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Agronomy, Volume 9, Issue 4 (April 2019)

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Cover Story (view full-size image) Magnaporthiopsis maydis is considered the most serious maize fungal pathogen in Israel and Egypt, [...] Read more.
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Open AccessArticle
Detecting Salt Tolerance in Doubled Haploid Wheat Lines
Agronomy 2019, 9(4), 211; https://doi.org/10.3390/agronomy9040211 - 25 Apr 2019
Viewed by 554
Abstract
Improving salt tolerance of genotypes requires a source of genetic variation and multiple accurate selection criteria for discriminating their salt tolerance. A combination of morpho-physiological and biochemical parameters and multivariate analysis was used to detect salt tolerance variation in 15 wheat lines developed [...] Read more.
Improving salt tolerance of genotypes requires a source of genetic variation and multiple accurate selection criteria for discriminating their salt tolerance. A combination of morpho-physiological and biochemical parameters and multivariate analysis was used to detect salt tolerance variation in 15 wheat lines developed by doubled haploid (DHL) technique. They were then compared with the salt-tolerant check cultivar Sakha 93. Salinity stress was investigated at three salinity levels (0, 100, and 200 mM NaCl) for 25 days. Considerable genetic variation was observed for all traits, as was high heritability (>60%) and genetic gain (>20%). Principal component analysis indicated the ability of nine traits (root number, root length, root dry weight, shoot length, shoot dry weight, specific root length, relative water content, membrane stability index, and catalase) to identify differences in salinity tolerance among lines. Three traits (shoot length, shoot dry weight, and catalase) were indicative of salt-tolerance, indicating their importance in improving and evaluating salt tolerant genotypes for breeding programs. The salinity tolerance membership index based on these three traits classified one new line (DHL21) and the check cultivar (Sakha 93) as highly salt-tolerant, DHL25, DHL26, DHL2, DHL11, and DHL5 as tolerant, and DHL23 and DHL12 as intermediate. Discriminant function analysis and MANOVA suggested differences among the five groups of tolerance. Among the donor genotypes, Sakha 93 remained the donor of choice for improving salinity tolerance during the seedling stage. The tolerated lines (DHL21, DHL25, DHL26, DHL2, DHL11, and DHL5) could be also recommended as useful and novel genetic resources for improving salinity tolerance of wheat in breeding programs. Full article
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Open AccessArticle
Grapevine Phenology of cv. Touriga Franca and Touriga Nacional in the Douro Wine Region: Modelling and Climate Change Projections
Agronomy 2019, 9(4), 210; https://doi.org/10.3390/agronomy9040210 - 25 Apr 2019
Viewed by 594
Abstract
Projections of grapevine phenophases under future climate change scenarios are strategic decision support tools for viticulturists and wine producers. Several phenological models are tested for budburst, flowering, and veraison and for two main grapevine varieties (cv. Touriga Franca and Touriga Nacional) growing [...] Read more.
Projections of grapevine phenophases under future climate change scenarios are strategic decision support tools for viticulturists and wine producers. Several phenological models are tested for budburst, flowering, and veraison and for two main grapevine varieties (cv. Touriga Franca and Touriga Nacional) growing in the Douro Demarcated Region. Four forcing models (Growing degree-days, Richardson, Sigmoid, and Wang) and three dormancy models (Bidabe, Smoothed Utah and Chuine), with different parameterizations and combinations, are used. New datasets, combing phenology with weather station data, widespread over the Douro wine region, were used for this purpose. The eight best performing models and parameterizations were selected for each phenophase and variety, based on performance metrics. For both cultivars, results revealed moderate performances (0.4 < R2 < 0.7) for budburst, while high performances (R2 > 0.7) were found for flowering and veraison, particularly when Growing degree-days or Sigmoid models are used, respectively. Climate change projections were based on a two-member climate model ensemble from the EURO-CORDEX project under RCP4.5. Projections depicted an anticipation of phenophase timings by 6, 8 or 10–12 days until the end of the century for budburst, flowering, and veraison, respectively. The inter-model variability is of approximately 2–4 days for flowering and veraison and 4–6 days for budburst. These results establish grounds for the implementation of a decision support system for monitoring and short-term prediction of grapevine phenology, thus promoting a more efficient viticulture. Full article
(This article belongs to the Special Issue Viticulture and Winemaking under Climate Change)
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Open AccessArticle
The Effect of Potassium and Sulfur Fertilization on Seed Quality of Faba Bean (Vicia faba L.)
Agronomy 2019, 9(4), 209; https://doi.org/10.3390/agronomy9040209 - 25 Apr 2019
Viewed by 443
Abstract
Faba bean seeds are regarded as a highly valuable protein source for human and animal nutrition. High yield and quality of faba bean require adequate mineral nutrition. The aim of the study was to assess the impact of potassium (K) and elemental sulfur [...] Read more.
Faba bean seeds are regarded as a highly valuable protein source for human and animal nutrition. High yield and quality of faba bean require adequate mineral nutrition. The aim of the study was to assess the impact of potassium (K) and elemental sulfur (S) on crude protein (CP) and tannin content (TC) in seeds, crude protein yield (CPY), and amino acid (AA) composition. Field trials were carried out during 2010–2013 in the temperate climate of Central Europe. The study assessed the influence of the following factors: variable soil K content and fertilization (K1, K2, K3, and K4) and elemental S application (0, 25, and 50 kg S ha−1). Plants were harvested at two growth stages to obtain immature seeds and mature seeds. K and S applications did not have a significant impact on CP and AA composition, including sulfur AA content. The TC decreased in response to increasing content of plant-available K in soil. In respect to CPY, the results indicate a positive response of faba bean to increasing K content in soil. The effect of S fertilization depended on the K treatment. The most beneficial influence of S on CPY was registered on K-poor soil. Full article
(This article belongs to the Section Soil and Plant Nutrition)
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Open AccessArticle
An Improved Mesocotyl Elongation Assay for the Rapid Identification and Characterization of Strigolactone-Related Rice Mutants
Agronomy 2019, 9(4), 208; https://doi.org/10.3390/agronomy9040208 - 25 Apr 2019
Viewed by 631
Abstract
Strigolactones (SLs) constitute an important class of plant hormones involved in diverse developmental activities in plant growth and host-parasite interaction. Although substantial progress has been made to understand this pathway, the mechanism of action is still elusive especially with its interaction with other [...] Read more.
Strigolactones (SLs) constitute an important class of plant hormones involved in diverse developmental activities in plant growth and host-parasite interaction. Although substantial progress has been made to understand this pathway, the mechanism of action is still elusive especially with its interaction with other phytohormones and downstream targets. Here we have utilized the negative role of strigolactones in rice (Oryza sativa L.) mesocotyl elongation as a morphological marker for the identification and characterization of new developmental mutants. We observed that deep sown seeds develop longer mesocotyl compared with the surface-grown seeds in the dark condition. Based on this observation, we have developed a method to access mesocotyl elongation consisting of the glass vessel and vermiculite as a growth media. Mesocotyl elongation in the modified deep sown system results in a many-fold increase compared to the surface-grown seeds in the dark condition. External application of SLs analog rac-GR24 rescued the elongated mesocotyl phenotype in the mutant defective in SLs synthesis but not the signaling mutant, demonstrating its applicability in the physiological experiments. The modified mesocotyl elongation assay can be used as a rapid method for characterization and identification of suppressors/enhancers and new developmental mutants in the SLs or its associated pathway saving a huge amount of time and space. Full article
(This article belongs to the Section Crop Breeding and Genetics)
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Open AccessArticle
Effect of Selenium Enrichment and Type of Application on Yield, Functional Quality and Mineral Composition of Curly Endive Grown in a Hydroponic System
Agronomy 2019, 9(4), 207; https://doi.org/10.3390/agronomy9040207 - 24 Apr 2019
Cited by 2 | Viewed by 512
Abstract
Selenium (Se) is an essential element for humans’ health and the recommended amount (RDA) of Se intake per adult is 55–70 µg day−1. The main source for Se intake is represented by diet, but its concentration in vegetables is generally limited [...] Read more.
