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Agronomy, Volume 4, Issue 4 (December 2014) , Pages 452-578

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Open AccessArticle
Genetic Dissection of QTL Associated with Grain Yield in Diverse Environments
Agronomy 2014, 4(4), 556-578; https://doi.org/10.3390/agronomy4040556
Received: 20 October 2014 / Revised: 24 November 2014 / Accepted: 27 November 2014 / Published: 5 December 2014
Cited by 6 | Viewed by 2501 | PDF Full-text (531 KB) | HTML Full-text | XML Full-text
Abstract
Wheat (Triticum aestivum L.) breeding programs strive to increase grain yield; however, the progress is hampered due to its quantitative inheritance, low heritability, and confounding environmental effects. In the present study, a winter wheat population of 159 recombinant inbred lines (RILs) was [...] Read more.
Wheat (Triticum aestivum L.) breeding programs strive to increase grain yield; however, the progress is hampered due to its quantitative inheritance, low heritability, and confounding environmental effects. In the present study, a winter wheat population of 159 recombinant inbred lines (RILs) was evaluated in six trials under rainfed, terminal drought, and fully-irrigated conditions, over four years. Quantitative trait locus/loci (QTL) mapping was conducted for grain yield main effect (GY) and the genotype × environment interaction (GEI) effect. A total of 17 QTL were associated with GY and 13 QTL associated with GEI, and nine QTL were mapped in the flanking chromosomal regions for both GY and GEI. One major QTL Q.Gy.ui-1B.2, explaining up to 22% of grain yield, was identified in all six trials. Besides the additive effect of QTL associated with GY, interactions among QTL (QTL × QTL interaction), QTL × environment, and QTL × QTL × environment were also observed. When combining the interaction effects, QTL Q.Gy.ui-1B.2 along with other QTL explained up to 52% of the variation in grain yield over the six trials. This study suggests that QTL mapping of complex traits such as grain yield should include interaction effects of QTL and environments in marker-assisted selection. Full article
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Open AccessReview
Review of Alternative Management Options of Vegetable Crop Residues to Reduce Nitrate Leaching in Intensive Vegetable Rotations
Agronomy 2014, 4(4), 529-555; https://doi.org/10.3390/agronomy4040529
Received: 29 September 2014 / Revised: 17 November 2014 / Accepted: 17 November 2014 / Published: 2 December 2014
Cited by 15 | Viewed by 2734 | PDF Full-text (504 KB) | HTML Full-text | XML Full-text
Abstract
Vegetable crop residues take a particular position relative to arable crops due to often large amounts of biomass with a N content up to 200 kg N ha−1 left behind on the field. An important amount of vegetable crops are harvested during [...] Read more.
Vegetable crop residues take a particular position relative to arable crops due to often large amounts of biomass with a N content up to 200 kg N ha−1 left behind on the field. An important amount of vegetable crops are harvested during late autumn and despite decreasing soil temperatures during autumn, high rates of N mineralization and nitrification still occur. Vegetable crop residues may lead to considerable N losses through leaching during winter and pose a threat to meeting water quality objectives. However, at the same time vegetable crop residues are a vital link in closing the nutrient and organic matter cycle of soils. Appropriate and sustainable management is needed to harness the full potential of vegetable crop residues. Two fundamentally different crop residue management strategies to reduce N losses during winter in intensive vegetable rotations are reviewed, namely (i) on-field management options and modifications to crop rotations and (ii) removal of crop residues, followed by a useful and profitable application. Full article
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Open AccessArticle
Genotype by Environment Effects on Potato Mini-Tuber Seed Production in an Aeroponics System
Agronomy 2014, 4(4), 514-528; https://doi.org/10.3390/agronomy4040514
Received: 1 September 2014 / Revised: 6 November 2014 / Accepted: 11 November 2014 / Published: 21 November 2014
Cited by 1 | Viewed by 3231 | PDF Full-text (292 KB) | HTML Full-text | XML Full-text
Abstract
In order to evaluate the environmental effect on plant development and mini-tuber production of a diverse group of potato genotypes grown under an aeroponic system, a G × E interaction experiment was carried out in greenhouses located at CIP’s experimental stations in La [...] Read more.
