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AGRICULTURE (475 journals)                  1 2 3 4 5 | Last

Aceh International Journal of Science and Technology     Open Access   (Followers: 1)
Acta agriculturae Slovenica     Open Access   (Followers: 5)
Acta Agrobotanica     Open Access   (Followers: 3)
Acta Agronomica Hungarica     Full-text available via subscription   (Followers: 1)
Acta Agronomica Sinica     Full-text available via subscription   (Followers: 6)
Acta Scientiarum. Animal Sciences     Open Access   (Followers: 1)
Acta Scientiarum. Technology     Open Access   (Followers: 1)
Acta Technologica Agriculturae     Open Access   (Followers: 3)
Advances in Agriculture     Open Access   (Followers: 1)
Advances in Agriculture & Botanics     Open Access   (Followers: 10)
Advances in Agriculture, Sciences and Engineering Research     Open Access   (Followers: 12)
Advances in Agronomy     Full-text available via subscription   (Followers: 11)
Advances in Life Science and Technology     Open Access   (Followers: 5)
AFBM Journal     Open Access  
Africa Development     Open Access   (Followers: 9)
Africa Research Bulletin: Political, Social and Cultural Series     Hybrid Journal   (Followers: 8)
African Journal of Agricultural Research     Open Access   (Followers: 3)
African Journal of Food Science     Open Access   (Followers: 4)
African Journal of Food, Agriculture, Nutrition and Development     Open Access   (Followers: 7)
African Journal of Horticultural Science     Open Access   (Followers: 2)
African Journal of Range & Forage Science     Hybrid Journal   (Followers: 5)
African Journal of Sustainable Development     Full-text available via subscription   (Followers: 5)
Agribusiness : an International Journal     Hybrid Journal   (Followers: 4)
Agricultura Tecnica     Open Access   (Followers: 6)
Agricultura Tropica et Subtropica     Open Access   (Followers: 2)
Agricultural Advances     Open Access   (Followers: 4)
Agricultural and Food Science     Open Access   (Followers: 19)
Agricultural Economics     Hybrid Journal   (Followers: 47)
Agricultural History     Full-text available via subscription   (Followers: 264)
Agricultural Research     Hybrid Journal   (Followers: 6)
Agricultural Science     Full-text available via subscription   (Followers: 6)
Agricultural Science     Open Access  
Agricultural Sciences     Open Access   (Followers: 8)
Agricultural Sciences in China     Full-text available via subscription   (Followers: 4)
Agricultural Systems     Hybrid Journal   (Followers: 21)
Agricultural Water Management     Hybrid Journal   (Followers: 17)
Agriculture     Open Access   (Followers: 5)
Agriculture & Food Security     Open Access   (Followers: 12)
Agriculture (Poľnohospodárstvo)     Open Access   (Followers: 1)
Agriculture and Agricultural Science Procedia     Full-text available via subscription   (Followers: 1)
Agriculture and Human Values     Hybrid Journal   (Followers: 11)
Agriculture, Ecosystems & Environment     Hybrid Journal   (Followers: 32)
Agriprobe     Full-text available via subscription  
Agrivita : Journal of Agricultural Science     Open Access   (Followers: 4)
Agro-Science     Full-text available via subscription  
Agroalimentaria     Open Access   (Followers: 1)
Agrociencia     Open Access   (Followers: 2)
Agrokémia és Talajtan     Full-text available via subscription   (Followers: 1)
Agronomía Colombiana     Open Access   (Followers: 1)
Agronomía Costarricense     Open Access   (Followers: 2)
Agronomía Mesoamericana     Open Access   (Followers: 1)
Agronomie Africaine     Full-text available via subscription  
Agronomy     Open Access   (Followers: 8)
Agrosearch     Open Access  
AI & Society     Hybrid Journal   (Followers: 2)
Alinteri Zirai Bilimler Dergisi : Alinteri Journal of Agricultural Sciences     Open Access  
Ambiência     Open Access  
Ambiente & Agua : An Interdisciplinary Journal of Applied Science     Open Access   (Followers: 1)
American Journal of Agricultural and Biological Sciences     Open Access   (Followers: 10)
American Journal of Botany     Full-text available via subscription   (Followers: 15)
American Journal of Economics and Sociology     Hybrid Journal   (Followers: 21)