Selenium (Se) is an essential element for humans’ health and the recommended amount (RDA) of Se intake per adult is 55–70 µg day−1. The main source for Se intake is represented by diet, but its concentration in vegetables is generally limited with respect to human needs. The aim of this research was to assess the effect of Se application rate and type (fertigation or foliar spray) on yield, functional properties and mineral composition of curly endive grown in a hydroponic system. Five levels of Se (0.0, 1.0, 2.0, 4.0 and 8.0 µmol L−1) were supplied via fertigation or by foliar spray in the form of selenate (Na2SeO4). The results show that a Se implementation of 4 μmol Se L−1 for plants enriched via fertigation and 8 μmol Se L−1 for plants biofortified via foliar spray successfully enhanced production performance parameters such as head weight (42.6% and 27.8%, respectively), SSC (16.7% and 14.3%, respectively), ascorbic acid (33.2% and 33.7%, respectively), total phenolic (58.9% and 54.5%, respectively) and Se concentration (22.2% and 20.3%, respectively). Furthermore, leaf Se concentration in plants enriched via fertigation ranged 0.71–17.61 mg kg−1 of dry weight (DW), whereas, in plant biofortified via foliar spray leaf Se concentration ranged 0.72–12.67 mg kg−1 DW. Plants grown with the highest dosage of Se distributed via fertigation or foliar spray showed a reduction in total-N leaf concentration by 39.4% and 28.6%, respectively, compared with the non-enriched plants. Our results indicate a consumption of 47.4 g day−1 of Se-enriched curly endive grown in soilless culture and treated with 8 μmol L−1 of selenate applied via foliar spray could be sufficient to cover the human physiological needs of this element. Full article
(This article belongs to the Special Issue Nutrition Management of Hydroponic Vegetable Crops)
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Open AccessArticle
Seasonal Variation in Diurnal Photosynthesis and Chlorophyll Fluorescence of Four Genotypes of Cassava (Manihot esculenta Crantz) under Irrigation Conditions in a Tropical Savanna Climate
Agronomy 2019, 9(4), 206; https://doi.org/10.3390/agronomy9040206 - 23 Apr 2019
Viewed by 654
Abstract
Photosynthesis performance during early vegetative growth is an important physiological trait determining yield of cassava, but limited information is currently available for the tropical savanna climate of Asia. Diurnal photosynthesis and chlorophyll fluorescence of the three-month-old plants of four commercial cassava genotypes (Rayong [...] Read more.
Photosynthesis performance during early vegetative growth is an important physiological trait determining yield of cassava, but limited information is currently available for the tropical savanna climate of Asia. Diurnal photosynthesis and chlorophyll fluorescence of the three-month-old plants of four commercial cassava genotypes (Rayong 9, RY9; Rayong 11, RY11; Kasetsart 50, KU50 and CMR38-125-77) grown under irrigation, were investigated in three seasons i.e., rainy, cool and hot. The mean daily net photosynthetic rate (Pn) across genotypes in the rainy season (11.75 µmolCO2/m2/s) was significantly lower than that in the cool season (14.60 µmolCO2/m2/s). Daily mean Pn in the hot season was 14.32 µmolCO2/m2/s. In the rainy season, maximum photochemical quantum yield of PSII (Fv/Fm) and effective quantum yield of PSII photochemistry (ΦPSII) were significantly higher than the other seasons, while electron transfer rate (ETR) and non-photochemical quenching (NPQ) were significantly lower. Genotypic variation was observed during the hot season in which RY11 had the highest and CMR38-125-77 the lowest mean daily Pn. The prominent mechanism to avoid damages from stress during afternoon in the hot season was to reduce leaf temperature by enhancing transpiration for RY11; to close stomata early for RY9, and to increase NPQ for CMR38-125-77. Full article
(This article belongs to the Special Issue Fluorescence Techniques: Understanding Crop Performance)
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Open AccessArticle
Investigation of Seed transmission in Peronospora belbahrii the Causal Agent of Basil Downy Mildew
Agronomy 2019, 9(4), 205; https://doi.org/10.3390/agronomy9040205 - 23 Apr 2019
Viewed by 651
Abstract
Downy mildew in sweet basil (Ocimum basilicum L.) caused by the oomycete pathogen Peronospora belbahrii Thines was first recorded in Israel in 2011. Within one year, the pathogen has spread all over the country, causing devastating economic damage to basil crops. Similar [...] Read more.
Downy mildew in sweet basil (Ocimum basilicum L.) caused by the oomycete pathogen Peronospora belbahrii Thines was first recorded in Israel in 2011. Within one year, the pathogen has spread all over the country, causing devastating economic damage to basil crops. Similar outbreaks were reported in Europe, the USA, and Asia. Seed transmission and seedling trade were suggested as possible explanations for this rapid spread. Here, we show that P. belbahrii can develop systemically in artificially inoculated basil plants in growth chambers. It may reach remote un-inoculated parts of the plant including the axillary buds but not the roots or seeds. To verify whether transmission of the disease occurs via seeds, we harvested seeds from severely infected, field-grown basil plants. Harvests were done in four seasons, from several basil cultivars growing in three locations in Israel. Microscopic examinations revealed external contamination with sporangia of P. belbahrii of untreated seeds, but not of surface-sterilized seeds. Pathogen-specific PCR assays confirmed the occurrence of the pathogen in untreated seeds, but not in surface-sterilized seeds. Contaminated seeds were grown (without disinfection) in pasteurized soil in growth chambers until the four–six leaf stage. None of several thousand plants showed any symptom or sporulation of downy mildew. PCR assays conducted with several hundred plants grown from contaminated seeds proved no latent infection in plants developed from such seeds. The results confirmed that (i) P. belbahrii can spread systemically in basil plants, but does not reach their roots or seeds; (ii) sporangia of P. belbahrii may contaminate the surface, but not the internal parts, of seeds produced by infected basil plants in the field: and (iii) contaminated seeds produce healthy plants, which carry no latent infection. The data suggest that P. belbahrii in Israel is seed-borne, but not seed-transmitted. Full article
(This article belongs to the Special Issue Etiology and Control of Crop Diseases)
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Open AccessArticle
Conservation of Soil Organic Carbon and Nitrogen Fractions in a Tallgrass Prairie in Oklahoma
Agronomy 2019, 9(4), 204; https://doi.org/10.3390/agronomy9040204 - 20 Apr 2019
Viewed by 566
Abstract
Native grasslands in the Great Plains of North America have mostly disappeared in the past century due to agricultural expansion. A grazing study was established on Paleustolls and Argiustolls supporting a remnant, but historically grazed tallgrass prairie in central Oklahoma. Stocking method of [...] Read more.
