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Agronomy, Volume 10, Issue 7 (July 2020) – 139 articles

Cover Story (view full-size image): Red mango fruit is more resistant to postharvest decay and chilling and is preferred by customers. In this work, we found that exogenous application of phytohormones, such as prohydrojasmon or abscisic acid, in combination with increased exposure to sunlight (pruning) enhanced the red fruit color. Those applications probably induced the phenylpropanoid biosynthesis pathway, leading to more appealing fruit, having only a minor effect on fruit ripening. Therefore, pruning regimes that expose the fruit to sunlight and preharvest treatments with phytohormones or their derivatives can increase the production of secondary metabolites such as flavonols and anthocyanins, enhancing the fruit quality, postharvest life, and fruit health properties. View this paper
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Article
Efficacy of Different Herbicides on Echinochloa colona (L.) Link Control and the First Case of Its Glyphosate Resistance in Greece
Agronomy 2020, 10(7), 1056; https://0-doi-org.brum.beds.ac.uk/10.3390/agronomy10071056 - 21 Jul 2020
Cited by 7 | Viewed by 1318
Abstract
E. colona is a C4 annual summer grass which is troublesome to major summer annual and perennial crops. Due to recent complaints by the farmers, the objectives of the present study were to evaluate the efficacy of penoxsulam, profoxydim, cycloxydim, cyhalofop-butyl, florpyrauxifen-benzyl [...] Read more.
E. colona is a C4 annual summer grass which is troublesome to major summer annual and perennial crops. Due to recent complaints by the farmers, the objectives of the present study were to evaluate the efficacy of penoxsulam, profoxydim, cycloxydim, cyhalofop-butyl, florpyrauxifen-benzyl and glyphosate against six E. colona accessions, and also to evaluate the response of these accessions to different rates of glyphosate in a dose-response experiment. In the first experiment, herbicides were applied at their maximum recommended label rates, while in the dose-response experiment, glyphosate was applied at six doses corresponding to 0, 1/4X, 1/2X, X, 2X, and 4X of the recommended rate. The dry weight of the biotypes TH8 and TH7 treated with profoxydim was 66% and 68% of the untreated control, respectively. The efficacy of cyhalofop-butyl against three accessions was lower than 30%, while two accessions were susceptible to this herbicide. The efficacy of penoxsulam against the biotypes ET2 and ET4 was lower than 10%, while dry weight of FT5 and TH8 was only reduced by 23%–28% as compared to the control. Cycloxydim application provided control higher than 75% at 21 days after treatment (DAT) of three accessions, while the majority of E. colona accessions was adequately controlled by the application of florpyrauxifen-benzyl. The response of the different accessions to glyphosate varied. The results of the glyphosate dose-response experiment revealed that the GR50 values of the resistant E. colona accessions ET2 and ET4 were up to 1098 and 1220 g a.e. ha−1 of glyphosate, respectively, whereas the GR50 value of the susceptible accession (FT5) was only 98 g a.e. ha−1. The resistance indices of ET2 and ET4 were 12.4 and 11.2, respectively, indicating that they have already developed resistance to glyphosate. Three more accessions could be also of developing resistant to glyphosate. This is the first report of glyphosate resistance from E. colona accessions in Greece, with indications of multiple resistance also present. Further research is needed in order to evaluate the efficacy of several herbicides under different soil and climatic conditions, conduct baseline sensitivity studies, reveal the evolvement of resistance patterns to glyphosate from accessions of Echinochloa spp., and search for alternative options of weed management in annual and perennial crops due to the clear indications of multiple resistance situations. Full article
(This article belongs to the Special Issue Herbicide Resistance in Weed Management)
Article
Evaluating Biochar-Microbe Synergies for Improved Growth, Yield of Maize, and Post-Harvest Soil Characteristics in a Semi-Arid Climate
Agronomy 2020, 10(7), 1055; https://0-doi-org.brum.beds.ac.uk/10.3390/agronomy10071055 - 21 Jul 2020
Cited by 12 | Viewed by 1327
Abstract
Arid and semi-arid regions are characterized by high temperature and low rainfall, leading to degraded agricultural soils of alkaline calcareous nature with low organic matter contents. Less availability of indigenous nutrients and efficacy of applied fertilizers are the major issues of crop production [...] Read more.
Arid and semi-arid regions are characterized by high temperature and low rainfall, leading to degraded agricultural soils of alkaline calcareous nature with low organic matter contents. Less availability of indigenous nutrients and efficacy of applied fertilizers are the major issues of crop production in these soils. Biochar application, in combination with plant growth promoting rhizobacteria with the ability to solubilize nutrients, can be an effective strategy for improving soil health and nutrient availability to crops under these conditions. Experiments were planned to evaluate the impact of biochar obtained from different sources in combination with acid-producing, nutrient-solubilizing Bacillus sp. ZM20 on soil biological properties and growth of maize (Zea mays L.) crops under natural conditions. Various biochar treatments, viz. wheat (Triticum aestivum L.) straw biochar, Egyptian acacia (Vachellia nilotica L.) biochar, and farm-yard manure biochar with and without Bacillus sp. ZM20, were used along with control. Soil used for pot and field trials was sandy loam in texture with poor water holding capacity and deficient in nutrients. Results of the pot trial showed that fresh and dry biomass, 1000 grain weight, and grain yield was significantly improved by application of biochar of different sources with and without Bacillus sp. ZM20. Application of biochar along with Bacillus sp. ZM20 also improved soil biological properties, i.e., soil organic matter, microbial biomass carbon, ammonium, and nitrate nitrogen. It was also observed that a combined application of biochar with Bacillus sp. ZM20 was more effective than a separate application of biochar. The results of wheat straw biochar along with Bacillus sp. ZM20 were better as compared to farm-yard manure biochar and Egyptian acacia biochar. Maximum increase (25.77%) in grain yield was observed in the treatment where wheat straw biochar (0.2%) was applied in combination with Bacillus sp. ZM20. In conclusion, combined application of wheat straw biochar (0.2%) inoculated with Bacillus sp. ZM20 was the most effective treatment in improving the biological soil properties, plant growth, yield, and quality of maize crop as compared to all other treatments. Full article
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Article
Continuous Monoculture of Alfalfa and Annual Crops Influence Soil Organic Matter and Microbial Communities in the Rainfed Loess Plateau of China
Agronomy 2020, 10(7), 1054; https://0-doi-org.brum.beds.ac.uk/10.3390/agronomy10071054 - 21 Jul 2020
Cited by 2 | Viewed by 1099
Abstract
Cropping systems are structured to maximize crop yields and increase sustainability in agricultural production. A field study was conducted to investigate different long-term cropping systems on soil organic matter and microbial communities. The cropping systems studied were: (i) a 14-year continuous alfalfa ( [...] Read more.
