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Agronomy, Volume 8, Issue 11 (November 2018)

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Open AccessArticle Morphological Assessment of Cultivated and Wild Amaranth Species Diversity
Agronomy 2018, 8(11), 272; https://doi.org/10.3390/agronomy8110272
Received: 7 October 2018 / Revised: 31 October 2018 / Accepted: 9 November 2018 / Published: 21 November 2018
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Abstract
Amaranthus L. is genus of C4 dicotyledonous herbaceous plants comprising approximately 70 species, with three subgenera, which contains both cultivated and wild types, where cultivated ones are used for food grains, leafy vegetables, potential forages and ornamentals. Grain amaranth are pseudocereals from three
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Amaranthus L. is genus of C4 dicotyledonous herbaceous plants comprising approximately 70 species, with three subgenera, which contains both cultivated and wild types, where cultivated ones are used for food grains, leafy vegetables, potential forages and ornamentals. Grain amaranth are pseudocereals from three species domesticated in North and South America and are notable for containing high amount of protein and minerals and balanced amino acid in their small seeds. Genetic diversity analysis of amaranths is important for development of core set of germplasm with widely diverse population and effective utilization of plant genetic resources. In this study, we evaluated a germplasm collection of 260 amaranth accessions from United State Department of Agriculture (USDA) and 33 accessions from Seed Savers’ Exchange (SSE). We evaluated morphological traits like blade pigmentation, blade shape, petiole pigmentation, branching index, flower color, stem color, inflorescence density, inflorescence shape, terminal inflorescence attitude, plant height and yield characteristics across all 293 accessions. We compared clustering within the USDA and SSE collection and across both collections. Data analysis of morphological data showed significant difference of petiole pigmentation, stem color, blade pigmentation, blade shape and flower color across different clusters of accessions of USDA unlike among different clusters of SSE where we found significant difference of only blade pigmentation, blade shape and flower color. The relationship depicted by neighbor-joining dendogram using the morphological markers was consistent with some but not all of the differences observed between species. Some divisions were found between cultivated and weedy amaranths that was substantiated by morphological characteristics but no separation of South and Central American species was observed. Substantial phenotypic plasticity limits the use of morphological analysis for phylogenetic analysis but does show that important morphological traits such as inflorescence type and plant architecture can cross species boundaries. Similarly, color variants for leaves, flowers and seeds are not exclusive to one cluster in our study nor to one species and can be used widely for breeding any of the cultigens, but not to species identification. Our findings will help in germplasm conservation of grain amaranths and facilitate in this crop’s improvement. It will also help on developing effective breeding programs involving different plant characteristics and morphological traits of Amaranths. Full article
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Open AccessArticle Genotypic Variation in Anthocyanins, Phenolic Compounds, and Antioxidant Activity in Cob and Husk of Purple Field Corn
Agronomy 2018, 8(11), 271; https://doi.org/10.3390/agronomy8110271
Received: 17 October 2018 / Revised: 18 November 2018 / Accepted: 19 November 2018 / Published: 21 November 2018
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Abstract
Information on phytochemicals in the cob and husk of field corn is important for the use of corn waste in the production of value-added corn products. The objectives of this study were to evaluate the variation in monomeric anthocyanin content (MAC), total phenolic
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Information on phytochemicals in the cob and husk of field corn is important for the use of corn waste in the production of value-added corn products. The objectives of this study were to evaluate the variation in monomeric anthocyanin content (MAC), total phenolic content (TPC), and antioxidant activity, as determined by 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging activity and Trolox equivalent antioxidant capacity (TEAC) in 53 purple field corn genotypes, and to study the correlations of these traits with color parameters. Fifty-three corn genotypes were planted in a randomized complete block design with three replications in two locations in the dry season of 2015/2016. The effects of genotype, location, and the interaction between genotype and location were significant for most characters. Genotypic variation contributed to a large portion of the total variance for all traits, accounting for 63.9–86.9%. Corn genotypes were classified into six groups based on MAC, TPC, and antioxidant activity determined by the DPPH and the TEAC methods. The highest MAC, TPC, and antioxidant activity were obtained in TB/KND//PF3 and TB/KND//PF8 for husk, and only TB/KND//PF8 for cob. They should be used as parental lines to develop corn varieties with high phytochemicals. Chroma (C*) and hue (H°) of color parameters could potentially be used as an indirect selection criterion for improving MAC, TPC, and antioxidant activity in cob. The information is useful for the improvement of phytochemicals in cob and husk of field corn. Full article
(This article belongs to the Section Crop Breeding and Genetics)
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Open AccessArticle Unveiling the Enigmatic Structure of TdCMO Transcripts in Durum Wheat
Agronomy 2018, 8(11), 270; https://doi.org/10.3390/agronomy8110270
Received: 2 October 2018 / Revised: 7 November 2018 / Accepted: 19 November 2018 / Published: 21 November 2018
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Abstract
Durum wheat is one of the oldest and most important edible cereal crops and its cultivation has considerable economic importance in many countries. However, adverse conditions, such as high irradiance and increasing salinity of soils, could lead to a decrease in productivity over
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Durum wheat is one of the oldest and most important edible cereal crops and its cultivation has considerable economic importance in many countries. However, adverse conditions, such as high irradiance and increasing salinity of soils, could lead to a decrease in productivity over the next few decades. Durum wheat plants under salinityare able toaccumulate glycine betaine to osmotically balance the cytosol and reduce oxidative stress, especially in young tissues. However, the synthesis of this fundamental osmolyte is inhibited by high light in T. durum even under salinity. Choline monooxygenase is the first enzyme involved in the glycine betaine biosynthetic pathway. Thus, to explain the glycine betaine inhibition, we analyzed the effect of both salinity and high light on the putative TdCMO gene expression. Thirty-eight TdCMO different transcripts were isolated in the young leaves of durum wheat grown in different stress conditions. All translated amino acid sequences, except for the TdCMO1a6 clone, showed a frame shift caused by insertions or deletions. The presence of different transcripts could depend on the presence of duplicated genes, different allelic forms, and alternative splicing events. TdCMO1a6 computational modeling of the 3D structure showed that in durum wheat, a putative CMO-like enzyme with a different Rieske type motif, is present and could be responsible for the glycine betaine synthesis. Full article
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Open AccessArticle Segmentation of Rice Seedlings Using the YCrCb Color Space and an Improved Otsu Method
Agronomy 2018, 8(11), 269; https://doi.org/10.3390/agronomy8110269
Received: 13 September 2018 / Revised: 2 November 2018 / Accepted: 15 November 2018 / Published: 19 November 2018
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Abstract
Rice seedling segmentation is a fundamental process of extracting the guidance line for automated rice transplanters with a visual navigation system, which can provide crop row information to ensure the transplanter plants seedlings along the crop row without damaging seedlings. However, obtaining accurate
