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Agronomy, Volume 10, Issue 2 (February 2020) – 163 articles

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Cover Story (view full-size image) Conventional methods for leaf area index (LAI) estimation are laborious and time-consuming, so it [...] Read more.
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Open AccessArticle
Nutrient Recycling, Wheat Straw Decomposition, and the Potential Effect of Straw Shear Strength on Soil Mechanical Properties
Agronomy 2020, 10(2), 314; https://doi.org/10.3390/agronomy10020314 - 24 Feb 2020
Cited by 1 | Viewed by 543
Abstract
This study aimed to explore the release rate (RR) of wheat straw nutrients during straw return to a paddy field and examined the possible relationship between wheat stalk shear strength and the content of the remaining components in wheat straw. We used the [...] Read more.
This study aimed to explore the release rate (RR) of wheat straw nutrients during straw return to a paddy field and examined the possible relationship between wheat stalk shear strength and the content of the remaining components in wheat straw. We used the nylon mesh bag technique to study the decomposition of straw nutrients such as total organic carbon (TOC), total nitrogen (TN), total phosphorus (TP), total potassium (TK), lignin, and cellulose over time. During the time span of 0–90 days, results showed a rapid decomposition rate with a diverse trend under different tillage operations. Furthermore, the decomposition rate was higher under the plough (PRP) conditions than under dry conditions (RP) or water rotation (PR). Moreover, under PRP conditions, the RR of TOC, TK, lignin, and cellulose increased, while the RR of TK was higher than 95% initially and then increased slightly. However, the carbon to nitrogen ratio was first increased and then decreased; similarly the RR of TP first increased and then decreased; a fluctuating pattern was observed for TN. Additionally, we found a strong correlation between wheat stalk shear strength and the remaining contents of lignin, hemicellulose, and cellulose, with R2 ≥ 0.91, which was higher than 0.82 after computing adjustments. Furthermore, the changing trend of nutrients and components and the relationship between shear strength and the content of the remaining components in wheat straw were used to evaluate the release characteristics of nutrients under straw return. The potential effects of the straw shear strength on soil mechanical properties were determined, providing a remarkable opportunity for acquiring nutrients for sustainable application of soil. Full article
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Open AccessArticle
Transcriptomic Analysis of Female Panicles Reveals Gene Expression Responses to Drought Stress in Maize (Zea mays L.)
Agronomy 2020, 10(2), 313; https://doi.org/10.3390/agronomy10020313 - 24 Feb 2020
Viewed by 505
Abstract
Female panicles (FPs) play an important role in the formation of yields in maize. From 40 days after sowing to the tasseling stage for summer maize, FPs are developing and sensitive to drought. However, it remains unclear how FPs respond to drought stress [...] Read more.
Female panicles (FPs) play an important role in the formation of yields in maize. From 40 days after sowing to the tasseling stage for summer maize, FPs are developing and sensitive to drought. However, it remains unclear how FPs respond to drought stress during FP development. In this study, FP differentiation was observed at 20 and 30 days after drought (DAD) and agronomic trait changes of maize ears were determined across three treatments, including well-watered (CK), light drought (LD), and moderate drought (MD) treatments at 20, 25, and 30 DAD. RNA-sequencing was then used to identify differentially expressed genes (DEGs) in FPs at 30 DAD. Spikelets and florets were suppressed in LD and MD treatments, suggesting that drought slows FP development and thus decreases yields. Transcriptome analysis indicated that 40, 876, and 887 DEGs were detected in LD/CK, MD/CK, and MD/LD comparisons. KEGG pathway analysis showed that ‘biosynthesis of other secondary metabolites’ and ‘carbohydrate metabolism’ were involved in the LD response, whereas ‘starch and sucrose metabolism’ and ‘plant hormone signal transduction’ played important roles in the MD response. In addition, a series of molecular cues related to development and growth were screened for their drought stress responses. Full article
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Open AccessArticle
A 1Ns Disomic Addition from Psathyrostachys Huashanica Keng Confers Resistance to Powdery Mildew in Wheat
Agronomy 2020, 10(2), 312; https://doi.org/10.3390/agronomy10020312 - 24 Feb 2020
Viewed by 401
Abstract
Powdery mildew is a fungal disease that threatens wheat production throughout the world. Breeding resistant cultivars is an effective way to reduce harm caused by powdery mildew. In this study, 35 wheat-Psathyrostachys huashanica-derived lines were developed by crossing common wheat and [...] Read more.
Powdery mildew is a fungal disease that threatens wheat production throughout the world. Breeding resistant cultivars is an effective way to reduce harm caused by powdery mildew. In this study, 35 wheat-Psathyrostachys huashanica-derived lines were developed by crossing common wheat and P. huashanica Keng (2n = 2x = 14, NsNs) using embryo culture. Resistance to powdery mildew in the derived lines was identified at the seedling and adult stages. Line H5-5-4-2 was selected with immunity to powdery mildew at both growth stages. The chromosome structure of this line was characterized by cytology, genomic in situ hybridization (GISH), and expressed sequence tag-sequence-tagged site (EST-STS) analysis. The chromosome configuration was 2n = 44 = 22II. Two P. huashanica chromosomes with strong hybridization signals were detected by GISH analysis. Among 83 EST-STS markers that covered all seven homologous groups in wheat, three pairs of STS markers, BE497584, BF202643, and BG262410, located in wheat homologous group 1 amplified clear specific bands related to P. huashanica. The results indicated that resistant line H5-5-4-2 was a wheat-P. huashanica 1Ns disomic addition line. Full article
(This article belongs to the Special Issue Analysis of Crop Genetic and Germplasm Diversity)
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Open AccessArticle
Analysis of Differences in the Choice of the Economic Value of Urban Trees in Madrid When Displayed in Situ and in Photographs
Agronomy 2020, 10(2), 311; https://doi.org/10.3390/agronomy10020311 - 23 Feb 2020
Viewed by 428
Abstract
The determination of an asset’s economic value has always been an important step in improving its management. The Madrid Region legislated the application of the first version of the Norma Granada as a method of appraising ornamental trees. However, the trees in the [...] Read more.
The determination of an asset’s economic value has always been an important step in improving its management. The Madrid Region legislated the application of the first version of the Norma Granada as a method of appraising ornamental trees. However, the trees in the city of Madrid are only assessed in terms of ecosystem services (i-Tree Eco). A photograph of the asset to be appraised is often used in studies on the valuation of publicly-owned socio-environmental assets such as trees or landscapes. As a tree’s value is very closely linked to its size and to a number of features that can be seen through direct observation of the specimen, it is important to verify the validity of photographs as a method for obtaining the public’s opinion. This work presents a comparison between the valuations chosen by members of the public when observing the tree in situ and in a photograph. The aim is to verify the validity of photographs for their application to a larger sample and to understand qualitatively how citizens assess the trees in a city. The following appraisal methods were used: the American method, Council of Tree Landscape Appraisers (CTLA), Norma Granada and the Burnley method. The survey consisted of ten specimens from ten different species, and ten surveys were taken for each stem, making a total of 100 for each tree species and 1000 surveys in all. The surveys were done randomly and individually. Each interviewed chose one of the three values they were shown when observing the specimen in the photograph and in situ; 84% of the 1000 surveys gave as a result the same value choice when looking at the specimen on site and seeing it in a photograph. Full article
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Open AccessArticle
Nitrogen, Phosphorus, and Potassium Resorption Responses of Alfalfa to Increasing Soil Water and P Availability in a Semi-Arid Environment
Agronomy 2020, 10(2), 310; https://doi.org/10.3390/agronomy10020310 - 22 Feb 2020
Viewed by 663
Abstract
In semi-arid areas, alfalfa (Medicago sativa L.) is widely grown, but its growth is often restricted due to limited rainfall and soil nutrients, particularly phosphorus (P). Nutrient resorption is an effective strategy for dealing with nutrient shortages. Alleviation of these limited resources [...] Read more.
