Abstract: ABSTRACT In Chile, the Eucalyptus nitens (H. Deane & Maiden) Maiden × E. globulus Labill. hybrid presents the highest production potential due to its desirable characteristics for the production of cellulose. Nevertheless, its low ability to rooting complicates the clonal propagation in nurseries, with the need for new alternatives to increase rooting. The objective of this research was to evaluate the effect of rhizobacteria in the adventitious rooting of mini-cuttings of two hybrid E. nitens × E. globulus clones, wherein 106 rhizospheric bacterial isolates from five species and hybrids of Eucalyptus spp. were used. The mini-cuttings were treated at the base with a 20 mL liquid suspension of rhizobacterial strains. In addition, cultured bacteria were applied by manual sprinklers in the rooting substrate. In the first trial, 38% of rhizobacteria increased significantly rooting of X-64 clone mini-cuttings. Of these, in a second trial, 50% of rhizobacteria maintained their effect in promoting the rooting in two clones, and in the third trial among the 20 strains evaluated, 10 strains increased rooting in both clones. The rhizobacteria that had the most consistent effect in the rooting increase of the mini-cuttings were species of Bacillus and Pseudomonas sp., as well as the genera Chryseobacterium, Mucilaginibacter and Rhodococcus sp., with these results, it is concluded that 10 rhizobacterial isolates have increased the adventitious rooting of minicuttings of two hybrid clones of E. nitens × E. globulus, and these inoculants could be used in periods of underperformance of minicuttings, in order to optimize their performance.
Abstract: ABSTRACT Long-term excessive application of inorganic fertilizers not only wastes resources but also contaminates the environment. The use of natural substitutes could overcome these drawbacks. We hypothesize that organic fertilizers could increase soil C, N sequestration and improve soil fertility more effectively than inorganic fertilizers, and that in particular effective microorganism (EM) could improve the effects of traditional compost. So, a long-term field experiment regarding improvement of soil fertility, protecting soil environment, and increasing of maize and wheat yield was conducted at China Agricultural University’s Qu-Zhou experiment station since 1993. Field experiment included EM compost treatment, traditional compost treatment, chemical fertilizer treatment, and unfertilized treatment. Soil organic C (SOC), total N, nutrient concentrations, pH, bulk density, and crop yields were determined. The results revealed that long-term repeated application of EM compost promoted soil C and N sequestration, increased soil nutrient contents, decreased soil pH and bulk density, enhanced crop yields in contrast to chemical fertilizer and control treatment. Soil organic C stocks (0-20 cm) were increased by 87.32%, 81.51%, 33.05%, 25.20% and soil total N stocks were increased by 93.26%, 77.53%, 37.64%, 34.83% in contrast to initial values in EM compost, traditional compost, chemical fertilizer and control treatments, respectively. Moreover, maize grain yields in EM compost, traditional compost, and chemical fertilizer treatments were significantly increased by 163.49%, 128.34%, 62.36% compared with control treatment, respectively. The effect of increased soil C and N sequestration, improving soil fertility and enhanced crop yields in application of compost appending EM was better than alone application of compost.
Abstract: ABSTRACT The petiole of Colocasia gigantea (Blume) Schott is an important agricultural and biological organ, which contains high dietary fiber, pyridoxine, and nicotinamide. However, available genomic resources of C. gigantea are scarce, and this restricts further genetic diversity research, linkage map construction, and marker-assisted selection in C. gigantea. A large-scale genomic DNA study of C. gigantea was conducted using the 454 sequencing technology to develop simple sequence repeats (SSRs). We identified 31 069 putative genomic C. gigantea SSRs, and 100 primers were randomly selected to validate their usefulness in 10 C. gigantea samples. The specificity of six primers yielded amplification products with expected sizes and exhibited polymorphism. The number of alleles per locus ranged from 3 to 7 alleles and the polymorphic information content (PIC) ranged from 0.561 to 0.756. The newly developed SSRs in this study should be useful tools for assessing genetic diversity, understanding population structure, and conserving and using C. gigantea effectively.
