment improved the fermentation quality of the dwarf Napiergrass silage when processed in summer.
      PubDate: 2017-02-06
      DOI: 10.3390/agronomy7010010
      Issue No: Vol. 7, No. 1 (2017)
       
  • Agronomy, Vol. 7, Pages 11: Towards Zinc Biofortification in Chickpea:
           Performance of Chickpea Cultivars in Response to Soil Zinc Application

    • Authors: Legesse Hidoto, Bunyamin Tar’an, Walelign Worku, Hussein Mohammed
      First page: 11
      Abstract: A field experiment was conducted at three locations in the southern region of Ethiopia during the 2012 and 2013 cropping seasons to evaluate chickpea cultivars for their response to soil zinc application, including agronomic performance, grain yield, grain zinc concentration, zinc and agronomic efficiency. Fifteen chickpea cultivars were evaluated in a randomized complete block design with three replications at each location and year. The highest number of pods (237) plant−1 was obtained from Butajira local landrace. The cultivar Naatolii produced the highest grain yield (2895 kg·ha−1), while the breeding line FLIP03-53C had the lowest yield (1700 kg·ha−1). The highest zinc concentrations of 47.5, 47.4, and 46.4 mg·kg−1 grain were obtained from the cultivar Arerti, and the two breeding lines FLIP07-27C and FLIP08-60C, respectively. The highest zinc efficiency (88%) was obtained from the Wolayita local landrace, whereas the highest agronomic efficiency of 68.4 kg yield increase kg−1 zinc application was obtained from the cultivar Naatolii. The current research identified chickpea cultivars with high grain zinc concentration, zinc efficiency, agronomic efficiency, and grain yield. The identification of cultivars with high grain zinc concentration allows the use of chickpea as a potential alternative to help to correct zinc deficiency, which is highly prevalent in the population of the region.
      PubDate: 2017-02-07
      DOI: 10.3390/agronomy7010011
      Issue No: Vol. 7, No. 1 (2017)
       
  • Agronomy, Vol. 7, Pages 12: Influence of Irrigation Scheduling Using
           Thermometry on Peach Tree Water Status and Yield under Different
           Irrigation Systems

    • Authors: Huihui Zhang, Dong Wang, Jim Gartung
      First page: 12
      Abstract: Remotely-sensed canopy temperature from infrared thermometer (IRT) sensors has long been shown to be effective for detecting plant water stress. A field study was conducted to investigate peach tree responses to deficit irrigation which was controlled using canopy to air temperature difference (ΔT) during the postharvest period at the USDA-ARS (U.S. Department of Agriculture, Agricultural Research Service) San Joaquin Valley Agricultural Sciences Center in Parlier, California, USA. The experimental site consisted of a 1.6 ha early maturing peach tree orchard. A total of 18 IRT sensors were used to control six irrigation treatments including furrow, micro-spray, and surface drip irrigation systems with and without postharvest deficit irrigation. During the postharvest period in the 2012–2013 and 2013–2014 growing seasons, ΔT threshold values at mid-day was tested to trigger irrigation in three irrigation systems. The results showed that mid-day stem water potentials (ψ) for well irrigated trees were maintained at a range of −0.5 to −1.2 MPa while ψ of deficit irrigated trees dropped to lower values. Soil water content in deficit surface drip irrigation treatment was higher compared to deficit furrow and micro-spray irrigation treatments in 2012. The number of fruits and fruit weight from peach trees under postharvest deficit irrigation treatment were less than those well-watered trees; however, no statistically significant (at the p < 0.05 level) reduction in fruit size or quality was found for trees irrigated by surface drip and micro-spray irrigation systems by deficit irrigation. Beside doubles, we found an increased number of fruits with deep sutures and dimples which may be a long-term (seven-year postharvest regulated deficit irrigation) impact of deficit irrigation on this peach tree variety. Overall, deployment of IRT sensors provided real-time measurement of canopy water status and the information is valuable for making irrigation management decisions.
      PubDate: 2017-02-09
      DOI: 10.3390/agronomy7010012
      Issue No: Vol. 7, No. 1 (2017)
       
  • Agronomy, Vol. 7, Pages 13: Is There a Positive Synergistic Effect of
           Biochar and Compost Soil Amendments on Plant Growth and Physiological
           Performance?

    • Authors: M. Seehausen, Nigel Gale, Stefana Dranga, Virginia Hudson, Norman Liu, Jane Michener, Emma Thurston, Charlene Williams, Sandy Smith, Sean Thomas
      First page: 13
      Abstract: The combination of biochar (BC) with compost has been suggested to be a promising strategy to promote plant growth and performance, but although “synergistic” effects have been stated to occur, full-factorial experiments are few, and explicit tests for synergism are lacking. We tested the hypothesis that a combination of BC and spent mushroom substrate (SMS) has a positive synergistic effect on plant growth and physiological performance in a nutrient-limited growing media. A greenhouse experiment with a full factorial design was conducted using mixed-wood BC (3.0 kg·m−2) and SMS (1.5 kg·m−2) (the combination was not co-composted) as organic soil amendments for the annual Abutilon theophrasti and the perennial Salix purpurea. Several measurements related to plant growth and physiological performance were taken throughout the experiment. Contrary to the hypothesis, we found that the combination of BC + SMS had neutral or antagonistic interactive effects on many plant growth traits. Antagonistic effects were found on maximum leaf area, above- and belowground biomass, reproductive allocation, maximum plant height, chlorophyll fluorescence, and stomatal conductance of A. theophrasti. The effect on S. purpurea was mostly neutral. We conclude that the generalization that BC and compost have synergistic effects on plant performance is not supported.
      PubDate: 2017-02-11
      DOI: 10.3390/agronomy7010013
      Issue No: Vol. 7, No. 1 (2017)
       
  • Agronomy, Vol. 7, Pages 14: Generation and Characterisation of a Reference
           Transcriptome for Phalaris (Phalaris aquatica L.)

    • Authors: Rebecca Baillie, Michelle Drayton, Luke Pembleton, Sukhjiwan Kaur, Richard Culvenor, Kevin Smith, German Spangenberg, John Forster, Noel Cogan
      First page: 14
      Abstract: Phalaris aquatica is a cool-season perennial grass species that is extensively cultivated in Australia, with additional usage in other areas of the world. Phalaris displays a number of desirable agronomic characteristics, although unfavourable traits include excessive seed shattering, sensitivity to aluminium toxicity, and several toxicosis syndromes. Varietal development has to date been based on traditional selection methods, but would benefit from the application of genomics-based approaches, which require the development of large-scale sequence resources. Due to a large nuclear DNA content, methods that target the expressed component of the genome and reduce the complexity of analysis are most amenable to current sequencing technologies. A reference unigene set has been developed by transcriptome sequencing of multiple tissues from a single plant belonging to the variety Landmaster. Comparisons have been made to gene complements from related species, as well as reference protein databases, and patterns of gene expression in different tissues have been evaluated. A number of candidate genes relevant to removal of undesirable attributes have been identified. The reference unigene set will provide the basis for detailed studies of differential gene expression and identification of candidate genes for potential transgenic deployment, as well as a critical resource for genotypic analysis to support future genomics-assisted breeding activities for phalaris improvement.
      PubDate: 2017-02-15
      DOI: 10.3390/agronomy7010014
      Issue No: Vol. 7, No. 1 (2017)
       
  • Agronomy, Vol. 7, Pages 15: Metabolite Profiling for Leaf Senescence in
           Barley Reveals Decreases in Amino Acids and Glycolysis Intermediates

    • Authors: Liliana Avila-Ospina, Gilles Clément, Céline Masclaux-Daubresse
      First page: 15
      Abstract: Leaf senescence is a long developmental phase important for plant performance and nutrient management. Cell constituents are recycled in old leaves to provide nutrients that are redistributed to the sink organs. Up to now, metabolomic changes during leaf senescence have been mainly studied in Arabidopsis (Arabidopsis thaliana L.). The metabolite profiling conducted in barley (Hordeum vulgare L.) during primary leaf senescence under two nitrate regimes and in flag leaf shows that amino acids, hexose, sucrose and glycolysis intermediates decrease during senescence, while minor carbohydrates accumulate. Tricarboxylic acid (TCA) compounds changed with senescence only in primary leaves. The senescence-related metabolite changes in the flag leaf were globally similar to those observed in primary leaves. The effect of senescence on the metabolite changes of barley leaves was similar to that previously described in Arabidopsis except for sugars and glycolysis compounds. This suggests a different role of sugars in the control of leaf senescence in Arabidopsis and in barley.
      PubDate: 2017-02-17
      DOI: 10.3390/agronomy7010015
      Issue No: Vol. 7, No. 1 (2017)
       
  • Agronomy, Vol. 7, Pages 16: Diurnal Leaf Starch Content: An Orphan Trait
           in Forage Legumes

    • Authors: Michael Ruckle, Michael Meier, Lea Frey, Simona Eicke, Roland Kölliker, Samuel Zeeman, Bruno Studer
      First page: 16
      Abstract: Forage legumes have a relatively high biomass yield and crude protein content, but their grazed and harvested biomass lacks the high-energy carbohydrates required to meet the productivity potential of modern livestock breeds. Because of their low carbohydrate content, forage legume diets are typically supplemented with starch rich cereal grains or maize (Zea mays), leading to the disruption of local nutrient cycles. Although plant leaves were first reported to accumulate starch in a diurnal pattern over a century ago, leaf starch content has yet to be exploited as an agronomic trait in forage crops. Forage legumes such as red clover (Trifolium pratense) have the genetic potential to accumulate up to one third of their leaf dry mass as starch, but this starch is typically degraded at night to support nighttime growth and respiration. Even when diurnal accumulation is considered with regard to the time the crop is harvested, only limited gains are realized due to environmental effects and post-harvest losses from respiration. Here we present original data for starch metabolism in red clover and place it in the broader context of other forage legumes such as, white clover (T. repens), and alfalfa (Medicago sativa). We review the application of recent advances in molecular breeding, plant biology, and crop phenotyping, to forage legumes to improve and exploit a potentially valuable trait for sustainable ruminant livestock production.
      PubDate: 2017-02-20
      DOI: 10.3390/agronomy7010016
      Issue No: Vol. 7, No. 1 (2017)
       
  • Agronomy, Vol. 7, Pages 17: Molecular Regulation of Flowering Time in
           Grasses

    • Authors: Fiorella Nuñez, Toshihiko Yamada
      First page: 17
      Abstract: Flowering time is a key target trait for extending the vegetative phase to increase biomass in bioenergy crops such as perennial C4 grasses. Molecular genetic studies allow the identification of genes involved in the control of flowering in different species. Some regulatory factors of the Arabidopsis pathway are conserved in other plant species such as grasses. However, differences in the function of particular genes confer specific responses to flowering. One of the major pathways is photoperiod regulation, based on the interaction of the circadian clock and environmental light signals. Depending on their requirements for day-length plants can be classified as long-day (LD), short-day (SD), and day-neutral. The CONSTANS (CO) and Heading Date 1 (Hd1), orthologos genes, are central regulators in the flowering of Arabidopsis and rice, LD and SD plants, respectively. Additionally, Early heading date 1 (Ehd1) induces the expression of Heading date 3a (Hd3a), conferring SD promotion and controls Rice Flowering Locus T 1 (RFT1) in LD conditions, independently of Hd1. Nevertheless, the mechanisms promoting flowering in perennial bioenergy crops are poorly understood. Recent progress on the regulatory network of important gramineous crops and components involved in flowering control will be discussed.
      PubDate: 2017-02-20
      DOI: 10.3390/agronomy7010017
      Issue No: Vol. 7, No. 1 (2017)
       
  • Agronomy, Vol. 7, Pages 18: Plant Responses to Salt Stress: Adaptive
           Mechanisms

    • Authors: Jose Acosta-Motos, Maria Ortuño, Agustina Bernal-Vicente, Pedro Diaz-Vivancos, Maria Sanchez-Blanco, Jose Hernandez
      First page: 18
      Abstract: This review deals with the adaptive mechanisms that plants can implement to cope with the challenge of salt stress. Plants tolerant to NaCl implement a series of adaptations to acclimate to salinity, including morphological, physiological and biochemical changes. These changes include increases in the root/canopy ratio and in the chlorophyll content in addition to changes in the leaf anatomy that ultimately lead to preventing leaf ion toxicity, thus maintaining the water status in order to limit water loss and protect the photosynthesis process. Furthermore, we deal with the effect of salt stress on photosynthesis and chlorophyll fluorescence and some of the mechanisms thought to protect the photosynthetic machinery, including the xanthophyll cycle, photorespiration pathway, and water-water cycle. Finally, we also provide an updated discussion on salt-induced oxidative stress at the subcellular level and its effect on the antioxidant machinery in both salt-tolerant and salt-sensitive plants. The aim is to extend our understanding of how salinity may affect the physiological characteristics of plants.
      PubDate: 2017-02-23
      DOI: 10.3390/agronomy7010018
      Issue No: Vol. 7, No. 1 (2017)
       
  • Agronomy, Vol. 7, Pages 19: Optimal Regulation of the Balance between
           Productivity and Overwintering of Perennial Grasses in a Warmer Climate

    • Authors: Åshild Ergon
      First page: 19
      Abstract: Seasonal growth patterns of perennial plants are linked to patterns of acclimation and de-acclimation to seasonal stresses. The timing of cold acclimation (development of freezing resistance) and leaf growth cessation in autumn, and the timing of de-acclimation and leaf regrowth in spring, is regulated by seasonal cues in the environment, mainly temperature and light factors. Warming will lead to new combinations of these cues in autumn and spring. Extended thermal growing seasons offer a possibility for obtaining increased yields of perennial grasses at high latitudes. Increased productivity in the autumn may not be possible in all high latitude regions due to the need for light during cold acclimation and the need for accumulating a carbohydrate storage prior to winter. There is more potential for increased yields in spring due to the availability of light, but higher probability of freezing events in earlier springs would necessitate a delay of de-acclimation, or an ability to rapidly re-acclimate. In order to optimize the balance between productivity and overwintering in the future, the regulation of growth and acclimation processes may have to be modified. Here, the current knowledge on the coordinated regulation of growth and freezing resistance in perennial grasses is reviewed.
      PubDate: 2017-02-23
      DOI: 10.3390/agronomy7010019
      Issue No: Vol. 7, No. 1 (2017)
       
  • Agronomy, Vol. 7, Pages 20: Using FACE Systems to Screen Wheat Cultivars
           for Yield Increases at Elevated CO2