American Journal of Potato Research     Hybrid Journal   (Followers: 2)
American Journal of Rural Development     Open Access   (Followers: 1)
Anais da Academia Brasileira de Ciências     Open Access   (Followers: 2)
Annales des Sciences Agronomiques     Full-text available via subscription  
Annals of Agricultural and Environmental Medicine     Open Access   (Followers: 1)
Annals of Agricultural Sciences     Open Access   (Followers: 1)
Annual Review of Resource Economics     Full-text available via subscription   (Followers: 11)
APCBEE Procedia     Partially Free   (Followers: 2)
Applied Economics Letters     Hybrid Journal   (Followers: 22)
Applied Financial Economics Letters     Hybrid Journal   (Followers: 7)
Arboricultural Journal : The International Journal of Urban Forestry     Hybrid Journal   (Followers: 7)
Archivos de Zootecnia     Open Access   (Followers: 4)
Arquivos do Instituto Biológico     Open Access  
Arthropod-Plant Interactions     Hybrid Journal   (Followers: 1)
Asian Economic Papers     Hybrid Journal   (Followers: 3)
Asian Journal of Agricultural Research     Open Access   (Followers: 4)
Asian Journal of Plant Sciences     Open Access   (Followers: 2)
Australian Cottongrower, The     Full-text available via subscription   (Followers: 1)
Australian Economic Papers     Hybrid Journal   (Followers: 5)
Australian Forest Grower     Full-text available via subscription   (Followers: 2)
Australian Forestry     Full-text available via subscription   (Followers: 4)
Australian Grain     Full-text available via subscription   (Followers: 4)
Australian Holstein Journal     Full-text available via subscription   (Followers: 1)
Australian Journal of Agricultural and Resource Economics     Hybrid Journal   (Followers: 5)
Australian Journal of Agricultural Engineering     Open Access  
Australian Sugarcane     Full-text available via subscription  
Avances en Investigacion Agropecuaria     Open Access   (Followers: 1)
Bangladesh Journal of Agricultural Research     Open Access   (Followers: 2)
Bangladesh Journal of Scientific Research     Open Access   (Followers: 1)
Berkala Ilmiah Pertanian     Open Access   (Followers: 1)
Bioagro     Open Access   (Followers: 1)
Biocatalysis and Agricultural Biotechnology     Hybrid Journal   (Followers: 5)
Biocontrol Science and Technology     Hybrid Journal   (Followers: 5)
Biodiversity     Hybrid Journal   (Followers: 24)
Biodiversity : Research and Conservation     Open Access   (Followers: 22)
Biological Agriculture & Horticulture : An International Journal for Sustainable Production Systems     Partially Free   (Followers: 14)
Biosystems Engineering     Hybrid Journal   (Followers: 1)
Biotemas     Open Access  
Bragantia     Open Access   (Followers: 2)

        1 2 3 4 5 | Last

Journal Cover   American Journal of Potato Research
  [SJR: 0.639]   [H-I: 26]   [4 followers]  Follow
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1874-9380 - ISSN (Online) 1099-209X
   Published by Springer-Verlag Homepage  [2300 journals]
  • R2 - like Gene Contributes to Resistance to Phytophthora infestans in
           Polish Potato Cultivar Bzura
    • Abstract: Abstract Potato cultivar Bzura bred in 1986 is one of the few European cultivars outstanding in high level of durable resistance to late blight, but its resistance has not been characterized. The presented study was aimed at clarifying bases of durable resistance in Bzura by testing its resistance and resistance in progeny individuals. In ten-year field experiment Bzura was significantly more resistant than mid-resistant standards Escort and Robijn, and only slightly less resistant than highly resistant Sárpo Mira. Bzura expressed also high resistance in detached leaflet tests when inoculated with specific isolates of Phytophthora infestans. It was found in Bzura progeny that this race-specific resistance segregated in 1:1 ratio and is governed by a major resistance gene R2-like. However, the long-lasting field resistance observed in Bzura could be explained by combination of R2-like gene and specific genetic background of this cultivar rather than by this gene exclusively.