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Rice seedling segmentation is a fundamental process of extracting the guidance line for automated rice transplanters with a visual navigation system, which can provide crop row information to ensure the transplanter plants seedlings along the crop row without damaging seedlings. However, obtaining accurate rice seedling segmentation in paddy fields is still a challenging task. In this paper, a rice seedling segmentation method in paddy fields is proposed. The method mainly consists of two steps: image graying and threshold segmentation. In the procedure of image graying, the RGB (Red Green Blue) seedling image is first converted into the YCrCb color space and a Cg component is constructed. A color-index 2Cg-Cb-Cr is then constructed for image graying based on the excess green index (2G-R-B), which can reduce the influence of illumination variation on the equality of image graying. For the second step, an improved Otsu method is proposed to segment rice seedlings. With respect to the improved Otsu method in this research, the background variance of within class variance is weighted by a probability parameter to ensure that the method works well for both bimodal and near-unimodal histogram images, and the search range of gray levels is constrained to reduce the time to search the segmentation threshold. Experimental results indicate that the proposed method achieves better segmentation results and reduces the computational cost compared with the traditional Otsu method and other improved Otsu methods. Full article
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Open AccessArticle Sustainability Evaluation of the Maize–Soybean Intercropping System and Maize Monocropping System in the North China Plain Based on Field Experiments
Agronomy 2018, 8(11), 268; https://doi.org/10.3390/agronomy8110268
Received: 20 September 2018 / Revised: 28 October 2018 / Accepted: 12 November 2018 / Published: 19 November 2018
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Abstract
Monocropping systems, which currently dominate China’s major grain production regions, contribute to resource scarcity and environmental pollution. Intercropping has the potential to improve resource use efficiency. However, prior studies of intercropping systems have generally focused on ecological, economic, and social consequences. Here, we
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Monocropping systems, which currently dominate China’s major grain production regions, contribute to resource scarcity and environmental pollution. Intercropping has the potential to improve resource use efficiency. However, prior studies of intercropping systems have generally focused on ecological, economic, and social consequences. Here, we make a comparative ecological sustainability analysis on energy capture and efficiency of maize monocropping and maize–soybean intercropping systems through emergy evaluation based on field experiments performed from 2012 to 2014. We find that maize monocropping shows higher sustainability than maize–soybean intercropping in the North China Plain at present. Quantitative results indicate that for maize monocropping, the emergy yield ratio (EYR) and emergy sustainability index (ESI) are 13.7% and 21.1% higher than that of intercropping systems, and the environmental loading ratio (ELR) is 7.3% lower than that of intercropping systems. To further test, we applied three levels of nitrogen fertilizer in intercropping systems (120 kg ha−1, 180 kg ha−1, 240 kg ha−1), and find that a reduced rate of N fertilizer for intercropped system leads to higher sustainability (ESI 5.3% higher) but still lower sustainability than maize monocropping. Key drivers of the different sustainability outcomes are decreased energy output and a larger proportion of labor input associated with intercropping systems. Full article
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Open AccessFeature PaperEditorial Biotic and Abiotic Stress Responses in Crop Plants
Agronomy 2018, 8(11), 267; https://doi.org/10.3390/agronomy8110267
Received: 6 November 2018 / Accepted: 15 November 2018 / Published: 19 November 2018
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Abstract
Agricultural productivity depends on increasingly extreme weather phenomena, and the use of germplasm that has to be continuously improved by plant breeders to become tolerant to various biotic and abiotic stresses. Molecular plant biologists try to understand the mechanisms associated with stress responses
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Agricultural productivity depends on increasingly extreme weather phenomena, and the use of germplasm that has to be continuously improved by plant breeders to become tolerant to various biotic and abiotic stresses. Molecular plant biologists try to understand the mechanisms associated with stress responses and provide knowledge that could be used in breeding programs. To provide a partial overview about our current understanding about molecular and physiological stress responses, and how this knowledge can be used in agriculture, we have edited a special issue on “Biotic and Abiotic Stress Responses in Crop Plants”. Contributions are from different fields including heat stress responses, stress responses during drought and salinity, as well as during flooding, and resistance and susceptibility to pathogenetic stresses and about the role of plant functional metabolites in biotic stress responses. Future research demand in particular areas of crop stress physiology is discussed, as well as the importance of translational research and investigations directly in elite crop plants and in the genetic resources available for breeding. Full article
(This article belongs to the Special Issue Biotic and Abiotic Stress Responses in Crop Plants)
Open AccessArticle Ergonomic Evaluation of Current Advancements in Blueberry Harvesting
Agronomy 2018, 8(11), 266; https://doi.org/10.3390/agronomy8110266
Received: 23 October 2018 / Revised: 7 November 2018 / Accepted: 14 November 2018 / Published: 17 November 2018
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Abstract
Work-related musculoskeletal disorders (MSDs) accounted for 32% of days-away-from-work cases in private industry in 2016. Several factors have been associated with MSDs, such as repetitive motion, excessive force, awkward and/or sustained postures, and prolonged sitting and standing, all of which are required in
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Work-related musculoskeletal disorders (MSDs) accounted for 32% of days-away-from-work cases in private industry in 2016. Several factors have been associated with MSDs, such as repetitive motion, excessive force, awkward and/or sustained postures, and prolonged sitting and standing, all of which are required in farm workers’ labor. While numerous epidemiological studies on the prevention of MSDs in agriculture have been conducted, an ergonomics evaluation of blueberry harvesting has not yet been systematically performed. The purpose of this study was to investigate the risk factors of MSDs for several types of blueberry harvesting (hand harvesting, semi-mechanical harvesting with hand-held shakers, and over-the-row machines) in terms of workers’ postural loads and self-reported discomfort using ergonomics intervention techniques. Five field studies in the western region of the United States between 2017 and 2018 were conducted using the Borg CR10 scale, electromyography (EMG), Rapid Upper Limb Assessment (RULA), the Cumulative Trauma Disorders (CTD) index, and the NIOSH (National Institute for Occupational Safety and Health) lifting equation. In evaluating the workloads of picking and moving blueberries by hand, semi-mechanical harvesting with hand-held shakers, and completely mechanized harvesting, only EMG and the NIOSH lifting equation were used, as labor for this system is limited to loading empty lugs and unloading full lugs. Based on the results, we conclude that working on the fully mechanized harvester would be the best approach to minimizing worker loading and fatigue. This is because the total component ratio of postures in hand harvesting with a RULA score equal to or greater than 5 was 69%, indicating that more than half of the postures were high risk for shoulder pain. For the semi-mechanical harvesting, the biggest problem with the shakers is the vibration, which can cause fatigue and various risks to workers, especially in the upper limbs. However, it would be challenging for small- and medium-sized blueberry farms to purchase automated harvesters due to their high cost. Thus, collaborative efforts among health and safety professionals, engineers, social scientists, and ergonomists are needed to provide effective ergonomic interventions. Full article