    • Authors: James Bunce
      First page: 20
      Abstract: Because of continuing increases in atmospheric CO2, identifying cultivars of crops with larger yield increases at elevated CO2 may provide an avenue to increase crop yield potential in future climates. Free-air CO2 enrichment (FACE) systems have most often been used with multiple replications of each CO2 treatment in order to increase confidence in the effect of elevated CO2. For screening of cultivars for yield increases at elevated CO2, less precision about the CO2 effect, but more precision about cultivar ranking within CO2 treatments is appropriate. As a small-scale test of this approach, three plots, each of four cultivars of wheat, were grown in single FACE and control plots over two years, and the cultivar rankings of yield at elevated and ambient CO2 were compared. Each replicate plot was the size used in traditional cultivar comparisons. An additional test using four smaller replicate plots per cultivar within one FACE and one ambient plot was used to compare nine cultivars in another year. In all cases, elevated CO2 altered the ranking of cultivars for yield. This approach may provide a more efficient way to utilize FACE systems for the screening of CO2 responsiveness.
      PubDate: 2017-02-24
      DOI: 10.3390/agronomy7010020
      Issue No: Vol. 7, No. 1 (2017)
       
  • Agronomy, Vol. 7, Pages 21: Effect of Sowing Method and N Application on
           Seed Yield and N Use Efficiency of Winter Oilseed Rape

    • Authors: Klaus Sieling, Ulf Böttcher, Henning Kage
      First page: 21
      Abstract: In northern Europe, replacing winter barley with winter wheat as the preceding crop for winter oilseed rape (Brassica napus L.; WOSR) often results in a delayed WOSR sowing and poor autumn growth. Based on data from a field experiment running in 2009/2010, 2010/2011, and 2012/2013, this study aims (i) to investigate how a delayed sowing method affects seed yield, N offtake with the seeds, and apparent N use efficiency (NUE) of WOSR; (ii) to test the ability of autumn and spring N fertilization to compensate for the negative effects of a delayed sowing method; and (iii) to estimate the minimum autumnal growth for optimal seed yield. In order to create sufficiently differentiated canopies, a combination of four sowing methods (first week of August until the third week of September) and four autumn N treatments (0, 30, 60, and 90 kg·N·ha−1) was established. Each of these 16 different canopies was fertilized with 5 N amounts (0/0, 40/40, 80/80, 120/120, 140/140 kg·N·ha−1) in spring in order to estimate separate N response curves. Above-ground N accumulation in autumn and seed yield and N offtake by the seeds were determined. Plant establishment after mid-September significantly decreased seed yield. Autumn N fertilization of at least 30 kg·N·ha−1 increased seed yield and N offtake by the seeds without any significant interaction with sowing method and spring N supply. However, the pathway(s) remain(s) unclear. Spring N fertilization up to 130 kg·N·ha−1 (estimated by a Linear-Plateau N response curve) increased seed yield. NUE decreased with increasing N supply, where WOSR used autumn N to a lesser extent than spring N. An above-ground N uptake of at least 10–15 kg·N·ha−1 at the end of autumn growth was required to achieve high seed yields. From an environmental point of view, optimal autumn growth should be attained by choosing an adequate sowing method, not by applying additional N in autumn.
      PubDate: 2017-02-28
      DOI: 10.3390/agronomy7010021
      Issue No: Vol. 7, No. 1 (2017)
       
  • Agronomy, Vol. 7, Pages 22: Raising Crop Productivity in Africa through
           Intensification

    • Authors: Zerihun Tadele
      First page: 22
      Abstract: The population of Africa will double in the next 33 years to reach 2.5 billion by 2050. Although roughly 60% of the continent’s population is engaged in agriculture, the produce from this sector cannot feed its citizens. Hence, in 2013 alone, Africa imported 56.5 million tons of wheat, maize, and soybean at the cost of 18.8 billion USD. Although crops cultivated in Africa play a vital role in their contribution to Food Security, they produce inferior yields compared to those in other parts of the world. For instance, the average cereal yield in Africa is only 1.6 t·ha−1 compared to the global 3.9 t·ha−1. Low productivity in Africa is also related to poor soil fertility and scarce moisture, as well as a variety of insect pests, diseases, and weeds. While moisture scarcity is responsible for up to 60% of yield losses in some African staple cereals, insect pests inflict annually substantial crop losses. In order to devise a strategy towards boosting crop productivity on the continent where food insecurity is most prevalent, these production constraints should be investigated and properly addressed. This review focuses on conventional (also known as genetic) intensification in which crop productivity is raised through breeding for cultivars with high yield-potential and those that thrive well under diverse and extreme environmental conditions. Improved crop varieties alone do not boost crop productivity unless supplemented with optimum soil, water, and plant management practices as well as the promotion of policies pertaining to inputs, credit, extension, and marketing. Studies in Kenya and Uganda have shown that the yield of cassava can be increased by 140% in farmers’ fields using improved varieties and management practices. In addition to traditional organic and inorganic fertilizers, biochar and African Dark Earths have been found to improve soil properties and to enhance productivity, although their availability and affordability to African farmers remains to be explored. The concept of Integrated Soil Fertility Management (ISFM) has been successfully implemented in some African countries in the Great Lake Region. Other innovative technologies favorably accepted by farmers are the “Push-pull System” (an elegant method of controlling a devastating insect pest and a parasitic weed) and NERICA (New Rice for Africa, in which rice varieties with desirable nutritional and agronomic properties were developed by crossing Asian and African rice). This review calls for African governments and institutions not only to provide conducive environments but also to abide by the Maputo 2003 Declaration where they agreed to invest 10% of their national budget to agricultural research and development as the outcome has a positive impact on productivity and ultimately improves the livelihood of farmers.
      PubDate: 2017-03-08
      DOI: 10.3390/agronomy7010022
      Issue No: Vol. 7, No. 1 (2017)
       
  • Agronomy, Vol. 7, Pages 23:
           The Role of Specialized Photoreceptors in the 
           Protection of Energy‐Rich Tissues

    • Authors: Ian Major, Javier Moreno, Marcelo Campos
      First page: 23
      Abstract: The perception and absorption of light by plants is a driving force in plant evolutionary history, as plants have evolved multiple photoreceptors to perceive different light attributes including duration, intensity, direction and quality. Plant photoreceptors interpret these signals from the light environment and mold plant architecture to maximize foliar light capture. As active sites of the production and accumulation of energy‐rich products, leaves are targets of pests and pathogens, which have driven the selection of physiological processes to protect these energy‐rich tissues. In the last ten years, several research groups have accumulated evidence showing that plant photoreceptors control specific molecular programs that define plant growth and immune processes. Here, we discuss recent knowledge addressing these roles in Arabidopsis and show that (1) plant immune responses affect energy acquisition and partitioning; (2) plant photoreceptors interpret the light environment and control growth and immune processes; and finally; (3) defense and light signaling pathways can be genetically manipulated to obtain plants able to grow and defend at the same time. This basic knowledge from Arabidopsis plants should lead new lines of applied research in crops.
      PubDate: 2017-03-08
      DOI: 10.3390/agronomy7010023
      Issue No: Vol. 7, No. 1 (2017)
       
  • Agronomy, Vol. 7, Pages 24: A Survey: Potential Impact of Genetically
           Modified Maize Tolerant to Drought or Resistant to Stem Borers in Uganda

    • Authors: Isaac Wamatsembe, Godfrey Asea, Stephan Haefele
      First page: 24
      Abstract: Maize production in Uganda is constrained by various factors, but especially drought and stem borers contribute to significant yield losses. Genetically modified (GM) maize with increased drought tolerance and/or Bt insect resistance (producing the Bacillus thuringiensis Cry protein) is considered as an option. For an ex ante impact analysis of these technologies, a farmer survey was carried out in nine districts of Uganda, representing the major farming systems. The results showed that farmers did rate stem borer and drought as the main constraints for maize farming. Most farmers indicated a positive attitude towards GM maize, and 86% of all farmers said they would grow GM maize. Farmer estimated yield losses to drought and stem borer damage were on average 54.7% and 23.5%, respectively, if stress occurred. Taking the stress frequency into consideration (67% for both), estimated yield losses were 36.5% and 15.6% for drought and stem borer, respectively. According to the ex-ante partial budget analysis, Bt hybrid maize could be profitable, with an average value/cost ratio of 2.1. Drought tolerant hybrid maize had lower returns and a value/cost ratio of 1.5. Negative returns occurred mainly for farmers with non-stressed grain yields below 2 t·ha−1. The regulatory framework in Uganda needs to be finalized with consideration of strengthening key institutions in the maize sector for sustainable introduction of GM maize.
      PubDate: 2017-03-17
      DOI: 10.3390/agronomy7010024
      Issue No: Vol. 7, No. 1 (2017)
       
  • Agronomy, Vol. 6, Pages 44: Simulating the Probability of Grain Sorghum
           Maturity before the First Frost in Northeastern Colorado

    • Authors: Gregory McMaster, Debora Edmunds, Sally Jones, Jerry Johnson, Merle Vigil
      First page: 44
      Abstract: Expanding grain sorghum [Sorghum bicolor (L.) Moench] production northward from southeastern Colorado is thought to be limited by shorter growing seasons due to lower temperatures and earlier frost dates. This study used a simulation model for predicting crop phenology (PhenologyMMS) to estimate the probability of reaching physiological maturity before the first fall frost for a variety of agronomic practices in northeastern Colorado. Physiological maturity for seven planting dates (1 May to 12 June), four seedbed moisture conditions affecting seedling emergence (from Optimum to Planted in Dust), and three maturity classes (Early, Medium, and Late) were simulated using historical weather data from nine locations for both irrigated and dryland phenological parameters. The probability of reaching maturity before the first frost was slightly higher under dryland conditions, decreased as latitude, longitude, and elevation increased, planting date was delayed, and for later maturity classes. The results provide producers with estimates of the reliability of growing grain sorghum in northeastern Colorado.
      PubDate: 2016-09-27
      DOI: 10.3390/agronomy6040044
      Issue No: Vol. 6, No. 4 (2016)
       
  • Agronomy, Vol. 6, Pages 45: Replenishing Humic Acids in Agricultural Soils

    • Authors: Michael Susic
      First page: 45
      Abstract: For many decades, it was commonly believed that humic acids were formed in soils by the microbial conversion of plant lignins. However, an experiment to test whether these humic acids were formed prior to plant matter reaching the soil was never reported until the late 1980s (and then only as a side issue), even though humic acids were first isolated and reported in 1786. This was a serious omission, and led to a poor understanding of how the humic acid content of soils could be maintained or increased for optimum fertility. In this study, commercial sugar cane mulch and kelp extracts were extracted with alkali and analyzed for humic acid content. Humic acids in the extracts were positively identified by fluorescence spectrophotometry, and this demonstrated that humic acids are formed in senescent plant and algal matter before they reach the soil, where they are then strongly bound to the soil and are also resistant to microbial metabolism. Humic acids are removed from soils by wind and water erosion, and by water leaching, which means that they must be regularly replenished. This study shows that soils can be replenished or fortified with humic acids simply by recycling plant and algal matter, or by adding outside sources of decomposed plant or algal matter such as composts, mulch, peat, and lignite coals.
      PubDate: 2016-09-28
      DOI: 10.3390/agronomy6040045
      Issue No: Vol. 6, No. 4 (2016)
       
  • Agronomy, Vol. 6, Pages 46: Climate-Optimized Planting Windows for Cotton
           in the Lower Mississippi Delta Region

    • Authors: Saseendran Anapalli, William Pettigrew, Krishna Reddy, Liwang Ma, Daniel Fisher, Ruixiu Sui
      First page: 46
      Abstract: Unique, variable summer climate of the lower Mississippi (MS) Delta region poses a critical challenge to cotton producers in deciding when to plant for optimized production. Traditional 2–4 year agronomic field trials conducted in this area fail to capture the effects of long-term climate variabilities in the location for developing reliable planting windows for producers. Our objective was to integrate a four-year planting-date field experiment conducted at Stoneville, MS during 2005–2008 with long-term climate data in an agricultural system model and develop optimum planting windows for cotton under both irrigated and rainfed conditions. Weather data collected at this location from 1960 to 2015 and the CSM-CROPGRO-Cotton v4.6 model within the Root Zone Water Quality Model (RZWQM2) were used. The cotton model was able to simulate both the variable planting date and variable water regimes reasonably well: relative errors of seed cotton yield, aboveground biomass, and leaf area index (LAI) were 14%, 12%, and 21% under rainfed conditions and 8%, 16%, and 15% under irrigated conditions, respectively. Planting windows under both rainfed and irrigated conditions extended from mid-March to mid-June: windows from mid-March to the last week of May under rainfed conditions, and from the last week of April to the end of May under irrigated conditions were better suited for optimum yield returns. Within these windows, rainfed cotton tends to lose yield from later plantings, but irrigated cotton benefits; however, irrigation requirements increase as the planting windows advance in time. Irrigated cotton produced about 1000 kg·ha−1 seed cotton more than rainfed cotton, with irrigation water requirements averaging 15 cm per season. Under rainfed conditions, there is a 5%, 14%, and 27% chance that the seed cotton production is below 1000, 1500, and 2000 kg·ha−1, respectively. Information developed in this paper can help MS farmers in decision support for cotton planting.
      PubDate: 2016-09-29
      DOI: 10.3390/agronomy6040046
      Issue No: Vol. 6, No. 4 (2016)
       
  • Agronomy, Vol. 6, Pages 47: Weed Suppression and Performance of Grain
           Legumes Following an Irrigated Rice Crop in Southern Australia

    • Authors: K. M. Shamsul Haque, Brian Dunn, Geoff Beecher, Philip Eberbach, Mike Dyall-Smith, Julia Howitt, Leslie Weston
      First page: 47
      Abstract: Post-rice irrigated soils offer several potential advantages for the growth of subsequent crops, but Australian producers have often been reluctant to grow grain legumes immediately following a rice crop due to physico-chemical constraints. A field experiment was thus conducted to explore the potential for producing grain legumes following rice in comparison to those following a fallow during 2012 and 2013. Two grain legumes, field pea and faba bean, were sown 5, 7 and 12 weeks after rice harvest in 2013 at Yanco, NSW, and plant growth indicators and grain yield were compared. Early sowing of field pea following rice gave the best outcome, with plants flowering three weeks earlier and yielding 1330 kg·ha−1 more grain than after fallow. In contrast, faba bean yield was 35 kg·ha−1 less after rice than after fallow across the three sowing dates. Higher pea yield was consistent with the early emergence of seedlings, higher light interception and overall greater plant growth following rice. Post-rice crops also had 10-fold less weed infestation than crops in a similarly-established fallow treatment and, thus, required far less weed management. Legume crops sown at the later seeding date had significantly reduced (~50%–60%) yields compared to those of the first two sowings; this is most likely a reflection of reduced temperatures and day lengths experienced during vegetative and reproductive growth phases.
      PubDate: 2016-09-29
      DOI: 10.3390/agronomy6040047
      Issue No: Vol. 6, No. 4 (2016)
       
  • Agronomy, Vol. 6, Pages 48: Fermentation Quality of Round-Bale Silage as
           Affected by Additives and Ensiling Seasons in Dwarf Napiergrass
           (Pennisetum purpureum Schumach)