Abstract: ABSTRACT In the second half of 20th century the awareness of importance of landraces for the future, led to organized collecting missions for numerous plant species. A total of 2217 maize (Zea mays L.) landraces, collected in the former Yugoslavia, are stored at Maize Research Institute (MRIZP) gene bank. During 2014, new collecting missions were organized in the eastern and western parts of Macedonia. According to collecting site and kernel type, 14 samples from the Faculty of Agricultural Sciences and Food, R. Macedonia were chosen for the comparison and identification of possible duplicates, through coupling with the 16 MRIZP gene bank accessions from the same area and kernel characteristics. Phenotypic characterization was done for 21 traits according to International Board for Plant Genetic Resources descriptors for maize. The Principal Component Analysis (PCA) identifies five PCs with Eigenvalue > 1, explaining 80% of the total phenotypic variation. The most discriminative traits with the strongest positive associations were tasseling and silking dates, plant height, leaf length and ear length. Compared to the ex-situ populations, the number of alleles and the number of specific alleles, showed a significant decrease in the in situ populations. Twelve unique alleles were detected in samples from MRIZP gene bank, and only four were found in new Macedonian samples. Cluster analysis of morphological and molecular markers distinguished groups of maize accessions with distinctive morphological traits and genetic profiles that will be useful for conservation, and management of gene bank collection, as well as for possible utilization in breeding.
Abstract: ABSTRACT Indirect selection based on highly correlated characters is a common strategy in genetic improvement to quickly and accurately identify genotypes with good agronomic characteristics. The objective of this research study was to quantify existing associations between root agronomic and anatomical characters in maize (Zea mays L.) populations for possible indirect selection. The following agronomic characters were considered: Plant height, ear insertion height, relative ear position, plant lodging, plant breakage, and grain productivity. Measured anatomical characters included total root area, central cylinder area, epidermis thickness, exodermis thickness, endodermis thickness, cortical parenchyma thickness, number of metaxylem vessels, phloem area, cortex thickness, and metaxylem area. The genotypic correlation analysis showed significant associations at the 1% probability level between the following anatomical and agronomic characters: Endodermis thickness and plant height, exodermis thickness and plant breakage, and exodermis thickness and grain productivity. The canonical analysis of variance showed significant effects by the chi-square test for three of the five canonical pairs. The first canonical pair showed a positive relationship between plant height and total root area (4.142) and a negative relationship with the central cylinder area (-4.080), indicating that genotypes with greater total root area and lower central cylinder area can give rise to larger plants. These results indicated the possibility of an indirect selection of taller or shorter plants in the earlier growth stages using anatomical root characters.
Abstract: ABSTRACT Bemisia tabaci (Gennadius), the vector of Tomato chlorosis virus (ToCV), is one of the major pests of tomato (Solanum lycopersicum L. var. lycopersicum), potentially causing up to 100% yield loss. The purpose of this research was to effectively reduce intrusion by B. tabaci and control damage from ToCV in protected cultivations. The treatments included the use of a regular solar greenhouse as a control (CK); greenhouses I and II with 60- and 80-mesh insect-proof nets, respectively, that were installed in both houses at the front and upper ventilations; and greenhouse III with the addition of not only the 80-mesh insect-proof net as in greenhouse II but also a ventilating pipeline to the back wall. The effects of mesh size and back wall ventilation on the greenhouse temperature and humidity, number of B. tabaci, and level of ToCV infection were studied. Under all conditions tested (from 2014-2016), the temperature of greenhouse III with installed netting was reduced by drilling holes through the back wall and nonsignificant difference existed in the average relative humidity between greenhouses II and III. Importantly, the number of B. tabaci and ToCV infection rate were effectively controlled in greenhouse III, ranging from 0.03 to 0.33 adults per sampled plant and from 0% to 6.67% of virus incidence. Thus, installing 80-mesh insect-proof netting at the front and upper ventilation areas as well as adding a ventilating pipeline to the back wall could effectively reduce the number of B. tabaci and prevent ToCV damage.