In semi-arid areas, alfalfa (Medicago sativa L.) is widely grown, but its growth is often restricted due to limited rainfall and soil nutrients, particularly phosphorus (P). Nutrient resorption is an effective strategy for dealing with nutrient shortages. Alleviation of these limited resources using film mulch and P fertilization—which are common practices in semi-arid areas—can affect the internal recycling of such nutrients. Little is known about such effects in alfalfa and the relationship between resorption efficiency and forage yield. We conducted a two-year field experiment in the semi-arid Loess Plateau of China using film mulch and P fertilization to investigate the response to long-term increasing soil water and P availability on leaf nitrogen (N), P, and potassium (K) concentrations and nutrient resorption characteristics in alfalfa. In green leaves, mulching significantly increased P concentration by an average of 5.5% but it had no significant effect on N concentration over two years, and it decreased K concentration by 16.1% in 2017. P fertilization significantly increased N concentrations to a greater degree in 2018 (8.1%) than 2017 (1.6%). P fertilization also significantly increased P concentrations by an average of 34.1% over two years. In contrast, P fertilization significantly decreased K concentration in the mulched treatment by an average of 17.3% in 2017 and 21.8% in 2018, but it had no effect in the no-mulch treatment. In senescent leaves, mulching significantly increased N concentration by an average of 3.9% and P concentration by an average of 16.7%, but it had no significant effect on K concentration over two years, while P fertilization significantly decreased N and K concentrations over two years by an average of 7.5%, and 32.8%, respectively. P fertilization significantly increased senesced P concentration by an average of 11.9% in 2017 and 17.5% in 2018; and year × mulching × P fertilization had a significant interaction on senesced leaf P concentration. For resorption efficiency, mulching decreased P resorption efficiency by an average of 3.0%, but it had no impact on N or K resorption efficiency, while P fertilization increased the N, P, and K resorption efficiencies in alfalfa by an average of 6.8%, 6.2%, and 76.4% over two years, respectively. Interactive effects of mulching and P fertilization were found on P and K resorption efficiencies over time. In addition, N and K resorption efficiencies were significantly higher in 2018 than in 2017. The application of P fertilizer without mulching resulted in positive correlations between forage yield and N, P, and K resorption efficiencies, but no correlations were observed under film mulch. That is, mulching changed the relationship between forage yield and N, P, and K resorption efficiencies in alfalfa, suggesting that N, P, and K resorption efficiencies may not be related to high yield. Our results provide new insights into the role of nutrient resorption in alfalfa in response to increasing soil water and P availability and the relationship between resorption efficiency and forage yield, which will help us to improve alfalfa yield in semi-arid regions. Full article
(This article belongs to the Section Soil and Plant Nutrition)
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Open AccessArticle
Estimation of Genetic Diversity in Seven Races of Native Maize from the Highlands of Mexico
Agronomy 2020, 10(2), 309; https://doi.org/10.3390/agronomy10020309 - 22 Feb 2020
Viewed by 619
Abstract
Characterizing the genetic diversity of maize (Zea mays L.) populations by their morphological and molecular attributes makes it possible to place populations into specific groups; thus, facilitating the design of procedures for their optimum and sustainable use. In this study, data from [...] Read more.
Characterizing the genetic diversity of maize (Zea mays L.) populations by their morphological and molecular attributes makes it possible to place populations into specific groups; thus, facilitating the design of procedures for their optimum and sustainable use. In this study, data from two lines of evidence were analyzed simultaneously to robustly classify maize populations and to determine their genetic relationships. Seven maize races of the central high plateau of Mexico were characterized using a combined analysis of 13 morphological traits and 31 microsatellite loci. The germplasm assessed included samples of 119 accessions held at Mexican germplasm banks. Cluster and principal component analyses were performed. Also, genetic and geographic relationships among the accessions were determined. Principal component analysis separated the different accessions into well-defined groups using first three principal components. The accessions of Arrocillo Amarillo and Elotes Cónicos races did not exhibit a grouping pattern, indicating greater genetic complexity. Better grounded grouping and phylogenetic relationships were obtained when traits of both lines of evidence were used simultaneously. Full article
(This article belongs to the Special Issue Analysis of Crop Genetic and Germplasm Diversity)
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Open AccessReview
Increase of Miscanthus Cultivation with New Roles in Materials Production—A Review
Agronomy 2020, 10(2), 308; https://doi.org/10.3390/agronomy10020308 - 21 Feb 2020
Viewed by 567
Abstract
Recent changes in the EU green aims can help to overcome economic obstacles in the slow upscaling of Miscanthus cultivation. Using Miscanthus can permanently fix CO 2 within building materials thereby aiding the EU climate goals with the increased use of regrowing materials, [...] Read more.
Recent changes in the EU green aims can help to overcome economic obstacles in the slow upscaling of Miscanthus cultivation. Using Miscanthus can permanently fix CO 2 within building materials thereby aiding the EU climate goals with the increased use of regrowing materials, as well as carbon fixation. Economic obstacles in the slow upscaling of Miscanthus cultivation are targeted by recent changes in the greening aims in the EU. Miscanthus can fulfill a valuable dual function in aiding the EU climate goals by achieving permanent CO 2 fixation within building materials. In contrast to energetic use, persistent applications create stable markets allowing for a reduced risk in the establishment of long term cultured perennial crops. However, the development of different building materials requires an understanding of the combination of the biological and technical aspects. This work presents an overview of the development of the general aspects for the agricultural product Miscanthus and the scientifically reported developments of Miscanthus used as feedstock in polymers, particle boards, and cementitious materials. While the product performance can be evaluated, the understanding of the influence by the input biomass as a main contributor to the product performance needs to be reinforced to be successful with a goal-oriented development of Miscanthus based products. The key feedstock parameters governing the technical performance of the materials are identified and the knowledge gaps are described. Full article
(This article belongs to the Special Issue Bioenergy Crops: Current Status and Future Prospects)
Open AccessArticle
Initial Development of Corn Seedlings after Seed Priming with Nanoscale Synthetic Zinc Oxide
Agronomy 2020, 10(2), 307; https://doi.org/10.3390/agronomy10020307 - 21 Feb 2020
Viewed by 670
Abstract
Nanofertilizers are increasingly explored for sustainable micronutrient delivery in agriculture. Pre-treating seeds with nanofertilizers prior to planting (i.e., seed priming) reduces concerns about nanoparticle (NP) fertilizer non-target dispersion; however, priming formulations and concentrations must be carefully selected to avoid germination inhibition and toxicity. [...] Read more.