(This article belongs to the Special Issue Berry Crop Production and Protection)
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Open AccessArticle A Cucumber AGAMOUS-LIKE 15 (AGL15) MADS-Box Gene Mediates Abnormal Leaf Morphology in Arabidopsis
Agronomy 2018, 8(11), 265; https://doi.org/10.3390/agronomy8110265
Received: 19 October 2018 / Revised: 9 November 2018 / Accepted: 13 November 2018 / Published: 17 November 2018
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Abstract
The AGL15 subfamily MADS-box proteins play vital roles in various developmental processes, such as floral transition, somatic embryogenesis, and leaf and fruit development. In this work, an AtAGL15 ortholog, CsMADS26, was cloned from cucumber (Cucumis sativus L.). The open reading frame
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The AGL15 subfamily MADS-box proteins play vital roles in various developmental processes, such as floral transition, somatic embryogenesis, and leaf and fruit development. In this work, an AtAGL15 ortholog, CsMADS26, was cloned from cucumber (Cucumis sativus L.). The open reading frame (ORF) of CsMADS26 is 669 bp in length, encoding a predicted protein of 222 amino acids. The CsMADS26 protein contains a highly conserved MADS-box domain and a variable C domain, as well as less conserved I and K domains. Phylogenetic relationship analysis revealed that CsMADS26 was clustered into the AGL15 clade of AGL15 subfamily. Expression analysis based on qRT-PCR showed that CsMADS26 is mainly expressed in reproductive organs including flowers and fruits. Transgenic Arabidopsis plants with ectopic expression of CsMADS26 exhibited curled rosette and cauline leaves, and the leaf size was much smaller than that of wild-type (WT) plants. These results provide clues for the functional characterization of CsMADS26 in the future. Full article
(This article belongs to the Section Crop Breeding and Genetics)
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Open AccessArticle Effect of Seaweed Aqueous Extracts and Compost on Vegetative Growth, Yield, and Nutraceutical Quality of Cucumber (Cucumis sativus L.) Fruit
Agronomy 2018, 8(11), 264; https://doi.org/10.3390/agronomy8110264
Received: 24 October 2018 / Revised: 10 November 2018 / Accepted: 12 November 2018 / Published: 15 November 2018
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Abstract
The objective of this research was to evaluate the production and phytochemical quality of cucumber (Cucumis sativus) fruits, in response to the foliar application of different seaweed extracts. This study was carried out under shadow mesh conditions in the autumn–winter agricultural
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The objective of this research was to evaluate the production and phytochemical quality of cucumber (Cucumis sativus) fruits, in response to the foliar application of different seaweed extracts. This study was carried out under shadow mesh conditions in the autumn–winter agricultural cycle at the Instituto Tecnológico de Torreón, Torreón, Coahuila, Mexico. The experimental design was completely random, using six treatments with six repetitions each. The treatments evaluated were: Macrocystis pyrifera, Bryothamnion triquetrum, Ascophyllum nodosum, Grammatophora spp., Macrocystis integrifolia, and a control treatment with inorganic fertilization. The substrate used was a mixture of sand and vermicompost. The yield, commercial size, and phytochemical compounds of the fruit were evaluated. Results showed that the yield using Steiner solution (6.75 kg m−2) was higher than that obtained with Bryothamnion triquetrum algae (6.07 kg m−2). Regarding the phenolic content, the extracts surpassed the control treatment, with Macrocystis pyrifera and Macrocystis integrifolia being statistically equal, with values of 47.37 and 43.73 mg equiv. of Ac. Gallic 100 g fresh weight, respectively. The antioxidant capacity by ABTS+ and DPPH+ methods was higher using the treatment with Macrocystis pyrifera algae with 149.4 and 454.1 μM equiv Trolox/100 g fresh base, respectively. This treatment also presented the highest value of vitamin C with 5.07 mg/100 g fresh base, being 27% greater than the control treatment. Algae extracts increased the quality of the fruits by obtaining the highest antioxidant capacity, making their use a viable option to minimize the application of conventional fertilizers, thereby attenuating the effects on the environment and improving the health of the population. Full article
(This article belongs to the Special Issue Organic Farming: Impacts on Food Quality and Human Health)
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Open AccessArticle Improving High-Latitude Rice Nitrogen Management with the CERES-Rice Crop Model
Agronomy 2018, 8(11), 263; https://doi.org/10.3390/agronomy8110263
Received: 8 October 2018 / Revised: 9 November 2018 / Accepted: 11 November 2018 / Published: 15 November 2018
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Abstract
Efficient use of nitrogen (N) fertilizer is critically important for China’s food security and sustainable development. Crop models have been widely used to analyze yield variability, assist in N prescriptions, and determine optimum N rates. The objectives of this study were to use
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Efficient use of nitrogen (N) fertilizer is critically important for China’s food security and sustainable development. Crop models have been widely used to analyze yield variability, assist in N prescriptions, and determine optimum N rates. The objectives of this study were to use the CERES-Rice model to simulate the N response of different high-latitude, adapted flooded rice varieties to different types of weather seasons, and to explore different optimum rice N management strategies with the combinations of rice varieties and types of weather seasons. Field experiments conducted for five N rates and three varieties in Northeast China during 2011–2016 were used to calibrate and evaluate the CERES-Rice model. Historical weather data (1960–2014) were classified into three weather types (cool/normal/warm) based on cumulative growing degree days during the normal growing season for rice. After calibrating the CERES-Rice model for three varieties and five N rates, the model gave good simulations for evaluation seasons for top weight (R2 ≥ 0.96), leaf area index (R2 ≥ 0.64), yield (R2 ≥ 0.71), and plant N uptake (R2 ≥ 0.83). The simulated optimum N rates for the combinations of varieties and weather types ranged from 91 to 119 kg N ha−1 over 55 seasons of weather data and were in agreement with the reported values of the region. Five different N management strategies were evaluated based on farmer practice, regional optimum N rates, and optimum N rates simulated for different combinations of varieties and weather season types over 20 seasons of weather data. The simulated optimum N rate, marginal net return, and N partial factor productivity were sensitive to both variety and type of weather year. Based on the simulations, climate warming would favor the selection of the 12-leaf variety, Longjing 21, which would produce higher yield and marginal returns than the 11-leaf varieties under all the management strategies evaluated. The 12-leaf variety with a longer growing season and higher yield potential would require higher N rates than the 11-leaf varieties. In summary, under warm weather conditions, all the rice varieties would produce higher yield, and thus require higher rates of N fertilizers. Based on simulation results using the past 20 years of weather data, variety-specific N management was a practical strategy to improve N management and N partial factor productivity compared with farmer practice and regional optimum N management in the study region. The CERES-Rice crop growth model can be a useful tool to help farmers select suitable precision N management strategies to improve N-use efficiency and economic returns. Full article
(This article belongs to the Special Issue Plant Mineral Nutrition: Principles and Perspectives)