Abstract: ABSTRACT Papaya (Carica papaya L.) is an important fruit crop in many tropical and subtropical countries; it is commercially propagated through seeds, which lead to production of non true-to-type plants. Grafting for mass multiplication of the selected variety is therefore necessary. The objective of this study was to determine the influence of rootstock age and grafting season on the success of cleft grafting and growth of grafted plants under greenhouse conditions. The trial was conducted using an experimental randomized complete block design with 4A × 2B factorial scheme, four blocks, and 15 grafted plants per experimental unit. Factor A represented four rootstock ages (1, 2, 3, and 6 mo) and factor B represented two grafting seasons (summer and autumn). Results showed that rootstock age and grafting season had a significant effect on all the parameters: sprouting time, percentage of graft success, scion sprout length, and number of new leaves per graft. The youngest rootstock age (1 mo) achieved the best results for all the parameters. The best season for grafting was summer. The treatment combination of 1-mo-old rootstocks in summer produced minimum sprouting time (8.40 d), the highest percentage of graft success (93.33%), and graft growth in the greenhouse. Therefore, 1-mo-old rootstocks and grafting in summer or autumn should be used to propagate papaya by cleft grafting.
Abstract: ABSTRACT The conversion of native forests into intensive agricultural cropping affects soil quality and ecosystem functionality in tropical dry areas. Although many indicators have been used to assess soil quality, the most sensitive indicators are biochemical attributes. Absolute enzymatic activity (fluorescein diacetate hydrolysis, dehydrogenase, (-glucosidase, urease, arylsulfatase, and acid and alkaline phosphatases), soil organic C (SOC), microbial biomass C (MBC), and specific enzymes per unit of SOC and MBC were measured in forests and perennial (tomato, pangola grass, cotton passion fruit, and cashew nuts) and annual (bean, cabbage, pigeon pea, and fennel) crops. The changes in soils covered with perennial crops differed from those covered with annual crops as regards biochemical soil attributes. The multivariate analysis grouped the Entisols covered with annual crops far from the forest soils, which indicated that intensive management results in drastic changes in the biochemical quality of Entisols in tropical dry areas. The absolute (-glucosidase activity varied from 18.3 to 100.6 (g p-nitrophenol g-1 soil h-1. The tomato areas showed higher dehydrogenase activity with a value of 181.5 (L H g-1 soil. The absolute (-glucosidase, arylsulfatase, and alkaline phosphatase activity and the specific fluorescein diacetate hydrolysis/SOC, (-glucosidase/SOC, arylsulfatase/SOC, acid phosphatase/SOC, (-glucosidase/MBC, and acid phosphatase/MBC can be used as quality indicators of Entisols cultivated with perennial and annual crops. In addition, pasture soil could have a similar biochemical quality as forest soils in tropical dry areas.
Abstract: ABSTRACT Root-knot nematodes are among the main agents that negatively affect the pepper and sweet pepper crop (Capsicum annuum L.), especially Meloidogyne incognita, M. javanica, and M. enterolobii. The objective of this study was to evaluate genotypes of C. annuum L. var. annuum in their response to infection by M. incognita race 3, M. javanica, and M. enterolobii. The experiment was conducted using a completely randomized design arranged in a 27 × 3 factorial scheme with six replicates and each plot consisted of one plant. The experiment was carried out at the UNESP-FCAV in Jaboticabal, Sao Paulo, Brazil. The genotypes were in plastic pots containing an autoclaved mixture of soil, sand, and bovine manure under greenhouse conditions, and they were evaluated for the reproduction index and reproduction factor at 90 d after inoculation. Thirteen genotypes were classified as resistant, based on the reproductive factor, and highly resistant, based on the reproduction index, to M. javanica, while six were resistant and highly resistant materials to M. incognita race 3. No materials resistant to M. enterolobii were identified. The genotypes CNPH 698, CNPH 701, CNPH 702, CNPH 717, and CNPH 718 were simultaneously classified as resistant to M. incognita race 3 and M. javanica based on the reproduction factor.
Abstract: ABSTRACT The dithiocarbamate fungicide thiram is extensively used in oil palm (Elaeis guineensis Jacq.) nurseries for protecting oil palm seedlings from diseases caused by Melanconium, Glomerella and Rhizoctonia sp. The factors affecting thiram dissipation were studied under tropical conditions at two experimental sites situated in oil palm nurseries with two soil types namely: Clay loam and sandy clay loam. The field experimental plots were treated with thiram at two dosages (using the knapsack sprayers) (1) at the recommended dosage (25.6 g ai plot-1) and (2) at double the recommended dosage (51.2 g ai plot-1). Thiram residue was detected in the sandy clay loam and clay loam soils on treatment day (0 day) and from 1 to 3 d after treatment (DAT), respectively. The level of residue detected increased in soil depth. The results demonstrated that thiram dissipation was influenced by soil properties such as organic matter and clay content, and preferential flow was found to be the main pathway of thiram in the soil profile. The dissipation of thiram residue was observed in both the clay loam and sandy clay loam soils, to the depth of 50 and 30 cm of the soil profile, respectively, and the half-life was found to be less than 1 d. These findings suggest that thiram is safe for use as a foliar application on oil palm seedlings due to its short life span in the soil and its low risk potential for groundwater contamination.