Cropping systems are structured to maximize crop yields and increase sustainability in agricultural production. A field study was conducted to investigate different long-term cropping systems on soil organic matter and microbial communities. The cropping systems studied were: (i) a 14-year continuous alfalfa (Medicago sativa L.) (CA), (ii) a 9-year alfalfa removed and rotated with 4–5 years continuous annual crops (spring wheat (Triticum aestivum L.), maize (Zea mays L.), potato (Solanum tuberosum L.), and millet (Panicum miliaceum L.)), and (iii) a 5-year field fallow after alfalfa. Results showed that continued annual crops decreased total organic C and labile organic C by 10 to 20% and 17 to 34% in the topsoil (0–30 cm), and by 15 to 35% and 20 to 46% in the subsoil (30–60 cm), respectively, compared with CA. Similar trends were found in soil total N concentration, which decreased by 7 to 20% in the topsoil. Highest microbial biomass C was found in CA. Shannon-Wiener diversity and substrate richness of soil microbes measured by Biolog EcoPlates was significantly affected by cropping system with CA exhibiting a higher degree of soil microbial functional diversity in the topsoil, while the lowest values were found in the alfalfa-potato system. The higher soil organic matter content and functional diversity of soil microbe in CA indicates that soil nutrition and microbial activity did not limit alfalfa development and growth in the dryland area. The lower microbial activity and functional diversity observed in the potato field indicates the importance of crop selection in cropping systems. Full article
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Article
Synthesis of Dacus Pheromone, 1,7-Dioxaspiro[5.5]Undecane and Its Encapsulation in PLLA Microspheres for Their Potential Use as Controlled Release Devices
Agronomy 2020, 10(7), 1053; https://0-doi-org.brum.beds.ac.uk/10.3390/agronomy10071053 - 21 Jul 2020
Cited by 2 | Viewed by 1285
Abstract
Olive fruit fly Dacus oleae is a well-known pest infecting the bark of olive fruit, leading to reduction of extracted olive oil properties. Among chemicals proposed for Dacus oleae population control, pheromone 1,7-dioxaspiro(5.5)undecane (DSU), Dacus pheromone, is considered as a promising agent, which [...] Read more.
Olive fruit fly Dacus oleae is a well-known pest infecting the bark of olive fruit, leading to reduction of extracted olive oil properties. Among chemicals proposed for Dacus oleae population control, pheromone 1,7-dioxaspiro(5.5)undecane (DSU), Dacus pheromone, is considered as a promising agent, which is added in several traps. However, all proposed systems manage to sufficiently deliver DSU for only two weeks. Furthermore, an additional problem is the limited available amount of pheromone to use in such systems. To overcome this, in the present study, a novel synthetic procedure of DSU is described, including only five steps. Intermediate products were studied by High Resolution Mass Spectroscopy Electrospray Ionization (HRMS-ESI) (m/z), while the resulting DSU was further characterized by 1H and 13C-NMR. Synthesized DSU was further encapsulated in poly(L-lactic acid) (PLLA) microparticles in three different concentrations; 5, 10 and 20% w/w. Its successful incorporation was studied by FT-IR, XRD and differential scanning calorimeter (DSC) while two procedures, liquid extraction and solid phase microextraction, followed by GC-MS analysis, was used for quantification of pheromone to microparticles. It was found that microparticles loading was over 85% for all three formulations. Its release showed a prolonged profile for microparticles containing 20% w/w DSU, lasting four weeks, while the quantity of DSU released reached 100%. These microparticles could be appropriate to control Dacus oleae population. Full article
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Article
Differences in Metabolic and Physiological Responses between Local and Widespread Grapevine Cultivars under Water Deficit Stress
Agronomy 2020, 10(7), 1052; https://0-doi-org.brum.beds.ac.uk/10.3390/agronomy10071052 - 21 Jul 2020
Cited by 4 | Viewed by 1322
Abstract
Climate change forecasts suggest temperature increases and lower rainfall rates, both of which challenge viticulture, particularly in semi-arid areas where water availability is critical. In this scenario, the use of the genetic variability in grapevine varieties reported around the world represents an important [...] Read more.
Climate change forecasts suggest temperature increases and lower rainfall rates, both of which challenge viticulture, particularly in semi-arid areas where water availability is critical. In this scenario, the use of the genetic variability in grapevine varieties reported around the world represents an important strategy for the selection of climate-resilient cultivars. In this work, physiological and metabolomics analyses were conducted to compare the water deficit stress (WDS) responses of red and white, local and widespread grapevines cultivars. Leaf gas exchange, water use efficiency (WUE) and water relation parameters were determined in plants under well-watered and WDS conditions alongside assessment of the levels of foliar primary metabolites using gas-chromatography coupled to mass-spectrometry. Results denote that red and white local cultivars displayed more adapted physiological performance under WDS as compared to the widely-distributed ones. Multivariate analyses and specific changes in leaf primary metabolites indicate genotype-specific responses of local cultivars as compared to widespread ones. Differences in ascorbate-related and shikimate/phenylpropanoid metabolism could explain the better physiological performance under WDS in red local as compared to widespread cultivars. On the other hand, coordinated changes in respiratory- and stress-related sugars and amino acids could underlie the better WUE under WDS in the white local cultivar. All these results suggest several metabolic targets that could be useful as metabolic markers or for metabolic engineering in grapevine breeding programs to improve drought tolerance. Full article
(This article belongs to the Special Issue Tackling Grapevine Water Relations in a Global Warming Scenario)
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Article
Long-Term Yield and Quality Performance of Perennial Energy Grasses (Agropyron spp.) on Marginal Land
Agronomy 2020, 10(7), 1051; https://0-doi-org.brum.beds.ac.uk/10.3390/agronomy10071051 - 21 Jul 2020
Cited by 5 | Viewed by 927
Abstract
The cultivation of perennial grasses is one of the most desirable alternatives as energy feedstock, but it is difficult to achieve competitive yields under Mediterranean marginal conditions. The aim of this study was to assess the performance of three cool-season grasses (Agropyron [...] Read more.