In order to evaluate the environmental effect on plant development and mini-tuber production of a diverse group of potato genotypes grown under an aeroponic system, a G × E interaction experiment was carried out in greenhouses located at CIP’s experimental stations in La Molina (Lima) and Huancayo (Junín). Five contrasting environments were set-up and evaluated. A combined Analysis of Variance was performed for the variables “days to tuber set”, “days to senescence” and “plant height”. An Additive Main Effects and Multiplicative Interaction (AMMI) Analysis was performed for yield variables: mini-tuber “weight” and “number of mini-tubers” per plant. There was a high variation in all the responses to the treatments. “Days to tuber set” was influenced by genetic responses, temperature and greenhouse Photosynthetically Active Radiation intensity. Considerable increases in the length of the vegetative cycle and plant height were recorded for all genotypes, and these were particularly notable in the warmer coastal environments. AMMI analysis showed that yield variables were primarily influenced by the genotypic effect followed by the genotype by environment interaction effect. The Venturana variety (T2) was the best performing genotype with a total average mini-tuber “weight” of 644 g per plant while the Chucmarina variety (T1) performed best for the variable “number of mini-tubers” with an overall average of 60.2 mini-tubers per plant. Both showed stability across different environments for these variables. The advanced clones T3 (395434.1), T5 (397077.16) and T6 (397073.16) showed stability for yield variables, but their performance was below the overall average of the trial. It is recommended that the environment and management should ideally be tailored to the genotype as this will result in significant yield gains. Full article
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Open AccessArticle
Nitrogen Fertilizer Sources and Application Timing Affects Wheat and Inter-Seeded Red Clover Yields on Claypan Soils
Agronomy 2014, 4(4), 497-513; https://doi.org/10.3390/agronomy4040497
Received: 7 October 2014 / Revised: 21 October 2014 / Accepted: 31 October 2014 / Published: 11 November 2014
Cited by 3 | Viewed by 2944 | PDF Full-text (376 KB) | HTML Full-text | XML Full-text
Abstract
Controlled-release N fertilizer, such as polymer-coated urea (PCU), may be a fall N management option for wheat (Triticum aestivum L.) grown in poorly-drained claypan soils. Field research evaluated (1) urea release from fall-applied PCU in 2006 and 2007; (2) broadcast fall-spring split [...] Read more.
Controlled-release N fertilizer, such as polymer-coated urea (PCU), may be a fall N management option for wheat (Triticum aestivum L.) grown in poorly-drained claypan soils. Field research evaluated (1) urea release from fall-applied PCU in 2006 and 2007; (2) broadcast fall-spring split (25%:75%) of N sources; and (3) a single fall (100%) application of PCU, urea, urea plus NBPT (N-(n-butyl) thiophosphoric triamide] (U + NBPT), ammonium nitrate (AN), or urea ammonium nitrate (UAN) at 0, 56, 84, and 112 kg·N·ha−1 on wheat yield, wheat biomass, N uptake by wheat, and frost-seeded red clover (FSC) (Trifolium pratense L.) forage yield (2004–2007). PCU applied in fall released less than 30% urea by February. Urea released from PCU by harvest was 60% and 85% in 2006 and 2007, respectively. In poorly-drained soils, wheat yields ranked PCU > AN > U + NBPT > urea ≥ UAN over the rates evaluated for fall-only application. PCU was a viable fall-applied N source, with yields similar to or greater than urea or U + NBPT split-applied. Split-N applications of AN, urea, UAN, and U + NBPT generally resulted in greater wheat yields than a fall application. Enhanced efficiency fertilizers provide farmers with flexible options for maintaining high yielding production systems. Full article
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Open AccessArticle
Assessing Microbial Contributions to N2O Impacts Following Biochar Additions
Agronomy 2014, 4(4), 478-496; https://doi.org/10.3390/agronomy4040478
Received: 12 June 2014 / Revised: 18 October 2014 / Accepted: 22 October 2014 / Published: 7 November 2014
Cited by 4 | Viewed by 2726 | PDF Full-text (446 KB) | HTML Full-text | XML Full-text
Abstract
Varying degrees of soil nitrous oxide (N2O) mitigation have been observed following biochar applications. Laboratory incubation experiments were conducted using soils from agriculture, forest, prairie, and a sterilized sand to examine the relative contributions of bacteria and fungi to this N [...] Read more.
Varying degrees of soil nitrous oxide (N2O) mitigation have been observed following biochar applications. Laboratory incubation experiments were conducted using soils from agriculture, forest, prairie, and a sterilized sand to examine the relative contributions of bacteria and fungi to this N2O alteration. Selective chemical inhibitors were used to distinguish the relative contributions of fungal and bacterial groups to N2O production/suppression in each soil type following a fast-pyrolysis macadamia nut shell biochar (10% w/w) addition. Overall, suppressed production of N2O was initially observed between the agricultural and prairie soils following biochar addition and stimulation of N2O production was observed in the biochar amended forest soil. However, if the N2O production that was observed in the biochar control (sterile sand and biochar = 4.2 ± 0.7 ng-N g−1 day−1) was subtracted from all treatments, N2O production following biochar addition was consistently lower in all soils following biochar additions. In terms of the microbial contributions, there were no significant differences in N2O production between the microbial inhibitor treatments, despite CO2 production rate differences. Therefore, the response in the N2O production to biochar could not be directly attributed to a particular microbial group (fungi or bacteria). These results suggest the presence of abiotic production or consumption routes for nitrogen species in biochar amended soils. Full article
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Open AccessTechnical Note
A Calculation Tool for Analyzing Nitrogen Use Efficiency in Annual and Perennial Crops
Agronomy 2014, 4(4), 470-477; https://doi.org/10.3390/agronomy4040470
Received: 10 September 2014 / Revised: 18 October 2014 / Accepted: 31 October 2014 / Published: 5 November 2014
Cited by 7 | Viewed by 8712 | PDF Full-text (284 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Assessment of crop nitrogen use efficiency (NUE) is important in agricultural research. Various approaches exist to analyze NUE. A recently proposed NUE concept is further developed and a calculation tool for practical use presented. A critical component in the NUE concept is the [...] Read more.