Native grasslands in the Great Plains of North America have mostly disappeared in the past century due to agricultural expansion. A grazing study was established on Paleustolls and Argiustolls supporting a remnant, but historically grazed tallgrass prairie in central Oklahoma. Stocking method of beef cattle was differentiated into continuous and rotational treatments (10 sub-paddocks) in 2009 and these treatments continued until present. Soil was sampled in 2009 and 2012 at depths of 0–6, 6–12, 12–20, and 20–30 cm and in 2017 at depths of 0–15 and 15–30 cm. Total, particulate, microbial biomass, and mineralizable C and N fractions were highly stratified with depth, having 2–10 times greater concentration at a depth of 0–6 cm as that at 20–30 cm. Strong associations existed among most of these soil organic C and N fractions, given the large range that resulted from sampling at multiple depths. No discernable differences in soil organic C and N fractions occurred due to stocking method at any sampling time or depth. Evidence for biological nitrification inhibition suggested a mechanism for conservation of available N with less opportunity for loss. In addition, strong association of available N with biologically active C indicated slow, but sustained release of N that was strongly coupled to C cycling. We conclude that stocking method had a neutral effect on conservation of already high antecedent conditions of soil organic C and N fractions during the first 8 years of differentially imposed management. Full article
(This article belongs to the Special Issue Grassland Management for Sustainable Agroecosystems)
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Open AccessArticle
Towards Predictive Modeling of Sorghum Biomass Yields Using Fraction of Absorbed Photosynthetically Active Radiation Derived from Sentinel-2 Satellite Imagery and Supervised Machine Learning Techniques
Agronomy 2019, 9(4), 203; https://doi.org/10.3390/agronomy9040203 - 20 Apr 2019
Cited by 3 | Viewed by 679
Abstract
Sorghum crop is grown under tropical and temperate latitudes for several purposes including production of health promoting food from the kernel and forage and biofuels from aboveground biomass. One of the concerns of policy-makers and sorghum growers is to cost-effectively predict biomass yields [...] Read more.
Sorghum crop is grown under tropical and temperate latitudes for several purposes including production of health promoting food from the kernel and forage and biofuels from aboveground biomass. One of the concerns of policy-makers and sorghum growers is to cost-effectively predict biomass yields early during the cropping season to improve biomass and biofuel management. The objective of this study was to investigate if Sentinel-2 satellite images could be used to predict within-season biomass sorghum yields in the Mediterranean region. Thirteen machine learning algorithms were tested on fortnightly Sentinel-2A and Sentinel-2B estimates of the fraction of Absorbed Photosynthetically Active Radiation (fAPAR) in combination with in situ aboveground biomass yields from demonstrative fields in Italy. A gradient boosting algorithm implementing the xgbtree method was the best predictive model as it was satisfactorily implemented anywhere from May to July. The best prediction time was the month of May followed by May–June and May–July. To the best of our knowledge, this work represents the first time Sentinel-2-derived fAPAR is used in sorghum biomass predictive modeling. The results from this study will help farmers improve their sorghum biomass business operations and policy-makers and extension services improve energy planning and avoid energy-related crises. Full article
(This article belongs to the Special Issue Remote Sensing Applications for Agriculture and Crop Modelling)
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Open AccessArticle
Comparison between Chemical Fertilization and Integrated Nutrient Management: Yield, Quality, N, and P Contents in Dendranthema grandiflorum (Ramat.) Kitam. Cultivars
Agronomy 2019, 9(4), 202; https://doi.org/10.3390/agronomy9040202 - 19 Apr 2019
Viewed by 591
Abstract
To assess the effects of a new integrated nutrient management protocol on yield and cut stem quality, root morphology, N accumulation, nitrogen utilization efficiency (NUE), and P content in tissue, a biennial (2011 and 2012) chrysanthemum cut flower cultivation was carried out. In [...] Read more.
To assess the effects of a new integrated nutrient management protocol on yield and cut stem quality, root morphology, N accumulation, nitrogen utilization efficiency (NUE), and P content in tissue, a biennial (2011 and 2012) chrysanthemum cut flower cultivation was carried out. In both years, two nutrition management (CNM: conventional NM and INM: integrated NM) treatments and two Dendranthema grandiflorum (Ramat.) Kitamura cultivar (“White CV1” and “Yellow CV2”) treatments were compared. The treatments were arranged in a split-plot design with three replicates. CNM was fertilized using a recommended dose fertilization of mineral NPK; INM treatment was fertilized using a half dose (50%) of CNM plus a combined usage of N organic fertilizer, seaweed extract (Ascophyllum nodosum), and microrganism consortium (Glomus sp. and Bacillus sp.). Yield at harvest (+19%), number of leaves (+33%), leaf area (+46%), number of flower heads (+27%), and total aboveground dry weight (+40%) were significantly increased by the INM application compared to the control. In terms of the root system, the increase was evident in terms of length (+174%), volume (+167%), projected area (+166%), and surface area (+165%), tips (+175%), forks (+285%), and crossings (+464%). The greatest N accumulation, in both years, was registered by INM treatment at harvest: +94% in 2011 and +55% in 2012. Differences in the NM were evident in the NUE, which was highest in CNM (on average 162) compared to INM (on average 142). In both years the P content in above-ground chrysanthemum tissues was in the order of head > leaves > stems, which was maintained in both INM and CNM treatments. A higher yield (138 stems m−2) was obtained in “CV2 Yellow” compared to “CV1 White” (120 stems m−2). Based on our findings, applying INM to chrysanthemum improves yield, cut flower quality, and plant nutrient uptake, in an agro–environmentally sustainable way. A basic economic analysis on fertilizers, cost gross production, and takings difference obtained, was carried out. Full article
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Open AccessArticle
Tetraploid Wheats: Valuable Source of Phytosterols and Phytostanols
Agronomy 2019, 9(4), 201; https://doi.org/10.3390/agronomy9040201 - 19 Apr 2019
Cited by 1 | Viewed by 401
Abstract
Phytosterols are known as healthy compounds obtained mainly from oilseed crops. Cereals were also studied for their sterols content. Few insights have been devoted to other tetraploid species than emmer and durum wheats. This work examined phytosterol and phytostanol content in seed of [...] Read more.