      PubDate: 2015-02-13
  • Attainable CO 2 Emission of Ware Potatoes Under High Yield Conditions in
           Southern Chile
    • Abstract: Abstract The objective of the analysis was to calculate the attainable CO2 emissions associated with the production of one ton of potatoes in a high yield environment in southern Chile. Two field experiments were performed. The first field experiment used an optimal sowing date while the second experiment used a late sowing date. In each experiment, treatments were the factorial combination of (i) four N fertilization rates (0, 75, 150 and 250 kg N ha−1) and (ii) four P fertilization rates (0, 150, 300 33 and 450 kg P2O5 ha−1). The Cool Farm Tool – Potato (CFT) was used to calculate the amount of CO2 produced per one ton of potatoes and LINTUL-Potato was used to simulate potential yields. High variations in tuber yields were observed across experiments (90 and 36 t ha−1). The average tuber yield in experiment one (82 t ha−1) was greater than experiment two (51 t ha−1). Tuber yields were not significantly affected by N fertilization in either experiment. In contrast, tuber yield responded (P < 0.01) positively to P fertilization (10–82 %). The gaps between maximum and potential yields simulated in experiments one and two were 4 and 14 %, respectively. In experiment one, the average total CO2 emissions per ton of potatoes were lower than experiment two (41 and 72 kg CO2 eq t−1, respectively). In both experiments the total CO2 emissions were affected (P < 0.01) by both N and P fertilization. We conclude an average CO2 emission of 46 CO2 eq t−1 could be considered an attainable value for potato production systems with high technology intending to improve their carbon footprints in southern Chile.
      PubDate: 2015-02-12
  • A One-Step, Real-Time Reverse Transcription Loopmediated Isothermal
           Amplification Assay to Detect Potato Virus Y
    • Abstract: Abstract Potato viruses such as Potato virus Y (PVY) cause diseases that affect potato quality and thus damage potato production worldwide. Current tests for viral infection use double-antibody sandwich enzyme linked immunosorbent assays (DAS‑ELISA) or reverse transcription polymerase chain reaction (RT-PCR)/real-time RT-PCR. Despite many advantages, these assays have a number of drawbacks that affect cost and time of diagnosis. Reverse transcription loop-mediated isothermal amplification (RT-LAMP) allows fast detection of target RNA. Here, we developed a closed-tube real-time RT‑LAMP assay for fluorescent detection of PVY. Specific RT-LAMP primers were designed to target the conserved region of the sequence encoding the PVY coat protein. The assay was specific and facilitated sensitive PVY detection in a single tube at 65 °C. The time-to-positive values depended on the PVY concentration in tested samples. The effectiveness of RT‑LAMP in testing field-grown plants compared favorably with DAS‑ELISA and RT-PCR; under the tested conditions, RT-LAMP was about 1000-fold more sensitive than DAS‑ELISA and lateral flow assay (LFA) and about 10-fold more sensitive than RT‑PCR. Thus, this fluorescent RT-LAMP assay has great potential for routine detection of PVY.
      PubDate: 2015-02-11
  • High-Fidelity PCR Improves the Detection of ‘ Candidatus
           Liberibacter solanacearum’ in Potato Tubers
    • Abstract: Abstract Zebra chip disease (ZC) of potato tubers, caused by the unculturable bacterium ‘Candidatus Liberibacter solanacearum’ (Lso) can be difficult to detect from potato tuber tissue. The polymerase chain reaction is an important tool for the detection of plant pathogens, but there are limits to its sensitivity. High-fidelity PCR incorporates a proofreading enzyme with 3′-5′ exonuclease activity and has been shown to increase detection of pathogens when the titer is low or when large amounts of competitor DNA or other host cellular contents inhibit PCR amplification. In this study, high-fidelity PCR and conventional PCR protocols were performed on tubers presenting ZC symptoms. Asymptomatic tubers were used as control. The high-fidelity PCR increased detection of Lso from symptomatic tubers by 30–40 % over conventional PCR. Slight modifications were made from previous high-fidelity protocols to decrease testing time and simplify the protocol.
      PubDate: 2015-02-11
  • The Effect of High Temperature Occurring in Subsequent Stages of Plant
           Development on Potato Yield and Tuber Physiological Defects
    • Abstract: Abstract Potato (Solanum tuberosum L.) is characterized by specific temperature requirements and develops best at about 20 °C. High temperatures during the growing season cause an array of changes in potato plants, which affect its development and may lead to a drastic reduction in economic yield. In natural conditions drought and heat stress are two different types of abiotic stresses that occur in the field simultaneously or separately, in the case of irrigation use on potato plantations. The aim of this work was to assess the response of six potato cultivars to high temperature during the subsequent stages of plant growth under conditions of good soil moisture and drought. The pot experiment was carried out with the cultivars: Aruba, Desirée, Etola, Finezja, Flaming and Tetyda. The impact of high temperature day/ night 35 °C/25 °C on potato plants was tested in three periods: June 16–30, July 1–15 and July 16–30. In these periods half of the plants were watered to a level close to optimal, while the other half remained without irrigation. Final harvest was performed after full maturity of plants in the control combination. Our studies confirm the view that potato productivity is greatly reduced at temperatures higher than optimum. Here we demonstrated that tested potato cultivar’s response to high temperature during the growing season is dependent on the growth stage. The earlier a heat occurs, the more negative its impact on the growth and total yield of potatoes. The results obtained in this study indicate that among the tested cultivars ‘Tetyda’ was the most tolerant to high temperature acting on the plants during the growing season. Our research shows that the total yield is not the only indicator of potato tolerance to high temperature during the growing season, but the assessment should also take into account the occurrence of secondary tuberization and physiological defects of tubers.