The cultivation of perennial grasses is one of the most desirable alternatives as energy feedstock, but it is difficult to achieve competitive yields under Mediterranean marginal conditions. The aim of this study was to assess the performance of three cool-season grasses (Agropyron spp.) from an agronomic and energetic point of view by comparing the dry matter (DM) yields, rain use efficiency, chemical composition, and biomass quality over an eight-year period in Spain under marginal rainfed conditions. The tall wheatgrass (Agropyron elongatum (Host) Beauv.) cultivars, Alkar (4.8 Mg DM·ha−1) and Jose (4.7 Mg DM·ha−1), achieved the highest yields. Productions below 0.5 Mg DM·ha−1 were obtained when rainfall was lower than 150 mm between March and June. The biomass obtained from the tested grasses showed relatively high contents of ash, silicon, and alkali elements. Net calorific values ranged between 16.7 and 18.5 MJ·kg−1 db. Differences in the composition among species and cultivars are not likely to affect their combustion behavior from a practical point of view. The ash content, as well as the concentrations of K, S, Na, and Cl, tended to decrease over the years. The results offered would be very useful for the implementation of this type of crop in marginal land. Full article
(This article belongs to the Special Issue Sustainable Management and Utilization of Permanent Grassland)
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Article
Browning of Early and Late-Harvested ‘Empire’ Apples Affected by Cold Storage and 1-MCP
Agronomy 2020, 10(7), 1050; https://0-doi-org.brum.beds.ac.uk/10.3390/agronomy10071050 - 21 Jul 2020
Cited by 1 | Viewed by 949
Abstract
The effects of harvest time, 1-methylcyclopropene (1-MCP) and air storage time on the susceptibility of flesh browning in ‘Empire’ apples were studied during a seven-day shelf life period after air storage at 0.5 °C for seven months. Early- or late-harvested ‘Empire’ apples without [...] Read more.
The effects of harvest time, 1-methylcyclopropene (1-MCP) and air storage time on the susceptibility of flesh browning in ‘Empire’ apples were studied during a seven-day shelf life period after air storage at 0.5 °C for seven months. Early- or late-harvested ‘Empire’ apples without 1-MCP increased production of ethylene, respiration rates and internal ethylene concentration during the shelf life. Respiration rates increased in the late-harvested fruit for the shelf life period with/without 1-MCP treatment. The 1-MCP-treated fruit was approximately 10 N firmer than fruit not treated with 1-MCP at an early harvest for the entire shelf life duration. Peroxidase activity and percent change in electrical conductivity in the flesh were elevated in late-harvested fruit for the shelf life duration, whereas polyphenol oxidase activities were found to be stimulated by 1-MCP treatment, regardless of harvest time. Late-harvested fruit treated with 1-MCP exhibited increased susceptibility to flesh browning during shelf life, mostly due to reduction of the antioxidant defense mechanism of the fruits to stress in extending storage life, increasing polyphenol oxidase (PPO) activity and electrolyte leakage rate. Full article
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Article
Impact of Effective Microorganisms (EM) Application on the Physical Condition of Haplic Luvisol
Agronomy 2020, 10(7), 1049; https://0-doi-org.brum.beds.ac.uk/10.3390/agronomy10071049 - 21 Jul 2020
Cited by 1 | Viewed by 984
Abstract
The study set out to determine changes in the soil air-water properties, the water-stable aggregate share and organic carbon content as effects of a five-year application of effective microorganisms (EM-A). The hypothesis that long-term applied EM-A biopreparations have a positive effect on the [...] Read more.
The study set out to determine changes in the soil air-water properties, the water-stable aggregate share and organic carbon content as effects of a five-year application of effective microorganisms (EM-A). The hypothesis that long-term applied EM-A biopreparations have a positive effect on the soil physical condition has not been confirmed. Haplic Luvisols originating from silt were studied in a field experiment after EM-A biopreparation treatment. The soil samples with the natural structure preserved intact were collected three times each year. The properties of the soil determined in the study were: particle density, total organic carbon content, bulk density, total porosity, air capacity, air permeability, soil moisture at sampling, field water capacity, available water content, unavailable water content, and water-stable aggregate content. The ratio of field water capacity and total porosity (FC/TP) was calculated. It was found that EM-A application primarily leads to a decrease in the content of organic carbon and water-stable aggregates. This was an adverse effect. Total organic carbon (TOC) and water-stable aggregates proved to be very sensitive indicators for assessing the soil physical condition. However, changes in soil compaction and air–water properties did not show significant deterioration. Our research addresses the data gaps about EM application to soil. Full article
(This article belongs to the Special Issue Soil Degradation Prevention and Restoration at Farm and Field Scale)
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Article
Straw Removal Effects on Sugarcane Root System and Stalk Yield
Agronomy 2020, 10(7), 1048; https://0-doi-org.brum.beds.ac.uk/10.3390/agronomy10071048 - 21 Jul 2020
Cited by 4 | Viewed by 1264
Abstract
The sugarcane (Saccharum spp. L.) mechanical harvesting system leaves a large amount of straw mulch on the soil surface. The straw mulch may affect soil conditions, root regrowth, and sugarcane yield. Thus, this study assessed the response of sugarcane root system growth and [...] Read more.