Abstract: ABSTRACT In Chile, high moisture corn (Zea mays L. [HMC]) has been included mainly in diets for grazing dairy cows on pastures with high crude protein, and is an alternative that improves nutrients supply and rumen synchrony between energy and protein provided by the diet. In addition, supplementation with HMC results in an increase of fatty acids (FA) in milk, desirable for human health. The aim of this study was to evaluate the effect of herbage allowance (HA) and type of supplement on milk FA composition in grazing dairy cows during spring. Thirty-two multiparous Holstein-Friesian dairy cows (533 ± 71 kg BW; 53 ± 4 d in milk [DIM[ and milk yield 23.8 ± 4.2 kg d-1) were randomly assigned to four dietary treatments resulting from the combination of two HA levels (low 20 vs. moderate 30 kg DM cow1 d-1) and two types of supplements HMC and cracked wheat [Triticum aestivum L., CW]) offered at 3.5 kg DM cow-1 d-1. Total FA intake was greater for moderate HA (547.8 g d-1) than low HA (527.2 g d-1) (P < 0.05); but did not affect milk yield, milk constituents and milk FA composition (P > 0.05). Supplementation with HMC increased milk production by 2.3 kg d-1 compared with CW. Cows supplemented with HMC showed a greater intake of total FA (564 g d-1) and had greater concentrations of long-chain monounsaturated FA in milk (27.13 g 100 g-1) compared to cows supplemented with CW (511.0 g d-1 total FA intake and 25.39 g 100 g-1 in milk, respectively) (P < 0.05). It is concluded that grazing dairy cows supplemented with HMC during spring produced milk with higher concentrations of desirable FA, independently of the HA level.
Abstract: ABSTRACT Non-systemic logging, cattle browsing and grazing with the site natural vegetation can modify tree covers in native forests and alter the quantity and quality of organic matter entering the soil and hence its overall quality. The objective of this study was to evaluate the effect of modifying tree covers by uncontrolled logging and grazing processes on soil quality, in a mature and unmanaged roble (Nothofagus obliqua (Mirb.) Blume) forest. Soil quality was evaluated under partly-closed (PC), partly-open (PO), and open (OP) forest covers, and two soil depths. The indicators used were soil organic C (SOC), potential net N mineralization (N-min), and nitrification (N-NO3), soil microbial respiration (SMR), microbial biomass C (MBC), soil aggregates, and light fraction (LF). At 0-5 cm soil depth SMR and MBC in PC cover was approximately 12% higher than in PO and OP covers. For the same soil depth N-min in PC cover was 68% and 95% higher than in PO and OP covers, respectively; and for N-NO3 PC cover was 45% higher than PO cover. OP tree cover presented a negative N-NO3 (immobilization). Dry weight for LF fraction in OP cover (labile OM) was 90% and 67% lower respect PC and PO covers, respectively (P < 0.05). The soil quality and the activity of its microbial processes were affected by alteration of tree cover, as well by the anthropic action of logging and extensive grazing, the soil in OP cover was the most affected.