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Open AccessErratum Erratum: The Adoption of Good Practices for Pesticides and Veterinary Drugs Use among Peasant Family Farmers of Chile; Agronomy 2018, 8, 219
Agronomy 2018, 8(11), 262; https://doi.org/10.3390/agronomy8110262
Received: 13 November 2018 / Accepted: 13 November 2018 / Published: 13 November 2018
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Abstract
Due to a mistake during the production process, there was a spelling error in one of the author names in the original published version [...] Full article
Open AccessArticle Green Manuring Effect on Changes of Soil Nitrogen Fractions, Maize Growth, and Nutrient Uptake
Agronomy 2018, 8(11), 261; https://doi.org/10.3390/agronomy8110261
Received: 10 September 2018 / Revised: 8 November 2018 / Accepted: 9 November 2018 / Published: 12 November 2018
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Abstract
Green manure is a promising, at least partial, substitution for chemical fertilizer in agriculture, especially for nitrogen (N), which in soil can be radically changed by exogenous input. However, it is not well understood how, after green manure incorporation, soil N changes coordinate
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Green manure is a promising, at least partial, substitution for chemical fertilizer in agriculture, especially for nitrogen (N), which in soil can be radically changed by exogenous input. However, it is not well understood how, after green manure incorporation, soil N changes coordinate with crop N uptake and consequently contribute to fertilizer reduction in a maize–green manure rotation. A four-year field study was performed consisting of (1) control, no fertilization; (2) F100, recommended inorganic fertilization alone; (3) G, green manure incorporation alone; (4) F70 + G (70% of F100 plus G); (5) F85 + G; and (6) F100 + G. The results show that treatments with 15–30% reduction of inorganic fertilizer (i.e., F70 + G and F85 + G) had similar grain yield, dry matter (DM) accumulation, and N uptake as F100 treatment. F100 + G maize had 17% greater DM and 15% more N uptake at maturity relative to F100. Of the five soil N fractions examined, dissolved organic N (DON) and mineral N (Nmin) explained over 70% of the variation of maize DM and N accumulation. Partial least squares path modeling further revealed that soil N fractions had positive indirect effects on DM production through N uptake, which might be coordinated with improved DON and Nmin status at both early and mid-late stages of maize growth. Overall, the results highlight enhanced maize production with reduced fertilizer inputs based on green manure incorporation in temperate regions. Full article
(This article belongs to the Special Issue Fertilizer Application on Crop Yield)
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Open AccessReview Development and Use of Simple Sequence Repeats (SSRs) Markers for Sugarcane Breeding and Genetic Studies
Agronomy 2018, 8(11), 260; https://doi.org/10.3390/agronomy8110260
Received: 13 October 2018 / Revised: 3 November 2018 / Accepted: 7 November 2018 / Published: 12 November 2018
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Recently-developed molecular markers are becoming powerful tools, with applications in crop genetics and improvement. Microsatellites, or simple sequence repeats (SSRs), are widely used in genetic fingerprinting, kinship analysis, and population genetics, because of the advantages of high variability from co-dominant and multi-allelic polymorphisms,
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Recently-developed molecular markers are becoming powerful tools, with applications in crop genetics and improvement. Microsatellites, or simple sequence repeats (SSRs), are widely used in genetic fingerprinting, kinship analysis, and population genetics, because of the advantages of high variability from co-dominant and multi-allelic polymorphisms, and accurate and rapid detection. However, more recent evidence suggests they may play an important role in genome evolution and provide hotspots of recombination. This review describes the development of SSR markers through different techniques, and the detection of SSR markers and applications for sugarcane genetic research and breeding, such as cultivar identification, genetic diversity, genome mapping, quantitative trait loci (QTL) analysis, paternity analysis, cross-species transferability, segregation analysis, phylogenetic relationships, and identification of wild cross hybrids. We also discuss the advantages and disadvantages of SSR markers and highlight some future perspectives. Full article
(This article belongs to the Special Issue Breeding and Genetics of Sugarcane and Other Sugar Crops)
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Open AccessArticle Nitrogen Use Efficiency of Watermelon Grafted onto 10 Wild Watermelon Rootstocks under Low Nitrogen Conditions
Agronomy 2018, 8(11), 259; https://doi.org/10.3390/agronomy8110259
Received: 3 October 2018 / Revised: 30 October 2018 / Accepted: 5 November 2018 / Published: 12 November 2018
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Abstract
Nitrogen availability is the key determinant of plant growth and development. The improvement of nitrogen use efficiency (NUE) in crops is an important consideration. In fruit and vegetables, such as watermelon, rootstocks are often utilized to control soil borne diseases and improve plant
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Nitrogen availability is the key determinant of plant growth and development. The improvement of nitrogen use efficiency (NUE) in crops is an important consideration. In fruit and vegetables, such as watermelon, rootstocks are often utilized to control soil borne diseases and improve plant performance to a range of abiotic stresses. In this study, we evaluated the efficacy of 10 wild watermelon rootstocks (ZXG-516, ZXG-941, ZXG-945, ZXG-1250, ZXG-1251, ZXG-1558, ZXG-944, ZXG-1469, ZXG-1463, and ZXG-952) to improve the plant growth and nitrogen use efficiency (NUE) of the watermelon cultivar: Zaojia 8424. Nitrogen use efficiency (NUE) is a comprehensive parameter that represents the ability of a plant to absorb nitrogen (N) and convert the supplied resources to the dry biomass. Wild watermelon rootstocks substantially improved plant growth, rate of photosynthesis, stomatal conductivity, intercellular carbon dioxide concentration, rate of transpiration, nitrogen uptake efficiency, nitrogen use efficiency, and nitrogen utilization efficiency of watermelon. NUE of watermelon grafted onto ZXG-945, ZXG-1250, and ZXG-941 was improved by up to 67%, 77%, and 168%, respectively, at optimum N supply. Similarly, at low N supply (0.2 mM), NUE of watermelon grafted onto ZXG-1558 and ZXG-516 was improved by up to 104% and 175%, respectively. In conclusion, grafting onto some wild rootstocks can improve nitrogen use efficiency of watermelon, and this improved nitrogen use efficiency could be attributed to better N uptake efficiency of wild watermelon rootstocks. Full article
(This article belongs to the Section Horticultural and Floricultural Crops)
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Open AccessArticle Characterization of Interspecific Hybrids between Flowering Chinese Cabbage and Chinese Kale
Agronomy 2018, 8(11), 258; https://doi.org/10.3390/agronomy8110258
Received: 17 September 2018 / Revised: 1 November 2018 / Accepted: 1 November 2018 / Published: 12 November 2018
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Abstract
Interspecific hybridization is considered to be an important driving force in the evolution, diversification, and formation of plant species. We selected one flowering Chinese cabbage variety and three Chinese kale varieties to make hybrids. Heterologous haploid offspring were obtained by embryo rescue and
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Interspecific hybridization is considered to be an important driving force in the evolution, diversification, and formation of plant species. We selected one flowering Chinese cabbage variety and three Chinese kale varieties to make hybrids. Heterologous haploid offspring were obtained by embryo rescue and heterologous diploids were obtained by colchicine doubling. A total of 108 individuals of the F2, F3 and F4 generations from three parental combinations were investigated for field traits and SSR (simple sequence repeats) markers. The results showed trait separation and the appearance and disappearance of SSR bands in the hybrids, showing significant differences among parental combinations and among the different generations. This proved that the phenotypes of the initial generations of allopolyploids were not stable. This study not only enriches the genetic resources available for breeding flowering Chinese cabbage and Chinese kale, but lays a theoretical foundation for exploring the segregation of traits in distant hybrids and in different generations. Full article