    • Authors: Satoru Fukagawa, Yasuyuki Ishii, Ikuo Hattori
      First page: 48
      Abstract: Fermentation quality of dwarf napiergrass (Pennisetum purpureum Schumach) was estimated for additives lactic acid bacteria and Acremonium cellulase (LAB + AC), fermented juice of epiphytic lactic acid bacteria (FJLB), and a no-additive control in 2006 via two ensiling methods—round-bale and vinyl-bag methods in 2006—and via two ensiling seasons—summer and autumn of 2013. Fermentation quality of dwarf napiergrass ensiled in the summer season was improved by the input of additives, with the highest quality in LAB + AC, followed by FJLB; the lactic acid content was higher, and the pH and sum of the butyric, caproic, and valeric acid contents were lower, resulting in an increase in the V-score value by each additive. The ensiling method in autumn without additives affected fermentation quality, mainly due to the airtightness, which was higher for round-bale processing than in vinyl bags, even with the satisfactory V-score of 72. Fermentation in round bales without additives had a higher quality in autumn than in summer, possibly due to the higher concentration of mono- and oligo-saccharides. Thus, it was concluded that dwarf napiergrass can be produced to satisfactory-quality silage by adding LAB + AC or FJLB in summer and even in the absence of additives in autumn.
      PubDate: 2016-10-18
      DOI: 10.3390/agronomy6040048
      Issue No: Vol. 6, No. 4 (2016)
       
  • Agronomy, Vol. 6, Pages 49: Evidence for Heterosis in Italian Ryegrass
           (Lolium multiflorum Lam.) Based on Inbreeding Depression in F2 Generation
           Offspring from Biparental Crosses

    • Authors: Junping Wang, Luke Pembleton, Noel Cogan, John Forster
      First page: 49
      Abstract: Italian ryegrass is one of the most important temperate forage grasses on a global basis. Improvement of both dry matter yield and quality of herbage have been major objectives of pasture grass breeding over the last century. F1 and F2 progeny sets derived from controlled pair-crosses between selected Italian ryegrass genotypes have been evaluated for yield and nutritive quality under field conditions. Linear regression of the performance of F1 families under sward conditions on parental genotype means in a spaced plant trial was significant for quality characteristics, but not for herbage yield. This result suggests that phenotypic selection of individual plants from spaced plant nursery is feasible for improvement of nutritive quality traits, but not for yield. The presence of significant heterosis within F1 populations was demonstrated by reduced herbage production in subsequent F2 populations (generated by one cycle of full-sib mating), an up to 22.1% total herbage yield in fresh weight, and a 30.5% survival rate at the end of the second reproductive cycle. Potential optimal crosses for exploiting such heterosis are discussed, based on construction and the inter-mating of complementary parental pools, for the implementation of a novel F1 hybrid production strategy.
      PubDate: 2016-10-27
      DOI: 10.3390/agronomy6040049
      Issue No: Vol. 6, No. 4 (2016)
       
  • Agronomy, Vol. 6, Pages 50: Commercial Humates in Agriculture: Real
           Substance or Smoke and Mirrors?

    • Authors: Graham Lyons, Yusuf Genc
      First page: 50
      Abstract: Soil humic substances (HS) are known to be beneficial for soils and plants, and most published studies of HS and humates, usually conducted under controlled conditions, show benefits. However, the value of commercial humate application in the field is less certain. This review attempts to answer the question: How effective are commercial humates in the field? Commercial humates, especially K humate, are used widely in agriculture today as “soil conditioners”. A wide range of benefits is claimed, including growth of beneficial soil microbes; deactivation of toxic metals; improvements in soil structure including water retention capacity, enhanced nutrient and micronutrient uptake and photosynthesis; resistance to abiotic stress, including salinity; and increased growth, yield and product quality. Despite this, there is a surprising lack of solid evidence for their on-farm effectiveness and findings are often inconsistent. The industry relies largely on anecdotal case studies to promote humates, which are often applied at unrealistically low levels. It is recommended that products should be well characterised, physically and chemically, and that careful field studies be conducted on foliar humate application and pelletised humates at realistic rates, targeted to the seedling rhizosphere, for a variety of crops in a range of soils, including low C sandy and saline soils.
      PubDate: 2016-10-28
      DOI: 10.3390/agronomy6040050
      Issue No: Vol. 6, No. 4 (2016)
       
  • Agronomy, Vol. 6, Pages 51: Quantitative Trait Loci (QTL) Identification
           in the Progeny of a Polycross

    • Authors: Laurence Pauly, Sandrine Flajoulot, Jérôme Garon, Bernadette Julier, Vincent Béguier, Philippe Barre
      First page: 51
      Abstract: Connected multiparental crosses are valuable for detecting quantitative trait loci (QTL) with multiple alleles. The objective of this study was to show that the progeny of a polycross can be considered as connected mutiparental crosses and used for QTL identification. This is particularly relevant in outbreeding species showing strong inbreeding depression and for which synthetic varieties are created. A total of 191 genotypes from a polycross with six parents were phenotyped for plant height (PH) and plant growth rate (PGR) and genotyped with 82 codominant markers. Markers allowed the identification of the male parent for each sibling and so the 191 genotypes were divided into 15 full-sib families. The number of genotypes per full-sib family varied from 2 to 28. A consensus map of 491 cM was built and QTL were detected with MCQTL-software dedicated to QTL detection in connected mapping populations. Two major QTL for PH and PGR in spring were identified on linkage groups 3 and 4. These explained from 12% to 22% of phenotypic variance. The additive effects reached 12.4 mm for PH and 0.11 mm/C°d for PGR. This study shows that the progenies of polycrosses can be used to detect QTL.
      PubDate: 2016-10-28
      DOI: 10.3390/agronomy6040051
      Issue No: Vol. 6, No. 4 (2016)
       
  • Agronomy, Vol. 6, Pages 52: Phosphorus Deficiency Alters Nutrient
           Accumulation Patterns and Grain Nutritional Quality in Rice

    • Authors: Terry Rose, Tobias Kretzschmar, Lei Liu, Graham Lancaster, Matthias Wissuwa
      First page: 52
      Abstract: The accumulation of biomass and mineral nutrients during the post-anthesis period was investigated in field-grown rice plants cultivated in phosphorus (P)-sufficient vs. P-deficient soil. Phosphorus deficiency reduced biomass accumulation by around 30%, and reduced the accumulation of all nutrients in aboveground plant biomass except sulfur (S) and copper (Cu). Ultimately, grain zinc (Zn), Cu, and calcium (Ca) concentrations were significantly higher in P-deficient plants, while grain magnesium (Mg) concentrations were significantly lower. While P deficiency caused a 40% reduction in the concentration of the anti-nutrient phytate in the grain, this was offset by a 40% reduction in grain starch lysophospholipids, which have positive benefits for human health and grain quality.
      PubDate: 2016-10-28
      DOI: 10.3390/agronomy6040052
      Issue No: Vol. 6, No. 4 (2016)
       
  • Agronomy, Vol. 6, Pages 53: Soil Chemistry Factors Confounding Crop
           Salinity Tolerance—A Review

    • Authors: Pichu Rengasamy
      First page: 53
      Abstract: The yield response of various crops to salinity under field conditions is affected by soil processes and environmental conditions. The composition of dissolved ions depend on soil chemical processes such as cation or anion exchange, oxidation-reduction reactions, ion adsorption, chemical speciation, complex formation, mineral weathering, solubility, and precipitation. The nature of cations and anions determine soil pH, which in turn affects crop growth. While the ionic composition of soil solution determine the osmotic and ion specific effects on crops, the exchangeable ions indirectly affect the crop growth by influencing soil strength, water and air movement, waterlogging, and soil crusting. This review mainly focuses on the soil chemistry processes that frustrate crop salinity tolerance which partly explain the poor results under field conditions of salt tolerant genotypes selected in the laboratory.
      PubDate: 2016-10-29
      DOI: 10.3390/agronomy6040053
      Issue No: Vol. 6, No. 4 (2016)
       
  • Agronomy, Vol. 6, Pages 54: Improvement of Salinity Stress Tolerance in
           Rice: Challenges and Opportunities

    • Authors: Thi Hoang, Thach Tran, Thuy Nguyen, Brett Williams, Penelope Wurm, Sean Bellairs, Sagadevan Mundree
      First page: 54
      Abstract: Rice (Oryza sativa L.) is an important staple crop that feeds more than one half of the world’s population and is the model system for monocotyledonous plants. However, rice is very sensitive to salinity and is the most salt sensitive cereal crop with a threshold of 3 dSm−1 for most cultivated varieties. Despite many attempts using different strategies to improve salinity tolerance in rice, the achievements so far are quite modest. This review aims to discuss challenges that hinder the improvement of salinity stress tolerance in rice as well as potential opportunities for enhancing salinity stress tolerance in this important crop.
      PubDate: 2016-10-31
      DOI: 10.3390/agronomy6040054
      Issue No: Vol. 6, No. 4 (2016)
       
  • Agronomy, Vol. 6, Pages 55: Genetic Diversity in Barley and Wheat for
           Tolerance to Soil Constraints

    • Authors: Yash Dang, Jack Christopher, Ram Dalal
      First page: 55
      Abstract: Surface soil sodicity as well as subsoil salinity, acidity, and phytotoxic concentrations of chloride (Cl) are major soil constraints to crop production in many soils of sub-tropical, north-eastern Australia. The identification of genotypes tolerant to these soil constraints may be an option to maintain and improve productivity on these soils. We evaluated performance of 11 barley and 17 wheat genotypes grown on two sites <0.5 km apart. Compared to the non-sodic site, the sodic site had significantly higher Cl concentration (>800 mg·Cl·kg−1) in the subsoil (0.9–1.3 m soil depth) and higher exchangeable sodium percentage (ESP) (>6%) in the surface and subsoil. Barley grain yield and plant available water capacity (PAWC) were reduced between 5%–25% and 40%–66%, respectively, for different genotypes at the sodic site as compared to the non-sodic site. For wheat genotypes, grain yield was between 8% and 33% lower at the sodic site compared to the non-sodic site and PAWC was between 3% and 37% lower. Most barley and wheat genotypes grown at the sodic site showed calcium (Ca) deficiency symptoms on younger leaves. Analysis of the youngest fully mature leaf (YML) confirmed that genotypes grown at the sodic site with Ca concentration < 0.2% exhibited deficiency symptoms. Grain yields of both barley and wheat genotypes grown on the sodic and non-sodic sites increased significantly with increasing Ca and K in YML and decreased significantly with increasing Na and Cl concentrations in YML. Sodium (Na) concentrations in YML of wheat genotypes grown at the sodic site were 10-fold higher than those from the non-sodic site whereas this increase was only two-fold in barley genotypes. In step-wise regression, the PAWC of barley and wheat genotypes grown on sodic and non-sodic sites was the principal determinant of variability of barley and wheat grain yield. Including the Ca concentration in the YML of wheat genotypes and K:Na ratio in the YML of barley genotypes significantly improved the prediction of grain yield in the regression analysis. Barley genotypes, Mackay and Kaputar, were relatively susceptible while Baronesse and Grout were relatively more tolerant to sodicity. Wheat genotypes Gregory and Stampede were generally relatively more susceptible to sodicity, and genotypes Baxter, Hume, and the experimental line HSF1-255 were relatively more tolerant than the former group.
      PubDate: 2016-11-02
      DOI: 10.3390/agronomy6040055
      Issue No: Vol. 6, No. 4 (2016)
       
  • Agronomy, Vol. 6, Pages 56: Development of a Molecular Breeding Strategy
           

    • Authors: Pieter Badenhorst, Kevin Smith, German Spangenberg
      First page: 56
      Abstract: Molecular breeding tools, such as genetic modification, provide forage plant breeders with the opportunity to incorporate high value traits into breeding programs which, in some cases, would not be available using any other methodology. Despite the potential impact of these traits, little work has been published that seeks to optimize the strategies for transgenic breeding or incorporate transgenic breeding with other modern genomics-assisted breeding strategies. As the number of new genomics assisted breeding tools become available it is also likely that multiple tools may be used within the one breeding program. In this paper we propose a strategy for breeding genetically-modified forages using perennial ryegrass as an example and demonstrate how this strategy may be linked with other technologies, such as genomic selection. Whilst the model used is perennial ryegrass the principles outlined are valid for those designing breeding strategies for other outcrossing forage species.
      PubDate: 2016-11-02
      DOI: 10.3390/agronomy6040056
      Issue No: Vol. 6, No. 4 (2016)
       
  • Agronomy, Vol. 6, Pages 57: Spatial Relation of Apparent Soil Electrical
           Conductivity with Crop Yields and Soil Properties at Different Topographic
           Positions in a Small Agricultural Watershed

    • Authors: Gurbir Singh, Karl Williard, Jon Schoonover
      First page: 57
      Abstract: Use of electromagnetic induction (EMI) sensors along with geospatial modeling provide a better opportunity for understanding spatial distribution of soil properties and crop yields on a landscape level and to map site-specific management zones. The first objective of this research was to evaluate the relationship of crop yields, soil properties and apparent electrical conductivity (ECa) at different topographic positions (shoulder, backslope, and deposition slope). The second objective was to examine whether the correlation of ECa with soil properties and crop yields on a watershed scale can be improved by considering topography in modeling ECa and soil properties compared to a whole field scale with no topographic separation. This study was conducted in two headwater agricultural watersheds in southern Illinois, USA. The experimental design consisted of three basins per watershed and each basin was divided into three topographic positions (shoulder, backslope and deposition) using the Slope Position Classification model in ESRI ArcMap. A combine harvester equipped with a GPS-based recording system was used for yield monitoring and mapping from 2012 to 2015. Soil samples were taken at depths from 0–15 cm and 15–30 cm from 54 locations in the two watersheds in fall 2015 and analyzed for physical and chemical properties. The ECa was measured using EMI device, EM38-MK2, which provides four dipole readings ECa-H-0.5, ECa-H-1, ECa-V-0.5, and ECa-V-1. Soybean and corn yields at depositional position were 38% and 62% lower than the shoulder position in 2014 and 2015, respectively. Soil pH, total carbon (TC), total nitrogen (TN), Mehlich-3 Phosphorus (P), Bray-1 P and ECa at depositional positions were significantly higher compared to shoulder positions. Corn and soybeans yields were weakly to moderately (<±0.75) correlated with ECa. At the deposition position at the 0–15 cm depth ECa-H-0.5 was weakly correlated (r < ±0.50) with soil pH and was moderately correlated (r = ±0.50–±0.75) with organic matter (OM), calcium (Ca) and sulfur (S). Slope variation from 1%–20% at the research site had a strong influence on soil properties at watershed scale. When data from all topographic positions were combined together in all basins spatial interpolation between Mehlich-3 P and ECa-H-0.5 resulted in a larger cross validation RMSE compared to individual shoulder and backslope positions. Results demonstrated that topographic position should be considered while making correlations of ECa with soil properties. Methods of delineating topography positions presented in this paper can easily be replicated on other fields with similar landscape characteristics and EMI sensor based survey techniques can certainly improve and help in making detailed prediction maps of soil properties.
      PubDate: 2016-11-06
      DOI: 10.3390/agronomy6040057
      Issue No: Vol. 6, No. 4 (2016)
       