      PubDate: 2015-02-11
  • Characteristics of Polish Isolates of Fusarium sambucinum : Molecular
           Identification, Pathogenicity, Diversity and Reaction to Control Agents
    • Abstract: Abstract Pathogenicity of 28 Polish isolates of F. sambucinum to potato tubers, their sensitivity to control agents, diversity among isolates and molecular methods of species identification were examined. All isolates were pathogenic to potato tubers and differences in pathogenicity were found. Isolates on the PDA were classified into three different color groups of mycelium (B - bright-beige, P - salmon pink, R - rose) that varied in pathogenicity and mycelium growth rate on PDA. P colonies showed the greatest tuber damage, but they grew the slowest on the PDA. Isolates showed varied reaction to different concentrations of 4 control agents (M - mancozeb, C- captan, CO - copper oxychloride and GE - grapefruit extract). The highest mycelium growth inhibition (MGI) was caused by M and the lowest by CO. Strong MGI by GE was observed especially for P isolates. Individual isolates showed different susceptibility to the control agents. Identification of isolates was determined in PCR assay with species specific FSF1/FSR1 primers, by sequencing of DNA fragments derived from ITS regions and the translation elongation factor-1 alpha gene (TEF). Sequence of the ITS regions were identical for all isolates. Analysis of the TEF DNA fragments showed one SNP (transition C↔T) in the sequences of isolates from the three different color groups.
      PubDate: 2015-02-01
  • Screening Potato Cultivars for new Sources of Resistance to Potato virus Y
    • Abstract: Abstract Potato virus Y (PVY) strains have been defined based on genetic reactions in potato indicators expressing hypersensitive reaction (HR) response due to the presence of three different N genes, and also based on genomic information. Nine strains are known currently, with five PVY strains defined biologically, PVYO, PVYC, PVYZ, PVYN, and PVYE. The genetic background of the majority of North American potato cultivars has so far been poorly characterized for the presence of N genes inducing HR towards different PVY strains. Here, the HR response was studied in eight potato cultivars, elicited by five strains of PVY circulating in North America. These PVY isolates included representative isolates of PVYN-Wi, PVYNA-N, PVYO, PVYZ, and PVYN strains. Potato cultivars tested included Russet Burbank, Russet Norkotah, Shepody, Ranger Russet, Western Russet, Alturas, Rio Grande Russet, and Yukon Gem, grown in the U.S., and standard indicators Desiree and Maris Bard with the known genetic background. Three additional strains, PVYN:O, PVY-NE11, and PVYE, were tested on Yukon Gem. Virus-free potato plants were mechanically inoculated with PVY inoculum, and local and systemic foliar symptoms were observed for 8 weeks post-inoculation under different climate-controlled conditions. Virus status of the inoculated plants was tested starting at 3 weeks post-inoculation, by serotype-specific ELISA and RT-PCR, in order to monitor successful infections and confirm the identity of the inoculated PVY isolate. This systematic approach allowed us to identify Ny tbr and Nz tbr genes present in several North American cultivars. Two more new, putative N genes were postulated to be expressed in the cultivar Yukon Gem, and one additional putative N gene was postulated to be expressed in two cultivars, Yukon Gem and Rio Grande Russet. These N genes may represent valuable sources of resistance against multiple strains of PVY.