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Open AccessArticle The Influence of Water and Nitrogen Availability on the Expression of End-Use Quality Parameters of Spring Wheat
Agronomy 2018, 8(11), 257; https://doi.org/10.3390/agronomy8110257
Received: 24 September 2018 / Revised: 1 November 2018 / Accepted: 4 November 2018 / Published: 10 November 2018
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Wheat (Triticum aestivum L.) grain quality is determined by multiple physical and chemical attributes. However, previous studies mainly focused on protein quantity and composition, which may not be adequate for understanding grain quality, especially end-use quality. Field experiments were conducted at two
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Wheat (Triticum aestivum L.) grain quality is determined by multiple physical and chemical attributes. However, previous studies mainly focused on protein quantity and composition, which may not be adequate for understanding grain quality, especially end-use quality. Field experiments were conducted at two locations for two years to better understand how and to what extent water and nitrogen (N) availability affect flour end-use quality. Four drought stress levels (i.e., mild, moderate, severe, and well-watered) and four N rates (i.e., zero, low, medium, and high) were applied to two spring wheat cultivars (i.e., Dayn and Egan). Evaluated end-use quality traits, including milling quality, mixograph parameters, flour protein and gluten contents, solvent retention capacity (SRC), and baking quality. Most end-use quality parameters were not significantly different between the well-watered treatment and mild drought stress in both cultivars. Nitrogen availability above the low rate (168 kg N ha−1) failed to further improve most end-use quality traits in either cultivar. Among all the end-use quality traits, lactic acid SRC may be a reliable indicator of flour end-use quality. These results indicate that mild drought stress (i.e., a 25% reduction in irrigation throughout the growing season) may not negatively affect end-use quality and excessive N fertilization offers minimal improvement in end-use quality. Such information could facilitate the development of irrigation and fertilization guidelines targeting at grain quality. Full article
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Open AccessArticle Effects of Maize Residue Biochar Amendments on Soil Properties and Soil Loss on Acidic Hutton Soil
Agronomy 2018, 8(11), 256; https://doi.org/10.3390/agronomy8110256
Received: 22 September 2018 / Revised: 6 November 2018 / Accepted: 6 November 2018 / Published: 10 November 2018
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Abstract
Soil acidification is a serious challenge and a major cause of declining soil and crop productivity in the Eastern parts of South Africa (SA). An incubation experiment investigated effects of different maize residue biochar rates on selected soil properties and soil loss in
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Soil acidification is a serious challenge and a major cause of declining soil and crop productivity in the Eastern parts of South Africa (SA). An incubation experiment investigated effects of different maize residue biochar rates on selected soil properties and soil loss in acidic Hutton soils. Biochar amendment rates were 0%, 2.5%, 5%, 7.5%, and 10% (soil weight) laid as a completely randomized design. Soil sampling was done on a 20-day interval for 140 days to give a 5 × 7 factorial experiment. Rainfall simulation was conducted at 60, 100 and 140 days after incubation to quantify soil loss. Relative to the control biochar amendments significantly improved soil physicochemical properties. After 140 days, biochar increased soil pH by between 0.34 to 1.51 points, soil organic carbon (SOC) by 2.2% to 2.34%, and microbial activity (MBC) by 496 to 1615 mg kg−1 compared to control. Soil aggregation (MWD) changes varied from 0.58 mm to 0.70 mm for the duration of the trial. Soil loss significantly decreased by 27% to 70% under biochar amendment compared to control. This indicates that maize residue biochar application has the potential to improve the soil properties and reduce soil loss in the degraded acidic Hutton soil. Full article
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Open AccessArticle Linking Soil Microbial Properties with Plant Performance in Acidic Tropical Soil Amended with Biochar
Agronomy 2018, 8(11), 255; https://doi.org/10.3390/agronomy8110255
Received: 4 September 2018 / Revised: 17 October 2018 / Accepted: 22 October 2018 / Published: 8 November 2018
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Abstract
Soil microbial properties are frequently used as indicators of soil fertility. However, the linkage of these properties with crop biomass is poorly documented especially in biochar amended soil with high carbon:nitrogen (C:N). A short-term field trial was conducted to observe the growth response
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Soil microbial properties are frequently used as indicators of soil fertility. However, the linkage of these properties with crop biomass is poorly documented especially in biochar amended soil with high carbon:nitrogen (C:N). A short-term field trial was conducted to observe the growth response of maize to biochar treatment in a highly weathered Ultisol of humid tropics and to observe the possible linkage of the measured microbial properties with maize biomass. Soil microbial biomass (carbon (C), nitrogen (N), phosphorus (P)), enzyme activity (β-glucosidase, urease, phosphodiesterase) and gene abundance (bacterial 16S rRNA, fungal ITS) were analyzed. For comparison, total soil C, N, and P were also analyzed. The data revealed no significant linkage of soil C, N, and P with maize biomass. A significant association of enzyme activity and gene abundance with maize biomass was not recorded. Strong positive correlation between maize above ground biomass with microbial biomass N was found (r = 0.9186, p < 0.01). Significant negative correlation was recorded between microbial biomass C:N with maize biomass (r = −0.8297, p < 0.05). These statistically significant linkages observed between microbial biomass and maize biomass suggests that microbial biomass can reflect the soil nutrient status, and possibly plant nutrient uptake. Estimation of microbial biomass can be used as a fertility indicator in soil amended with high C:N organic matter in the humid tropics. Full article
(This article belongs to the Section Soil and Plant Nutrition)
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Open AccessArticle Quantification of Oil Content in Intact Sugar Beet Seed by Near-Infrared Spectroscopy
Agronomy 2018, 8(11), 254; https://doi.org/10.3390/agronomy8110254
Received: 23 October 2018 / Revised: 5 November 2018 / Accepted: 6 November 2018 / Published: 8 November 2018
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Abstract
Sugar beet seed oil reserves play an important role in successful germination and seedling development. The purpose of this study was to establish a non-destructive near-infrared (NIR) methodology with good predictive accuracy to quantify stored seed oil in sugar beet seed. Reflectance NIR
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Sugar beet seed oil reserves play an important role in successful germination and seedling development. The purpose of this study was to establish a non-destructive near-infrared (NIR) methodology with good predictive accuracy to quantify stored seed oil in sugar beet seed. Reflectance NIR spectra were acquired from viable monogerm seeds. Calibration equations were developed using partial least squares. The optimized calibration model reached a Pearson correlation of 0.946; an independent prediction test reached a correlation of 0.919 and a Root Mean Square Error of Prediction of 0.388. The possible role of the outer pericarp in the prediction of oil content was additionally considered. The results indicate that the model is suitable for a rapid and accurate determination of the oil content in both polished and unpolished sugar beet seeds. This NIR application might help to understand the role of seed energy reservoirs in sugar beet germination and further plant growth. Full article