The sugarcane (Saccharum spp. L.) mechanical harvesting system leaves a large amount of straw mulch on the soil surface. The straw mulch may affect soil conditions, root regrowth, and sugarcane yield. Thus, this study assessed the response of sugarcane root system growth and stalk yield to different rates of straw removal. An experiment was conducted in a Rhodic Kandiudox with sand clay loam texture to test the impact of four rates of straw removal: no removal (18.9 Mg ha−1 of dry mass); moderate removal (8.7 Mg ha−1); high removal (4.2 Mg ha−1) and total removal on sugarcane root system and stalk yield. Higher concentrations of roots (60%) were found in the first 40 cm of soil. Moderate straw removal resulted in higher root mass (3.6 Mg ha−1) and stalk production (23 Mg ha−1 of dry mass). However, no straw removal reduced root mass by <40% (2099 kg ha−1) and reduced stalk yield by >20% (105 Mg ha−1). Through regression analysis, it was estimated that retaining between 8.5 and 13 Mg ha−1 of straw resulted in the highest root mass and stalk yield. Managing straw removal to retain a moderate amount enables producers to sustain suitable soil conditions for sugarcane root growth and stalk production while providing straw for industrial use. Full article
(This article belongs to the Section Farming Sustainability)
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Article
Effect of Conversion to Organic Farming on Pest and Disease Control in French Vineyards
Agronomy 2020, 10(7), 1047; https://doi.org/10.3390/agronomy10071047 - 20 Jul 2020
Cited by 5 | Viewed by 1463
Abstract
Since 2006, an increasing number of French vineyards have chosen to convert to organic farming. One major change in vineyard practices includes replacing chemical pesticides with copper and sulfur-based products in line with Council Regulation (EC) No. 834/2007. This change can make overall [...] Read more.
Since 2006, an increasing number of French vineyards have chosen to convert to organic farming. One major change in vineyard practices includes replacing chemical pesticides with copper and sulfur-based products in line with Council Regulation (EC) No. 834/2007. This change can make overall management and pest and disease control more difficult and potentially lead to yield losses. From 2013 to 2016, a network of 48 vineyard plots, in southern France, under conventional management and in conversion to organic farming were monitored throughout the three-year conversion phase to investigate the grapevine phytosanitary management of four major pests and diseases and variations in control efficiency. The severity of downy and powdery mildew, grape berry moths, and Botrytis bunch rot were assessed and linked to the protection strategy. The findings showed that pests and diseases were controlled in the third year of conversion at similar efficiency levels as in conventional farming. However, the first two years of conversion were a transitional and less successful period during which higher incidences of cryptogamic diseases were observed. This demonstrates a need for winegrowers to receive more in-depth technical advice and support, especially on pest and disease control, during this critical transition period. Full article
(This article belongs to the Special Issue Organic vs. Conventional Cropping Systems)
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Article
Crop Yield Prediction through Proximal Sensing and Machine Learning Algorithms
Agronomy 2020, 10(7), 1046; https://0-doi-org.brum.beds.ac.uk/10.3390/agronomy10071046 - 20 Jul 2020
Cited by 29 | Viewed by 2792
Abstract
Proximal sensing techniques can potentially survey soil and crop variables responsible for variations in crop yield. The full potential of these precision agriculture technologies may be exploited in combination with innovative methods of data processing such as machine learning (ML) algorithms for the [...] Read more.
Proximal sensing techniques can potentially survey soil and crop variables responsible for variations in crop yield. The full potential of these precision agriculture technologies may be exploited in combination with innovative methods of data processing such as machine learning (ML) algorithms for the extraction of useful information responsible for controlling crop yield. Four ML algorithms, namely linear regression (LR), elastic net (EN), k-nearest neighbor (k-NN), and support vector regression (SVR), were used to predict potato (Solanum tuberosum) tuber yield from data of soil and crop properties collected through proximal sensing. Six fields in Atlantic Canada including three fields in Prince Edward Island (PE) and three fields in New Brunswick (NB) were sampled, over two (2017 and 2018) growing seasons, for soil electrical conductivity, soil moisture content, soil slope, normalized-difference vegetative index (NDVI), and soil chemistry. Data were collected from 39–40 30 × 30 m2 locations in each field, four times throughout the growing season, and yield samples were collected manually at the end of the growing season. Four datasets, namely PE-2017, PE-2018, NB-2017, and NB-2018, were then formed by combing data points from three fields to represent the province data for the respective years. Modeling techniques were employed to generate yield predictions assessed with different statistical parameters. The SVR models outperformed all other models for NB-2017, NB-2018, PE-2017, and PE-2018 dataset with RMSE of 5.97, 4.62, 6.60, and 6.17 t/ha, respectively. The performance of k-NN remained poor in three out of four datasets, namely NB-2017, NB-2018, and PE-2017 with RMSE of 6.93, 5.23, and 6.91 t/ha, respectively. The study also showed that large datasets are required to generate useful results using either model. This information is needed for creating site-specific management zones for potatoes, which form a significant component for food security initiatives across the globe. Full article
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Article
Chemical Properties of Soil in Four-Field Crop Rotations under Organic and Conventional Farming Systems
Agronomy 2020, 10(7), 1045; https://0-doi-org.brum.beds.ac.uk/10.3390/agronomy10071045 - 20 Jul 2020
Cited by 11 | Viewed by 1166
Abstract
In agriculture, the farming system significantly affects chemical soil properties. The organic system, which is based among others on the use of natural (organic) fertilizers, promotes increased soil contents of humus, organic C, and micronutrients. The conventional system, in turn, may cause soil [...] Read more.