Phytosterols are known as healthy compounds obtained mainly from oilseed crops. Cereals were also studied for their sterols content. Few insights have been devoted to other tetraploid species than emmer and durum wheats. This work examined phytosterol and phytostanol content in seed of six tetraploid wheat species cultivated during two successive years under rainfed organic conditions in Auch (near Toulouse, France). Sterols (free and esterified sterols) were measured by gas-chromatography-flame ionisation detector. Mean value of sterols + stanols content was 99.5 mg 100 g−1 DW. The main sterol was β-sitosterol. Results showed a year effect on sterol content, whatever the wheat species. This could be explained by the differences in climatic conditions prevailing during plant cycle and grain filling. A large variability for sterols content was found between species and within each species. Emmer wheat revealed the lowest values for all sterols and stanols. Higher values of sterols were obtained in durum wheat. This work is the first report studying T. carthlicum, T. polonicum, T. turgidum, T. timopheevi. These species exhibited intermediate values of sterol contents between emmer and durum wheats. Wheat tetraploid species showed interesting levels of sterols and could serve as a great source of these healthy compounds mainly in Mediterranean region where they are consumed as wholegrain. Variation in climatic conditions could help to manage the level of these secondary metabolites. Full article
Open AccessArticle
Association of Physiological Responses and Root Distribution Patterns of Ratooning Ability and Yield of the Second Ratoon Cane in Sugarcane Elite Clones
Agronomy 2019, 9(4), 200; https://doi.org/10.3390/agronomy9040200 - 19 Apr 2019
Viewed by 414
Abstract
Poor ratooning ability for sugarcane can limit crop productivity and profitability of sugarcane growers. The objective of this study was to determine the association of physiological responses and root distribution patterns on the yield of the second ratoon cane, and the relationships between [...] Read more.
Poor ratooning ability for sugarcane can limit crop productivity and profitability of sugarcane growers. The objective of this study was to determine the association of physiological responses and root distribution patterns on the yield of the second ratoon cane, and the relationships between these traits. Seventeen sugarcane genotypes were planted in a randomized complete block design with four replications. The second ratoon crop was evaluated for germination percentage, cane yield, Soil Plant Analysis Development (SPAD) chlorophyll meter reading (SCMR), chlorophyll fluorescence, relative water content (RWC), specific leaf area (SLA), and stomatal conductance. Root length density (RLD) was evaluated through the auger method. The root samples were divided into upper and lower soil layers in order to study root distribution patterns. Sugarcane genotypes were significantly different for RLD, germination percentage, and cane yield. Root distribution patterns were classified into three groups based on the RLD. High RLD between plants in the upper soil layers at 90 days after harvest (DAH) was positively correlated with high germination, whereas high RLD between rows in the lower soil layers at 90 and 270 DAH was associated with high cane yield. RWC at 90 DAH and stomatal conductance at 180 DAH were closely related to germination percentage, whereas chlorophyll fluorescence and stomatal conductance at 180 DAH were closely related to cane yield. Full article
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Open AccessArticle
Drought Stress Tolerance Screening of Elite American Breeding Rice Genotypes Using Low-Cost Pre-Fabricated Mini-Hoop Modules
Agronomy 2019, 9(4), 199; https://doi.org/10.3390/agronomy9040199 - 18 Apr 2019
Viewed by 521
Abstract
Drought is a major abiotic stress factor affecting the growth and development of plants at all stages. Developing a screening tool for identifying drought stress tolerance during seedling establishment is important in the deployment of rice varieties suited to water-limited growing environments. An [...] Read more.
Drought is a major abiotic stress factor affecting the growth and development of plants at all stages. Developing a screening tool for identifying drought stress tolerance during seedling establishment is important in the deployment of rice varieties suited to water-limited growing environments. An experiment was conducted to evaluate 100 rice genotypes, mostly belonging to the tropical japonica subspecies, for drought stress tolerance using low-cost, pre-fabricated mini-hoop structures. The rice seedlings were subjected to two different soil moisture regimes- control pots managed at 100% and drought pots at 50% field capacity, from 12 to 30 days after sowing (DAS). Several morpho-physiological parameters including root traits were measured to assess the response of genotypes to drought stress. Significant moisture stress × genotype interactions were found for most of the parameters measured. A cumulative drought stress response index (CDSRI) was developed by adding the individual response indices of all cultivars. Based on CDSRI and standard deviation values, 5 and 28 genotypes were identified as highly sensitive and sensitive to drought, respectively, and 45 as moderately sensitive. On the other hand, 16 and 6 genotypes were classified as tolerant and highly tolerant to drought, respectively. Cheniere, a released cultivar, and RU1402174, an experimental breeding line, were identified as the least and most tolerant to drought among the 100 genotypes tested. Significant linear correlation coefficients were obtained between CDSRI and root growth parameters (R2 = 0.91, n = 100) and CDSRI with shoot growth parameters (R2 = 0.48, n = 100), revealing the importance of root traits in studying and identifying drought tolerant lines during the seedling establishment stages in rice. The tolerant rice genotypes identified will be valuable for rice scientists in studying the mechanism for early season drought as well as for rice breeders for developing new genotypes best suited under growing environments prone to early-season drought. Full article
(This article belongs to the Section Crop Breeding and Genetics)
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Open AccessArticle
Optimum Sowing Dates for High-Yield Maize when Grown as Sole Crop in the North China Plain
Agronomy 2019, 9(4), 198; https://doi.org/10.3390/agronomy9040198 - 18 Apr 2019
Viewed by 441
Abstract
The maize sole cropping system solves problems related to ground water resource shortages and guarantees food security in the North China Plain. Using optimal sowing dates is an effective management practice for increasing maize yield. The goal of this study was to explore [...] Read more.
The maize sole cropping system solves problems related to ground water resource shortages and guarantees food security in the North China Plain. Using optimal sowing dates is an effective management practice for increasing maize yield. The goal of this study was to explore an optimum sowing date for high-yield maize. Six sowing dates (SDs) from early April to late June with intervals of 10 to 20 days between SD—SD1 (early April), SD2 (mid to late April), SD3 (early May), SD4 (mid to late May), SD5 (early June), SD6 (late June)—were applied from 2012 to 2017. The results showed that yield was correlated with the sowing date based on the thermal time before sowing (r = 0.62**), which was defined as the pre-thermal time (PTt), and that the yield was steadily maintained at a high level (>10,500 kg ha−1) when PTt was greater than 479 °C. To satisfy the growing degree-days required for maturity, maize needs to be sown before a PTt of 750 °C. Data analysis of the results from 2014, 2015, and 2017 revealed the following: i) Most of the grain-filling parameters of late-sown dates (SD4, SD5 and SD6) were better than those in early-sown dates (SD1, SD2, and SD3) in all years, because of the high daily maximum temperature (Tmax) and wide diurnal temperature (Td) from silking to blister (R1–R2) of early-sown dates. The weight of maximum grain-filling rate (Wmax) of SD3 decreased compare with SD4 by the narrow Td from blister to physiological maturity (R2–R6) in all years (−5, −12, and −33 mg kernel−1 in 2014, 2015, and 2017, respectively). ii) In 2017, the pollination failure rates of early-sown dates were 8.4~14.5%, which was caused by the high Tmax and Td of R1–R2. The apical kernel abortion rates were 28.6 (SD2) and 38.7% (SD3), which were affected by Tmax and Td during R2–R6. iii) Compared with late-sown dates, the wide Td of early-sown dates in R1–R2 was caused by higher Tmax, but the narrow Td in R2-R6 was caused by higher Tmin. Our results indicate that high-yielding maize can be obtained by postponing the sowing date with a PTt of 480~750 °C, which can prevent the negative effects of the high Tmax of R1–R2 and high Tmin of R2–R6 on kernel number and weight formation. Moreover, these above-mentioned traits should be considered for heat tolerance breeding to further increase the maize yield. Full article
(This article belongs to the Section Innovative Cropping Systems)
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Open AccessArticle
Effects of Natural Hail on the Growth, Physiological Characteristics, Yield, and Quality of Vitis vinifera L. cv. Thompson Seedless under Mediterranean Growing Conditions
Agronomy 2019, 9(4), 197; https://doi.org/10.3390/agronomy9040197 - 17 Apr 2019
Viewed by 646
Abstract
Hailstorms are typically localized events, and very little is known about their effect on crops. The objective of this study was to examine the physiological and vine performance responses to natural hail, registered four weeks after full bloom, of field-grown Thompson seedless ( [...] Read more.