(This article belongs to the Special Issue Breeding and Genetics of Sugarcane and Other Sugar Crops)
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Open AccessArticle Workflow to Establish Time-Specific Zones in Precision Agriculture by Spatiotemporal Integration of Plant and Soil Sensing Data
Agronomy 2018, 8(11), 253; https://doi.org/10.3390/agronomy8110253
Received: 20 September 2018 / Revised: 31 October 2018 / Accepted: 1 November 2018 / Published: 7 November 2018
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Abstract
Management zones (MZs) are used in precision agriculture to diversify agronomic management across a field. According to current common practices, MZs are often spatially static: they are developed once and used thereafter. However, the soil–plant relationship often varies over time and space, decreasing
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Management zones (MZs) are used in precision agriculture to diversify agronomic management across a field. According to current common practices, MZs are often spatially static: they are developed once and used thereafter. However, the soil–plant relationship often varies over time and space, decreasing the efficiency of static MZ designs. Therefore, we propose a novel workflow for time-specific MZ delineation based on integration of plant and soil sensing data. The workflow includes four steps: (1) geospatial sensor measurements are used to describe soil spatial variability and in-season plant growth status; (2) moving-window regression modelling is used to characterize the sub-field changes of the soil–plant relationship; (3) soil information and sub-field indicator(s) of the soil–plant relationship (i.e., the local regression slope coefficient[s]) are used to delineate time-specific MZs using fuzzy cluster analysis; and (4) MZ delineation is evaluated and interpreted. We illustrate the workflow with an idealized, yet realistic, example using synthetic data and with an experimental example from a 21-ha maize field in Italy using two years of maize growth, soil apparent electrical conductivity and normalized difference vegetation index (NDVI) data. In both examples, the MZs were characterized by unique combinations of soil properties and soil–plant relationships. The proposed approach provides an opportunity to address the spatiotemporal nature of changes in crop genetics × environment × management interactions. Full article
(This article belongs to the Special Issue Remote Sensing Applications for Agriculture and Crop Modelling)
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Open AccessArticle Seed Plumpness of Rice with Inhibition Expression of Starch Branching Enzymes and Starch Properties, Grain Position on Panicle
Agronomy 2018, 8(11), 252; https://doi.org/10.3390/agronomy8110252
Received: 30 July 2018 / Revised: 9 October 2018 / Accepted: 1 November 2018 / Published: 4 November 2018
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Abstract
Cereal crops with inhibition expression of starch branching enzyme (SBE) contain highly resistant starch in the endosperm, and have potential health benefits for human. However, seed plumpness is significantly different, with different inhibition effects of SBE expression, resulting in differently shrunken seeds. In
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Cereal crops with inhibition expression of starch branching enzyme (SBE) contain highly resistant starch in the endosperm, and have potential health benefits for human. However, seed plumpness is significantly different, with different inhibition effects of SBE expression, resulting in differently shrunken seeds. In this study, a transgenic resistant starch rice line, which has highly resistant starch and is developed through inhibition expression of SBEs, had non-, slightly, and moderately shrunken seeds with plumpness from high to low. The differently shrunken seeds had significantly different seed weight and starch content. Different morphological starch granules were detected in the endosperm and had similar spatial distribution pattern among the non-, slightly, and moderately shrunken seeds. Starches from differently shrunken seeds had similar amylose content and amylopectin structure. The protein amount of amylose/amylopectin synthesis key enzymes in endosperm was no different between differently shrunken seeds. The primary branch of the panicle had a higher percentage of non-shrunken seeds than did the secondary branch at the same part of the panicle. From the upper part to the base of the panicle, non-shrunken seeds gradually decreased but slightly and moderately shrunken seeds gradually increased. The above results indicated that the differently shrunken seeds in transgenic rice line had the same SBE dosage, and the starch morphology and structure had no relationship with seed plumpness. The grain position on the panicle influenced seed plumpness, but had no effect on starch properties. Full article
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Open AccessArticle Rigput Brome (Bromus diandrus Roth.) Management in a No-Till Field in Spain
Agronomy 2018, 8(11), 251; https://doi.org/10.3390/agronomy8110251
Received: 1 October 2018 / Revised: 31 October 2018 / Accepted: 1 November 2018 / Published: 4 November 2018
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Abstract
The adoption of no-till (NT) in the semi-arid region of Mediterranean Spain has promoted a weed vegetation change, where rigput brome (Bromus diandrus Roth) represents a main concern. In order to avoid complete reliance on herbicides, the combination of several control methods,
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The adoption of no-till (NT) in the semi-arid region of Mediterranean Spain has promoted a weed vegetation change, where rigput brome (Bromus diandrus Roth) represents a main concern. In order to avoid complete reliance on herbicides, the combination of several control methods, without excluding chemical ones, can contribute to an integrated weed management (IWM) system for this species. In this field study, 12 three-year management programs were chosen, in which alternative non-chemical methods—delay of sowing, crop rotation, sowing density and pattern, stubble removal—are combined with chemical methods to manage B. diandrus in winter cereals under NT. Moreover, their effects on weed control and crop productivity were analyzed from the point of view of the efficiency of the control methods, based on a previously developed emergence model for B. diandrus. All management programs were effective in reducing the weed infestation, despite the different initial weed density between blocks. For high weed density levels (60–500 plants m−2), two years of specific managements resulted in ≥99% reduction of its population. For even higher density levels, three years were needed to assure this reduction level. Both the emergence of the weed and the crop yields are mainly driven by the seasonal climatic conditions in this semi-arid area. For this reason, among the non-chemical methods, only crop rotation and sowing delay contributed to an effective weed population decrease as well as an increase in the economic income of the yield. The other alternative methods did not significantly contribute to controlling the weed. This work demonstrates that mid-term management programs combining chemical with non-chemical methods can effectively keep B. diandrus under control with economic gains compared to traditional field management methods in semi-arid regions. Full article
(This article belongs to the Special Issue Weed Management & New Approaches)
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Open AccessArticle Genome-Wide Identification and Expression Profiling Analysis of the Galactinol Synthase Gene Family in Cassava (Manihot esculenta Crantz)
Agronomy 2018, 8(11), 250; https://doi.org/10.3390/agronomy8110250
Received: 10 October 2018 / Revised: 29 October 2018 / Accepted: 1 November 2018 / Published: 3 November 2018
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Abstract
Galactinol synthases (GolSs) are the key enzymes that participate in raffinose family oligosaccharides (RFO) biosynthesis, which perform a big role in modulating plant growth and response to biotic or abiotic stresses. To date, no systematic study of this gene family has been conducted