  • Agronomy, Vol. 6, Pages 58: Industrial Hemp in North America: Production,
           Politics and Potential

    • Authors: Jerome Cherney, Ernest Small
      First page: 58
      Abstract: Most of the Western World banned the cultivation of Cannabis sativa in the early 20th century because biotypes high in ∆9-tetrahydrocannabinol (THC, the principal intoxicant cannabinoid) are the source of marijuana. Nevertheless, since 1990, dozens of countries have authorized the licensed growth and processing of “industrial hemp” (cultivars with quite low levels of THC). Canada has concentrated on hemp oilseed production, and very recently, Europe changed its emphasis from fiber to oilseed. The USA, historically a major hemp producer, appears on the verge of reintroducing industrial hemp production. This presentation provides updates on various agricultural, scientific, social, and political considerations that impact the commercial hemp industry in the United States and Canada. The most promising scenario for the hemp industry in North America is a continuing focus on oilseed production, as well as cannabidiol (CBD), the principal non-intoxicant cannabinoid considered by many to have substantial medical potential, and currently in great demand as a pharmaceutical. Future success of the industrial hemp industry in North America is heavily dependent on the breeding of more productive oilseed cultivars, the continued development of consumer goods, reasonable but not overly restrictive regulations, and discouragement of overproduction associated with unrealistic enthusiasm. Changing attitudes have generated an unprecedented demand for the cannabis plant and its products, resulting in urgent needs for new legislative, regulatory, and business frameworks, as well as scientific, technological, and agricultural research.
      PubDate: 2016-11-12
      DOI: 10.3390/agronomy6040058
      Issue No: Vol. 6, No. 4 (2016)
       
  • Agronomy, Vol. 6, Pages 59: Considerations for Managing Agricultural
           Co-Existence between Transgenic and Non-Transgenic Cultivars of
           Outcrossing Perennial Forage Plants in Dairy Pastures

    • Authors: Kevin Smith, German Spangenberg
      First page: 59
      Abstract: Many of the major forage species used in agriculture are outcrossing and rely on the exchange of pollen between individuals for reproduction; this includes the major species used for dairy production in grazing systems: perennial ryegrass (Lolium perenne L.) and white clover (Trifolium repens L.). Cultivars of these species have been co-existing since contrasting cultivars were developed using plant breeding, but the consequences and need for strategies to manage co-existence have been made more prominent with the advent of genetic modification. Recent technological developments have seen the experimental evaluation of genetically modified (GM) white clover and perennial ryegrass, although there is no current commercial growing of GM cultivars of these species. Co-existence frameworks already exist for two major cross-pollinated grain crops (canola and maize) in Europe, and for alfalfa (Medicago sativa L.) in the US, so many of the principles that the industry has developed for co-existence in these crops such as detection techniques, segregation, and agronomic management provide lessons and guidelines for outcrossing forage species, that are discussed in this paper.
      PubDate: 2016-11-25
      DOI: 10.3390/agronomy6040059
      Issue No: Vol. 6, No. 4 (2016)
       
  • Agronomy, Vol. 6, Pages 60: Haploid and Doubled Haploid Techniques in
           Perennial Ryegrass (Lolium perenne L.) to Advance Research and Breeding

    • Authors: Rachel Begheyn, Thomas Lübberstedt, Bruno Studer
      First page: 60
      Abstract: The importance of haploid and doubled haploid (DH) techniques for basic and applied research, as well as to improve the speed of genetic gain when applied in breeding programs, cannot be overstated. They have become routine tools in several major crop species, such as maize (Zea mays L.), wheat (Triticum aestivum L.), and barley (Hordeum vulgare L.). DH techniques in perennial ryegrass (Lolium perenne L.), an important forage species, have advanced to a sufficiently successful and promising stage to merit an exploration of what their further developments may bring. The exploitation of both in vitro and in vivo haploid and DH methods to (1) purge deleterious alleles from germplasm intended for breeding; (2) develop mapping populations for genetic and genomic studies; (3) simplify haplotype mapping; (4) fix transgenes and mutations for functional gene validation and molecular breeding; and (5) hybrid cultivar development are discussed. Even with the comparatively modest budgets of those active in forage crop improvement, haploid and DH techniques can be developed into powerful tools to achieve the acceleration of the speed of genetic gain needed to meet future agricultural demands.
      PubDate: 2016-11-28
      DOI: 10.3390/agronomy6040060
      Issue No: Vol. 6, No. 4 (2016)
       
  • Agronomy, Vol. 6, Pages 61: Variation and Correlations among European and
           North American Orchardgrass Germplasm for Herbage Yield and Nutritive
           Value

    • Authors: Joseph Robins, B. Bushman, Ulf Feuerstein, Greg Blaser
      First page: 61
      Abstract: Efforts to improve water-soluble carbohydrate (WSC) concentrations are common in perennial forage grass breeding. Perennial ryegrass (Lolium perenne) breeding has been very successful in developing new cultivars with high WSC and high agronomic performance. Breeding efforts are ongoing to improve the WSC of other perennial forage grasses, such as orchardgrass (Dactylis glomerata). The United States Department of Agriculture Forage and Range and Deutsche Saatveredelung orchardgrass breeding programs cooperated to characterize the expression and genotype by environment interaction (GEI) of water-soluble carbohydrates in a collection of orchardgrass populations from both breeding programs. Additionally, the effort characterized the relationship between water-soluble carbohydrates and other agronomic and nutritive value traits in these populations. Overall, the Deutsche Saatveredelung populations had higher herbage mass (15%), rust resistance (59%), and later maturity. The Forage and Range Research populations had higher water-soluble carbohydrates (4%), nutritive value, and earlier maturity. However, results were highly dependent on GEI. Differences were very pronounced at the French and German field locations, but less pronounced at the two US locations. Combining the germplasm from the Forage and Range Research and Deutsche Saatveredelung programs may be a way to develop an improved base germplasm source that could then be used separately in the EU and US for water-soluble carbohydrate and other trait improvement.
      PubDate: 2016-12-02
      DOI: 10.3390/agronomy6040061
      Issue No: Vol. 6, No. 4 (2016)
       
  • Agronomy, Vol. 6, Pages 62: QTL for Water Use Related Traits in Juvenile
           Barley

    • Authors: Gwendolin Wehner, Christiane Balko, Frank Ordon
      First page: 62
      Abstract: Water use efficiency (WUE) is a trait of prime interest in cases of drought stress because it provides information on biomass production in limited water conditions. In order to get information on WUE and additional water use related traits, i.e., dry weight (DW), fresh weight (FW), total leaf water (LW) and leaf water content (WC), greenhouse pot experiments were conducted on 156 barley genotypes (Hordeum vulgare L.) for control (70% maximal water capacity of soil) and drought stress conditions (20% of the maximal water capacity of soil). Significant correlations between WUE and the other water use related traits (r ≤ 0.65) were determined in juvenile barley, and genotypes suited for improving drought stress tolerance in early developmental stages were identified. Furthermore, based on the significant effects of genotypes and treatments, as well as their interaction, data were used for genome wide association studies (GWAS) resulting in the identification of 14 marker trait associations (MTAs) corresponding to four quantitative trait loci (QTL). For WUE, four MTAs were detected mostly located on barley chromosome 4H. For four MTAs, functional annotations related to the involvement in response to abiotic stress were found. These markers may be of special interest for breeding purposes in cases when they will be validated and also detected in later growth stages.
      PubDate: 2016-12-08
      DOI: 10.3390/agronomy6040062
      Issue No: Vol. 6, No. 4 (2016)
       
  • Agronomy, Vol. 6, Pages 39: Influence of Formulation on the Cuticular
           Penetration and on Spray Deposit Properties of Manganese and Zinc Foliar
           Fertilizers

    • Authors: Alvin Alexander, Mauricio Hunsche
      First page: 39
      Abstract: Foliar fertilization, or the application of nutrient solutions to the foliage of plants, has become a very important tool as a supplement to traditional soil fertilization. So far, knowledge about the real mechanisms of foliar nutrient uptake is still limited. In this study different manganese (Mn) and zinc (Zn) carriers differing in their solubility and chemical characteristics (chelated or non-chelated, with or without the presence of a surfactant-penetrant) were compared with regard to their penetration characteristics through enzymatically-isolated cuticles. The experiments were explicitly conducted under high humidity conditions in order not to penalize compounds with a higher deliquescent point. The results show that Mn penetrates more rapidly through the cuticle than Zn ions for unknown reasons. The addition of a surfactant-penetrant enhances the penetration rate in the case of Mn ions. This trend is much less pronounced for zinc ions. Formulations based on insoluble carriers, such as carbonate or oxide, only poorly penetrate through the cuticle. In order to rapidly control micronutrient deficiency problems, only fully water soluble micronutrient carriers should be used.
      PubDate: 2016-06-30
      DOI: 10.3390/agronomy6030039
      Issue No: Vol. 6, No. 3 (2016)
       
  • Agronomy, Vol. 6, Pages 40: Impact of Climate Change on Cultivar Choice:
           

    • Authors: Janna Macholdt, Bernd Honermeier
      First page: 40
      Abstract: The objective of this study is to understand which requirements for cereal cultivars—with regard to climate change adaptation—are in demand by farmers and advisors, and to clarify whether there are any differences in their assessments. A comparative survey was used to collect data from 410 farmers and 114 advisors in Germany. The majority of both farmers and advisors reported perceivable effects of climatic change on plant production. The increase in droughts and hot spells, the increased incidence of torrential rain, and mild winters were mentioned as the main effects of climate change. For climate change adaptation, the farmers and advisors mostly relied on a locally-adapted cultivar selection. It is estimated that eco-stability, grain yield, resistance to lodging and drought tolerance are important cultivar properties. In the study, farmers and advisors equally pointed out the need for additional cultivar evaluation according to eco-stability. Finally, only minor differences regarding farmers’ and advisors’ assessments were found within the study. The outcome of this research points to the need of implementing farmers’ demands in cultivar recommendations. For example, an impartial assessment of cultivars’ eco-stability could help support the choice of cultivars and reduce the growing risks in cereal production with regard to climate change.
      PubDate: 2016-07-22
      DOI: 10.3390/agronomy6030040
      Issue No: Vol. 6, No. 3 (2016)
       
  • Agronomy, Vol. 6, Pages 41: Special Issue: Nitrogen Transport and
           Assimilation in Plants

    • Authors: Bertrand Hirel, Anne Krapp
      First page: 41
      Abstract: The doubling of the world’s agricultural production for the past four decades has been associated with a seven-fold increase in nitrogen (N) fertilization [1] which has caused major detrimental impacts onthediversityandfunctioningofthenon-agriculturalbacterial,animalandplantecosystems,notably through the process of freshwater and marine ecosystem eutrophication [2].[...]
      PubDate: 2016-08-29
      DOI: 10.3390/agronomy6030041
      Issue No: Vol. 6, No. 3 (2016)
       
  • Agronomy, Vol. 6, Pages 42: Synergistic Effects of Agronet Covers and
           Companion Cropping on Reducing Whitefly Infestation and Improving Yield of
           Open Field-Grown Tomatoes

    • Authors: Stella Mutisya, Mwanarusi Saidi, Arnold Opiyo, Mathieu Ngouajio, Thibaud Martin
      First page: 42
      Abstract: Tomatoes (Lycopersicon esculentum Mill) are one of the biggest vegetable crops in the world, supplying a wide range of vitamins, minerals and fibre in human diets. In the tropics, tomatoes are predominantly grown under sub-optimal conditions by subsistence farmers, with exposure to biotic and abiotic stresses in the open field. Whitefly (Bemisia tabaci Gennadius) is one of the major pests of the tomato, potentially causing up to 100% yield loss. To control whitefly, most growers indiscriminately use synthetic insecticides which negatively impact the environment, humans, and other natural pest management systems, while also increasing cost of production. This study sought to investigate the effectiveness of agronet covers and companion planting with aromatic basil (Ocimum basilicum L.) as an alternative management strategy for whitefly in tomatoes and to evaluate the use of these treatments ontomato growth and yield. Two trials were conducted at the Horticulture Research and Training Field, Egerton University, Njoro, Kenya. Treatments comprised a combination of two factors, (1) growing environment (agronet and no agronet) and (2) companion planting with a row of basil surrounding tomato plants, a row of basil in between adjacent rows of tomato, no companion planting. Agronet covers and companion cropping with a row of basil planted between adjacent tomato rows significantly lowered B. tabaci infestation in tomatoes by 68.7%. Better tomato yields were also recorded in treatments where the two treatments were used in combination. Higher yield (13.75 t/ha) was obtained from tomatoes grown under agronet cover with a basil row planted in between adjacent rows of the tomato crop compared to 5.9 t/ha in the control. Non-marketable yield was also lowered to5.9 t/ha compared to 9.8 t/ha in the control following the use of the two treatments in combination. The results of this study demonstrate the potential viability of using companion cropping and agronet covers in integrated management of B. tabaci and improvement of tomato yield.
      PubDate: 2016-09-19
      DOI: 10.3390/agronomy6030042
      Issue No: Vol. 6, No. 3 (2016)
       
  • Agronomy, Vol. 6, Pages 43: Soil Tillage Systems and Wheat Yield under
           Climate Change Scenarios

    • Authors: Pieranna Servadio, Simone Bergonzoli, Claudio Beni
      First page: 43
      Abstract: In this study, the effects of three different main preparatory tillage operations: ploughing at 0.4 m (P40) and 0.20 m (P20) depth and harrowing at 0.20 m depth (MT) were investigated. The tillage operations were carried out at two different times, as the soil water content increased over time from rainfall: (low, 58% (LH) and high, 80% (HH) of field capacity). Results obtained from the soil monitoring carried out before and after tillage showed high values of soil strength in terms of Penetration resistance and shear strength particularly in deeper soil layers at lower water content. During tillage, fossil-fuel energy requirements for P40 LH and P20 LH were 25% and 35% higher, respectively, with respect to the HH treatments and tractor slip was very high (P40 LH = 32.4%) with respect to the P40 HH treatment (16%). Soil water content significantly influenced tractor performance during soil ploughing at 0.40 m depth but no effect was observed for the MT treatment. The highly significant linear relations between grain yield and soil penetration resistance highlight how soil strength may be good indicator of soil productivity. We conclude that ploughing soil to a 0.20 m depth or harrowing soil to a 0.20 m depth is suitable for this type of soil under climate change scenarios.
      PubDate: 2016-09-20
      DOI: 10.3390/agronomy6030043
      Issue No: Vol. 6, No. 3 (2016)
       