Hailstorms are typically localized events, and very little is known about their effect on crops. The objective of this study was to examine the physiological and vine performance responses to natural hail, registered four weeks after full bloom, of field-grown Thompson seedless (Vitis vinifera L.) grapevines, one of the most important table grape varieties cultivated in Greece and especially in the Corinthian region in northeastern Peloponnese. Leaf gas exchange, vegetative growth, vine balance indices, cane wood reserves, yield components, and fruit chemical composition were recorded from hail-damaged vines and compared with control vines. Visibly, the extent of the hailstorm damage was great enough to injure or remove leaves as well as cause partial stem bruising and partial injury or total cracking of berries. Our results indicated that natural hail did not affect leaf photosynthesis, berry weight, total acidity, and cane wood reserves but significantly reduced the total leaf area, yield, and the total phenolics of berries at harvest. At the same time, hail-damaged vines increased the leaf area of lateral canes and presented a higher total soluble solid (TSS) accumulation, while no effect on the next year’s fertility was registered. The present work is the first attempt to enhance our understanding of the vegetative yield, berry quality, and physiological responses of grapevines to natural hail, which is an extreme and complex natural phenomenon that is likely to increase due to climate change. Full article
(This article belongs to the Special Issue Viticulture and Winemaking under Climate Change)
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Open AccessTechnical Note
Correcting Pervasive Errors in Genotypic Datasets to Develop Genetic Maps
Agronomy 2019, 9(4), 196; https://doi.org/10.3390/agronomy9040196 - 16 Apr 2019
Viewed by 493
Abstract
Genetic mapping studies provide improved estimates for novel genomic loci, allelic effects and gene action controlling important traits. Such mapping studies are regularly performed by using a combination of genotypic data (e.g., genotyping markers tagging genetic variation within populations) and phenotypic data of [...] Read more.
Genetic mapping studies provide improved estimates for novel genomic loci, allelic effects and gene action controlling important traits. Such mapping studies are regularly performed by using a combination of genotypic data (e.g., genotyping markers tagging genetic variation within populations) and phenotypic data of appropriately structured mapping populations. Randomly obtained DNA information and more recent high-throughput genome sequencing efforts have dramatically increased the ability to obtain genetic markers for any plant species. Despite the presence of constantly and rapidly increasing genotypic data, necessary steps to determine whether specific markers can be associated with genetic variation may often be initially neglected, meaning that ever-growing genotypic markers do not necessarily maximize the power of mapping studies and often generate false results. To address this issue, we present a framework for analyzing genotypic data while developing a genetic linkage map. Our goal is to raise awareness of a stepwise procedure in the development of genetic maps as well as to outline the current and potential contribution of this procedure to minimize bias caused by errors in genotypic datasets. Empirical results obtained from the R/qtl package for the statistical language/software R are prepared with details of how we handled genotypic data to develop the genetic map of a major plant species. This study provides a stepwise procedure to correct pervasive errors in genotypic data while developing genetic maps. For use in custom follow-up studies, we provide input files and written R codes. Full article
(This article belongs to the Special Issue Advances in Genotyping Platforms for Crop Improvement)
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Open AccessArticle
Participation of Wheat and Rye Genome in Drought Induced Senescence in Winter Triticale (X Triticosecale Wittm.)
Agronomy 2019, 9(4), 195; https://doi.org/10.3390/agronomy9040195 - 16 Apr 2019
Viewed by 424
Abstract
The aim of the study was to identify the regions of triticale genome responsible for senescence under drought induced during the generative stage. We performed quantitative analysis of chlorophylls (a and b), carotenoids, soluble carbohydrates, and phenolic compounds. QTL (Quantitative Trait [...] Read more.
The aim of the study was to identify the regions of triticale genome responsible for senescence under drought induced during the generative stage. We performed quantitative analysis of chlorophylls (a and b), carotenoids, soluble carbohydrates, and phenolic compounds. QTL (Quantitative Trait Loci) calculations were based on a previously developed and characterized genetic map involving 92 lines of doubled haploid derived from F1 hybrid ‘Hewo’ × ‘Magnat’ and two DH parental lines (‘Hewo’ and ‘Magnat’). We identified seven QTLs, including four on chromosome 2A, one on chromosome 1R, and two on chromosome 6R. Only three loci, QSPh.2A.1, QSC.2A.2 and QSC.2A.4 mapped single traits, i.e., the content of soluble phenolics and carbohydrates. Single QTL (QCSPh.1R) was responsible for changes in the levels of chlorophyll a and b, carotenoids and soluble phenolics. The remaining three loci, QCSPhC.2A.3, QCSPhC.6R.1 and QCSPhC.6R.2 controlled changes in the entire set of investigated traits. We also identified candidate genes for the investigated traits. The loci on chromosome 2A encoded proteins responsible for oligosaccharide transportation and mechanical properties of xylem and the genes regulating carbohydrate metabolism. The chromosomes 1R and 6R contained functional genes possibly associated with carbohydrate and phenolic metabolism. Full article
Open AccessArticle
Production, Leaf Quality and Antioxidants of Perennial Wall Rocket as Affected by Crop Cycle and Mulching Type
Agronomy 2019, 9(4), 194; https://doi.org/10.3390/agronomy9040194 - 16 Apr 2019
Cited by 3 | Viewed by 492
Abstract
The plastic mulch has raised a disposal issue, which has been diverting the research focus on biodegradable film as an alternative. Research was carried out in southern Italy in 2016–2017 and 2017–2018 in order to assess the effects of three crop cycles (autumn-winter, [...] Read more.
The plastic mulch has raised a disposal issue, which has been diverting the research focus on biodegradable film as an alternative. Research was carried out in southern Italy in 2016–2017 and 2017–2018 in order to assess the effects of three crop cycles (autumn-winter, winter, spring) in factorial combination with three soil mulching types (a MaterBi biodegradable black film; a brown photoselective low density polyethylene (LDPE) film; a black-standard LDPE film) and a non-mulched control, on leaves yield, quality and antioxidants of greenhouse grown Diplotaxis tenuifolia (L.) D.C. The spring cycle was the shortest and best enhanced plant growth and yield. The non-mulched control caused an 11% yield reduction compared to the mulching treatments average (12.4 t ha−1). The soil temperature was highest under photoselective and standard LDPE films. The Soil Plant Analysis Development (SPAD) index was 17.4% higher in the leaves grown in mulched soil. Winter season and biodegradable mulch led to higher leaf dry residue and organic acids. Leaf nitrate content was highest in winter and under mulching. The spring cycle, the biodegradable and photoselective LDPE film resulted in the highest antioxidant compound content and activity. The biodegradable polymer improved leaf quality, showing suitable features for sustainable production. Full article
(This article belongs to the Section Horticultural and Floricultural Crops)
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Open AccessArticle
Compost as a Substitute for Mineral N Fertilization? Effects on Crops, Soil and N Leaching
Agronomy 2019, 9(4), 193; https://doi.org/10.3390/agronomy9040193 - 15 Apr 2019
Viewed by 625
Abstract
A three-year study was conducted to test the fertilization properties of different types of compost as the total or partial mineral nitrogen fertilization substitute in an herbaceous crop succession (Zea mays L., Triticum aestivum L. and Helianthus annus L.). Four types of [...] Read more.