Nanofertilizers are increasingly explored for sustainable micronutrient delivery in agriculture. Pre-treating seeds with nanofertilizers prior to planting (i.e., seed priming) reduces concerns about nanoparticle (NP) fertilizer non-target dispersion; however, priming formulations and concentrations must be carefully selected to avoid germination inhibition and toxicity. Here we investigate changes in corn seed germination and seedling development after seed priming with ZnO NPs, ZnO bulk and ZnCl2. To evaluate the effects sterile seeds were immersed in priming solutions of 0, 20, 40, 80, 160 mg L−1 Zn for the three Zn sources. Following an 8 h priming the seeds were evaluated for germination and vigor for 5 days on germination paper. Root and shoot lengths were measured as well as fresh and dry biomass. Compared to the control, the ZnO NP and ZnCl2 seed priming promoted beneficial effects. ZnO NP seed-priming exhibited a concentration dependent profile in improving seedling growth, with greatest benefit around 80 mg L−1, providing 17%, 25% and 12% higher values than control for germination, root length, and dry biomass production, respectively. In contrast, seeds primed with bulk ZnO did not differ from the control. These findings support NP-seed priming as an alternative to delivery of essential micronutrients, such as zinc, to corn seedlings. Full article
(This article belongs to the Special Issue Nanotechnology Applications in Agriculture System)
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Open AccessArticle
Morphological Diversity and Bioactive Compounds in Wall Rocket (Diplotaxis erucoides (L.) DC.)
Agronomy 2020, 10(2), 306; https://doi.org/10.3390/agronomy10020306 - 21 Feb 2020
Cited by 1 | Viewed by 443
Abstract
Wall rocket is a wild vegetable with interest to become a crop. However, the information regarding morphological variability in the species is scarce, despite the interest it has received for breeding programs. In addition, evaluating the phytochemical composition can also be useful for [...] Read more.
Wall rocket is a wild vegetable with interest to become a crop. However, the information regarding morphological variability in the species is scarce, despite the interest it has received for breeding programs. In addition, evaluating the phytochemical composition can also be useful for developing materials of a high quality. In this study, forty-four populations were evaluated for selected morphoagronomic traits and contents in ascorbic acid (AA), total phenolics (TP), and nitrates (NO3). Wall rocket plants had, on average, an intermediate growth habit and a good response to transplant. Moderate variability, mainly for size-related traits, was found, with low to moderate heritability estimates (H2 < 0.35). A Principal Component Analysis revealed that some materials may be selected for differenced traits. On the other hand, wall rocket materials had, on average, high contents in AA (53 mg 100 g−1) and TP (116 mg CAE 100 g−1) but also accumulated high levels of NO3 (891 mg 100 g−1). Significant positive correlations were found for AA and TP, which could be exploited for increasing the antioxidant activity and properties of the final product. We provide new information on the variation of wall rocket for traits of morphological and phytochemical interest, which together with other traits, such as the profile of glucosinolates, can be useful for the selection of materials in future breeding programs. Full article
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Open AccessArticle
Factors Controlling Soil Organic Carbon Sequestration of Highland Agricultural Areas in the Mae Chaem Basin, Northern Thailand
Agronomy 2020, 10(2), 305; https://doi.org/10.3390/agronomy10020305 - 21 Feb 2020
Cited by 3 | Viewed by 531
Abstract
Understanding the effect of the environment, crop types, and land management practices on the organic carbon sequestration of top soil is crucial for adopting management strategies in highland agricultural areas. The objectives of this study are: (1) to estimate top soil organic carbon [...] Read more.
Understanding the effect of the environment, crop types, and land management practices on the organic carbon sequestration of top soil is crucial for adopting management strategies in highland agricultural areas. The objectives of this study are: (1) to estimate top soil organic carbon density (SOCD) of different crop types and (2) to analyze the factors controlling top SOCD in highland agricultural areas. The top soil layers from 0 to 30 cm depths were collected from the Mae Chaem basin, Northern Thailand. The results showed that the highest top SOCD was found soil used for growing upland rice, which contained an average of 58.71 Mg C ha−1. A significant difference between the top SOCD was detected between areas where minimum tillage and conventional tillage of various crops, with average of values 59.17 and 41.33 Mg C ha−1, respectively, for areas growing strawberries; 61.14 and 37.58 Mg C ha−1, respectively, for cabbage, and 71.15 and 39.55 Mg C ha−1, respectively, for maize. At higher elevation, the top SOCD was high, which may be due to high clay content and low temperature. Increased use of chemical fertilizers lead to increases in top SOCD, resulting in increased crop yields. Elevation, bulk density, N and K2O fertilizers were the main factors controlling the top SOCD at all sites. Full article
(This article belongs to the Special Issue Conservation Tillage in Sustainable Agro-Ecosystems)
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Open AccessArticle
The Effect of Various Tillage Systems on Productivity of Narrow-Leaved Lupin-Winter Wheat-Winter Triticale-Winter Barley Rotation
Agronomy 2020, 10(2), 304; https://doi.org/10.3390/agronomy10020304 - 21 Feb 2020
Viewed by 615
Abstract
Legumes are increasingly important crops in most European Union (EU) countries because of the growing demand for feed protein, and also because they have been shown to improve the characteristics of soil. The main part of the crop rotation is taken up by [...] Read more.
Legumes are increasingly important crops in most European Union (EU) countries because of the growing demand for feed protein, and also because they have been shown to improve the characteristics of soil. The main part of the crop rotation is taken up by cereals, but they are connected with undesirable side effects, such as the unilateral utilization of ingredients and the heightened risk of plant diseases, e.g., Fusarium. Simplification of farming methods has become increasingly popular as growers search for cheaper production technologies. However, the effects of long-term simplification in tillage practices on the production and economics of narrow-leafed lupine (NL) cultivation have not been studied. In 2012–2016, we carried out a field experiment in Poland with a one-factorial design with four replications. The aim of the experiment was to evaluate the productivity effect of conventional tillage (CT), reduced tillage (RT) and no-tillage (NT) on NL-winter wheat (WW)-winter triticale (WT)-winter barley (WB), rotation. Our results show that the productivity of this crop rotation was lower under RT and NT systems than under CT. From a practical point of view, the reduction of cultivation in rotation with 75% of cereals caused a decrease in yield in all species, which can result in resign of using the RT and NT in conditions of Albic Luvisols soil, as classified according to the World Reference Base (WRB). The highest incomes were found when the CT system was used with NL. Although income losses exceeded the value of savings in both minimalized soil tillage systems (RT and NT), all tillage systems of NL were profitable. Full article
(This article belongs to the Special Issue Conservation Tillage in Sustainable Agro-Ecosystems)
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Open AccessArticle
Droplet Deposition and Control of Planthoppers of Different Nozzles in Two-Stage Rice with a Quadrotor Unmanned Aerial Vehicle
Agronomy 2020, 10(2), 303; https://doi.org/10.3390/agronomy10020303 - 20 Feb 2020
Viewed by 558
Abstract
Previous studies have confirmed that choosing nozzles that produce coarser droplets could reduce the risk of pesticide spray drift, but this conclusion is based on a large volume of application, and it is easy to ignore how this impacts the control effect. The [...] Read more.