  • Agronomy, Vol. 6, Pages 21: Different Responses of the Quality Parameters
           of Coriandrum sativum to Organic Substrate Mixtures and Fertilization

    • Authors: Neith Pacheco L., Julia Cano-Sosa, Fernando Poblano C., Ingrid Rodríguez-Buenfil, Ana Ramos-Díaz
      First page: 21
      Abstract: In order to standardize the quality of agricultural products, it is necessary to control the factors affecting plant development, such as plant nutrition. The best results in terms of homogeneity of the quality of vegetable crops were achieved using inert substrates and application of nutrients; however, production costs are high due to the cost of irrigation systems and substrate management and importation. This work aims to evaluate the effect of the local substrate mix and the amount of organic fertilizer on different quality parameters of coriander. To evaluate the quality of coriander, we considered different parameters such as size, biomass, antioxidant capacity and aroma (evaluated by volatile compounds detection with gas chromatography). The results show that the culture system differentially affects each parameter, and the compounds associated with the aroma of coriander and the diameter of plants are sensitive to the culture system, while the length of plants, number of leaves and antioxidant activity are not affected by the concentration of fertilizer. Moreover, organic farming conditions do not reduce quality parameters of the crops when using adequate fertilization. Additionally, local substrates would be practical substitutes for expensive importations.
      PubDate: 2016-04-05
      DOI: 10.3390/agronomy6020021
      Issue No: Vol. 6, No. 2 (2016)
       
  • Agronomy, Vol. 6, Pages 22: Wheat Sown with Narrow Spacing Results in
           Higher Yield and Water Use Efficiency under Deficit Supplemental
           Irrigation at the Vegetative and Reproductive Stage

    • Authors: Mubshar Hussain, Shahid Farooq, Khawar Jabran, Muhammad Ijaz, Abdul Sattar, Waseem Hassan
      First page: 22
      Abstract: A decrease in water resources around the globe in irrigated agriculture has resulted in a steep decline in irrigation water availability. Therefore, management options for efficient use of available irrigation water are inevitable. Deciding the critical time, frequency and amount of irrigation are compulsory to achieve higher crop outputs. Hence, this two-year field study was conducted to assess the role of different row spacings, i.e., 20, 25 and 30 cm, on growth, productivity, and water use efficiency (WUE) of wheat under deficit supplemental irrigation (DSI) at the vegetative and reproductive phase by using surplus supplemental irrigation (SSI) throughout the growing season as the control. DSI at both growth stages, and the reproductive stage in particular, changed the crop allometry, yield and net income of wheat. However, narrow spacing (20 cm) resulted in efficient use of available irrigation water (DSI and SSI) with higher yield, WUE and economic returns. Interestingly, wider spacing resulted in a higher number of grains per spike with higher 1000-grain weight under SSI and DSI, but final yield output remained poor due to a lower number of productive tillers. It was concluded that reducing irrigation during the vegetative stage is less damaging compared with the reproductive phase; therefore, sufficient supplemental irrigation must be added at the reproductive stage, particularly during grain-filling. Further, narrow spacing (20 cm) resulted in efficient utilization of available irrigation water; therefore, wheat must be grown at a narrow spacing to ensure the efficient utilization of available irrigation water.
      PubDate: 2016-04-06
      DOI: 10.3390/agronomy6020022
      Issue No: Vol. 6, No. 2 (2016)
       
  • Agronomy, Vol. 6, Pages 23: Assessing Nitrogen Use Efficiency and Nitrogen
           Loss in a Forage-Based System Using a Modeling Approach

    • Authors: Chiara Piccini, Claudia Di Bene, Roberta Farina, Bruno Pennelli, Rosario Napoli
      First page: 23
      Abstract: In intensive agriculture, N supply often exceeds crop requirements, even in nitrate vulnerable zones (NVZ). In farmland, the N surplus gives rise to NO3− leaching and consequent groundwater pollution. The present study aimed at proposing measures to reduce N leaching and hence improve N efficiency in a buffalo livestock farm located in the NVZ of Latina plain (Central Italy). The farm was cultivated with forage crops in a double annual crop rotation: Italian ryegrass (Lolium multiflorum Lam.) in winter and silage corn (Zea mays L.) in summer. Mineral and organic fertilizers were supplied to both crops. The annual N budget and soil solution NO3-N concentrations were evaluated using a modeling approach. The performance of the WinEPIC model in simulating the response of the NO3-N concentration in percolation to the N application rate was assessed and validated by field measurements of the NO3-N concentration in the soil solution. Three scenarios were proposed to identify the best practice to minimize the environmental impact of N application without significant yield loss. Also, recommendations of best practices in N fertilization and animal manure spreading were given. This study thus provides useful preliminary information for decision-making in agriculture/environmental policies.
      PubDate: 2016-04-12
      DOI: 10.3390/agronomy6020023
      Issue No: Vol. 6, No. 2 (2016)
       
  • Agronomy, Vol. 6, Pages 24: Evaluation of African-Bred Maize Germplasm
           Lines for Resistance to Aflatoxin Accumulation

    • Authors: Robert Brown, W. Williams, Gary Windham, Abebe Menkir, Zhi-Yuan Chen
      First page: 24
      Abstract: Aflatoxins, produced by the fungus Aspergillus flavus, contaminate maize grain and threaten human food and feed safety. Plant resistance is considered the best strategy for reducing aflatoxin accumulation. Six maize germplasm lines, TZAR101–TZAR106, were released by the International Institute of Tropical Agriculture-Southern Regional Research Center (IITA-SRRC) maize breeding collaboration for use in African National Programs and U.S. maize breeding programs. The present investigation was conducted to evaluate aflatoxin reduction by these lines in a U.S. environment. As germplasm lines, resistance was demonstrated by the lines tested in 2010 and 2014 trials. In 2010, TZAR106 was among the lines with the lowest toxin accumulation, and in 2014, along with TZAR102, supported low aflatoxin. When evaluated as single cross hybrids in 2012, 2013 and 2014, several crosses involving IITA-SRRC lines accumulated low toxin. In 2012, TZAR103 × HBA1 was one of 4 lines with the lowest concentration of aflatoxin. In 2014, five IITA-SRRC hybrids were among the lowest with TZAR102 × Va35 and TZAR102 × LH132 being the two lowest. Results demonstrate significant aflatoxin reduction by IITA-SRRC lines in a U.S. aflatoxin-conducive environment (at Mississippi State University). Further testing in different locations and environments is needed to further evaluate the potential usefulness of these germplasm lines.
      PubDate: 2016-04-15
      DOI: 10.3390/agronomy6020024
      Issue No: Vol. 6, No. 2 (2016)
       
  • Agronomy, Vol. 6, Pages 25: Emerging and Established Technologies to
           Increase Nitrogen Use Efficiency of Cereals

    • Authors: Juan Herrera, Gerardo Rubio, Lilia Häner, Jorge Delgado, Carlos Lucho-Constantino, Samira Islas-Valdez, Didier Pellet
      First page: 25
      Abstract: Nitrogen (N) fertilizers are one of the most expensive inputs in agricultural settings. Additionally, the loss of N increases costs, contributes to soil acidification, and causes off-site pollution of the air, groundwater and waterways. This study reviews current knowledge about technologies for N fertilization with potential to increase N use efficiency and reduce its negative effects on the environment. Classic inorganic sources such as urea and ammonium sulfate are the major sources utilized, while controlled N release fertilizers have not been significantly adopted for cereals and oil crops. Microorganisms, with the exception of Rhizobium sp. in soybeans, are also not widely used nowadays (e.g., plant growth-promoting bacteria and cynobacteria). The interest in implementing new N fertilization knowledge is stimulating the development of sensors to diagnose the N status and decision support systems for integrating several variables to optimize sources, rates and methods of application. Among potential new technologies we identified the incipient development of nanofertilizers, nutrient formulations to coat seeds, and recycled nutrients. Furthermore, increasing concern about the environmental consequences of N may facilitate the implementation of innovations outside the farm such as more effective regulations to guide N fertilization and methods to manufacture N fertilizers that are more energy-efficient and less CO2 equivalent emitting.
      PubDate: 2016-04-19
      DOI: 10.3390/agronomy6020025
      Issue No: Vol. 6, No. 2 (2016)
       
  • Agronomy, Vol. 6, Pages 26: Nitrogen Economy and Nitrogen Environmental
           Interactions in Conifers

    • Authors: Rafael Cañas, Fernando de la Torre, Maria Pascual, Concepción Avila, Francisco Cánovas
      First page: 26
      Abstract: Efficient acquisition, assimilation and economy of nitrogen are of special importance in trees that must cope with seasonal periods of growth and dormancy over many years. The ability to accumulate nitrogen reserves and to recycle N determine to a great extent the growth and production of forest biomass. The metabolic relevance of two key amino acids, arginine and phenylalanine, as well as other processes potentially involved in the nitrogen economy of conifers are discussed in the current review. During their long life cycles, conifers not only cope with cyclical annual and long-term changes in the environment but also interact with other organisms such as herbivores and symbionts. The interactions of biotic and abiotic factors with conifer nitrogen metabolism will also be outlined in this review.
      PubDate: 2016-04-20
      DOI: 10.3390/agronomy6020026
      Issue No: Vol. 6, No. 2 (2016)
       
  • Agronomy, Vol. 6, Pages 27: Apricot Breeding at the Faculty of
           Horticulture in Lednice

    • Authors: Boris Krška, Zdeněk Vachůn
      First page: 27
      Abstract: The aim of the apricot-breeding program in the Horticultural Faculty in Lednice, that has been developed since 1981, is to obtain new adaptable cultivars, which combine most of the valuable biological traits. Standard breeding techniques, such as crossing by emasculation and hand pollination, self-pollination and open pollination, were employed. A total of 1.154 crossings were produced from more than 110 different parents. So far more than 20,000 seedlings have been obtained, of which about 13,000 have already been evaluated. The most interesting selections were grafted and planted in trial orchards (we now have more than 650 elite genotypes). Ten of these have already been registered, and further promising new hybrids have been submitted for registration and law right protection (Betinka, Candela, Sophia and Adriana). The basic prerequisite for the initiation of the breeding program was a large collection of genetic resources, established and gradually supplemented since the 1970s. At the present time, we preserve and manage more than 300 accessions of apricot trees. In the frame of the descriptive work of the genetic resources and in order to use in breeding, a collection of apricots has been evaluated. We selected the genotypes and characters relating to an increased level of adaptation to the environment.
      PubDate: 2016-04-21
      DOI: 10.3390/agronomy6020027
      Issue No: Vol. 6, No. 2 (2016)
       
  • Agronomy, Vol. 6, Pages 28: Development and Integration of an SSR-Based
           Molecular Identity Database into Sugarcane Breeding Program

    • Authors: Yong-Bao Pan
      First page: 28
      Abstract: Sugarcane breeding is very difficult and it takes 12 to 14 years to develop a new cultivar for commercial production. This is because sugarcane varieties are highly polyploid, inter-specific hybrids with 100 to 130 chromosomes that may vary across geographical areas. Other obstacles/constraints include the small size of flowers that may not synchronize but may self-pollinate, difficulty in distinguishing hybrids from self progenies, extreme (G × E) interactive effect, and potential variety mis-identification during vegetative propagation and varietal exchange. To help cane breeders circumvent these constraints, a simple sequence repeats (SSR)-based molecular identity database has been developed at the United States Department of Agriculture-Agricultural Research Service, Sugarcane Research Unit in Houma, LA. Since 2005, approximately 2000 molecular identities have been constructed for clones of sugarcane and related Saccharum species that cover geographical areas including Argentina, Australia, Bangladesh, China, Colombia, India, Mexico, Pakistan, South Africa, Thailand, USA (Louisiana, Florida, Texas, and Hawaii), and Venezuela. The molecular identity database is updated annually and has been utilized to: (1) provide molecular descriptors to newly registered cultivars; (2) identify in a timely fashion any mislabeled or unidentifiable clones from cross parents and field evaluation plots; (3) develop de novo clones of energy cane with S. spontaneum cytoplasm; (4) provide clone-specific fingerprint information for assessing cross quality and paternity of polycross; (5) determine genetic relatedness of parental clones; (6) select F1 hybrids from (elite × wild) or (wild × elite) crosses; and (7) investigate the inheritance of SSR markers in sugarcane. The integration of the molecular identity database into the sugarcane breeding program may improve the overall efficacy of cultivar development and commercialization.
      PubDate: 2016-04-25
      DOI: 10.3390/agronomy6020028
      Issue No: Vol. 6, No. 2 (2016)
       
  • Agronomy, Vol. 6, Pages 29: Little Potential of Spring Wheat Genotypes as
           a Strategy to Reduce Nitrogen Leaching in Central Europe

    • Authors: Juan Herrera, Christos Noulas, Peter Stamp, Didier Pellet
      First page: 29
      Abstract: Nitrogen (N) losses negatively impact groundwater quality. Spring wheat genotypes varying in N-fertilizer recovery were studied (by using lysimeters) for their potential to minimize NO3-N leaching during spring and summer, over a three-year period. Additionally, we examined to what extent root growth and NO3-N leaching explain the well-known difference found between apparent and isotopic N recovery. The genotypes were grown under low (2 g m−2) and high (27 g m−2) N fertilizer supply. On average, the apparent and isotopic recoveries of N fertilizer by wheat were 43% and 51%, respectively. The three genotypes varied in fertilizer N recovery but not in NO3-N leaching, which only accounted for 15% of the applied N fertilizer. The differences in N uptake, fertilizer N recovery and root growth among the genotypes were not associated with the leached NO3-N because root growth and N uptake were not well synchronized with NO3-N leaching. Already at stem elongation 70% to 98% of the season-long NO3-N leaching had already taken place. Thus, the ability to minimize in-season NO3-N leaching by using spring wheat genotypes with higher fertilizer N recovery was limited because maximum N leaching occurred in the early crop season.
      PubDate: 2016-05-09
      DOI: 10.3390/agronomy6020029
      Issue No: Vol. 6, No. 2 (2016)
       
  • Agronomy, Vol. 6, Pages 30: Design, Development, and Performance
           Evaluation of a Trash-Board Moldboard Plow for the Interaction between
           Soil and Straw with Two Different Water Content Levels