A three-year study was conducted to test the fertilization properties of different types of compost as the total or partial mineral nitrogen fertilization substitute in an herbaceous crop succession (Zea mays L., Triticum aestivum L. and Helianthus annus L.). Four types of compost (i. green cuttings and depuration sludge, ii. green cuttings, organic fraction of municipal wastes and other organic materials, iii. green cuttings, iv. green cuttings and organic fraction of municipal wastes) and eight fertilization treatments (combining: unfertilized control, 100% mineral fertilization, 100% compost, and 50% compost +50% mineral fertilization) were evaluated in terms of: (i) crop yields and nitrogen uptake, (ii) soil organic carbon and nitrate nitrogen soil contents variation, and (iii) residual nitrate nitrogen leached at the end of the experiment. Maize grain yield ranged from 5.2 ± 1.0 Mg ha−1 to 7.4 ± 0.7 Mg ha−1 with the highest value in the mineral fertilization treatment and the lowest values in the 100% compost fertilization. Wheat and sunflower grain yields were not significantly different among control, mineral, compost, or mineral/compost fertilization treatments with average values of 5.1 ± 0.7 Mg ha−1 and 2.3 ± 0.3 Mg ha−1, respectively. Cumulative crop yield at the end of the three years was not affected by the compost type, but was affected by fertilization treatment (highest values with mineral and 50% compost +50% mineral fertilization). The compost application did not highlight a relevant effect on soil organic carbon. Under 100% of compost fertilization, the crops did not take up a large amount of the N supplied, but it did not generate an increase of NO3-N leaching in the percolation water. Obtained results show the good fertilization properties of compost whereas the amendment property was not relevant, probably due to the low rates applied and the short experimental period. Full article
(This article belongs to the Special Issue Sustainable Cropping Systems)
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Open AccessReview
Microalgal Biostimulants and Biofertilisers in Crop Productions
Agronomy 2019, 9(4), 192; https://doi.org/10.3390/agronomy9040192 - 15 Apr 2019
Cited by 4 | Viewed by 1121
Abstract
Microalgae are attracting the interest of agrochemical industries and farmers, due to their biostimulant and biofertiliser properties. Microalgal biostimulants (MBS) and biofertilisers (MBF) might be used in crop production to increase agricultural sustainability. Biostimulants are products derived from organic material that, applied in [...] Read more.
Microalgae are attracting the interest of agrochemical industries and farmers, due to their biostimulant and biofertiliser properties. Microalgal biostimulants (MBS) and biofertilisers (MBF) might be used in crop production to increase agricultural sustainability. Biostimulants are products derived from organic material that, applied in small quantities, are able to stimulate the growth and development of several crops under both optimal and stressful conditions. Biofertilisers are products containing living microorganisms or natural substances that are able to improve chemical and biological soil properties, stimulating plant growth, and restoring soil fertility. This review is aimed at reporting developments in the processing of MBS and MBF, summarising the biologically-active compounds, and examining the researches supporting the use of MBS and MBF for managing productivity and abiotic stresses in crop productions. Microalgae are used in agriculture in different applications, such as amendment, foliar application, and seed priming. MBS and MBF might be applied as an alternative technique, or used in conjunction with synthetic fertilisers, crop protection products and plant growth regulators, generating multiple benefits, such as enhanced rooting, higher crop yields and quality and tolerance to drought and salt. Worldwide, MBS and MBF remain largely unexploited, such that this study highlights some of the current researches and future development priorities. Full article
(This article belongs to the Special Issue Biofortification of Crops)
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Open AccessArticle
Synergistic and Antagonistic Effects of Poultry Manure and Phosphate Rock on Soil P Availability, Ryegrass Production, and P Uptake
Agronomy 2019, 9(4), 191; https://doi.org/10.3390/agronomy9040191 - 15 Apr 2019
Viewed by 605
Abstract
To maintain grassland productivity and limit resource depletion, scarce mineral P (phosphorus) fertilizers must be replaced by alternative P sources. The effect of these amendments on plant growth may depend on physicochemical soil parameters, in particular pH. The objective of this study was [...] Read more.
To maintain grassland productivity and limit resource depletion, scarce mineral P (phosphorus) fertilizers must be replaced by alternative P sources. The effect of these amendments on plant growth may depend on physicochemical soil parameters, in particular pH. The objective of this study was to investigate the effect of soil pH on biomass production, P use efficiency, and soil P forms after P amendment application (100 mg kg−1 P) using poultry manure compost (PM), rock phosphate (RP), and their combination (PMRP). We performed a growth chamber experiment with ryegrass plants (Lolium perenne) grown on two soil types with contrasting pH under controlled conditions for 7 weeks. Chemical P fractions, biomass production, and P concentrations were measured to calculate plant uptake and P use efficiency. We found a strong synergistic effect on the available soil P, while antagonistic effects were observed for ryegrass production and P uptake. We conclude that although the combination of PM and RP has positive effects in terms of soil P availability, the combined effects of the mixture must be taken into account and further evaluated for different soil types and grassland plants to maximize synergistic effects and to minimize antagonistic ones. Full article
(This article belongs to the Special Issue Grassland Management for Sustainable Agroecosystems)
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Open AccessArticle
Mulch Treatment Effect on Weed Biomass and Yields of Organic Sweetpotato Cultivars
Agronomy 2019, 9(4), 190; https://doi.org/10.3390/agronomy9040190 - 13 Apr 2019
Viewed by 641
Abstract
Weeds are a challenge, particularly in organic agriculture, due to restrictions on the application of synthetic herbicides and chemicals. A preliminary cultivar evaluation trial of organic sweetpotato was conducted in 2015 at Tennessee State University certified organic farm. Three mulches: wheat straw, pine [...] Read more.
Weeds are a challenge, particularly in organic agriculture, due to restrictions on the application of synthetic herbicides and chemicals. A preliminary cultivar evaluation trial of organic sweetpotato was conducted in 2015 at Tennessee State University certified organic farm. Three mulches: wheat straw, pine needle, and black plastic mulch, along with a control (no mulch), were evaluated for their weed management abilities in a sweetpotato field. Four cultivars of sweetpotato were planted in 0.91 m wide mulch beds with 0.3 m row spacing anddrip irrigated with four replications. Data was collected during the growing season on the dry weight of weeds that emerged in a quadrat and yield components at harvest. Results of two-way ANOVA revealed that mulch treatments affected the weed biomass, weed density, and cull yields. Though the use of mulches had no significant effect on other yield components of sweetpotato in this study; it was beneficial for weed management. Full article
(This article belongs to the Special Issue Weed Management & New Approaches)
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Open AccessArticle
Comparison of Energy Used and Effects on Bulk Density and Yield by Tillage Systems in a Semiarid Condition of Mexico
Agronomy 2019, 9(4), 189; https://doi.org/10.3390/agronomy9040189 - 13 Apr 2019
Viewed by 427
Abstract
Energy used for tillage is an input with a high impact on the cost of crop production; it is desirable to till the soil using minimum energy. The objective of this study was to compare the specific energy expenditure, effect on soil bulk [...] Read more.