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Galactinol synthases (GolSs) are the key enzymes that participate in raffinose family oligosaccharides (RFO) biosynthesis, which perform a big role in modulating plant growth and response to biotic or abiotic stresses. To date, no systematic study of this gene family has been conducted in cassava (Manihot esculenta Crantz). Here, eight MeGolS genes are isolated from the cassava genome. Based on phylogenetic background, the MeGolSs are clustered into four groups. Through predicting the cis-elements in their promoters, it was discovered that all MeGolS members act as hormone-, stress-, and tissue-specific related elements to different degrees. MeGolS genes exhibit incongruous expression patterns in various tissues, indicating that different MeGolS proteins might have diverse functions. MeGolS1 and MeGolS36 are highly expressed in leaves and midveins. MeGolS36 are highly expressed in fibrous roots. Quantitative real-time Polymerase Chain Reaction (qRT-PCR) analysis indicates that several MeGolSs, including MeGolS1, 2, 5, 6, and 7, are induced by abiotic stresses. microRNA prediction analysis indicates that several abiotic stress-related miRNAs target the MeGolS genes, such as mes-miR156, 159, and 169, which also respond to abiotic stresses. The current study is the first systematic research of GolS genes in cassava, and the results of this study provide a basis for further exploration the functional mechanism of GolS genes in cassava. Full article
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Open AccessReview Breeding Low-Cadmium Wheat: Progress and Perspectives
Agronomy 2018, 8(11), 249; https://doi.org/10.3390/agronomy8110249
Received: 26 September 2018 / Revised: 12 October 2018 / Accepted: 31 October 2018 / Published: 3 November 2018
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Abstract
Farmland cadmium (Cd) contamination has adverse impacts on both wheat grain yield and people’s well-being through food consumption. Safe farming using low-Cd cultivars has been proposed as a promising approach to address the farmland Cd pollution problem. To date, several dozen low-Cd wheat
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Farmland cadmium (Cd) contamination has adverse impacts on both wheat grain yield and people’s well-being through food consumption. Safe farming using low-Cd cultivars has been proposed as a promising approach to address the farmland Cd pollution problem. To date, several dozen low-Cd wheat cultivars have been screened worldwide based on a Cd inhibition test, representing candidates for wheat Cd minimization. Unfortunately, the breeding of low-Cd wheat cultivars with desired traits or enhanced Cd exclusion has not been extensively explored. Moreover, the wheat Cd inhibition test for variety screening and conventional breeding is expensive and time-consuming. As an alternative, low-Cd wheat cultivars that were developed with molecular genetics and breeding approaches can be promising, typically by the association of marker-assisted selection (MAS) with conventional breeding practices. In this review, we provide a synthetics view of the background and knowledge basis for the breeding of low-Cd wheat cultivars. Full article
(This article belongs to the Section Crop Breeding and Genetics)
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Open AccessArticle The Effect of an Edible Coating with Tomato Oily Extract on the Physicochemical and Antioxidant Properties of Garambullo (Myrtillocactus geometrizans) Fruits
Agronomy 2018, 8(11), 248; https://doi.org/10.3390/agronomy8110248
Received: 9 October 2018 / Revised: 30 October 2018 / Accepted: 1 November 2018 / Published: 3 November 2018
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Abstract
The Myrtillocactus geometrizans (Mart. ex. Pfeiff.) fruit, locally called garambullo, is an important source of bioactive compounds, mainly betalains, polyphenols, and ascorbic acid. However, information on the application of post-harvest technologies that prolong the shelf life of the fruits is still insufficient. The
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The Myrtillocactus geometrizans (Mart. ex. Pfeiff.) fruit, locally called garambullo, is an important source of bioactive compounds, mainly betalains, polyphenols, and ascorbic acid. However, information on the application of post-harvest technologies that prolong the shelf life of the fruits is still insufficient. The objective of the present research was to evaluate the effect of a gelatin coating incorporating 0%, 1%, or 3% tomato oily extract (TOE), compared to a control (without coating), on the physicochemical and antioxidant properties of garambullo fruits stored for 15 days at 5 °C. The gelatin coatings with TOE significantly (p ≤ 0.05) delayed changes in weight loss, brix degrees, titratable acidity and pH, compared to the control during storage. Fruits coated with TOE-gelatin had a higher content of betalains, ascorbic acid, total phenols, and flavonoids. The results showed that a higher concentration of phytochemicals increased antioxidant activity in vitro; the maximum values found for Trolox equivalents per kg of fresh weight were 10.46 and 17.65 mM for the 2,2′-diphenyl-1-picrylhydrazyl (DPPH) and Trolox Equivalent Antioxidant Capacity Method (TEAC) tests, respectively. The gelatin coating with TOE-3% (COTE-3%) reduced water loss by 1.66 times, compared to the control. In addition, the fruits covered with COTE-3% showed the highest concentration of bioactive compounds during storage. Full article
Open AccessArticle Comparative Analysis of the Transcriptional Response of Tolerant and Sensitive Wheat Genotypes to Drought Stress in Field Conditions
Agronomy 2018, 8(11), 247; https://doi.org/10.3390/agronomy8110247
Received: 11 October 2018 / Revised: 31 October 2018 / Accepted: 31 October 2018 / Published: 2 November 2018
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Abstract
Drought stress is one of the most adverse environmental limiting factors for wheat (Triticum aestivum L.) productivity worldwide. For better understanding of the molecular mechanism of wheat in response to drought, a comparative transcriptome approach was applied to investigate the gene expression
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Drought stress is one of the most adverse environmental limiting factors for wheat (Triticum aestivum L.) productivity worldwide. For better understanding of the molecular mechanism of wheat in response to drought, a comparative transcriptome approach was applied to investigate the gene expression change of two wheat cultivars, Jimai No. 47 (drought-tolerant) and Yanzhan No. 4110 (drought-sensitive) in the field under irrigated and drought-stressed conditions. A total of 3754 and 2325 differential expressed genes (DEGs) were found in Jimai No. 47 and Yanzhan No. 4110, respectively, of which 377 genes were overlapped, which could be considered to be the potential drought-responsive genes. GO (Gene Ontology) analysis showed that these DEGs of tolerant genotype were significantly enriched in signaling transduction and MAP (mitogen-activated protein) kinase activity, while that of sensitive genotype was involved in photosynthesis, membrane protein complex, and guard cell differentiation. Furthermore, 32 and 2 RNA editing sites were identified in drought-tolerant and sensitive genotypes under drought compared to irrigation, demonstrating that RNA editing also plays an important role in response to drought in wheat. This study investigated the gene expression pattern and RNA editing sites of two wheat cultivars with contrasting tolerance in field condition, which will contribute to a better understanding of the molecular mechanism of drought tolerance in wheat and beyond. Full article
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Open AccessArticle Effects of Cultivar, Nitrogen Rate, and Planting Density on Rice-Grain Quality
Agronomy 2018, 8(11), 246; https://doi.org/10.3390/agronomy8110246
Received: 13 September 2018 / Revised: 23 October 2018 / Accepted: 1 November 2018 / Published: 2 November 2018
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Abstract
To achieve superior rice-grain quality, more emphasis has been placed on the genetic diversity of breeding programs, although this improvement could be seriously restricted in the absence of comparable agricultural management practices. Nitrogen (N) application and planting density are two important agronomic practices