In agriculture, the farming system significantly affects chemical soil properties. The organic system, which is based among others on the use of natural (organic) fertilizers, promotes increased soil contents of humus, organic C, and micronutrients. The conventional system, in turn, may cause soil acidification if high rates of mineral (particularly nitrogen) fertilization are used. The crop plant species also modifies soil chemistry by providing different (quantitatively and qualitatively) crop residues. The study was conducted over the period 2013–2016 in Czesławice (Lublin Region, Poland). The aim of this study was to determine the content of some chemical components determining the quality of loess soil on which four plant species were grown under organic and conventional farming systems. This research involved the determination of some parameters of the chemical composition of the soil: soil pH, total sorption capacity, humus content, macronutrient (P, K, Mg) and micronutrient (B, Cu, Mn, Zn) content, organic carbon, and total nitrogen content. The content of different forms of nitrogen, N-NO3 and N-NH4, was also determined. The experimental design included two crop rotations (organic and conventional) in which identical plant species were grown: potato—winter wheat—field bean—spring barley. The experiment was established on loess soil with the grain size distribution of silt loam and classified as good wheat soil complex (soil class II). It was carried out as a split-plot design in three replicates, and the area of a single plot was 80 m2. Soil samples were taken using a soil sampling tube from an area of 0.20 m2 (from the 0–25 cm layer) in each plot at the end of the growing season of the specific crops grown. Over the four year study period, it was found that the organic system contributed to an increased soil content of magnesium, boron, copper, manganese, zinc, organic carbon, and total nitrogen. Moreover, organic cropping promoted more favorable soil pH and higher soil humus content. Organic cropping significantly improved the total sorption capacity of the soil compared to conventional cultivation. Moreover, the organic system contributed to a higher soil content of nitrogen in the form of N-NH4 and its lower content in the form of N-NO3. Under the conventional system, in turn, a higher soil phosphorus and potassium content was observed. To sum up, the study confirmed the assumed hypothesis that the organic farming system would contribute to an improvement in the chemical quality indicators of loess soil. Regardless of the cropping system, potato and field bean had the most beneficial effect on soil chemistry, whereas cereal crops showed the weakest effect. Winter wheat and spring barley had an effect on significantly lower total sorption capacity of the soil and a significantly lower soil content of N-NO3 and N-NH4. Full article
(This article belongs to the Special Issue Organic vs. Conventional Cropping Systems)
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Review
Spatial Modelling of Within-Field Weed Populations; a Review
Agronomy 2020, 10(7), 1044; https://0-doi-org.brum.beds.ac.uk/10.3390/agronomy10071044 - 20 Jul 2020
Cited by 7 | Viewed by 1671
Abstract
Concerns around herbicide resistance, human risk, and the environmental impacts of current weed control strategies have led to an increasing demand for alternative weed management methods. Many new weed management strategies are under development; however, the poor availability of accurate weed maps, and [...] Read more.
Concerns around herbicide resistance, human risk, and the environmental impacts of current weed control strategies have led to an increasing demand for alternative weed management methods. Many new weed management strategies are under development; however, the poor availability of accurate weed maps, and a lack of confidence in the outcomes of alternative weed management strategies, has hindered their adoption. Developments in field sampling and processing, combined with spatial modelling, can support the implementation and assessment of new and more integrated weed management strategies. Our review focuses on the biological and mathematical aspects of assembling within-field weed models. We describe both static and spatio-temporal models of within-field weed distributions (including both cellular automata (CA) and non-CA models), discussing issues surrounding the spatial processes of weed dispersal and competition and the environmental and anthropogenic processes that affect weed spatial and spatio-temporal distributions. We also examine issues surrounding model uncertainty. By reviewing the current state-of-the-art in both static and temporally dynamic weed spatial modelling we highlight some of the strengths and weaknesses of current techniques, together with current and emerging areas of interest for the application of spatial models, including targeted weed treatments, economic analysis, herbicide resistance and integrated weed management, the dispersal of biocontrol agents, and invasive weed species. Full article
(This article belongs to the Special Issue The Application of Models for Weed Management in Cropping Systems)
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Article
Sensory Attributes and Consumer Acceptability of 12 Microgreens Species
Agronomy 2020, 10(7), 1043; https://0-doi-org.brum.beds.ac.uk/10.3390/agronomy10071043 - 19 Jul 2020
Cited by 21 | Viewed by 2119
Abstract
Microgreens are gaining increasing recognition among consumers, acclaimed for their freshness and health promoting properties associated with densely fortified secondary metabolites. These immature greens enhance human diet and enrich it with sharp colors and flavors. While numerous species are being tested for agronomic [...] Read more.
Microgreens are gaining increasing recognition among consumers, acclaimed for their freshness and health promoting properties associated with densely fortified secondary metabolites. These immature greens enhance human diet and enrich it with sharp colors and flavors. While numerous species are being tested for agronomic and nutritional suitability, consumer acceptance of appearance, texture, and flavor is critical for the microgreens’ marketplace success. This study investigates whether sensory attributes and visual appearance affect consumer preference for microgreens and their willingness to consume them. By means of a consumer test, the sensory attributes of 12 microgreens species were evaluated, wherein a partial least squares structural equation model was developed to link sensorial attributes to willingness to eat the product. The results showed that although visual appearance of the microgreens was largely appreciated, consumer acceptance overall was mainly determined by flavor and texture. In particular, the lower the astringency, sourness, and bitterness, the higher the consumer acceptability of microgreens. Among the 12 examined species, mibuna and cress scored the lowest acceptance by consumers, while Swiss chard and coriander were the most appreciated, being therefore good candidates to be introduced in Western country markets. In addition, both Swiss chard and coriander have been identified by previous literature as good dietary source of phenolic antioxidants. Full article
(This article belongs to the Special Issue Sprouts, Microgreens and Edible Flowers as Novel Functional Foods)
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Article
Effect of Light Spectrum on Gas Exchange, Growth and Biochemical Characteristics of Einkorn Seedlings
Agronomy 2020, 10(7), 1042; https://0-doi-org.brum.beds.ac.uk/10.3390/agronomy10071042 - 19 Jul 2020
Cited by 6 | Viewed by 1057
Abstract
The use of Light Emitting Diode (LED) lights in microscale vegetable production is more and more widespread. In this context, the effect of light spectrum on photosynthesis, growth, shoot yield, pigment content, and nutritional status of einkorn seedlings (Triticum monococcum L. ssp. [...] Read more.