Previous studies have confirmed that choosing nozzles that produce coarser droplets could reduce the risk of pesticide spray drift, but this conclusion is based on a large volume of application, and it is easy to ignore how this impacts the control effect. The difference from the conventional spray is that the carrier volume of Unmanned Aerial Vehicle (UAV) is very limited. Little was known about how to choose suitable nozzles with UAV’s limited volume to ensure appropriate pest control. Droplet deposition with the addition of adjuvant and the LU110-010, LU110-015, and LU110-020 nozzles and control of planthoppers within nozzles treatments were studied by a quadrotor UAV in rice (Tillering and Flowering stages). Allura Red (10 g/L) was used as a tracer and Kromekote cards were used to collect droplet deposits. The results indicate that the density of the droplets covered by the LU110-01 nozzle is well above other treatments, while the differences in droplet deposition and coverage are not significant. The deposition and coverage were improved with the addition of adjuvant, especially in LU110-01 nozzles’ treatment. The control effects of rice planthoppers treated by LU110-01 nozzle were 89.4% and 90.8% respectively, which were much higher than 67.6% and 58.5% of LU110-020 nozzle at 7 days in the Tillering and Flowering stage. The results suggest that selecting a nozzle with a small atomizing particle size for UAV could improve the control effect of planthoppers. Full article
(This article belongs to the Section Agricultural Engineering)
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Open AccessArticle
Effect of Drought Stress at Reproductive Stages on Growth and Nitrogen Metabolism in Soybean
Agronomy 2020, 10(2), 302; https://doi.org/10.3390/agronomy10020302 - 20 Feb 2020
Cited by 2 | Viewed by 490
Abstract
This study aims to determine variability among soybean (Glycine max (L.) Merr.) cultivars under drought conditions and how nitrogen metabolites, metabolism-related enzymes, and gene expression vary during soybean growth. Three soybean cultivars, Shennong17 (CV.SN17), Shennong8 (CV.SN8), and Shennong12 (CV.SN12), were grown in [...] Read more.
This study aims to determine variability among soybean (Glycine max (L.) Merr.) cultivars under drought conditions and how nitrogen metabolites, metabolism-related enzymes, and gene expression vary during soybean growth. Three soybean cultivars, Shennong17 (CV.SN17), Shennong8 (CV.SN8), and Shennong12 (CV.SN12), were grown in pot culture and subjected to drought stress at reproductive stages for 45 days. The results showed that long-term drought stress decreased biomass allocation to reproductive organs, weakened antioxidant capacity, and reduced seed weight, effects that were less pronounced in CV.SN12 compared with those in CV.SN8 and CV.SN17. Drought stress decreased the concentrations of nitrogen and soluble protein but increased nitrate concentration in leaves. This was related to the significantly reduction of nitrogen metabolism efficiency, including decreased activities of nitrogen metabolism enzymes, and downregulated expression of GmNR, GmNiR, GmGS, and GmGOGAT. Drought stress increased the concentrations of free amino acid, proline, and soluble sugar in leaves to enhance the osmotic adjustment ability. Furthermore, soybean seed weight showed significantly correlation (p < 0.05) with nitrogen-metabolism-related parameters. Based on the performance of growth, nitrogen metabolism, and yield attributes, CV.SN12 showed the highest tolerance to drought, followed by CV.SN8 and CV.SN17. In addition, these nitrogen-metabolism-related parameters could be used in soybeans to select for drought tolerance. Full article
(This article belongs to the Special Issue Functional Metabolism in Crops/Agronomy)
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Open AccessArticle
Geoaccumulation and Ecological Risk Indexes in Papaya Cultivation Due to the Presence of Trace Metals
Agronomy 2020, 10(2), 301; https://doi.org/10.3390/agronomy10020301 - 20 Feb 2020
Viewed by 553
Abstract
The aim of this research was to evaluate the impact of heavy metals on Maradol papaya cultivation soil, through the geoaccumulation index (Igeo) and the ecological potential risk index (RI). Soil samples from 15 locations in the Cotaxtla municipality of Veracruz, [...] Read more.
The aim of this research was to evaluate the impact of heavy metals on Maradol papaya cultivation soil, through the geoaccumulation index (Igeo) and the ecological potential risk index (RI). Soil samples from 15 locations in the Cotaxtla municipality of Veracruz, Mexico were tested for pH, soil texture, and concentrations of lead (Pb), chromium (Cr), cadmium (Cd), zinc (Zn), copper (Cu), and organic matter (MO). The pH varied between values of 5.5 ± 0.10 and 7.7 ± 0.22, while the MO varied from 1.57% ± 0.97% to 13.1% ± 1.342%. The type of soil texture represented 48% sandy loam, 40% loam, 8% clay loam, and 4% silt-loam. For heavy metals, average levels were found in the following order Cr (0.695 ± 0.018) > Zn (0.615 ± 0.016) > Pb (0.323 ± 0.012) > Cu (0.983 ± 0.011) > Cd (0.196 ± 0.011) mg kg−1. The Igeo values from 96% of the analyzed sampling points were below zero and were considered uncontaminated. The other 4% of samples, from the Potrerillo1 (PT) site, had Igeo values of 1.13, where the highest concentration of Cd was found, which indicates moderate contamination levels. The RI index at the PT site was in the category of moderate contamination, and the rest of the points correspond to the category of low pollution. Full article
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Open AccessArticle
Evaluation of Tillage, At-Planting Treatment, and Nematicide on Tobacco Thrips (Thysanoptera: Thripidae) and Reniform Nematode (Tylenchida: Hoplolamidae) Management in Cotton
Agronomy 2020, 10(2), 300; https://doi.org/10.3390/agronomy10020300 - 20 Feb 2020
Viewed by 426
Abstract
There are numerous early-season pests of cotton, Gossypium hirsutum L., that are economically important, including tobacco thrips, Frankliniella fusca (Hinds), and reniform nematode, Rotylenchulus reniformis (Linford & Oliveira). Both of these species have the potential to reduce plant growth and delay crop maturity, [...] Read more.
There are numerous early-season pests of cotton, Gossypium hirsutum L., that are economically important, including tobacco thrips, Frankliniella fusca (Hinds), and reniform nematode, Rotylenchulus reniformis (Linford & Oliveira). Both of these species have the potential to reduce plant growth and delay crop maturity, ultimately resulting in reduced yields. A field study was conducted during 2015 and 2016 to evaluate the influence of tillage, at-planting insecticide treatment, and nematicide treatment on pest management, cotton development, and yield. Treatment factors consisted of two levels of tillage (no-tillage and conventional tillage); seven levels of at-planting insecticide treatments (imidacloprid, imidacloprid plus thiodicarb, thiamethoxam, thiamethoxam plus abamectin, acephate plus terbufos, aldicarb, and an untreated control); and two levels of nematicide (no nematicide and 1,3-dichloropropene). There were no significant interactions between tillage, at-planting insecticide treatment, or nematicide for any parameters nor was there a difference in the main effect of nematicide on thrips control or damage. The main effects of tillage and at-planting insecticide treatment impacted thrips densities and damage. The no-tillage treatments and aldicarb in-furrow or acephate seed treatment plus terbufos in-furrow significantly reduced thrips populations. Early-season plant response was impacted by tillage and at-planting insecticide treatment; however, that did not result in significant yield differences. In regard to nematicide treatment, the use of 1,3-dichloropropene resulted in lower yields than the untreated. Full article
(This article belongs to the Special Issue Integrating Pest Management into Agricultural Production Systems)
Open AccessArticle
Study Regarding the Potential Use of a Spent Microbial Biomass in Fertilizer Manufacturing
Agronomy 2020, 10(2), 299; https://doi.org/10.3390/agronomy10020299 - 19 Feb 2020
Viewed by 496
Abstract
A spent biomass, which results from the biopharma industry, is stabilized and functionalized by biosorption with microelements. The efficiency of this new biomaterial was tested in two experiments: 1) In a mixture with soil to determine its effects of the germination capacity of [...] Read more.