Assessment of crop nitrogen use efficiency (NUE) is important in agricultural research. Various approaches exist to analyze NUE. A recently proposed NUE concept is further developed and a calculation tool for practical use presented. A critical component in the NUE concept is the plants’ mean nitrogen (N) content during the main growth period (N’). The N’ is delimited by the critical crop phenology stages initiating and terminating accelerated crop N uptake. Especially when experimental treatments and/or crop cultivars cause great variation in phenology, it is often not feasible to perform destructive plant harvests at the critical phenology stages for all treatments and cultivars, which may result in inaccurate estimates of N’ and, ultimately, the NUE components N uptake efficiency and yield-specific N efficiency. A method is proposed to accurately calculate the crop N contents at the relevant critical phenology stages even when sampling is made at other time points. The only requirements are two separate destructive plant harvests performed within the main growth period, together with the time points for the critical phenology events. The method was exemplified using data from wheat and the perennial energy crop Salix, and an electronic calculation tool for the various NUE components is provided. Full article
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Open AccessArticle
Candidate Gene Identification for a Lethal Chlorophyll-Deficient Mutant in Soybean
Agronomy 2014, 4(4), 462-469; https://doi.org/10.3390/agronomy4040462
Received: 15 September 2014 / Revised: 22 October 2014 / Accepted: 27 October 2014 / Published: 31 October 2014
Cited by 6 | Viewed by 2433 | PDF Full-text (281 KB) | HTML Full-text | XML Full-text
Abstract
Chlorophyll-deficient mutants have been studied persistently to understand genetic mechanisms controlling metabolic pathways. A spontaneous chlorophyll-deficient lethal mutant was observed in self-pollinated progeny of a soybean cultivar “BSR 101”. Observed segregation patterns indicated single-gene recessive inheritance for this lethal-yellow mutant. The objectives of [...] Read more.
Chlorophyll-deficient mutants have been studied persistently to understand genetic mechanisms controlling metabolic pathways. A spontaneous chlorophyll-deficient lethal mutant was observed in self-pollinated progeny of a soybean cultivar “BSR 101”. Observed segregation patterns indicated single-gene recessive inheritance for this lethal-yellow mutant. The objectives of this investigation were to develop a genetic linkage map of the region containing the lethal-yellow (YL_PR350) gene and identify putative candidate genes for this locus. The YL_PR350 gene was mapped to chromosome 15 and is flanked by BARCSOYSSR_15_1591 and BARCSOYSSR_15_1597. This region physically spans ~153 kb and there are 14 predicted genes that lie in this region. The predicted gene Glyma.15g275900 is an excellent candidate for the YL_PR350 gene as it is homologous to an Arabidopsis gene, At3g08010, which codes for a chloroplast-localized protein (ATAB2) involved in the biogenesis of Photosystem I and II. This thylakoid membrane protein is crucial for photosynthesis in Arabidopsis. Future characterization of the candidate gene may enhance our knowledge about photosynthesis, a complex metabolic process critical for sustainability of plants. Full article
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Open AccessArticle
Mapping the Spatial Variability of Soil Acidity in Zambia
Agronomy 2014, 4(4), 452-461; https://doi.org/10.3390/agronomy4040452
Received: 17 June 2014 / Revised: 25 September 2014 / Accepted: 28 September 2014 / Published: 14 October 2014
Cited by 4 | Viewed by 2329 | PDF Full-text (5509 KB) | HTML Full-text | XML Full-text
Abstract
A common strategy for ameliorating soil acidity is the application of agricultural lime. However, this measure is hampered by the lack of high resolution soil maps that can enable lime application according to the spatial variability of soil pH in an area. Therefore, [...] Read more.
A common strategy for ameliorating soil acidity is the application of agricultural lime. However, this measure is hampered by the lack of high resolution soil maps that can enable lime application according to the spatial variability of soil pH in an area. Therefore, this study was carried out to map soil acidity in South Eastern Zambia. The objective of the study was to apply geostatistical procedures to mapping soil acidity in the country. Ordinary kriging was performed on a set of 119 soil samples collected from the 0–20 cm soil layer whose pH was determined by the electrometric method. The kriging model that was developed was found to be satisfactory with low prediction errors (root mean square error 0.36). Thus, the map produced could be used to draw up strategies for management of soil acidity in the area. Full article
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