      PubDate: 2015-02-01
  • Yield Response and Late Blight Reaction of Potato Genotypes in Rwanda
    • Abstract: Abstract Potato (Solanum tuberosum L.) genotypes with relatively high yield level and resistance to the late blight disease are being developed by the International Potato Centre (CIP) and made available to developing countries. However, for effective breeding for high yield and late blight resistance, these CIP materials and locally adapted genotypes need to be evaluated and screened under target growing environmental conditions. The objectives of the study were to determine yield response and late blight resistance of potato genotypes grown in Rwanda and candidate clones obtained from CIP and to identify suitable parents for breeding. A total of 44 potato genotypes, 30 acquired from CIP and 14 local varieties were evaluated under three environments (Kinigi, Rwerere and Nyamagabe). Experiments were laid out in an 11 × 4 alpha lattice design with two replications. Data were collected on late blight severity (%) based on the relative area under the disease progress curve (RAUDPC: 100 % max), total tuber yield, marketable tuber weight and dry matter content. Genotypes had significant differences on blight resistance and yield levels among test locations. Eight genotypes (391,047.34, 393,385.39, 393,280.82, 396,036.201, Gikungu, Ngunda, Kigega and Nderera) were identified as promising parents for subsequent crosses. The selected genotypes display farmers-preferred traits, productive flowers, high to medium late blight resistance and high yields.
      PubDate: 2015-02-01
  • The Effects of Chlorpropham Exposure on Field-Grown Potatoes
    • Abstract: Abstract Chlorpropham (CIPC) is a highly effective potato (Solanum tuberosum L.) sprout inhibitor. Some export regulations require CIPC or other sprout inhibitor to be applied to potatoes as a general phytosanitary measure. In addition, due to trucking and temporary storage issues, seed potatoes may be inadvertently exposed to CIPC. The objective of this 2-year study was to document the effects of several low rates of CIPC application or contamination on emergence, yield, and grade of the subsequent crop. CIPC was sprayed on whole ‘Russet Burbank’ seed tubers at rates of 0, 1.3, 2.5, 5.0, and 10.0 ppm CIPC. Seed tubers were cut, planted and grown under typical commercial practices for Idaho. Low rates of CIPC (1.3 and 2.5 ppm) applied to tubers resulted in significant delays in emergence compared to the untreated control. Some plants failed to emerge from seed treated with 5 or 10 ppm CIPC. CIPC treatment resulted in total yield decreases of 26 % (2.5 ppm CIPC) to 78 % (10 ppm CIPC) in 2009 and 36 % (1.3 ppm CIPC) to 94 % (10 ppm CIPC) in 2010 compared to the untreated controls in each respective year. Harvested tuber size profile was significantly altered by CIPC applications with higher rates producing smaller potatoes. These dramatic reductions in yield reinforce the importance of avoiding all potential for CIPC contamination of seed. The study also documents the severe consequences of planting commercial potatoes exported for consumption that have been treated with CIPC.
      PubDate: 2015-02-01
  • Propensity for Flying and Walking by the Colorado Potato Beetles Treated
           with Imidacloprid
    • Abstract: Abstract The Colorado potato beetle, Leptinotarsa decemlineata (Say) is a very serious pest of potatoes which is highly mobile and capable of rapid evolution of resistance to chemical control. Insect movement, resulting in gene flow between resistant and susceptible populations, is considered to be an important factor affecting the development and spread of insecticide resistance. We investigated the movement of adult Colorado potato beetles by flight and by walking following the treatment with a sublethal dose of imidacloprid in the laboratory. Imidacloprid had a pronounced negative effect on beetle mobility. The proportion of beetles flying and walking, as well as the number and duration of performed flights, were significantly decreased for the treated beetles. Since local selection followed by long-distance dispersal have been reported to lead to serious area-wide problems with the insecticide-resistant Colorado potato beetle, long-term suppression of flight activity recorded in our study suggests that imidacloprid applications may reduce outflow of resistant alleles.