A spent biomass, which results from the biopharma industry, is stabilized and functionalized by biosorption with microelements. The efficiency of this new biomaterial was tested in two experiments: 1) In a mixture with soil to determine its effects of the germination capacity of cereals and vegetables, and 2) in a formulation of mixed fertilizers to determine its influence on the development and production of the two types of vegetables. The results obtained during germination experiments performed in pots showed that at a biomass concentration less than 20%, the germination output was greater than 95% and the germination index was almost 1. The experiments performed in land on vegetables (including Solanum lycopersicum and Capsicum annuum) featured six types of fertilizers formulated with new biomaterials. The obtained results indicated that two types of fertilizers (N 10:0:0 and NP 5:5:0), which were formulated with functionalized biomass and featured the microelements Co, Cu, Fe, Mn, and Zn, exhibited significant effects when compared with vegetables cultivated on unfertilized soil surfaces (the untreated variant). The studies regarding the effect of the new fertilizers obtained based on spent biomass from biopharma industry indicate the following: a) This material, even if it is stabilized and functionalized, cannot be used as such as a germination substrate for vegetables; in addition, it cannot be introduced into soil together with cereals seeds (during the autumn work), because the germination can be affected negatively; b) the functionalized biomass can be used in the formulation of different types of fertilizers; if these fertilizers are introduced into soil with the autumn plowing, then they may have a positive influence on the yield of some species of vegetable, such as Solanum lycopersicum and Capsicum annum. The new fertilizers have a major environmental impact due to: 1) Removal of waste, which results from pharmaceutical biosyntheses, with significant impact on soil pollution, due to its storage in the form of waste dumps, on the soil; 2) recovery and reinsertion into the natural circuit of nutrients like C, N, P, K, Mg, and Ca contained in spent biomass, by their reuse in agriculture; and 3) high content of compounds with C from spent biomass can improve in time the content of fulvic and humic acids in soil, with a positive effect on soil characteristics from an agronomic point of view. Full article
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Open AccessArticle
Improved Management Efficacy of Late Leaf Spot on Peanut Through Combined Application of Prothioconazole with Fluxapyroxad and Pyraclostrobin
Agronomy 2020, 10(2), 298; https://doi.org/10.3390/agronomy10020298 - 19 Feb 2020
Cited by 1 | Viewed by 441
Abstract
Late leaf spot, caused by Nothopassalora personata, is the most economically important fungal disease affecting peanut foliage in South Carolina and can result in combined management and yield loss costs of greater than 490 dollars/ha. Application of protectant fungicides is a critical [...] Read more.
Late leaf spot, caused by Nothopassalora personata, is the most economically important fungal disease affecting peanut foliage in South Carolina and can result in combined management and yield loss costs of greater than 490 dollars/ha. Application of protectant fungicides is a critical part of effective integrated management under commercial production, and their strategic alternation and combination in management programs can provide enhanced control. Trials were conducted in Blackville, SC, from 2017 to 2019 to investigate whether combinations of prothioconazole with fluxapyroxad plus pyraclostrobin could provide more efficacious management of late leaf spot compared to either product alone. Two applications of 0.11 kg/ha prothioconazole with 0.05 kg/ha fluxapyroxad plus 0.1 kg/ha pyraclostrobin resulted in significantly (p < 0.05) less (24% to 42%) peanut canopy defoliation compared to the same number of applications of either product applied individually, with the combined application reflecting significant (p < 0.0202) synergism compared to component products as assessed through independent action methodology. An increased rate of fluxapyroxad plus pyraclostrobin application (0.1 and 0.2 kg/ha, respectively), with 0.16 kg/ha prothioconazole did not improve management relative to their combination at the examined lower rate (p = 0.89). Peanut yield was not adversely affected following combined applications. Cost-effectiveness of this combination depends on the actual disease intensity and yield potential of a given crop. Full article
Open AccessArticle
Diversification and Management Practices in Selected European Regions. A Data Analysis of Arable Crops Production
Agronomy 2020, 10(2), 297; https://doi.org/10.3390/agronomy10020297 - 19 Feb 2020
Viewed by 784
Abstract
In the European Union, various crop diversification systems such as crop rotation, intercropping and multiple cropping, as well as low-input management practices, have been promoted to sustain crop productivity while maintaining environmental quality and ecosystem services. We conducted a data analysis to identify [...] Read more.
In the European Union, various crop diversification systems such as crop rotation, intercropping and multiple cropping, as well as low-input management practices, have been promoted to sustain crop productivity while maintaining environmental quality and ecosystem services. We conducted a data analysis to identify the benefits of crop associations, alternative agricultural practices and strategies in four selected regions of Europe (Atlantic, Boreal, Mediterranean North and Mediterranean South) in terms of crop production (CP). The dataset was derived from 54 references with a total of 750 comparisons and included site characteristics, crop information (diversification system, crop production, tillage and fertilization management) and soil parameters. We analyzed each effect separately, comparing CP under tillage management (e.g., conventional tillage vs. no tillage), crop diversification (e.g., monoculture vs. rotation), and fertilization management (e.g., mineral fertilization vs. organic fertilization). Compared with conventional tillage (CT), CP was higher by 12% in no tillage (NT), in fine- and medium-textured soils (8–9%) and in arid and semiarid sites located in the Mediterranean Region (24%). Compared to monoculture, diversified cropping systems with longer crop rotations increased CP by 12%, and by 12% in soils with coarse and medium textures. In relation to fertilization, CP was increased with the use of slurry (40%), and when crop residues were incorporated (39%) or mulched (74%). Results showed that conversion to alternative diversified systems through the use of crop rotations, with NT and organic fertilization, results in a better crop performance. However, regional differences related to climate and soil-texture-specific responses should be considered to target local measures to improve soil management. Full article
(This article belongs to the Section Farming Sustainability)
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Open AccessArticle
Response of Common Bean Cultivars and Lines to Aluminum Toxicity
Agronomy 2020, 10(2), 296; https://doi.org/10.3390/agronomy10020296 - 19 Feb 2020
Viewed by 368
Abstract
The soils in the common bean-producing regions (Phaseolus vulgaris L.) of Brazil are usually acid and conta\y66\yin toxic levels of aluminum (Al) for plants. This ion causes yield losses by inhibiting root cell expansion, thus reducing water and nutrient uptake. This study [...] Read more.
The soils in the common bean-producing regions (Phaseolus vulgaris L.) of Brazil are usually acid and conta\y66\yin toxic levels of aluminum (Al) for plants. This ion causes yield losses by inhibiting root cell expansion, thus reducing water and nutrient uptake. This study investigates the optimal Al concentration for the screening of genotypes in hydroponics cultivation and tries to identify cultivars and lines for cultivation in Al-toxic soils. The study consisted of two series of experiments. In the first one, four cultivars were evaluated at five Al concentrations (0, 2.5, 5, 7.5 and 10 ppm) and in the second, four independent tests were carried out (1-carioca, 2-black, 3-red, and 4-white), each with seven genotypes and two Al concentrations (0 and 4 ppm). The optimized concentration of Al in the first stage was 4 ppm, which allowed the early identification of genotypes with less affected development under Al toxicity in the second stage. The common bean cultivars IPR Quero-Quero (carioca group), BRS Esplendor (black group), KID 44 (red group), and WLine 5 (white group) may be indicated for cultivation under Al toxicity. Full article
(This article belongs to the Section Crop Breeding and Genetics)
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Open AccessArticle
The Analysis of Pinus pinaster SnRKs Reveals Clues of the Evolution of This Family and a New Set of Abiotic Stress Resistance Biomarkers
Agronomy 2020, 10(2), 295; https://doi.org/10.3390/agronomy10020295 - 19 Feb 2020
Viewed by 881
Abstract
Climate change is increasing the intensity and incidence of environmental stressors, reducing the biomass yields of forestry species as Pinus pinaster. Selection of new stress-tolerant varieties is thus required. Many genes related to plant stress signaling pathways have proven useful for this [...] Read more.