Abstract: ABSTRACT Agronomy practices aimed at wheat (Triticum aestivum L.) grain Zn biofortification are important to alleviate Zn deficiency in humans, especially for those resource-poor people owing to subsistence on diets dominated by cereal-based foods with low concentrations and bioavailability of Zn. To promote understanding of source-sink flow processes affecting biofortification of wheat with Zn, effects of different source/sink manipulations on grain Zn accumulation by wheat were examined in pot and field at two locations. Treatments included foliar applications of deionized water, sucrose, ZnSO4, sucrose + Zn, defoliation, spike shading or partial removal of spikes. Results showed sucrose + Zn significantly increased grain Zn concentration more than Zn alone. Grain Zn concentration with sucrose + Zn averaged 66 mg kg-1 for ‘Kenong 9204’ and 59 mg kg-1 for ‘Liangxing 99’ in pot, and ranged from 42 to 58 mg kg-1 for ‘Liangxing 99’, ‘Jinan 17’, ‘Jimai 20’, ‘Jimai 22’, and ‘Luyuan 502’ under field, approaching the field-grown target 60 mg kg-1 proposed by World Health Organization. Molar ratios of phytic acid/Zn and phytic acid × Ca/Zn of ‘Jinan 17’, ‘Jimai 20’ or ‘Luyuan 502’ with sucrose + Zn were reduced to be < 15 and < 200, respectively, suggesting higher Zn bioavailability. Defoliation or spike shading decreased grain weight, Zn concentration and content. It is concluded that grain Zn accumulation of wheat can be affected by the source-sink relationship of Zn and/or carbohydrate, and the foliar spray ‘sucrose + Zn’ is recommended for increasing concentration and bioavailability of Zn in wheat grains.
Abstract: ABSTRACT Sunburn in apples is caused by excessive solar radiation and high temperatures. Shade netting is used to control sun damage in apple (Malus domestica Borkh.) orchards. The physiological aspects of the effectiveness of this technique have not yet been fully understood. The objective was to study the variation in chlorophyll fluorescence in apples exposed to environmental conditions of radiation and temperature under netting, to better understand the physiological aspects in the effectiveness of this technique to control sun damage. From 50 and up to 150 d after flowering (DAF), maximum photochemical quantum efficiency of photosystem II (Fv/Fm), incidence of photosynthetically active radiation (PAR, µmol m-2 s-1), and fruit surface temperature (FST, °C) were evaluated in netted and non-netted ‘Fuji’ and ‘Gala’ apple orchards with 20% shade netting, as well as at harvest in fruit picked from the tree. Netting reduced sunburn by 9% for ‘Gala’ and 5% for ‘Fuji’. For ‘Gala’, netting reduced FST from 2 to 5 °C and 2 to 3 °C for ‘Fuji’ compared to the control (P < 0.05). The PAR decreased by 27% for ‘Gala’ and 22% for ‘Fuji’ compared to the control (P < 0.05). The mean value of Fv/Fm was 12% in ‘Gala’ and 3% in ‘Fuji’ lower than under netting. This difference in Fv/Fm was maintained in fruit picked from the tree and was 13% in ‘Gala’ and 8% in ‘Fuji’. The effectiveness of nets as a measure to control sun damage in apples is related to the ability of this technique to reduce the photo-inhibition process on the fruit skin.
Abstract: ABSTRACT Among the forgotten varieties within the Chilean wine industry, ‘Carignan’ grapevines (Vitis vinifera L.) in the Maule Valley, Chile, have been rediscovered by viticulturist and winemakers, producing very interesting wines and well recognized worldwide. Phenolic compounds are secondary metabolites, and there has been much interest in potential health benefits of polyphenols as antioxidants. The aim of this work was to study grape phenolic composition from ‘Carignan’ vineyards growing in eight different sites of the Maule Valley during the 2016 vintage. Phenolic compounds were analyzed by HPLC-DAD. The results showed that, as expected, the most abundant anthocyanin, flavonol, flavanol and hydroxycinnamic acid in ‘Carignan’ grapes were malvidin-3-glc varying from 279.56 to 428.68 mg kg-1, quercetin-3-glucoside+rutin ranging from 27.64 to 82.69 mg kg-1, procyanidin B1 varying from 39.13 to 72.84 mg kg-1 and trans-coutaric acid varying from 27.14 to 72.76 mg kg-1, respectively. trans-Piceid was the only stilbene identified, which ranged from 1.06 to 7.67 mg kg-1. Climate conditions more than soil characteristics affected grape ripening. Generally, grapes from Curtiduría (Cur) and El Peumal (Peu) presented a faster ripening, in terms of technological maturity, than grapes harvested from the rest of the sites, regarding day of season. In most of the phenolic compounds, grapes from Peu, presented higher concentration than grapes from the rest of the sites. Thus, location conditioned phenolic composition in grapes. These findings are of importance for the Chilean wine industry in relation to the viticultural management of the ‘Carignan’ variety, regarding climatic conditions, soil characteristics and ripening within the Maule Valley.
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