    • Authors: Farid Abdallah, Weimin Ding, Qishuo Ding, Genxing Pan
      First page: 30
      Abstract: A two-year field study was conducted to investigate the performance of a lightweight trash-board moldboard plow (with and without a trash-board), as influenced by stubble height and water content. Both fields were measured for the performance of a trash-board moldboard plow when used during the optimization of the plowing depth, the water content, and the reaction forces. The results showed that in the first year, when a trash-board was required, the results were significantly different. The fields had lower draft and reaction force in the soil with only stubble height, which was greater than that in the soil with dense straw for all water content levels. This was also observed in the second year for the whole depth. This study shows that the moldboard plow with a trash-board provided minimum draft and reaction forces with only straw and heavy straw. The results indicate that straw nearby shear significantly increased displacement for all treatments, with variance of straw nearby moldboard. Hence, the results verify that a trash-board continuously created large soil fragmentation with different water content. Straw labels create a position of straw which also allows for better results. It is important to install trash-boards with the moldboard plow for heavy straw incorporation.
      PubDate: 2016-05-06
      DOI: 10.3390/agronomy6020030
      Issue No: Vol. 6, No. 2 (2016)
       
  • Agronomy, Vol. 6, Pages 31: Towards a Better Understanding of Agronomic
           Efficiency of Nitrogen: Assessment and Improvement Strategies

    • Authors: Francesco Montemurro, Mariangela Diacono
      First page: 31
      Abstract: Agronomic N-use efficiency is the basis for economic and environmental efficiency, and an effective agro-ecosystem management practice, improving nutrient use efficiency, is a crucial challenge for a more sustainable production of horticultural, industrial and cereal crops. However, discrepancy between theory and practice still exists, coming from large gaps in knowledge on net-N immobilization/mineralization rates in agro-ecosystems, as well as on the effects of indigenous and applied N to crop response. A more thorough understanding of these topics is essential to improve N management in agricultural systems. To this end, the present Special Issue collects research findings dealing with different aspects of agronomic efficiency of N in different agro-ecosystems, and environmental impact derived from fertilization management practices. In particular, the Special Issue contains selected papers, which concern a wide range of topics, including analyzing tools, options of management, calculation equation and modeling approaches.
      PubDate: 2016-05-10
      DOI: 10.3390/agronomy6020031
      Issue No: Vol. 6, No. 2 (2016)
       
  • Agronomy, Vol. 6, Pages 32: Prairies Thrive Where Row Crops Drown: A
           Comparison of Yields in Upland and Lowland Topographies in the Upper
           Midwest US

    • Authors: Adam von Haden, Mathew Dornbush
      First page: 32
      Abstract: Cellulosic biofuel production is expected to increase in the US, and the targeted establishment of biofuel agriculture in marginal lands would reduce competition between biofuels and food crops. While poorly drained, seasonally saturated lowland landscape positions are marginal for production of row crops and switchgrass (Panicum virgatum L.), it is unclear whether species-diverse tallgrass prairie yield would suffer similarly in saturated lowlands. Prairie yields typically increase as graminoids become more dominant, but it is uncertain whether this trend is due to greater aboveground net primary productivity (ANPP) or higher harvest efficiency in graminoids compared to forbs. Belowground biomass, a factor that is important to ecosystem service provisioning, is reduced when switchgrass is grown in saturated lowlands, but it is not known whether the same is true in species-diverse prairie. Our objectives were to assess the effect of topography on yields and live belowground biomass in row crops and prairie, and to determine the mechanisms by which relative graminoid abundance influences tallgrass prairie yield. We measured yield, harvest efficiency, and live belowground biomass in upland and lowland landscape positions within maize silage (Zea mays L.), winter wheat (Triticum aestivum L.), and restored tallgrass prairie. Maize and winter wheat yields were reduced by more than 60% in poorly drained lowlands relative to well-drained uplands, but diverse prairie yields were equivalent in both topographic settings. Prairie yields increased by approximately 45% as the relative abundance of graminoids increased from 5% to 95%. However, this trend was due to higher harvest efficiency of graminoids rather than greater ANPP compared to forbs. In both row crops and prairie, live belowground biomass was similar between upland and lowland locations, indicating consistent biomass nutrient sequestration potential and soil organic matter inputs between topographic positions. While poorly drained, lowland landscape positions are marginal lands for row crops, they appear prime for the cultivation of species-diverse tallgrass prairie for cellulosic biofuel.
      PubDate: 2016-05-13
      DOI: 10.3390/agronomy6020032
      Issue No: Vol. 6, No. 2 (2016)
       
  • Agronomy, Vol. 6, Pages 33: Impact of Pre-Anthesis Water Deficit on Yield
           and Yield Components in Barley (Hordeum vulgare L.) Plants Grown under
           Controlled Conditions

    • Authors: Zakaria Al-Ajlouni, Ayed Al-Abdallat, Abdul Al-Ghzawi, Jamal Ayad, Jamal Abu Elenein, Nisreen Al-Quraan, P. Baenziger
      First page: 33
      Abstract: Drought at pre-anthesis stages can influence barley growth and results in yield losses. Therefore, it is important to understand how drought at pre-anthesis can affect different traits associated with yield reduction in barley. The objective of this study was to understand the relevance of the genetic background of major flowering time genes in barley plants subjected to pre-anthesis drought and its impact on yield and yield components. A glasshouse experiment using a Randomized Complete Block Design was conducted to investigate the effect of drought and its timing on yield and yield components on eleven barley genotypes, which were selected to represent genetic diversity of major flowering time genes (PPDH1, PPDH2, HvVrn1, HvVrn2 and HvVrn3). Barley plants were exposed to three water regimes, non-stressed and stressed, which was applied at two pre-anthesis growth stages, tillering (SS) and stem elongation (SE). Results identified differences among genotypes in all measured traits. Grain yield, grain number and "thousand kernel weight" were reduced in all genotypes due to drought, irrespective of the growth stage. Early flowering genotypes had better performance as reflected in higher yield compared with late flowering genotypes. Results verified the fundamental importance of early flowering to improve productivity in response to pre-anthesis drought. The results of this study can help in selecting barley lines for future breeding purposes with improved resilience to drought conditions in Mediterranean environments.
      PubDate: 2016-05-18
      DOI: 10.3390/agronomy6020033
      Issue No: Vol. 6, No. 2 (2016)
       
  • Agronomy, Vol. 6, Pages 34: Effect of Irrigation Timing on Root Zone Soil
           

    • Authors: Xuejun Dong, Wenwei Xu, Yongjiang Zhang, Daniel Leskovar
      First page: 34
      Abstract: High air temperatures during the crop growing season can reduce harvestable yields in major agronomic crops worldwide. Repeated and prolonged high night air temperature stress may compromise plant growth and yield. Crop varieties with improved heat tolerance traits as well as crop management strategies at the farm scale are thus needed for climate change mitigation. Crop yield is especially sensitive to night-time warming trends. Current studies are mostly directed to the elevated night-time air temperature and its impact on crop growth and yield, but less attention is given to the understanding of night-time soil temperature management. Delivering irrigation water through drip early evening may reduce soil temperature and thus improve plant growth. In addition, corn growers typically use high-stature varieties that inevitably incur excessive respiratory carbon loss from roots and transpiration water loss under high night temperature conditions. The main objective of this study was to see if root-zone soil temperature can be reduced through drip irrigation applied at night-time, vs. daytime, using three corn hybrids of different above-ground architecture in Uvalde, TX where day and night temperatures during corn growing season are above U.S. averages. The experiment was conducted in 2014. Our results suggested that delivering well-water at night-time through drip irrigation reduced root-zone soil temperature by 0.6 °C, increase root length five folds, plant height 2%, and marginally increased grain yield by 10%. However, irrigation timing did not significantly affect leaf chlorophyll level and kernel crude protein, phosphorous, fat and starch concentrations. Different from our hypothesis, the shorter, more compact corn hybrid did not exhibit a higher yield and growth as compared with taller hybrids. As adjusting irrigation timing would not incur an extra cost for farmers, the finding reported here had immediate practical implications for farm scale adaptation to hot environments.
      PubDate: 2016-05-19
      DOI: 10.3390/agronomy6020034
      Issue No: Vol. 6, No. 2 (2016)
       
  • Agronomy, Vol. 6, Pages 35: Municipal Compost as a Nutrient Source for
           Organic Crop Production in New Zealand

    • Authors: Abie Horrocks, Denis Curtin, Craig Tregurtha, Esther Meenken
      First page: 35
      Abstract: About 1% of New Zealand farmland is managed organically. Nitrogen is the nutrient most likely to limit organic crop production. A potential solution is incorporation of compost to supply N. About 726,000 t of municipal garden and kitchen wastes are sent to landfills annually. Composting offers a means of reducing the impact of landfill wastes on the wider environment. Organically certified compost (N content typically 2% to 2.5%) is available from some municipal composting plants. To be effectively used on organic farms, the rate of N release (mineralization) must be known. Laboratory incubations were conducted to quantify mineralization of compost N under controlled (temperature and moisture) conditions. Nitrogen availability and crop yields from a one-off application of compost (25–100 t·ha−1) were also assessed in two field trials (using cereal and forage crops). The results suggested that a relatively small part (13%–23%) of compost N was used by the crops in 3–4 years. Much of this was mineral N present at the time of application. Mineralization rates in the laboratory and field studies were much lower than expected from published work or compost C:N ratio (considered an important indicator of N mineralization potential of composts).
      PubDate: 2016-05-20
      DOI: 10.3390/agronomy6020035
      Issue No: Vol. 6, No. 2 (2016)
       
  • Agronomy, Vol. 6, Pages 36: The Elusive Boreal Forest Thaumarchaeota

    • Authors: Malin Bomberg
      First page: 36
      Abstract: In recent years, Archaea have, with increasing frequency, been found to colonize both agricultural and forest soils in temperate and boreal regions. The as yet uncultured group I.1c of the Thaumarchaeota has been of special interest. These Archaea are widely distributed in mature vegetated acidic soils, but little has been revealed of their physiological and biological characteristics. The I.1c Thaumarchaeota have been recognized as a microbial group influenced by plant roots and mycorrhizal fungi, but appear to have distinct features from their more common soil dwelling counterparts, such as the Nitrosotalea or Nitrososphaera. They appear to be highly dependent on soil pH, thriving in undisturbed vegetated soils with a pH of 5 or below. Research indicate that these Archaea require organic carbon and nitrogen sources for growth and that they may live both aerobically and anaerobically. Nevertheless, pure cultures of these microorganisms have not yet been obtained. This review will focus on what is known to date about the uncultured group I.1c Thaumarchaeota formerly known as the “Finnish Forest Soil” (FFS) Archaea.
      PubDate: 2016-06-15
      DOI: 10.3390/agronomy6020036
      Issue No: Vol. 6, No. 2 (2016)
       
  • Agronomy, Vol. 6, Pages 37: The Effect of Anaerobic and Aerobic Fish
           Sludge Supernatant on Hydroponic Lettuce

    • Authors: Simon Goddek, Zala Schmautz, Ben Scott, Boris Delaide, Karel Keesman, Sven Wuertz, Ranka Junge
      First page: 37
      Abstract: The mobilization of nutrients from fish sludge (i.e., feces and uneaten feed) plays a key role in optimizing the resource utilization and thus in improving the sustainability of aquaponic systems. While several studies have documented the aerobic and anaerobic digestion performance of aquaculture sludge, the impact of the digestate on plant growth has yet to be understood. The present study examines the impact of either an aerobic or an anaerobic digestion effluent on lettuce plant growth, by enriching a mixture of aquaculture and tap water with supernatants from both aerobic and anaerobic batch reactors. The lettuce plants grown in the hydroponic system supplied with supernatant from an anaerobic reactor had significantly better performance with respect to weight gain than both, those in the system where supernatant from the aerobic reactor was added, as well as the control system. It can be hypothesized that this effect was caused by the presence of NH4+ as well as dissolved organic matter, plant growth promoting rhizobacteria and fungi, and humic acid, which are predominantly present in anaerobic effluents. This study should therefore be of value to researchers and practitioners wishing to further develop sludge remineralization in aquaponic systems.
      PubDate: 2016-06-21
      DOI: 10.3390/agronomy6020037
      Issue No: Vol. 6, No. 2 (2016)
       
  • Agronomy, Vol. 6, Pages 38: In Winter Wheat, No-Till Increases Mycorrhizal
           Colonization thus Reducing the Need for Nitrogen Fertilization

    • Authors: Julien Verzeaux, David Roger, Jérôme Lacoux, Elodie Nivelle, Clément Adam, Hazzar Habbib, Bertrand Hirel, Frédéric Dubois, Thierry Tetu
      First page: 38
      Abstract: Arbuscular mycorrhizal fungi (AMF) play a major role in the uptake of nutrients by agricultural plants. Nevertheless, some agricultural practices can interrupt fungal-plant signaling and thus impede the establishment of the mycorrhizal symbiosis. A field experiment performed over a 5-year period demonstrated that both the absence of tillage and of nitrogen (N) fertilization improved AMF colonization of wheat roots. Moreover, under no-till conditions, N uptake and aboveground biomass production did not vary significantly between N-fertilized and N-unfertilized plots. In contrast, both N uptake and above ground biomass were much lower when N fertilizer was not added during conventional tillage. This finding strongly suggests that for wheat, no-till farming is a sustainable agricultural system that allows a gradual reduction in N fertilizer use by promoting AMF functionality and at the same time increasing N uptake.
      PubDate: 2016-06-21
      DOI: 10.3390/agronomy6020038
      Issue No: Vol. 6, No. 2 (2016)
       
  • Agronomy, Vol. 6, Pages 1: Contribution of Nitrogen Uptake and
           Retranslocation during Reproductive Growth to the Nitrogen Efficiency of
           Winter Oilseed-Rape Cultivars (Brassica napus L.) Differing in Leaf
           Senescence

    • Authors: Fabian Koeslin-Findeklee, Walter Horst
      First page: 1
      Abstract: Genotypic variation in N efficiency defined as high grain yield under limited nitrogen (N) supply of winter oilseed-rape line-cultivars has been predominantly attributed to N uptake efficiency (NUPT) through maintained N uptake during reproductive growth related to functional stay-green. For investigating the role of stay-green, N retranslocation and N uptake during the reproductive phase for grain yield formation, two line cultivars differing in N starvation-induced leaf senescence were grown in a field experiment without mineral N (N0) and with 160 kg N·ha−1 (N160). Through frequent harvests from full flowering until maturity N uptake, N utilization and apparent N remobilization from vegetative plant parts to the pods could be calculated. NUPT proved being more important than N utilization efficiency (NUE) for grain yield formation under N-limiting (N0) conditions. For cultivar differences in N efficiency, particularly N uptake during flowering (NUPT) and biomass allocation efficiency (HI) to the grains, were decisive. Both crop traits were related to delayed senescence of the older leaves. Remobilization of N particularly from stems and leaves was more important for pod N accumulation than N uptake after full flowering. Pod walls (high N concentrations) and stems (high biomass) mainly contributed to the crop-residue N at maturity. Decreasing the crop-inherent high N budget surplus of winter oilseed-rape requires increasing the low N remobilization efficiency particularly of pod-wall N to the grains. Addressing this conclusion, multi-year and -location field experiments with an extended range of cultivars including hybrids are desirable.
      PubDate: 2016-01-04
      DOI: 10.3390/agronomy6010001
      Issue No: Vol. 6, No. 1 (2016)
       