The use of Light Emitting Diode (LED) lights in microscale vegetable production is more and more widespread. In this context, the effect of light spectrum on photosynthesis, growth, shoot yield, pigment content, and nutritional status of einkorn seedlings (Triticum monococcum L. ssp. monococcum), germinated and grown in a nutrient solution, was investigated. Plants were subjected to six different LED light treatments, all having a photon flux density (PFD) of 200 μmol m−2 s−1. Two light treatments were monochromatic (red or blue), three dichromatic (blue and red in the proportion), and one of a wider spectrum (selected as a control). All the light treatments affected the morphological, biochemical, and nutritional status of einkorn seedlings. Overall, the dichromatic treatments were the most effective in stimulating biomass production, CO2 assimilation, and evapotranspiration, as well as contents in chlorophyll a and b and carotenoids, and additionally nitrogen, phosphorous, manganese, iron, and zinc. These results are of relevance for the beneficial effects of dichromatic LED treatments in maximizing einkorn shoot yield and nutritional values, and in limiting energy consumption in indoor cultivation. Full article
(This article belongs to the Special Issue Control of LED Lighting Based on Plant Physiological Principles)
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Article
Study of C, N, P and K Release from Residues of Newly Proposed Cover Crops in a Spanish Olive Grove
Agronomy 2020, 10(7), 1041; https://0-doi-org.brum.beds.ac.uk/10.3390/agronomy10071041 - 18 Jul 2020
Cited by 3 | Viewed by 1150
Abstract
Cover crops (CC)s are increasingly employed by farmers in olive groves. Spontaneous soil cover is the most commonly used CC. Its continuous utilization changes ruderal flora. It is necessary to study new CCs. Living CCs provide C and nutrients to soil during decomposition. [...] Read more.
Cover crops (CC)s are increasingly employed by farmers in olive groves. Spontaneous soil cover is the most commonly used CC. Its continuous utilization changes ruderal flora. It is necessary to study new CCs. Living CCs provide C and nutrients to soil during decomposition. Information on this issue in olive groves is scarce. A 4-year field study involving grab sampling of Brachypodium distachyon, Sinapis alba and spontaneous CC residues was conducted to study C and nutrient release from cover crop residues. Throughout the decomposition cycles, C, N and P release accounted for 40 to 58% of the C, N and P amounts in the residues after mowing. Most K was released (80–90%). Expressed in kg per hectare, the release of C and N in Brachypodium (C: 4602, N: 181, P: 29, K: 231) and Sinapis (C: 4806, N: 152, P: 18, K: 195) was greater than that in spontaneous CC (C: 3115, N: 138, P: 21, K: 256). The opposite results were observed for K. The Rickman model, employed to estimate the amount of C, N and P in residues, yielded a good match between the simulated and measured values. In comparison to spontaneous CC, the newly proposed CCs have a higher potential to provide soil with C and N. Full article
(This article belongs to the Special Issue Mediterranean Olive Trees and Olive Oil under Climate Change)
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Review
Nuclear Magnetic Resonance with Fast Field-Cycling Setup: A Valid Tool for Soil Quality Investigation
Agronomy 2020, 10(7), 1040; https://0-doi-org.brum.beds.ac.uk/10.3390/agronomy10071040 - 18 Jul 2020
Cited by 9 | Viewed by 2034
Abstract
Nuclear magnetic resonance (NMR) techniques are largely employed in several fields. As an example, NMR spectroscopy is used to provide structural and conformational information on pure systems, while affording quantitative evaluation on the number of nuclei in a given chemical environment. When dealing [...] Read more.
Nuclear magnetic resonance (NMR) techniques are largely employed in several fields. As an example, NMR spectroscopy is used to provide structural and conformational information on pure systems, while affording quantitative evaluation on the number of nuclei in a given chemical environment. When dealing with relaxation, NMR allows understanding of molecular dynamics, i.e., the time evolution of molecular motions. The analysis of relaxation times conducted on complex liquid–liquid and solid–liquid mixtures is directly related to the nature of the interactions among the components of the mixture. In the present review paper, the peculiarities of low resolution fast field-cycling (FFC) NMR relaxometry in soil science are reported. In particular, the general aspects of the typical FFC NMR relaxometry experiment are firstly provided. Afterwards, a discussion on the main mathematical models to be used to “read” and interpret experimental data on soils is given. Following this, an overview on the main results in soil science is supplied. Finally, new FFC NMR-based hypotheses on nutrient dynamics in soils are described Full article
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Review
Recovery of Phosphorus from Waste Water Profiting from Biological Nitrogen Treatment: Upstream, Concomitant or Downstream Precipitation Alternatives
Agronomy 2020, 10(7), 1039; https://0-doi-org.brum.beds.ac.uk/10.3390/agronomy10071039 - 18 Jul 2020
Cited by 12 | Viewed by 2071
Abstract
Mined phosphate rock is the largest source of phosphorus (P) for use in agriculture and agro-industry, but it also is a finite resource irregularly distributed around the world. Alternatively, waste water is a renewable source of P, available at the local scale. In [...] Read more.
Mined phosphate rock is the largest source of phosphorus (P) for use in agriculture and agro-industry, but it also is a finite resource irregularly distributed around the world. Alternatively, waste water is a renewable source of P, available at the local scale. In waste water treatment, biological nitrogen (N) removal is applied according to a wide range of variants targeting the abatement of the ammonium content. Ammonium oxidation to nitrate can also be considered to mitigate ammonia emission, while enabling N recovery. This review focuses on the analysis of alternatives for coupling biological N treatment and phosphate precipitation when treating waste water in view of producing P-rich materials easily usable as fertilisers. Phosphate precipitation can be applied before (upstream configuration), together with (concomitant configuration), and after (downstream configuration) N treatment; i.e., chemically induced as a conditioning pre-treatment, biologically induced inside the reactor, and chemically induced as a refining post-treatment. Characteristics of the recovered products differ significantly depending on the case studied. Currently, precipitated phosphate salts are not typified in the European fertiliser regulation, and this fact limits marketability. Nonetheless, this topic is in progress. The potential requirements to be complied by these materials to be covered by the regulation are overviewed. The insights given will help in identifying enhanced integrated approaches for waste water treatment, pointing out significant needs for subsequent agronomic valorisation of the recovered phosphate salts, according to the paradigms of the circular economy, sustainability, and environmental protection. Full article
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Review
State and Progress of Andean Lupin Cultivation in Europe: A Review
Agronomy 2020, 10(7), 1038; https://0-doi-org.brum.beds.ac.uk/10.3390/agronomy10071038 - 18 Jul 2020
Cited by 7 | Viewed by 2510
Abstract
Lupinus mutabilis is an important source of protein in different Andean countries, and its use in diets, particularly those of less wealthy individuals, has been observed for thousands of years. There is an increasing demand for protein crops suitable for Europe and this [...] Read more.