Energy used for tillage is an input with a high impact on the cost of crop production; it is desirable to till the soil using minimum energy. The objective of this study was to compare the specific energy expenditure, effect on soil bulk density, and forage yield of maize, by three tillage systems: Disk plow/Disk Harrow/planter (DDP), Chisel plow/Disk harrow/planter (CHDP) and No-Tillage (NT). Energy was measured for tillage operations in the summer season of 2013, 2016, and 2017. Bulk density in 2013 and 2016. Yield in 2013 and 2014. The variables of drawbar force (kN), working speed (m s−1), width (m), depth (m), fuel consumption (L ha−1), bulk density (g cm−3), and dry matter yield (Mg ha−1) were measured. Results showed that there were significant differences in the amount of energy used per ha; DDP used an average of 379.75 MJ, CHDP 135.01 MJ, and NT 26.43 MJ. The average energy applied to the soil mass for each system was 400 J kg−1 for DDP, 255.13 J kg−1 for CHDP, and for NT was 237.8 J kg−1. The overall energy efficiency was; 18.23% for DDP, 6.88% for CHDP, and 4.77% for N. The bulk density decreased significantly after three years for NT. There were no significant differences in dry matter yield. In the semiarid condition of Mexico, CHDP and NT are options for saving from 64% to 93% of energy, compared with DDP. Full article
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Open AccessReview
Cereal Root Interactions with Soilborne Pathogens—From Trait to Gene and Back
Agronomy 2019, 9(4), 188; https://doi.org/10.3390/agronomy9040188 - 13 Apr 2019
Viewed by 575
Abstract
Realizing the yield potential of crop plants in the presence of shifting pathogen populations, soil quality, rainfall, and other agro-environmental variables remains a challenge for growers and breeders worldwide. In this review, we discuss current approaches for combatting the soilborne phytopathogenic nematodes, Pratylenchus [...] Read more.
Realizing the yield potential of crop plants in the presence of shifting pathogen populations, soil quality, rainfall, and other agro-environmental variables remains a challenge for growers and breeders worldwide. In this review, we discuss current approaches for combatting the soilborne phytopathogenic nematodes, Pratylenchus and Heterodera of wheat and barley, and Meloidogyne graminicola Golden and Birchfield, 1965 of rice. The necrotrophic fungal pathogens, Rhizoctonia solani Kühn 1858 AG-8 and Fusarium spp. of wheat and barley, also are discussed. These pathogens constitute major causes of yield loss in small-grain cereals of the Pacific Northwest, USA and throughout the world. Current topics include new sources of genetic resistance, molecular leads from whole genome sequencing and genome-wide patterns of hosts, nematode or fungal gene expression during root-pathogen interactions, host-induced gene silencing, and building a molecular toolbox of genes and regulatory sequences for deployment of resistance genes. In conclusion, improvement of wheat, barley, and rice will require multiple approaches. Full article
(This article belongs to the Special Issue Root-Soil Interactions)
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Open AccessArticle
Propane Flaming as a New Approach to Control Mediterranean Invasive Weeds
Agronomy 2019, 9(4), 187; https://doi.org/10.3390/agronomy9040187 - 12 Apr 2019
Cited by 1 | Viewed by 521
Abstract
In recent decades, anthropogenic activity and climate changes have reshaped global weed dispersal and establishment in new territories. This study aimed to evaluate the effectiveness of propane flaming approach in the control of perennial invasive and native Mediterranean broadleaf and grass weeds. The [...] Read more.
In recent decades, anthropogenic activity and climate changes have reshaped global weed dispersal and establishment in new territories. This study aimed to evaluate the effectiveness of propane flaming approach in the control of perennial invasive and native Mediterranean broadleaf and grass weeds. The invasive weeds, Cyperus rotundus, Sorghum halepense, and Ecballium elaterium, were treated multiple times with a single propane dose (2.5 kg propane km−1), using the broadcast technique. The local annual weeds, Sinapis arvensis, Lavatera trimestris, and Avena sativa, were treated once at five propane doses (0–2.5 kg propane km−1), using the cross-row technique. Dose-response analysis was performed. Three applications provided effective control (up to >90%) for all tested perennials, and affected seed and flower production in Sorghum halepense and Ecballium elaterium, respectively. However, the timing of the sequential application had a significant impact on the degree of control, in terms of dry weight reduction and seed production. Weed density had an impact on control efficacy but was only a significant determinant for Ecballium elaterium. Cross-row application was effective during early growth stages of broadleaf weeds (ED50 < 1.2 kg propane km−1), but was less effective during later growth stages (ED50 > 2.6 kg propane km−1). For grass weeds, both early and late application were ineffective (ED50 > 4.1 kg propane km−1). More research is needed to optimize this weed control tactic for various cropping systems and weed species. Implementation of this novel approach into integrated weed management programs will increase the control efficacy of invasive weed under the projected climate changes and reduce the evolution of herbicide-resistant weeds. Full article
(This article belongs to the Special Issue Management and Control Methods for Invasive Plants in Agroecosystems)
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Open AccessArticle
Ethephon Improved Stalk Strength of Maize (Zea Mays L.) Mainly through Altering Internode Morphological Traits to Modulate Mechanical Properties under Field Conditions
Agronomy 2019, 9(4), 186; https://doi.org/10.3390/agronomy9040186 - 12 Apr 2019
Viewed by 460
Abstract
Stalk strength is critical for reducing maize stalk lodging and maintaining grain yield. Ethephon has been widely applied to molding compact plant-type to reduce the lodging risk in maize production. However, there is little information on how ethephon regulates internode mechanical properties to [...] Read more.
Stalk strength is critical for reducing maize stalk lodging and maintaining grain yield. Ethephon has been widely applied to molding compact plant-type to reduce the lodging risk in maize production. However, there is little information on how ethephon regulates internode mechanical properties to improve maize stalk strength. Multiyear field experiments (2013–2017) were conducted to determine the effects of foliar-applied ethephon on summer maize internode morphological, chemical and mechanical characteristics. The hypothetical structural equation model was used to analyze the contribution of ethephon-induced changes of internode morphological and chemical traits to stalk mechanical strength. Ethephon significantly reduced the basal internode length, while increasing internode diameters and breaking resistance. Meanwhile, ethephon significantly increased the ratio of structural dry matter to total dry matter and the amount of structural dry matter per unit length and volume. Mechanical assays suggested that ethephon significantly altered geometric properties and increased the maximum bending moment, maximum failure force, while depressing the material properties. Furthermore, correlation and path analyses revealed strong correlations and significant contribution of internode morphological properties to stalk mechanical strength, respectively. These results support the conclusion that ethephon-induced morphology alteration played a major role in improving maize internode strength. Full article
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Open AccessArticle
Line × Tester Analysis for Morphological and Fruit Biochemical Traits in Eggplant (Solanum melongena L.) Using Wild Relatives as Testers
Agronomy 2019, 9(4), 185; https://doi.org/10.3390/agronomy9040185 - 11 Apr 2019
Cited by 2 | Viewed by 601
Abstract
Wild relatives of eggplant are commonly exploited for eggplant improvement, but the genetic improvement relies on the information of the genetic basis of inheritance of traits. In this study, two eggplant lines, one with oriental and another with occidental cytoplasm, were crossed with [...] Read more.