      PubDate: 2015-02-01
  • The Influence of Ethephon Application Timing and Rate on Plant Growth,
           Yield, Tuber Size Distribution and Skin Color of Red LaSoda Potatoes
    • Abstract: Abstract Optimizing the response of growth regulators depends in part on finding the most appropriate application rate and timing. Preliminary trials indicate that ethephon (2-chloroethylphosphonic acid) may be useful for improving potato (Solanum tuberosum L.) tuber appearance and skin color of red-skinned cultivars, but relatively little is known about optimum application practices. Two separate trials were conducted at the University of Idaho Parma Research and Extension Center to evaluate the effect of ethephon foliar application timing and rate on plant growth, tuber yield, size distribution, and skin color of the cultivar Red LaSoda. Skin color was rated visually and by colorimeter at harvest and periodically throughout storage at 4 °C. In 2011, ethephon application timing did not influence plant height, total yield, tuber size or skin color but did affect some tuber size classes. In contrast, all of these parameters were significantly influenced by application timing in 2012. The optimum application timing to influence skin color was a relatively narrow window during initial flower development, to 10 days after initial flowering (coinciding with tuber initiation). Increasing rates of ethephon significantly reduced plant height, increased foliar injury symptoms, and reduced average tuber size, but did not influence total yield in Red LaSoda. Higher ethephon rates resulted in significantly darker tuber skin (lower L* values) and increased red color (increased chroma and reduce hue angle values) when compared to the non-treated control. Evaluation of samples held in storage showed that differences in skin color ratings at harvest were maintained throughout the storage period. It is concluded that two foliar applications of ethephon at a rate between 292 and 438 ml ha−1applied ten days apart, initiated at pre-bloom, will provide the optimum change in skin color and reduce average tuber size without reducing total yield.
      PubDate: 2015-02-01
  • Studies on varietal response to different strains of Potato virus Y (PVY)
           reveal hypersensitive resistance in Exploits to PVY O and extreme
           resistance in F87084 to all tested strains
    • Abstract: Abstract Potato cultivar Exploits and breeding clone F87084 have been considered resistant to Potato virus Y (PVY). To further explore the degree of resistance and whether the resistance is strain specific, these materials, together with cultivar Rochdale Gold-Dorée and breeding line F02010, were investigated for their response to different PVY strains including PVYO, PVYN:O, PVYNTN and PVYN. Both F02010 and Rochdale Gold-Dorée were readily infected with all tested PVY strains after either mechanical or graft inoculation, indicating susceptibility of the materials to PVY. F87084 was unable to be infected by any of the tested PVY strains as no ELISA-detectable level of PVY were found in plants after either mechanical or graft inoculation, demonstrating extreme resistance in F87084 to all strains of PVY tested. Exploits was infected with PVYN:O/PVYNTN/PVYN after either mechanical or graft inoculation, indicating susceptibility of the cultivar to these PVY strains. The cultivar was also infected readily with PVYO after graft inoculation. However, despite induction of local lesions on the inoculated leaves, mechanical inoculation with PVYO may or may not lead to systemic symptoms and ELISA-detectable level of PVY, depending on temperature. At low temperature (e.g., 22 °C), no visible systemic symptoms or ELISA-detectable level of PVY was found in the plants; whereas at high temperature (e.g., 30 °C), systemic symptoms and high level of PVY were detected in the plants. These results demonstrate that Exploits possesses temperature-dependent hypersensitive resistance to PVYO. Analysis of a segregating population of F87084 × F02010 revealed that the ER in F87084 is controlled by a dominant resistance gene.
      PubDate: 2015-02-01
  • Infection Risk Potential of South American Spongospora subterranea f.sp.
           subterranea Root Gall and Tuber Lesion Inoculum on Potato ( Solanum
           tuberosum ssp. tuberosum )
    • Abstract: Abstract Spongospora subterranea f. sp. subterranea causes the potato diseases powdery scab on tubers and galls on roots, and occurs in most potato production areas worldwide. The pathogen was probably introduced to Europe from South America in the 16th century. Three different genotype clusters have been found worldwide: the genetically variable groups from South America (native), and, in contrast, the nearly clonal group outside South America (invasive). An inoculation experiment was carried out with the long-day potato host ‘Agria’ comparing three different native Spongospora resting spore inocula with an invasive one, to determine the infection risk potential on a widely grown potato subspecies. All inocula led to root infection. Invasive tuber lesion sporosori from ‘Agria’ produced the greatest amount of infection, whereas the tuber lesion inoculum from the Venezuelan S. tuberosum ssp. tuberosum host and the root gall inoculum from the Colombian S. phureja host caused the least infections. The inoculum genotypes corresponded to all of the three previously described groups. Most root galls showed the invasive group type, independent of the inoculum. These results suggest that the most successful invasive genotype is still present in native pathogen populations and emphasize the need for continued quarantine vigilance to prevent new virulent recombinants of the pathogen.