Lupinus mutabilis is an important source of protein in different Andean countries, and its use in diets, particularly those of less wealthy individuals, has been observed for thousands of years. There is an increasing demand for protein crops suitable for Europe and this species is a potential candidate. Assessment of Lupinus mutabilis genetic material in European conditions started more than 40 years ago, with the characterization of a vast number of accessions from the Andean region. In this review, abiotic and biotic constraints to L. mutabilis cultivation in European soil and climatic conditions are discussed, and cultivation management practices are suggested. The beneficial interaction of L. mutabilis with Bradyrhizobium strains in the soil and various pollinator species is also discussed, and the effect of abiotic stresses on these interactions is highlighted. Prospects of alternative uses of L. mutabilis biomass in Northern Europe and opportunities for breeding strategies are discussed. In conclusion, the different approach to crop modeling for Southern and Northern European climatic conditions is highlighted. Full article
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Article
Temporal Responses to Direct and Induced Iron Deficiency in Parietaria judaica
Agronomy 2020, 10(7), 1037; https://0-doi-org.brum.beds.ac.uk/10.3390/agronomy10071037 - 18 Jul 2020
Cited by 1 | Viewed by 935
Abstract
Parietaria judaica grows in highly calcareous environments, overcoming the low bioavailability of Fe caused by elevated pH. The aim of this work was to investigate the temporal dynamics of root exudation of P. judaica under Fe deficiency conditions. As high concentrations of bicarbonate [...] Read more.
Parietaria judaica grows in highly calcareous environments, overcoming the low bioavailability of Fe caused by elevated pH. The aim of this work was to investigate the temporal dynamics of root exudation of P. judaica under Fe deficiency conditions. As high concentrations of bicarbonate and Ca2+ in calcareous soils interfere with the general plant mineral nutrition, two different alkaline growing conditions were applied to distinguish the effects due to the high pH from the responses induced by the presence of high calcium carbonate concentrations. Growth parameters and physiological responses were analyzed during a 7 day time course—shoot and root biomass, chlorophyll and flavonoid contents in leaves, root accumulation, and exudation of organic acids and phenolics were determined. Different responses were found in plants grown in the presence of bicarbonate and in the presence of an organic pH buffer, revealing a time- and condition-dependent response of P. judaica and suggesting a stronger stress in the buffer treatment. The high tolerance to alkaline conditions may be related to an earlier and greater exudation rate of phenolics, as well as to the synergistic effect of phenolics and carboxylic acids in root exudates in the late response. The identification of the main functional traits involved in tolerance to low Fe availability in a wild species could offer crucial inputs for breeding programs for application to crop species. Full article
(This article belongs to the Special Issue Role of Iron in Plant Nutrition, Growth and Metabolism)
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Article
Screening the FIGS Set of Lentil (Lens culinaris Medikus) Germplasm for Tolerance to Terminal Heat and Combined Drought-Heat Stress
Agronomy 2020, 10(7), 1036; https://0-doi-org.brum.beds.ac.uk/10.3390/agronomy10071036 - 18 Jul 2020
Cited by 8 | Viewed by 1726
Abstract
Lentil (Lens culinaris Medikus) is one of the most important cool season food legume crops grown in many countries. Seeds are typically rich in protein, fiber, prebiotic carbohydrates and minerals, such as iron and zinc. With changing climate and variability, the lentil [...] Read more.
Lentil (Lens culinaris Medikus) is one of the most important cool season food legume crops grown in many countries. Seeds are typically rich in protein, fiber, prebiotic carbohydrates and minerals, such as iron and zinc. With changing climate and variability, the lentil crop faces frequent droughts and heat stress of varying intensity in its major production zones. In the present study, a set of 162 lentil accessions selected through the Focused Identification of Germplasm Strategy (FIGS) were screened for tolerance to heat stress and combined heat-drought stresses under field conditions at two contrasting locations, namely Marchouch and Tessaout in Morocco. The results showed a significant genotypic variation for heat tolerance and combined heat-drought tolerance among the accessions at both locations. Based on the heat tolerance index (HTI), accessions, namely ILL 7833, ILL 6338 and ILL 6104, were selected as potential sources of heat tolerance at Marchouch, and ILL 7814 and ILL 8029 at Tessaout. Using the stress tolerance index (STI), ILL 7835, ILL 6075 and ILL 6362 were identified as the most tolerant lines (STI > 1) at Marchouch, and ILL 7814, ILL 7835 and ILL 7804 (STI > 1) at Tessaout, under the combined heat-drought stress conditions. Accession ILL 7835 was identified as a good source of stable tolerance to heat stress and combined heat-drought stress at both locations. Full article
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Article
Sulfur Uptake from Fertilizer Fortified with Sulfate and Elemental S in Three Contrasting Climatic Zones
Agronomy 2020, 10(7), 1035; https://0-doi-org.brum.beds.ac.uk/10.3390/agronomy10071035 - 17 Jul 2020
Cited by 4 | Viewed by 1530
Abstract
Field trials with labeled fertilizers can be used to provide information on fertilizer efficiency, residual value, and nutrient fate. We assessed the uptake from elemental S (ES) and sulfate S (SO4-S) in S-fortified monoammonium phosphate fertilizers by various crops at three [...] Read more.
Field trials with labeled fertilizers can be used to provide information on fertilizer efficiency, residual value, and nutrient fate. We assessed the uptake from elemental S (ES) and sulfate S (SO4-S) in S-fortified monoammonium phosphate fertilizers by various crops at three sites in Argentina, Brazil, and Canada. The S sources were labeled with 34S, and the 34S abundance in the plant tissue was analyzed at an early stage and at maturity over two consecutive years. At the sites in Argentina and Canada, the recovery of ES in the crop was smaller than that of SO4-S in the first year, while the opposite was true in the second year. At the Brazilian site, the recovery of ES was similar to that of SO4-S in the first year, but higher in the second year. In the Argentina and Canada sites, the cumulative recovery of SO4-S was >65% and that of ES was 20−25%. In the Brazilian site, the cumulative recovery of SO4-S was 9% and that of ES 16%. The higher recovery of ES than of SO4-S in the Brazilian site was attributed to leaching of added SO4-S and relatively fast oxidation of ES due to the warm climate. These results suggest that ES may be more suitable than SO4-S as a fertilizer S source in warm humid climates, while inclusion of SO4-S in the fertilizer is recommended in colder climates as slow oxidation limits the initial availability of ES. Full article
(This article belongs to the Section Soil and Plant Nutrition)
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Article
How Moderate Water Stress Can Affect Water Use Efficiency Indices in Potato
Agronomy 2020, 10(7), 1034; https://0-doi-org.brum.beds.ac.uk/10.3390/agronomy10071034 - 17 Jul 2020
Cited by 6 | Viewed by 922
Abstract
Since water is increasingly becoming an expensive and limited resource, it is necessary to improve crop water use efficiency (WUE) to save water while maintaining high yields. The objective of this research was to evaluate the effects of moderate water stress compared to [...] Read more.