Climate change is increasing the intensity and incidence of environmental stressors, reducing the biomass yields of forestry species as Pinus pinaster. Selection of new stress-tolerant varieties is thus required. Many genes related to plant stress signaling pathways have proven useful for this purpose with sucrose non-fermenting related kinases (SnRK), conserved across plant evolution and connected to different phosphorylation cascades within ABA- and Ca2+-mediated signaling pathways, as a good example. The modulation of SnRKs and/or the selection of specific SnRK alleles have proven successful strategies to increase plant stress resistance. Despite this, SnRKs have been barely studied in gymnosperms. In this work P. pinaster SnRK sequences (PpiSnRK) were identified through a homology- and domain-based sequence analysis using Arabidopsis SnRK sequences as query. Moreover, PpiSnRKs links to the gymnosperm stress response were modeled out of the known interactions of PpiSnRKs orthologs from other species with different signaling complexity. This approach successfully identified the pine SnRK family and predicted their central role into the gymnosperm stress response, linking them to ABA, Ca2+, sugar/energy and possibly ethylene signaling. These links made the gymnosperm kinases promising candidates into the search for new stress resistance-related biomarkers, which would be useful into future breeding strategies. Full article
(This article belongs to the Special Issue Functional Genomics Research of Crops)
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Open AccessArticle
Genome-Wide Identification, Structure Characterization, and Expression Profiling of Dof Transcription Factor Gene Family in Wheat (Triticum aestivum L.)
Agronomy 2020, 10(2), 294; https://doi.org/10.3390/agronomy10020294 - 19 Feb 2020
Cited by 3 | Viewed by 532
Abstract
DNA binding with one finger (Dof) proteins are plant-specific transcription factors with crucial roles in plant growth and stress response. Even so, little is known about them in wheat. In this study, 108 wheat Dof (TaDof) genes across 21 chromosomes were detected. Although [...] Read more.
DNA binding with one finger (Dof) proteins are plant-specific transcription factors with crucial roles in plant growth and stress response. Even so, little is known about them in wheat. In this study, 108 wheat Dof (TaDof) genes across 21 chromosomes were detected. Although variable in sequence length, molecular weight, and isoelectric point, all TaDof proteins contained conserved zinc-finger structures and were phylogenetically divided into 7 sub-groups. Exon/intron and motif analyses suggested that TaDof structures and conserved motifs were similar within sub-groups but diverse among sub-groups. Many segmental duplications were identified and Ka/Ks and inter-species synthetic analyses indicated that polyploidization was main reason for increased number of TaDofs. Prediction and experimental confirmation revealed that TaDofs functioned as transcription factors in the nucleus. Expression pattern profiling showed that TaDofs specifically affected growth and development, and biotic and abiotic stress responses. Wheat miRNAs and cis-regulator were predicted as essential players in molding TaDofs expression patterns. qRT-PCR analysis revealed that TaDofs were induced by salt and drought stresses. Customized annotation revealed that TaDofs were widely involved in phytohormone response, defense, growth and development, and metabolism. Our study provided a comprehensive understanding to wheat TaDofs. Full article
(This article belongs to the Special Issue Bioinformatics Applied to Genetic Improvement of Crop Species)
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Open AccessArticle
Investigating the Proper Application Rate of Nitrogen under Mulched Drip Irrigation to Improve the Yield and Quality of Tomato in Saline Soil
Agronomy 2020, 10(2), 293; https://doi.org/10.3390/agronomy10020293 - 19 Feb 2020
Cited by 1 | Viewed by 363
Abstract
Xinjiang is one of the most prolific tomato-planting areas in China. Here, we carried out a two-year (2017–2018) field experiment in Xinjiang to study the effects of different nitrogen (N) application rates on the spatial distribution of water and salt in the root [...] Read more.
Xinjiang is one of the most prolific tomato-planting areas in China. Here, we carried out a two-year (2017–2018) field experiment in Xinjiang to study the effects of different nitrogen (N) application rates on the spatial distribution of water and salt in the root zone, as well as their impacts on the yield and quality of tomatoes under mulched drip irrigation. The ideal ranges of N application rates for tomato yield and quality were examined under different salinity levels. Results indicated that soil water content and salinity increased with soil depth. Soil water content was closely related to soil salinity but not to N. Among the tested application rates, tomato yield was highest under the medium-high N (225–300 kg/ha) and low salt (4 g/kg) treatment. Under the highest salt level (10 g/kg), the low nitrogen treatment (150 kg/ha) was better than the high N treatment (300 kg/ha) at boosting tomato yield. Moreover, we found that salinity had a stronger effect on tomato quality than N. Based on these results, we were able to recommend ideal ranges for N (155–201 kg/ha) and salt (3.56–5.59 g/kg) while both are present in the soil. Full article
(This article belongs to the Section Water Use and Irrigation)
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Open AccessArticle
Changes in the Weed Seed Bank in Long-Term Establishment Methods Trials under Rice-Wheat Cropping System
Agronomy 2020, 10(2), 292; https://doi.org/10.3390/agronomy10020292 - 18 Feb 2020
Viewed by 500
Abstract
The rice–wheat cropping system in the Indo-Gangetic Plains is the backbone of food security in India. In the 1990s, due to the scarcity of resources, the traditional Crop Establishment (CE) method shifted from Conventional Till Puddle Transplanted Rice (CTPTR) to CT Direct Seeded [...] Read more.
The rice–wheat cropping system in the Indo-Gangetic Plains is the backbone of food security in India. In the 1990s, due to the scarcity of resources, the traditional Crop Establishment (CE) method shifted from Conventional Till Puddle Transplanted Rice (CTPTR) to CT Direct Seeded Rice (CTDSR) and Zero-Till DSR (ZTDSR) in paddy; and in wheat, from Conventional Till Wheat (CTW) to Zero Till Wheat (ZTW), with residue retention in rice (RRR) or in both rice and wheat (RRRW). Shift in CE methods led to change in Weed Seed Bank (WSB) dynamics and ultimately affected the weed management program. After five years of field trials, soil samples were drawn as per 2-factors factorial randomized block design. Factor-I comprised 4-CE methods, whereas factor-II consisted of 3-soil depths (0–10, 10–20 and 20–30 cm). Results showed CTPTR-CTW and ZTDSR-ZTW (RRRW) record the highest seed bank (SB) of grasses, sedges and BLWs as total weeds, in general; and predominant weeds like Echinochloa spp., Ammania baccifera, Commelina benghalensis and Digitaria sanguinalis, in particular. It also showed the higher species richness (DMg) and Shannon–Weaver (H’) indices. CTDSR-CTW and CTDSR-ZTW (RRR) show the lowest WSB and at par with Shannon–Weaver (H’) index; further, lowest species richness (DMg) under CTDSR-CTW. Species Evenness (J’) and Simpson index (λ) vary non-significantly with CE methods. Furthermore, 0–10 cm soil depth showed the highest SB of different category of total weed, predominant weeds as well as higher values of DMg, H’, and λ; whereas reverse trend was observed in Whittaker Statistic (βW). Interaction between CE methods and soil depth revealed most of WSB lying on the top layer in case of ZTDSR-ZTW (RRRW) and CTDSR-ZTW (RRR); while CTPTR-CTW showed almost uniform WSB distribution, and in case of CTDSR-CTW, a gradual decrease in WSB with soil depth. Full article
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Open AccessArticle
Economic Feasibility of Chemical Weed Control in Soybean Production in Serbia
Agronomy 2020, 10(2), 291; https://doi.org/10.3390/agronomy10020291 - 18 Feb 2020
Cited by 1 | Viewed by 459
Abstract
The aim of this study was to investigate the efficacy and phytotoxicity of herbicides in combinations and to determine their economic feasibility in the soybean crop. The trials were placed at two locations, Pobeda and Budisava (Serbia), during 2016 and 2018, organized in [...] Read more.