Wild relatives of eggplant are commonly exploited for eggplant improvement, but the genetic improvement relies on the information of the genetic basis of inheritance of traits. In this study, two eggplant lines, one with oriental and another with occidental cytoplasm, were crossed with four testers representing three wild species, namely, Solanum insanum, S.anguivi, and S. lichtensteinii. The Line × Tester cross produced a total of eight interspecific hybrids. Parents and their hybrids were evaluated for 3 biochemical, 12 morphological, and 8 Tomato Analyzer-based descriptors. A significant amount of variation was noticed for all 23 traits studied. The higher values for the specific combining ability (SCA) component were determined as compared to the general combining ability (GCA) component. The testers were more significant for most of the traits than the cultivated varieties. Positive heterosis was determined for the 12 characteristics and negative heterosis for the 11 attributes. Overall, S.anguivi, and S. lichtensteinii were better for the biochemical traits’ improvement, whereas S. insanum was a better tester for the morphological traits. Full article
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Open AccessArticle
Imbalanced Soil Chemical Properties and Mineral Nutrition in Relation to Growth and Yield Decline of Sesame on Different Continuously Cropped Upland Fields Converted Paddy
Agronomy 2019, 9(4), 184; https://doi.org/10.3390/agronomy9040184 - 11 Apr 2019
Viewed by 639
Abstract
Sesame (Sesamum indicum L.) is an important oilseed crop, but is negatively affected by continuous cropping. There is still a lack of information on the effect of continuous cropping on soil chemical properties and mineral nutrition related to sesame growth and yield [...] Read more.
Sesame (Sesamum indicum L.) is an important oilseed crop, but is negatively affected by continuous cropping. There is still a lack of information on the effect of continuous cropping on soil chemical properties and mineral nutrition related to sesame growth and yield decline. Therefore, we investigated sesame growth and yield, nutrient concentration and soil chemical properties on five fields with continuous cropping history: non-continuous cropping (Year 0) and durations of two, four, five and six years on an upland field converted paddy in Tottori, Japan. Results show that plant height significantly decreased by 18.76%, 15.22%, and 13.64% in the Year 4, Year 5 and Year 6 fields, respectively, compared to Year 0. The effect of continuous cropping was more pronounced on the 1000-seed weight decline than seed yield. Compared to Year 0, seed yield decreased by 52.86% in Year 2 with no significant differences among the Year 2, Year 4, Year 5 and Year 6 fields, whereas the 1000-seed weight decreased by 6.68% and 12.20% in the Year 2 and Year 5 fields, respectively, compared to Year 0. Plant leaf tissue N concentration significantly decreased in the Year 2, Year 4 and Year 6 fields compared to Year 0, whereas leaf tissue K concentration decreased in the Year 6 field. The increase in duration of continuous cropping years gradually altered soil chemical properties. Soil pH, exchangeable Ca and Mg and cation exchange capacity (CEC) gradually increased in the long duration of continuous cropping, whereas total N and C, exchangeable NH4+-N, urease, dehydrogenase and catalase activities decreased. Our study suggested that the decrease in soil available N and enzyme activities, and decrease in K nutrition due to competitive ion effect as a result of increase in soil Ca and Mg could possibly contribute to the growth and yield decline of continuous sesame on upland field converted paddy. Full article
(This article belongs to the Section Soil and Plant Nutrition)
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Open AccessArticle
Modeling Carbon and Water Fluxes of Managed Grasslands: Comparing Flux Variability and Net Carbon Budgets between Grazed and Mowed Systems
Agronomy 2019, 9(4), 183; https://doi.org/10.3390/agronomy9040183 - 10 Apr 2019
Viewed by 652
Abstract
The CenW ecosystem model simulates carbon, water, and nitrogen cycles following ecophysiological processes and management practices on a daily basis. We tested and evaluated the model using five years eddy covariance measurements from two adjacent but differently managed grasslands in France. The data [...] Read more.
The CenW ecosystem model simulates carbon, water, and nitrogen cycles following ecophysiological processes and management practices on a daily basis. We tested and evaluated the model using five years eddy covariance measurements from two adjacent but differently managed grasslands in France. The data were used to independently parameterize CenW for the two grassland sites. Very good agreements, i.e., high model efficiencies and correlations, between observed and modeled fluxes were achieved. We showed that the CenW model captured day-to-day, seasonal, and interannual variability observed in measured CO2 and water fluxes. We also showed that following typical management practices (i.e., mowing and grazing), carbon gain was severely curtailed through a sharp and severe reduction in photosynthesizing biomass. We also identified large model/data discrepancies for carbon fluxes during grazing events caused by the noncapture by the eddy covariance system of large respiratory losses of C from dairy cows when they were present in the paddocks. The missing component of grazing animal respiration in the net carbon budget of the grazed grassland can be quantitatively important and can turn sites from being C sinks to being neutral or C sources. It means that extra care is needed in the processing of eddy covariance data from grazed pastures to correctly calculate their annual CO2 balances and carbon budgets. Full article
(This article belongs to the Special Issue Grassland Management for Sustainable Agroecosystems)
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Open AccessArticle
Effect of Tillage Systems on Spatial Variation in Soil Chemical Properties and Winter Wheat (Triticum aestivum L.) Performance in Small Fields
Agronomy 2019, 9(4), 182; https://doi.org/10.3390/agronomy9040182 - 10 Apr 2019
Viewed by 505
Abstract
To investigate how tillage intensity modifies the small-scale spatial variability of soil and winter wheat parameters, field trials were conducted on small plots (12 m × 35 m) in three temperate environments in the Swiss midlands: Zollikofen in 1999 (loamy silt soil; Gleyic [...] Read more.
To investigate how tillage intensity modifies the small-scale spatial variability of soil and winter wheat parameters, field trials were conducted on small plots (12 m × 35 m) in three temperate environments in the Swiss midlands: Zollikofen in 1999 (loamy silt soil; Gleyic Cambisol) and Schafisheim in 1999 and in 2000 (sandy loam soil; Orthic Luvisol). Total soil nitrogen (Ntot), total carbon (Ctot) and pH were assessed after harvest. A regular nested grid pattern was applied with sampling intervals of 3 m and 1 m at 0–30 cm on a total of nine no-tillage (NT) and nine conventional tillage (CT) plots. At each grid point, wheat biomass, grain yield, N uptake and grain protein concentration were recorded. Small-scale structural variance of soil Ntot, Ctot and pH was slightly larger in NT than in CT in the topsoil in the tillage direction of the field. Wheat traits had a slightly greater small-scale variability in NT than in CT. Spatial relationships between soil and crop parameters were rather weak but more pronounced in NT. Our results suggest limited potential for variable-rate application of N fertilizer and lime for NT soils. Moderate nugget variances in soil parameters were usually higher in CT than in NT, suggesting that differences in spatial patterns between the tillage systems might occur at even smaller scales. Full article
(This article belongs to the Special Issue Precision Agriculture)
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