      PubDate: 2015-02-01
  • Relationship Between Plant Vascular Architecture and Within-Plant
           Distribution of ‘Candidatus Liberibacter solanacearum ’ in
    • Abstract: Abstract ‘Candidatus Liberibacter solanacearum’ is an important pathogen of Solanaceous crops that causes zebra chip disease of potato. This pathogen is transmitted among plants by the potato psyllid Bactericera cockerelli. Within-plant spatial variability in Liberibacter infection impedes the ability to detect the bacterium before the onset of visible symptoms. The goal of our study was to test whether vascular architecture of potato explains the uneven distribution of Liberibacter after inoculation of leaves. The movement of rhodamine B among leaves was used to identify vascular connectivity among leaves. Three weeks after inoculating a single leaf with Liberibacter, the pathogen infected significantly more leaflets that had direct vascular connectivity with the inoculated leaf than leaflets with minimal connectivity. In a separate study, significantly more psyllids confined to whole leaves with direct vascular connectivity to a Liberibacter-infected leaf acquired the pathogen than did psyllids confined to leaves with indirect or partial connectivity to the infected leaf. Using fluorescence in situ hybridization, the pathogen was observed in the inner and outer phloem above and below the export leaf, respectively, corresponding with passive movement of Liberibacter in the phloem. Results of this study indicate that the distribution of Liberibacter in potato is at least partly limited by vascular architecture. This knowledge should improve the design of sampling methods to detect Liberibacter in asymptomatic plants.
      PubDate: 2015-02-01
  • Influence of Location, Year, Potato Rotation, and Chemical Seed Treatment
           on Incidence and Severity of Silver Scurf on Progeny Tubers
    • Abstract: Abstract A three-year study was conducted in 1999, 2001, and 2002 to examine the influence of seed-borne inoculum and fludioxonil+mancozeb seed treatment on silver scurf (caused by Helminthosporium solani) development on progeny tubers at six locations under different potato rotations in the semi-arid U.S. Pacific Northwest. Disease-free pre-nuclear seed and diseased generation 3 seed was either treated or not treated with fludioxonil plus mancozeb, planted, and progeny tubers were harvested and then evaluated for silver scurf incidence and severity. Experiments were conducted in the southern Columbia Basin (Oregon), northern Columbia Basin (Washington), central Oregon, southern Oregon, western Idaho, and eastern Idaho under short (<3 years), normal (3–5 years), and long (>5 years) potato rotations over the three years for a total of 19 location-year-rotation combinations. Significant differences were observed among years and locations with disease incidence being highest in central Oregon. Progeny tubers from untreated generation 3 seed had significantly higher silver scurf incidence (18.4 %) and severity (1.3) compared to untreated progeny tubers from pre-nuclear seed (1.2 % and 0.04 for incidence and severity, respectively). Seed treatment with fludioxonil+mancozeb reduced incidence (3.8 %) and severity (0.2) significantly compared to the untreated control (15.8 % and 1.1 for incidence and severity, respectively). Significant (P < 0.0001) interactions between treatments and location-year-rotation were observed and additive main effects multiplicative interaction analysis discriminated those with high incidence, severity, and variability. These data indicate that seed, not soil, is the primary source of progeny tuber infection in the field in the Pacific Northwest. For long term storage, purchase of clean seed is an essential component for managing silver scurf.
      PubDate: 2015-02-01
  • Use of Hill Shape with Various Nitrogen Timing Splits to Improve
           Fertilizer Use Efficiency
    • Abstract: Abstract The efficient use of fertilizer nitrogen (N) is critical for potato production in regions with sandy soils as concerns for groundwater contamination have become more apparent. The interactive effects of different hill shapes and distribution of in-season N fertilizer applications at various timings were evaluated in a 3-year potato (Solanum tuberosum L. cv. Russet Burbank) field experiment on a sandy soil in central Wisconsin. A split-plot design was used with hill shape (standard, shaped-plateau, or pointed) as the main plots and 202 kg N ha−1 divided into two, three, or four applications as the split plots. Broader, flatter hills provided tuber yield increases of 7 to 10 %, tuber size and grade improvements of 8 to 25 %, and increased tuber N uptake an average of 22 % in some years; however, post-emergence hilling operations negatively affected yield and tuber size and grade out in 1 of 2 years. Splitting the N into three in-season applications (emergence, early tuberization, and tuberization + 20 days) increased tuber yield by about 4 % or tuber size by 19 % in years where rain increased leaching potential on this sandy soil, but further splitting increased the proportion of small tubers that passed a 5.1-cm screen. This study confirmed that more blocky-shaped hills with only one hilling operation at emergence can significantly benefit potato yield and quality, and fertilizer N use efficiency on these sandy soils.