The aim of this study was to investigate the efficacy and phytotoxicity of herbicides in combinations and to determine their economic feasibility in the soybean crop. The trials were placed at two locations, Pobeda and Budisava (Serbia), during 2016 and 2018, organized in a randomized block design with four replicates of all herbicide combinations (metribuzin + S-metolachlor; imazamox + oxasulfuron + typhenesulfuron-methyl; metribuzin + S-metolachlor + imazamox + oxasulfuron + typhenesulfuron-methyl; and bentazon + imazamox + typhenesulfuron-methyl). At the first location, 16 weed species were determined, while in the second location, 14 were determined. The highest reduction in the number of weeds was achieved at the first location, using a combination of herbicides metribuzin + S-metolachlor + imazamox + oxasulfuron + typhenesulfuron-methyl with a total efficacy that ranged from 96.98% to 97.40%. Only on the second location bentazone + imazamox + tifensulfuron-methyl showed passable phytotoxicity on soybean, during both years. Based on the established economic justification, in the combinations of metribuzin + S-metolachlor + imazamox + oxasulfuron + typhenesulfuron-methyl, yield was increased for 2350 kg/ha or 1.91 times more, according to the untreated variant at first location. The economic injury level at the most effective combination of herbicides was 52.70 weeds/m2. Full article
(This article belongs to the Section Weed Science and Weed Management)
Open AccessArticle
Changes in Storage and the Stratification Ratio of Soil Organic Carbon under Different Vegetation Types in Northeastern China
Agronomy 2020, 10(2), 290; https://doi.org/10.3390/agronomy10020290 - 18 Feb 2020
Viewed by 329
Abstract
The depth distribution of soil organic carbon (SOC) in a soil profile is important to examine the effects of different treatments on SOC sequestration. This study was conducted to determine the effects of different vegetation types on the concentration, storage, and stratification ratio [...] Read more.
The depth distribution of soil organic carbon (SOC) in a soil profile is important to examine the effects of different treatments on SOC sequestration. This study was conducted to determine the effects of different vegetation types on the concentration, storage, and stratification ratio (SR) of SOC in northeastern China. Five vegetation types, Leymus chinensis (LEY), Puccinellia tenuiflora (PUC), Echinochloa phyllopogon (ECH), saline seepweed (SUA), and Chloris virgata Swartz (CHL), were selected as treatments. Soil bulk density and SOC concentration were measured at 0 to 50 cm depth, and SOC storage and four SRs (SR1 [0–10:10–20 cm], SR2 [0–10:20–30 cm], SR3 [0–10:30–40 cm], and SR4 [0–10:40–50 cm]) were calculated under the five vegetation types. Results showed a pronounced reduction in SOC concentration with increasing soil depth. Vegetation types had significant effects on SOC concentration and storage. Under PUC, ECH, SUA, and CHL treatments, SOC concentrations (2.150, 1.068, 4.110, and 2.542 g kg−1, respectively) and storages (15.075, 7.273, 30.024, and 18.078 Mg ha−1, respectively) at 0–50 cm depth were lower than those under the LEY treatment. SR1 values were all < 2, while SR2, SR3, and SR4 values were all > 2 except for SR2 under ECH and SUA treatments. Vegetation types had significant effects on SR3 (p < 0.001) and SR4 (p = 0.040), while no significant differences were found for SR1 and SR2 due to the narrow range, with values of 0.248 and 0.553 for SR1 and SR2, respectively, among the vegetation types. These results indicated that the degraded soils have great potential to sequester organic carbon in northeastern China, and SR3 could be used as an effective index to show the changes in SOC concentration and soil quality in northeastern China. Full article
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Open AccessArticle
Optimizing Soil Fertility Management Strategies to Enhance Banana Production in Volcanic Soils of the Northern Highlands, Tanzania
Agronomy 2020, 10(2), 289; https://doi.org/10.3390/agronomy10020289 - 18 Feb 2020
Cited by 1 | Viewed by 553
Abstract
Banana is an important crop in high altitude areas of Tanzania, grown widely both as a food staple and as the main source of income. However, its production is constrained by low soil fertility, a result of gradual nutrient mining by the crop. [...] Read more.
Banana is an important crop in high altitude areas of Tanzania, grown widely both as a food staple and as the main source of income. However, its production is constrained by low soil fertility, a result of gradual nutrient mining by the crop. Currently, soil fertility management in banana-based farming systems in the country relies mainly on applications of animal manure. However, the amount of manure produced in most farms is not enough to replenish soil fertility due to the small number of animals kept by smallholder resource-poor farmers who are the major producers in the country. Field experiments were conducted at three sites with varying soil types and contrasting weather conditions along the altitudinal gradients on the slopes of the volcanic mountains of Kilimanjaro and Meru, northern Tanzania to (1) investigate the effect of mineral nitrogen (mineral N) fertilizer applications on the growth and yield of Mchare banana (Musa spp., AA, a traditional East African highland cooking banana sub-group), at the four levels of 0, 77, 153, and 230 kg N ha−1 year−1 as a starter strategy to improve the current soil fertility management strategies, and (2) evaluate the effect of the combined use of inorganic and organic N sources on growth and banana fruit production as an alternative strategy to manage soil fertility and minimize animal manure requirements. The treatment factors were trial sites (Tarakea, Lyamungo, and Tengeru) as the main factor and N fertilization strategies (as urea alone, sole cattle manure, and in combination with urea, sole common bean (Phaseolus vulgaris L.) haulms as well as in combination with urea) as a sub factor. Bean haulms and cattle manure were applied each year for two years. Fertilization at 153 kg N ha−1 year−1 derived solely from urea significantly (p < 0.001) resulted in high yield increment of up to 42% relative to the control. However, the increase was highest (52%) with the same N dose derived from cattle manure in combination with urea at 50% substitution. Sole bean haulms resulted in a smaller yield increment, the same as the lowest N dose from the sole urea fertilization treatment. The study concludes that soil fertility management in smallholder banana-based farming systems should not solely rely on animal manure and mineral fertilizers. Full article
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Open AccessArticle
Combined Addition of Bovine Bone and Cow Manure: Rapid Composting of Chestnut Burrs and Production of a High-quality Chestnut Seedling Substrate
Agronomy 2020, 10(2), 288; https://doi.org/10.3390/agronomy10020288 - 18 Feb 2020
Viewed by 388
Abstract
In China, chestnut burrs (CB) are produced at a rate of a million tons per year as the major byproduct of chestnut orchards. It is necessary to utilize the chestnut forest green waste and convert it into a valuable seedling media for the [...] Read more.