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To achieve superior rice-grain quality, more emphasis has been placed on the genetic diversity of breeding programs, although this improvement could be seriously restricted in the absence of comparable agricultural management practices. Nitrogen (N) application and planting density are two important agronomic practices influencing rice growth, yield, and grain quality. This study investigated the four main aspects of rice-grain quality, namely, milling (brown-rice, milled-rice, and head-rice percentage), appearance (length/width ratio, chalky-kernel percentage, and chalkiness), nutrition (protein content), and cooking and eating quality (apparent amylose content, gel consistency, and pasting viscosities) of two rice cultivars (Shendao 47 and Jingyou 586) under four N rates (0, 140, 180, and 220 kg ha−1), and three planting densities (25 × 104, 16.7 × 104, and 12.5 × 104 hills ha−1) in a field trial from 2015 to 2016. The four main aspects of rice-grain quality were significantly influenced by cultivar. Several aspects were affected by the interactions of N rate and cultivar. No significant interaction between N rate and plating density was detected for all grain-quality parameters. A higher N rate increased the percentages of brown rice and head rice, chalky-kernel percentage, and setback and peak time values, but reduced the length/width ratio, chalkiness, apparent amylose content, gel consistency, and peak-, trough-, and final-viscosity values. These results indicate that the N rate has a beneficial effect on milling and nutritional quality, but a detrimental effect on appearance and cooking and eating quality. Jingyou 586 and Shendao 47 had different responses to planting density in terms of grain quality. Our study indicates that low planting density for Jingyou 586, but a medium one for Shendao 47, is favorable for grain quality. Full article
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Open AccessArticle An Assessment of Low-Cost Techniques to Measure Ammonia Emission from Multi-Plots: A Case Study with Urea Fertilization
Agronomy 2018, 8(11), 245; https://doi.org/10.3390/agronomy8110245
Received: 21 September 2018 / Revised: 24 October 2018 / Accepted: 30 October 2018 / Published: 2 November 2018
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Abstract
Ammonia (NH3) emission from agriculture is an environmental threat and a loss of nitrogen for crop production. Mineral fertilizers and manure are significant sources of NH3; therefore, abatement technologies have been introduced to mitigate these emissions. The aim of
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Ammonia (NH3) emission from agriculture is an environmental threat and a loss of nitrogen for crop production. Mineral fertilizers and manure are significant sources of NH3; therefore, abatement technologies have been introduced to mitigate these emissions. The aim of this study was to demonstrate that low-cost measuring techniques are suitable to assess NH3 emissions in smaller plots, appropriate to test different managements. Two experiments were established to quantify NH3 emissions from urea application in a multi-plot design with radii of 5 (R5) and 20 m (R20). Field was bare soil partially surrounded by shelterbelts. Measurement techniques included passive flux samplers (Leuning), and passive concentration samplers (ALPHA) coupled to WindTrax dispersion model. NH3 emission from R5 was consistent with the emission from R20 when the surface-to-atmosphere exchange was not affected by shelterbelts, and wind speed near surface was greater than 1 m s−1. Both measurement methods gave unreliable NH3 quantification in combination with wind speed lower than 1 m s−1 and low emission strength. Cumulative emission over 60 h was 2% of the supplied N from the plots not affected by the shelterbelt, and 1% from the plots affected by shelterbelts, indicating that these structures can significantly reduce NH3 emissions. Full article
(This article belongs to the Section Soil and Plant Nutrition)
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Open AccessArticle Yield, Decomposition, Mineralization and Nitrification of Annual Legumes in an Oxisol
Agronomy 2018, 8(11), 244; https://doi.org/10.3390/agronomy8110244
Received: 12 August 2018 / Revised: 30 October 2018 / Accepted: 31 October 2018 / Published: 2 November 2018
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Abstract
Knowledge about seasonal and litter bag soil position effects on litter decomposition (k value), mineralization and nitrification rate of annual legumes in Puerto Rico is limited. This study determined dry matter yield (DMY), k value of litter bags placed below and above
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Knowledge about seasonal and litter bag soil position effects on litter decomposition (k value), mineralization and nitrification rate of annual legumes in Puerto Rico is limited. This study determined dry matter yield (DMY), k value of litter bags placed below and above the soil surface, mineralization and nitrification rates of Lablab purpureus cv. “Rongai” and Mucuna pruriens (Velvet bean) seeded in the wet and dry season in Oxisol soils (Typic Eustrustox). There was an interaction (p < 0.05) for season and legumes on DMY, k value and N content. “Rongai” DMY was higher for the dry than wet season while Velvet bean had an opposite seasonal response. Higher k value occurred in the wet season for legumes, but “Rongai” had higher k than Velvet bean. For both legumes, N content was higher on litter bag placed below-ground in both seasons. However, in the wet season, there was less N in the above ground litter position. Higher inorganic N was observed at 90 days of soil incubation (DOI) suggesting that N was not available prior to 42 DOI. Nitrification rate was higher for “Rongai” at 22 DOI and lower at 42 and 90 DOI for both legumes. Both legumes enhanced inorganic N, but, regardless of season, Rongai supplied nutrients to the soil faster than Velvet bean. “Rongai” because of its higher k value than Velvet bean is recommended for fast growing row or vegetable crops in Puerto Rico. Full article
(This article belongs to the Section Soil and Plant Nutrition)
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Open AccessArticle Non-Structural Carbohydrate Metabolism, Growth, and Productivity of Maize by Increasing Plant Density
Agronomy 2018, 8(11), 243; https://doi.org/10.3390/agronomy8110243
Received: 8 September 2018 / Revised: 28 October 2018 / Accepted: 30 October 2018 / Published: 2 November 2018
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Abstract
Increasing plant density seems to improve the productivity of maize crops, and the understanding of how the metabolism of non-structural carbohydrates is affected in plants under high crop density is critical. Thus, with the objective of further clarifying this issue, maize plants were
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Increasing plant density seems to improve the productivity of maize crops, and the understanding of how the metabolism of non-structural carbohydrates is affected in plants under high crop density is critical. Thus, with the objective of further clarifying this issue, maize plants were subjected to densities from 30,000 to 90,000 plants ha−1, and the plant growth, soluble sugars and starch contents, invertase and sucrose synthase activities, and plant production were evaluated. We found that the stalk is more sensitive to the increasing plant density than leaves and kernels. The dry weight of the stalk and leaves per single plant decreased more drastically from low to intermediate plant densities, while grain production was reduced linearly in all plant density ranges, leading to higher values of harvest index in intermediate plant densities. The sucrose concentration did not change in leaves, stalk, or kernels of plants subjected to increasing plant densities at the R4 stage. Also, the specific activity of soluble invertase, bound invertase, and sucrose synthase did not change in leaf, stalk, or kernels of plants subjected to increased plant density. The productivity was increased with the increase in plant density, using narrow row (0.45 m) spacing. Full article
(This article belongs to the Special Issue Environmental and Management Factor Contributions to Maize Yield)
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