  • Agronomy, Vol. 6, Pages 2: Silage Maize and Sugar Beet for Biogas
           Production in Rotations and Continuous Cultivation: Dry Matter and
           Estimated Methane Yield

    • Authors: Wiebke Brauer-Siebrecht, Anna Jacobs, Olaf Christen, Philipp Götze, Heinz-Josef Koch, Jan Rücknagel, Bernward Märländer
      First page: 2
      Abstract: Since silage maize is the main crop grown for biogas production (biomass crop) in Germany; its increasing cultivation is critically discussed in terms of social and agronomical aspects. To investigate if sugar beet is suitable as an alternative biomass crop to silage maize; three-year field trials with both biomass crops in rotations with winter wheat (food crop) and continuous cultivation were conducted at three highly productive sites. Dry matter (DM) yield per hectare was measured via field trials whereas methane yield per hectare was estimated via a calculation. Higher annual DM yield was achieved by silage maize (19.5–27.4 t∙ha−1∙a−1) compared to sugar beet root (10.7–23.0 t∙ha−1∙a−1). Dry matter yield was found to be the main driver for the estimated methane yield. Thus; higher estimated methane yield was produced by silage maize (6458–9388 Nm3∙ha−1) with overlaps to sugar beet root (3729–7964 Nm3∙ha−1). We; therefore; classify sugar beet as a suitable alternative biomass crop to silage maize; especially when cultivated in crop rotations with winter wheat. Additionally; we found that the evaluation of entire crop rotations compared to single crops is a more precise approach since it includes rotational effects.
      PubDate: 2016-01-02
      DOI: 10.3390/agronomy6010002
      Issue No: Vol. 6, No. 1 (2016)
       
  • Agronomy, Vol. 6, Pages 3: Weed Control with Cover Crops in Irrigated
           Potatoes

    • Authors: G.H. Mehring, J.E. Stenger, H.M. Hatterman-Valenti
      First page: 3
      Abstract: Field experiments at Oakes, ND, USA in 2010 and Carrington, ND, USA in 2011 were conducted to evaluate the potential for cover crops grown in the Northern Great Plains, USA in order to reduce weed emergence and density in irrigated potatoes. Treatments included five cover crop treatments and three cover crop termination treatments. Termination of cover crops was done with glyphosate, disk-till, and roto-till. Cover crop biomass accumulation was greatest for rye/canola and triticale at Oakes, and hairy vetch and hairy vetch/rye at Carrington. Cover crop and termination affected weed control 14, 29, and 51 days after planting (DAP) at Oakes. Weed control at Carrington was at least 90% for all cover crop and termination treatments at all three evaluation timings. Marketable yield at Oakes was greater when roto-till was used to terminate the cover crops compared with disk-till or herbicide, which is beneficial for organic systems where herbicides are not used. Marketable yield at Carrington was not affected by cover crop or termination treatments. Results suggest that cover crops can successfully be integrated into irrigated potato production for weed control with yields equal to no cover crop, and with attention to potential mechanical difficulties.
      PubDate: 2016-01-05
      DOI: 10.3390/agronomy6010003
      Issue No: Vol. 6, No. 1 (2016)
       
  • Agronomy, Vol. 6, Pages 4: Novel QTL for Stripe Rust Resistance on
           Chromosomes 4A and 6B in Soft White Winter Wheat Cultivars

    • Authors: Emily Klarquist, Xianming Chen, Arron Carter
      First page: 4
      Abstract: Stripe rust (caused by Puccinia striiformis f. sp. tritici) of wheat (Triticum aestivum) is a devastating disease in temperate regions when susceptible varieties are grown and environmental conditions sustain high disease pressures. With frequent and severe outbreaks, disease resistance is a key tool for controlling stripe rust on wheat. The goal of this research was to identify quantitative trait loci (QTL) involved in stripe rust resistance from the important US Pacific Northwest soft white winter wheat varieties “Eltan” and “Finch”. An F2:5 recombinant inbred line (RIL) mapping population of 151 individuals derived from the Finch × Eltan cross was developed through single seed descent. A linkage map comprising 683 unique single nucleotide polymorphism (SNP) loci and 70 SSR markers were used to develop 22 linkage groups consisting of 16 of the 21 chromosomes. Stripe rust data were collected on the RILs during the summers of 2012 to 2014. QTL analysis identified two genomic regions on chromosomes 4A (QYrel.wak-4A) and 6B (QYrfi.wak-6B) associated with resistance from Eltan and Finch, respectively. The results of the QTL analysis showed that QYrel.wak-4A and QYrfi.wak-6B reduced infection type and disease severity. Based upon both molecular and phenotypic differences, QYrel.wak-4A is a novel QTL for adult plant resistance (APR) to stripe rust.
      PubDate: 2016-01-06
      DOI: 10.3390/agronomy6010004
      Issue No: Vol. 6, No. 1 (2016)
       
  • Agronomy, Vol. 6, Pages 5: Extracellular Trapping of Soil Contaminants by
           Root Border Cells: New Insights into Plant Defense

    • Authors: Martha Hawes, Jean McLain, Monica Ramirez-Andreotta, Gilberto Curlango-Rivera, Yolanda Flores-Lara, Lindy Brigham
      First page: 5
      Abstract: Soil and water pollution by metals and other toxic chemicals is difficult to measure and control, and, as such, presents an ongoing global threat to sustainable agriculture and human health. Efforts to remove contaminants by plant-mediated pathways, or “phytoremediation”, though widely studied, have failed to yield consistent, predictable removal of biological and chemical contaminants. Emerging research has revealed that one major limitation to using plants to clean up the environment is that plants are programmed to protect themselves: Like white blood cells in animals, border cells released from plant root tips carry out an extracellular trapping process to neutralize threats and prevent injury to the host. Variability in border cell trapping has been found to be correlated with variation in sensitivity of roots to aluminum, and removal of border cell results in increased Al uptake into the root tip. Studies now have implicated border cells in responses of diverse plant roots to a range of heavy metals, including arsenic, copper, cadmium, lead, mercury, iron, and zinc. A better understanding of border cell extracellular traps and their role in preventing toxin uptake may facilitate efforts to use plants as a nondestructive approach to neutralize environmental threats.
      PubDate: 2016-01-12
      DOI: 10.3390/agronomy6010005
      Issue No: Vol. 6, No. 1 (2016)
       
  • Agronomy, Vol. 6, Pages 6: Acknowledgement to Reviewers of Agronomy in
           2015

    • Authors: Agronomy Editorial Office
      First page: 6
      Abstract: The editors of agronomy would like to express their sincere gratitude to the following reviewers for assessing manuscripts in 2015. [...]
      PubDate: 2016-01-22
      DOI: 10.3390/agronomy6010006
      Issue No: Vol. 6, No. 1 (2016)
       
  • Agronomy, Vol. 6, Pages 7: Integrating Wheat Canopy Temperatures in Crop
           System Models

    • Authors: Dorothee Neukam, Hella Ahrends, Adam Luig, Remy Manderscheid, Henning Kage
      First page: 7
      Abstract: Crop system models are generally parametrized with daily air temperatures recorded at 1.5 or 2 m height. These data are not able to represent temperatures at the canopy level, which control crop growth, and the impact of heat stress on crop yield, which are modified by canopy characteristics and plant physiological processes Since such data are often not available and current simulation approaches are complex and/or based on unrealistic assumptions, new methods for integrating canopy temperatures in the framework of crop system models are needed. Based on a forward stepwise-based model selection procedure and quantile regression analyses, we developed empirical regression models to predict winter wheat canopy temperatures obtained from thermal infrared observations performed during four growing seasons for three irrigation levels. We used daily meteorological variables and the daily output data of a crop system model as covariates. The standard cross validation revealed a root mean square error (RMSE) of ~0.8 °C, 1.5–2 °C and 0.8–1.2 °C for estimating mean, maximum and minimum canopy temperature, respectively. Canopy temperature of both water-deficit and fully irrigated wheat plots significantly differed from air temperature. We suggest using locally calibrated empirical regression models of canopy temperature as a simple approach for including potentially amplifying or mitigating microclimatic effects on plant response to temperature stress in crop system models.
      PubDate: 2016-01-22
      DOI: 10.3390/agronomy6010007
      Issue No: Vol. 6, No. 1 (2016)
       
  • Agronomy, Vol. 6, Pages 8: Agro-Morphological Evaluation of Rice (Oryza
           sativa L.) for Seasonal Adaptation in the Sahelian Environment

    • Authors: Daba Ndour, Diaga Diouf, Isaac Bimpong, Abdoulaye Sow, Ghislain Kanfany, Baboucarr Manneh
      First page: 8
      Abstract: In the Sahel zone of West Africa that extends from Senegal to Chad, temperatures can vary from less than 15 °C to 25 °C from November to February. These low temperatures affect the growth, development and yield of rice plants, and therefore constitute a major constraint to rice production in the Sahel. In order to identify rice varieties tolerant to cold stress at different developmental stages, a diverse set of 224 rice germplasm was evaluated for yield and yield-related traits in Ndiaye, Senegal, using three different sowing dates. The first sowing date (October 2010), was chosen so as to expose the rice plants to cold stress at the reproductive stage while the rice crop planted at the second sowing date (January 2011) experienced cold stress at the vegetative stage. The third sowing date (July 2011) was the normal planting date for irrigated rice in the Sahel and it served as the control date when the crop does not experience any cold stress throughout its growth cycle. Among the data collected, significant genetic variation was detected and genotype-by-environment interaction was also significant for the traits. At the vegetative stage, cold stress reduced tillering and plant vigor and delayed flowering but increased yield, whereas at the reproductive stage, aside from delaying flowering, cold stress also inhibited panicle exsertion and reduced panicle length, spikelet fertility, grain filling and strongly reduced yields. Principal Component Analysis and correlation analysis using agro-morphological traits helped to identify genotypes that were tolerant to cold stress at either the vegetative or the reproductive stage and the traits associated with high yield under cold stress at each of these stages. Our results can be used to develop cold tolerant rice varieties adapted to double cropping in the Sahelian zone of West Africa.
      PubDate: 2016-02-12
      DOI: 10.3390/agronomy6010008
      Issue No: Vol. 6, No. 1 (2016)
       
  • Agronomy, Vol. 6, Pages 9: Polymer-Coated Urea Delays Growth and
           Accumulation of Key Nutrients in Aerobic Rice but Does Not Affect Grain
           Mineral Concentrations

    • Authors: Terry Rose
      First page: 9
      Abstract: Enhanced efficiency nitrogen (N) fertilizers (EEFs) may improve crop recovery of fertilizer-N, but there is evidence that some EEFs cause a lag in crop growth compared to growth with standard urea. Biomass and mineral nutrient accumulation was investigated in rice fertilized with urea, urea-3,4-dimethylpyrazole phosphate (DMPP) and polymer-coated urea (PCU) to determine whether any delays in biomass production alter the accumulation patterns, and subsequent grain concentrations, of key mineral nutrients. Plant growth and mineral accumulation and partitioning to grains did not differ significantly between plants fertilized with urea or urea-DMPP. In contrast, biomass accumulation and the accumulation of phosphorus, potassium, calcium, magnesium, copper, zinc and manganese were delayed during the early growth phase of plants fertilized with PCU. However, plants in the PCU treatment ultimately compensated for this by increasing growth and nutrient uptake during the latter vegetative stages so that no differences in biomass or nutrient accumulation generally existed among N fertilizer treatments at anthesis. Delayed biomass accumulation in rice fertilized with PCU does not appear to reduce the total accumulation of mineral nutrients, nor to have any impact on grain mineral nutrition when biomass and grain yields are equal to those of rice grown with urea or urea-DMPP.
      PubDate: 2016-01-28
      DOI: 10.3390/agronomy6010009
      Issue No: Vol. 6, No. 1 (2016)
       
  • Agronomy, Vol. 6, Pages 10: Selected Abiotic and Biotic Environmental
           Stress Factors Affecting Two Economically Important Sugarcane Stalk Boring
           Pests in the United States

    • Authors: Allan Showler
      First page: 10
      Abstract: Sugarcane, Saccharum spp., in the United States is attacked by a number of different arthropod pests. The most serious among those pests are two stalk boring moths in the Family Crambidae: the sugarcane borer, Diatraea saccharalis (F.), and the Mexican rice borer, Eoreuma loftini (Dyar). The two species are affected by abiotic and biotic environmental stress factors. Water deficit and excessive soil nitrogen alter physical and physiochemical aspects of the sugarcane plant that make the crop increasingly vulnerable to E. loftini. Weed growth can be competitive with sugarcane but it also supports enhanced abundances and diversity of natural enemies that can suppress infestations of D. saccharalis. In an instance where the stalk borer is considered a stress factor, proximity of vulnerable crops to sugarcane can influence levels of E. loftini infestation of sugarcane. The adverse effects of each stress factor, in terms of stalk borer attack, can be reduced by adopting appropriate cultural practices, such as adequate irrigation, judicious use of nitrogen fertilizer, using noncompetitive weed growth, and not planting vulnerable crops near sugarcane fields. Understanding the relationships between stress factors and crop pests can provide valuable insights for plant breeders and tools for incorporation into integrated pest management strategies.
      PubDate: 2016-02-01
      DOI: 10.3390/agronomy6010010
      Issue No: Vol. 6, No. 1 (2016)
       
  • Agronomy, Vol. 6, Pages 11: Symbiotic Efficiency of Native and Exotic
           Rhizobium Strains Nodulating Lentil (Lens culinaris Medik.) in Soils of
           Southern Ethiopia

    • Authors: Wondwosen Tena, Endalkachew Wolde-Meskel, Fran Walley
      First page: 11
      Abstract: Lentil plays a major role in the food and nutritional security of low income Ethiopian families because of the high protein content of their seed; however, their productivity typically is low largely due to soil fertility limitations. Field and pot experiments were conducted during the 2011 cropping season to determine the effectiveness of Rhizobium strains on two cultivars of lentil in Southern Ethiopia. Six rhizobial inoculant treatments (four indigenous and two commercial inoculants), a nitrogen (N) fertilizer treatment (50 kg·urea·ha−1) and an absolute control (non-inoculated non-fertilized) were used. Inoculated plants produced significantly higher nodule number, nodule dry weight, grain yield and yield components than non-inoculated non-fertilized plants. Inoculation of field grown lentil with rhizobia strain Lt29 and Lt5 enhanced seed yield by 59% and 44%, respectively. Whereas urea fertilization enhanced yields by 40%. Similarly, grain yields were increased during the pot experiment by 92% and 67% over the control treatments by inoculation with Lt29 and Lt5, respectively. The highest levels of N fixation were achieved in plants inoculated with Lt29 (65.7% Ndfa). Both field and pot investigations indicate that inoculation of lentil with native rhizobial strains replace the need for inorganic N fertilization to optimize lentil yields.
      PubDate: 2016-02-17
      DOI: 10.3390/agronomy6010011
      Issue No: Vol. 6, No. 1 (2016)
       