In China, chestnut burrs (CB) are produced at a rate of a million tons per year as the major byproduct of chestnut orchards. It is necessary to utilize the chestnut forest green waste and convert it into a valuable seedling media for the sustainable cultivation of chestnut seedlings. In this study, we composted CB with two waste products of cattle farming, namely cow manure (CM) and bovine bone (BM). We also evaluated the potential of CB compost application in chestnut forest sustainability. Results indicated that the best combination was the addition of 15% BM and 55% CM. This combination significantly improved the composting environment by increasing pH, enhancing phosphorus concentration and mineral elements such as Ca, Na, Mg and Zn, and shortened the composting period to 38 days. This combination also resulted in the highest content of citric acid-P (109.20 times than the control treatment) and the lowest content of NH4+–N (0.28 times than control treatment) indicating a better N and P structure of the final compost product. This combination achieved a greater degradation rate of CB cellulose (61.45%), hemicellulose (37.87%), and a more significant degradation of outer epidermis structure. When CB compost was used as a growing media, a significant decrease in photosynthesis stress of chestnut seedlings was observed, which was mainly manifested as a decrease in photochemical quenching (qP) and an increase of the maximum efficiency of PSII photochemistry under dark-adaption (Fv/Fm). Addition of 10% CB compost (in volume basis) is suggested, which resulted in the tallest chestnut seedlings (59.83 cm) with a stem diameter of 0.91 cm after six months of growth. In summary, this research provides an environmentally friendly strategy for chestnut orchard sustainability: rapid composting of CB, then immediate application as a high-quality substrate for chestnut seedlings. Full article
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Open AccessArticle
Diversity and Effectivity of Indigenous Mesorhizobium Strains for Chickpea (Cicer arietinum L.) in Myanmar
Agronomy 2020, 10(2), 287; https://doi.org/10.3390/agronomy10020287 - 17 Feb 2020
Cited by 1 | Viewed by 409
Abstract
Chickpea (Cicer arietinum L.) is one of the world’s main leguminous crops that provide chief source of food for humans. In the present study, we characterized thirty isolates of indigenous chickpea rhizobia from Myanmar based on the sequence analysis of the bacterial [...] Read more.
Chickpea (Cicer arietinum L.) is one of the world’s main leguminous crops that provide chief source of food for humans. In the present study, we characterized thirty isolates of indigenous chickpea rhizobia from Myanmar based on the sequence analysis of the bacterial 16S rRNA gene. The sequence analysis confirmed that all isolates were categorized and identified as the genus Mesorhizobium and they were conspecific with M. plurifarium, M. muliense, M. tianshanense, and M. sp. This is the first report describing M. muliense, M. tianshanense, and M. plurifurium from different geographical distribution of indigenous mesorhizobia of chickpea in Myanmar. In order to substitute the use of chemical fertilizers in legume production, there is a need for the production of Biofertilizers with rhizobial inoculants. The effectiveness of Myanmar Mesorhizobim strains isolated from soil samples of major chickpea growing areas of Myanmar for plant growth and nitrogen fixation were studied in pot experiments. The nodule dry weight and acetylene reduction activity of the plant inoculated with Mesorhizobium tianshanense SalCP19 was significantly higher than the other tested isolates in Yezin-4 chickpea variety. But, Mesorhizobium sp. SalCP17 was showed high level of acetylene reduction activity per plant in Yezin-6 chickpea variety. Full article
(This article belongs to the Special Issue Mechanism of Rhizosphere Microorganisms Promoting Crop Growth)
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Open AccessArticle
Phytophthora Antagonism of Endophytic Bacteria Isolated from Roots of Black Pepper (Piper nigrum L.)
Agronomy 2020, 10(2), 286; https://doi.org/10.3390/agronomy10020286 - 17 Feb 2020
Viewed by 455
Abstract
In this study, 90 root samples were collected from 30 black pepper farms in three provinces in the Central Highlands of Vietnam. A total of 352 endophytic bacteria were isolated and their morphology described. An in vitro assay on the antifungal activity of [...] Read more.
In this study, 90 root samples were collected from 30 black pepper farms in three provinces in the Central Highlands of Vietnam. A total of 352 endophytic bacteria were isolated and their morphology described. An in vitro assay on the antifungal activity of these isolates was then conducted and 47 isolates were found to have antagonistic activity on Phytophthora fungi. The antifungal activity of the 47 isolates was evaluated in vivo by shoot assay. Among these 47 isolates, 6 were selected for further investigation. The six isolates were classified and identified by sequencing the 16S RNA gene and phylogeny. The results showed that all six endophytic bacteria belong to the following species of Bacillus genus: B. siamensis, B. amyloliquefaciens, B. velezenis, and B. methylotrophiycus. Enzymatic activity related to the antifungal activity of the six potent isolates was determined; it showed that they possessed high chitinase and protease activities. These isolates were applied for black pepper seedlings in greenhouse. The results showed three promising isolates: B. siamensis EB.CP6, B. velezensis EB.KN12, and B. methylotrophycus EB.KN13. Black pepper seedlings treated with the promising bacteria had the lowest rate of root disease (8.45–11.21%) and lower fatal rate (11.11–15.55%) compared to the control group (24.81% and 24.44%). In addition, the three promising isolates strongly affected the growth of the black pepper seedlings in greenhouse. The plant height, length of roots, and fresh biomass of the seedlings in the treated plots were higher than those in the control plots. Thus, the endophytic bacterial isolates have the potential to act as biocontrol agent for the sustainable production of black pepper. Full article
(This article belongs to the Special Issue Integrating Pest Management into Agricultural Production Systems)
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Open AccessArticle
A Functional Analysis of Pedotransfer Functions Developed for Sri Lankan soils: Applicability for Process-Based Crop Models
Agronomy 2020, 10(2), 285; https://doi.org/10.3390/agronomy10020285 - 17 Feb 2020
Viewed by 378
Abstract
As measurements are expensive and laborious, the estimation of soil hydraulic properties using pedotransfer functions (PTFs) has become popular worldwide. However, the estimation of soil hydraulic properties is not the final aim but an essential input value for other calculations and simulations, mostly [...] Read more.
As measurements are expensive and laborious, the estimation of soil hydraulic properties using pedotransfer functions (PTFs) has become popular worldwide. However, the estimation of soil hydraulic properties is not the final aim but an essential input value for other calculations and simulations, mostly in environmental and crop models. This modeling approach is a popular way to assess agricultural and environmental processes. However, it is rarely used in Sri Lanka because soil hydraulic data are rare. We evaluated the functionality of PTFs (developed to estimate field capacity (FC) and the permanent wilting point (PWP) of Sri Lankan soils) for process-based crop models. We used the Agricultural Production Systems sIMulator (APSIM) as the test model. Initially, we confirmed the importance of PWP (LL15) and FC (DUL) by assessing the sensitivity of the soil input parameters on the growth and yield of rice under rainfed conditions. We simulated the growth and yield of rice and the four selected outputs related to the APSIM soil module using the measured and estimated values of FC and PWP. These simulations were conducted for ten years in 16 locations of Sri Lanka, representing wet, intermediate, and dry zones. The simulated total aboveground dry matter and weight of the rough rice, using both input conditions (the measured and PTF-estimated soil hydraulic properties), showed good agreement, with no significant differences between each other. Outputs related to the soil module also showed good agreement, as no significant differences were found between the two input conditions (measured and PTF-estimated soil hydraulic properties). Although the DUL and LL15 are the most influential parameters for the selected outputs of APSIM–Oryza, the estimated FC and PWP values did not change the predictive ability of APSIM. In this way, the functionality of PTFs for APSIM crop modeling is confirmed. Full article
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