      PubDate: 2015-02-01
  • Rapid Cycling of Potato Tuber Generations by Overcoming Dormancy
    • Abstract: Abstract Dormancy hinders progress in attempts to fast track potato tuber generations. In this study, we evaluated the ability of gibberellic acid (GA) to overcome dormancy in freshly harvested tubers of 11 potato cultivars in 2 years of field trials. Tubers were wounded and dipped in 0, 10, 100, and 1,000 ppm GA. Then they were planted in the field 5 days later. Vine length and stem number were measured throughout the season. Tubers were also harvested and weighed. Cultivars varied in their response to GA treatment. However, for all cultivars, wounding followed by treatment with 10 or 100 ppm effectively overcame dormancy. The 1,000 ppm treatment produced excessive vine growth and lower yield compared to the lower concentrations. Consequently, wounding of freshly harvested tubers, followed by a dip in 10 or 100 ppm GA is recommended to overcome tuber dormancy in programs interested in rapid cycling.
      PubDate: 2015-02-01
  • Mechanical Transmission of Potato Virus Y (PVY) Through Seed Cutting and
           Plant Wounding
    • Abstract: Abstract The transmission of PVY strains, PVYO, PVYN:O, and PVYNTN via tuber cutting and plant wounding was investigated in PVY susceptible cultivars Shepody and Russet Norkotah. For the tuber cutting experiment, after one infected tuber was cut with a knife, four uninfected tubers were cut sequentially with the same knife without disinfecting it between the cuts. In the plant wounding experiments, wounds were induced in the healthy and infected plants of Shepody by bouncing, brushing, hammering, squeezing, and Carborundum rubbing treatments. These treatments allowed exchange of sap between the healthy and infected plants. Results demonstrated that seed cutting did not transmit PVY, whereas plant wounding treatments caused varying levels of PVY transmission, depending on the wounding treatment. Plant bouncing was the least effective whereas hammering was the most effective.
      PubDate: 2015-02-01
  • Low-Cost Potato Tissue Culture with Microwave and Bleach Media Preparation
           and Sterilization
    • Abstract: Abstract Labor and equipment costs are the main expenses in potato micropropagation. To determine if we could reduce costs associated with media sterilization, a disinfectant, sodium hypochlorite (NaOCl), in combination with microwave heating, were assayed as media sterilants. Incorporating a common 5 % NaOCl household beach at a concentration of 9 ppm (active chlorine) in media sterilized with an autoclave or microwave oven controlled microorganism growth and maintained plantlet growth performance. Non-sterile 473 ml (16 oz.) clear deli containers were selected as an inexpensive replacement for traditional culture vessels and were effectively sterilized with a 50 ppm (active chlorine) NaOCl solution. Reuse of the non-sterile clear deli containers and alternate media water sources were also tested but this decreased plantlet growth performance. Comparison of a controlled growth chamber and ambient laboratory conditions was also investigated. Microorganism growth was significantly less in a controlled growth chamber (5 %) as compared to uncontrolled conditions (26–36 %).
      PubDate: 2014-12-06
  • Soil Phosphorus Increases Dry Matter and Nutrient Accumulation and
           Allocation in Potato Cultivars
    • Abstract: Abstract Understanding the influence of P in the pattern of production and partitioning of dry matter (DM) and nutrients to the tubers of potato cultivars is critical for development of rational fertilization strategies to optimize tuber yield. The objective of this study was to evaluate the effect of soil P availability (Low P: 10 mg dm−3 and High P: 111 mg dm−3) in the leaf nutrients concentration, nutrients and DM accumulation and allocation to tubers of five potato cultivars (Agata, Asterix, Atlantic, Markies, and Mondial). The experiment was conducted under greenhouse conditions in pots containing 35 L of a Typic Acrortox soil. High P availability in the soil increased P concentrations in all plant organs, uptake of P and Cu, and DM production of all potato cultivars. The cultivars showed differences in the harvest index (HI) and uptake and allocation of N, K, Ca, Mg, S, Fe, Mn, and Zn to the tubers in response to P supply. Even with higher whole plant DM production and HI under high P availability in the soil, some of the cultivars did not increase the uptake and proportion allocated to the tubers of some nutrients as a response to the high P supply. This highly controlled greenhouse experiment was able to reveal cultivar differences in DM, HI, and nutrient accumulation influenced by P, a first step toward future studies exploiting these differences in the field production environment.
      PubDate: 2014-12-06
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