  • Agronomy, Vol. 6, Pages 12: Impact of the Disruption of ASN3-Encoding
           Asparagine Synthetase on Arabidopsis Development

    • Authors: Laure Gaufichon, Anne Marmagne, Tadakatsu Yoneyama, Toshiharu Hase, Gilles Clément, Marion Trassaert, Xiaole Xu, Maryam Shakibaei, Amina Najihi, Akira Suzuki
      First page: 12
      Abstract: The aim of this study was to investigate the role of ASN3-encoded asparagine synthetase (AS, EC 6.3.5.4) during vegetative growth, seed development and germination of Arabidopsis thaliana. Phenotypic analysis of knockout (asn3-1) and knockdown (asn3-2) T-DNA insertion mutants for the ASN3 gene (At5g10240) demonstrated wild-type contents of asparagine synthetase protein, chlorophyll and ammonium in green leaves at 35 days after sowing. In situ hybridization localized ASN3 mRNA to phloem companion cells of vasculature. Young siliques of the asn3-1 knockout line showed a decrease in asparagine but an increase in glutamate. The seeds of asn3-1 and asn3-2 displayed a wild-type nitrogen status expressed as total nitrogen content, indicating that the repression of ASN3 expression had only a limited effect on mature seeds. An analysis of amino acid labeling of seeds imbibed with (15N) ammonium for 24 h revealed that asn3-1 seeds contained 20% less total asparagine while 15N-labeled asparagine ((2-15N)asparagine, (4-15N)asparagine and (2,4-15N)asparagine) increased by 12% compared to wild-type seeds. The data indicate a fine regulation of asparagine synthesis and hydrolysis in Arabidopsis seeds.
      PubDate: 2016-02-14
      DOI: 10.3390/agronomy6010012
      Issue No: Vol. 6, No. 1 (2016)
       
  • Agronomy, Vol. 6, Pages 13: Application of Two Bioenergy Byproducts with
           Contrasting Carbon Availability to a Prairie Soil: Three-Year Crop
           Response and Changes in Soil Biological and Chemical Properties

    • Authors: Khaled Alotaibi, Jeff Schoenau
      First page: 13
      Abstract: The bioenergy industry produces a wide range of byproducts varying in their chemical composition depending on type of technology employed. In particular, pyrolysis and transesterification conversion processes generate C-rich byproducts of biochar (BC) and glycerol (GL), respectively, which can be added to soil. These two byproducts vary in their carbon availability, and comparing their effects when added to agricultural soil deserves attention. This study investigated the immediate and residual effects of a single application of BC and GL to a cultivated Brown Chernozem soil from the semi-arid region of southwestern Saskatchewan, Canada. In the first season following addition of amendments, BC and GL alone had no significant impact on all measured parameters. However, when combined with 50 kg urea N·ha−1 (BC + UR), the yields obtained were similar to those with 100 kg urea N·ha−1 alone. The GL with urea N (GL + UR) treatment had reduced crop yield and N uptake compared to urea alone in the year of application attributed to N immobilization, but had a positive residual effect in the second year due to remineralization. Both GL and GL + UR treatments enhanced dehydrogenase activity compared to other treatments whereas BC + UR tended to decrease microbial biomass C. The crop and soil response to application of biochar was less than observed in previous studies conducted elsewhere. Direct and residual effects of glycerol addition on the crop were more evident. An application rate greater than 2.8 t·ha−1 and 3.5 t·ha−1 for BC and GL, respectively, may be required to induce larger responses.
      PubDate: 2016-02-15
      DOI: 10.3390/agronomy6010013
      Issue No: Vol. 6, No. 1 (2016)
       
  • Agronomy, Vol. 6, Pages 14: Stability of the Inherent Target Metallome in
           Seed Crops and a Mushroom Grown on Soils of Extreme Mineral Spans

    • Authors: Gerhard Gramss, Klaus-Dieter Voigt
      First page: 14
      Abstract: Extremes in soil mineral supply alter the metallome of seeds much less than that of their herbage. The underlying mechanisms of mineral homeostasis and the “puzzle of seed filling” are not yet understood. Field crops of wheat, rye, pea, and the mushroom Kuehneromyces mutabilis were established on a set of metalliferous uranium mine soils and alluvial sands. Mineral concentrations in mature plants were determined from roots to seeds (and to fungal basidiospores) by ICP-MS following microwave digestion. The results referred to the concentrations of soil minerals to illustrate regulatory breaks in their flow across the plant sections. Root mineral concentrations fell to a mean of 7.8% in the lower stem of wheat in proportions deviating from those in seeds. Following down- and up-regulations in the flow, the rachis/seed interface configured with cuts in the range of 1.6%–12% (AsPbUZn) and up-regulations in the range of 106%–728% (CuMgMnP) the final grain metallome. Those of pea seeds and basidiospores were controlled accordingly. Soil concentration spans of 9–109× in CuFeMnNiZn shrank thereby to 1.3–2× in seeds to reveal the plateau of the cultivar’s desired target metallome. This was brought about by adaptations of the seed:soil transfer factors which increased proportionally in lower-concentrated soils. The plants thereby distinguished chemically similar elements (As/P; Cd/Zn) and incorporated even non-essential ones actively. It is presumed that high- and low-concentrated soils may impair the mineral concentrations of phloems as the donors of seed minerals. In an analytical and strategic top performance, essential and non-essential phloem constituents are identified and individually transferred to the propagules in precisely delimited quantities.
      PubDate: 2016-02-18
      DOI: 10.3390/agronomy6010014
      Issue No: Vol. 6, No. 1 (2016)
       
  • Agronomy, Vol. 6, Pages 15: Identification of Barley (Hordeum vulgare L.)
           Autophagy Genes and Their Expression Levels during Leaf Senescence,
           Chronic Nitrogen Limitation and in Response to Dark Exposure

    • Authors: Liliana Avila-Ospina, Anne Marmagne, Fabienne Soulay, Céline Masclaux-Daubresse
      First page: 15
      Abstract: Barley is a cereal of primary importance for forage and human nutrition, and is a useful model for wheat. Autophagy genes first described in yeast have been subsequently isolated in mammals and Arabidopsis thaliana. In Arabidopsis and maize it was recently shown that autophagy machinery participates in nitrogen remobilization for grain filling. In rice, autophagy is also important for nitrogen recycling at the vegetative stage. In this study, HvATGs, HvNBR1 and HvATI1 sequences were identified from bacterial artificial chromosome (BAC), complementary DNA (cDNA) and expressed sequence tag (EST) libraries. The gene models were subsequently determined from alignments between genome and transcript sequences. Essential amino acids were identified from the protein sequences in order to estimate their functionality. A total of twenty-four barley HvATG genes, one HvNBR1 gene and one HvATI1 gene were identified. Except for HvATG5, all the genomic sequences found completely matched their cDNA sequences. The HvATG5 gene sequence presents a gap that cannot be sequenced due to its high GC content. The HvATG5 coding DNA sequence (CDS), when over-expressed in the Arabidopsis atg5 mutant, complemented the plant phenotype. The HvATG transcript levels were increased globally by leaf senescence, nitrogen starvation and dark-treatment. The induction of HvATG5 during senescence was mainly observed in the flag leaves, while it remained surprisingly stable in the seedling leaves, irrespective of the leaf age during stress treatment.
      PubDate: 2016-02-22
      DOI: 10.3390/agronomy6010015
      Issue No: Vol. 6, No. 1 (2016)
       
  • Agronomy, Vol. 6, Pages 16: Organically Grown Soybean Production in the
           USA: Constraints and Management of Pathogens and Insect Pests

    • Authors: Glen Hartman, Michelle Pawlowski, Theresa Herman, Darin Eastburn
      First page: 16
      Abstract: Soybean is the most produced and consumed oil seed crop worldwide. In 2013, 226 million metric tons were produced in over 70 countries. Organically produced soybean represents less than 0.1% of total world production. In the USA, the certified organic soybean crop was grown on 53 thousand ha or 0.17% of the total soybean acreage in the USA (32 million ha) in 2011. A gradual increase in production of organically grown soybean has occurred since the inception of organic labeling due to increased human consumption of soy products and increased demand for organic soybean meal to produce organic animal products. Production constraints caused by pathogens and insect pests are often similar in organic and non-organic soybean production, but management between the two systems often differs. In general, the non-organic, grain-type soybean crop are genetically modified higher-yielding cultivars, often with disease and pest resistance, and are grown with the use of synthetic pesticides. The higher value of organically produced soybean makes production of the crop an attractive option to some farmers. This article reviews production and uses of organically grown soybean in the USA, potential constraints to production caused by pathogens and insect pests, and management practices used to reduce the impact of these constraints.
      PubDate: 2016-02-23
      DOI: 10.3390/agronomy6010016
      Issue No: Vol. 6, No. 1 (2016)
       
  • Agronomy, Vol. 6, Pages 17: Temporal Dynamics in Rhizosphere Bacterial
           Communities of Three Perennial Grassland Species

    • Authors: Cheryl Murphy, Bryan Foster, Cuilan Gao
      First page: 17
      Abstract: Rhizodeposition is considered a primary reason for the plant identity effect. However, the detection of distinct rhizosphere bacterial communities (RBC) with different plant species has been variable. The aim of this study was to examine the potential explanations for this variability using three perennial grassland species. In a Kansas field experiment, over two growing seasons, we sampled RBC during the active growth and flowering stages of Agrostis gigantea, Andropogon gerardii and Helianthus maximiliani to: (1) determine the extent of the plant identity effect among these species and if the effect was maintained over time; (2) assess if RBC showed seasonal patterns, corresponding to plant phenology; and (3) examine if soil properties were important for structuring these communities. We found that Helianthus RBC were distinct from those of Agrostis and Andropogon only when Helianthus was flowering. Further, Helianthus RBC exhibited seasonal shifts corresponding to plant phenology. In contrast, Agrostis and Andropogon RBC were similar over time and exhibited gradual non-seasonal changes in compositions. Similar results were observed when accounting for soil properties. Overall, the observance of a plant identity effect depended on the plant species and when RBC were sampled. The seasonality of RBC also depended on the plant species examined.
      PubDate: 2016-03-01
      DOI: 10.3390/agronomy6010017
      Issue No: Vol. 6, No. 1 (2016)
       
  • Agronomy, Vol. 6, Pages 18: An Update on Genetic Resistance of Chickpea to
           Ascochyta Blight

    • Authors: Mamta Sharma, Raju Ghosh
      First page: 18
      Abstract: Ascochyta blight (AB) caused by Ascochyta rabiei (Pass.) Labr. is an important and widespread disease of chickpea (Cicer arietinum L.) worldwide. The disease is particularly severe under cool and humid weather conditions. Breeding for host resistance is an efficient means to combat this disease. In this paper, attempts have been made to summarize the progress made in identifying resistance sources, genetics and breeding for resistance, and genetic variation among the pathogen population. The search for resistance to AB in chickpea germplasm, breeding lines and land races using various screening methods has been updated. Importance of the genotype × environment (GE) interaction in elucidating the aggressiveness among isolates from different locations and the identification of pathotypes and stable sources of resistance have also been discussed. Current and modern breeding programs for AB resistance based on crossing resistant/multiple resistant and high-yielding cultivars, stability of the breeding lines through multi-location testing and molecular marker-assisted selection method have been discussed. Gene pyramiding and the use of resistant genes present in wild relatives can be useful methods in the future. Identification of additional sources of resistance genes, good characterization of the host–pathogen system, and identification of molecular markers linked to resistance genes are suggested as the key areas for future study.
      PubDate: 2016-03-08
      DOI: 10.3390/agronomy6010018
      Issue No: Vol. 6, No. 1 (2016)
       
  • Agronomy, Vol. 6, Pages 19: Root Exudation: The Ecological Driver of
           Hydrocarbon Rhizoremediation

    • Authors: Fanny Rohrbacher, Marc St-Arnaud
      First page: 19
      Abstract: Rhizoremediation is a bioremediation technique whereby microbial degradation of organic contaminants occurs in the rhizosphere. It is considered to be an effective and affordable “green technology” for remediating soils contaminated with petroleum hydrocarbons. Root exudation of a wide variety of compounds (organic, amino and fatty acids, carbohydrates, vitamins, nucleotides, phenolic compounds, polysaccharides and proteins) provide better nutrient uptake for the rhizosphere microbiome. It is thought to be one of the predominant drivers of microbial communities in the rhizosphere and is therefore a potential key factor behind enhanced hydrocarbon biodegradation. Many of the genes responsible for bacterial adaptation in contaminated soil and the plant rhizosphere are carried by conjugative plasmids and transferred among bacteria. Because root exudates can stimulate gene transfer, conjugation in the rhizosphere is higher than in bulk soil. A better understanding of these phenomena could thus inform the development of techniques to manipulate the rhizosphere microbiome in ways that improve hydrocarbon bioremediation.
      PubDate: 2016-03-09
      DOI: 10.3390/agronomy6010019
      Issue No: Vol. 6, No. 1 (2016)
       
  • Agronomy, Vol. 6, Pages 20: NRT2.4 and NRT2.5 Are Two Half-Size
           Transporters from the Chlamydomonas NRT2 Family

    • Authors: Jose Higuera, Victoria Calatrava, Zaira González, Vicente Mariscal, Jose Siverio, Emilio Fernández, Aurora Galván
      First page: 20
      Abstract: The NRT2 transporters mediate High Affinity Nitrate/NitriteTransport (HAN/NiT), which are essential for nitrogen acquisition from these inorganic forms. The NRT2 proteins are encoded by a multigene family in plants, and contain 12 transmembrane-spanning domains. Chlamydomonas reinhardtii has six NRT2, two of which (NRT2.5 and NRT2.4) are located in Chromosome III, in tandem head to tail. cDNAs for these genes were isolated and their sequence revealed that they correspond to half-size NRT2 transporters each containing six transmembrane domains. NRT2.5 has long N- and C- termini sequences without known homology. NRT2.4 also contains long termini sequences but smaller than NRT2.5. Expression of both studied genes occurred at a very low level, slightly in darkness, and was not modified by the N or C source. Silencing of NRT2.4 by specific artificial miRNA resulted in the inhibition of nitrite transport in the absence of other HANNiT (NRT2.1/NAR2) in the cell genetic background. Nitrite transport activity in the Hansenula polymorpha Δynt::URA3 Leu2 mutant was restored by expressing CrNRT2.4. These results indicate that half-size NRT2 transporters are present in photosynthetic organisms and that NRT2.4 is a HANiT.
      PubDate: 2016-03-19
      DOI: 10.3390/agronomy6010020
      Issue No: Vol. 6, No. 1 (2016)
       
 
 
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