Since water is increasingly becoming an expensive and limited resource, it is necessary to improve crop water use efficiency (WUE) to save water while maintaining high yields. The objective of this research was to evaluate the effects of moderate water stress compared to well-watered conditions (supplying 50 or 100% of the maximum evapotranspiration (ETm)) on dry aboveground biomass yield (AB-Y), dry whole biomass yield (WB), tuber yield, irrigation WUE, and WUE at early harvest (E-TY, E-IWUE, E-YWUE), and at final harvest (F-TY, F-IWUE, F-YWUE), on WUE for dry aboveground biomass (AB-WUE) and for dry whole biomass (WB-WUE), on sink/source ratio and dry matter content of tubers in two potato cultivars—Sieglinde and Spunta, in two planting dates (early and late). Moderate water stress, compared to well-watered conditions, resulted in a small decrease in E-TY (−14%) and F-TY (−11%), but a high increase in E-IWUE (+69%) and F-IWUE (+78%), making savings in irrigation water of roughly 380 or 600 m3 per crop cycle in relation to early or final harvest. Moderate water stress improved in Sieglinde IWUE, YWUE, and WB-WUE at final harvest, whereas Spunta appeared more appropriate for early harvest. In the late planting date, the crop used water better compared to the early planting, resulting in a greater increase in IWUE (+77 vs. +66%) and an, albeit, slight increase in the WUE. It would, therefore, be convenient to apply the moderate water stress in the late planting, saving a further 100 m3 of irrigation water. The highest yield, IWUE, and YWUE were reached when moderate water stress was applied in both planting dates on cv. Spunta for early harvest and on cv. Sieglinde for final harvest. It was possible to increase WUE indices and save water, not only by water management, but also by choosing opportune planting dates and cultivars. Full article
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Review
CRISPR-Cas9 System for Plant Genome Editing: Current Approaches and Emerging Developments
Agronomy 2020, 10(7), 1033; https://0-doi-org.brum.beds.ac.uk/10.3390/agronomy10071033 - 17 Jul 2020
Cited by 25 | Viewed by 3037
Abstract
Targeted genome editing using CRISPR-Cas9 has been widely adopted as a genetic engineering tool in various biological systems. This editing technology has been in the limelight due to its simplicity and versatility compared to other previously known genome editing platforms. Several modifications of [...] Read more.
Targeted genome editing using CRISPR-Cas9 has been widely adopted as a genetic engineering tool in various biological systems. This editing technology has been in the limelight due to its simplicity and versatility compared to other previously known genome editing platforms. Several modifications of this editing system have been established for adoption in a variety of plants, as well as for its improved efficiency and portability, bringing new opportunities for the development of transgene-free improved varieties of economically important crops. This review presents an overview of CRISPR-Cas9 and its application in plant genome editing. A catalog of the current and emerging approaches for the implementation of the system in plants is also presented with details on the existing gaps and limitations. Strategies for the establishment of the CRISPR-Cas9 molecular construct such as the selection of sgRNAs, PAM compatibility, choice of promoters, vector architecture, and multiplexing approaches are emphasized. Progress in the delivery and transgene detection methods, together with optimization approaches for improved on-target efficiency are also detailed in this review. The information laid out here will provide options useful for the effective and efficient exploitation of the system for plant genome editing and will serve as a baseline for further developments of the system. Future combinations and fine-tuning of the known parameters or factors that contribute to the editing efficiency, fidelity, and portability of CRISPR-Cas9 will indeed open avenues for new technological advancements of the system for targeted gene editing in plants. Full article
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Article
Uniparental Inheritance of Salinity Tolerance and Beneficial Phytochemicals in Rice
Agronomy 2020, 10(7), 1032; https://0-doi-org.brum.beds.ac.uk/10.3390/agronomy10071032 - 17 Jul 2020
Cited by 3 | Viewed by 1464
Abstract
Salinity stress is one of the most problematic constraints to significantly reduce rice productivity. The Saltol QTL (quantitative trait locus) has been known as one among many principal genes/QTLs responsible for salinity tolerance in rice. However, the introgression of the Saltol QTL from [...] Read more.
Salinity stress is one of the most problematic constraints to significantly reduce rice productivity. The Saltol QTL (quantitative trait locus) has been known as one among many principal genes/QTLs responsible for salinity tolerance in rice. However, the introgression of the Saltol QTL from the donor (male) into the recipient (female) cultivars induces great recessions from the progeny generation, which results in heavy fieldwork and greater cost and time required for breeding. In this study, the F1 generation of the cross TBR1 (female cultivar, salinity tolerant) × KD18 (male cultivar, salinity susceptible) was preliminarily treated with N-methyl-N-nitrosourea (MNU) to induce the mutants M1. Results on physiological traits show that all the M2 (self-pollinated from M1) and M3 (self-pollinated from M2) individuals obtain salinity tolerant levels as the recurrent TBR1. Twelve SSR (simple sequence repeat) markers involved in the Saltol QTL (RM493, RM562, RM10694, RM10720, RM10793, RM10852, RM13197, RM201, RM149, RM508, RM587, and RM589) and other markers related to yield-contributing traits and disease resistance, as well as water and nitrogen use, have efficacy that is polymorphic. The phenotype and genotype analyses indicate that the salinity tolerant Saltol QTL, growth parameter, grain yield and quality, pest resistance, water and nitrogen use efficacy, and beneficial phytochemicals including antioxidants, momilactone A (MA) and momilactone B (MB) are uniparentally inherited from the recurrent (female) TBR1 cultivar and stabilized in the M2 and M3 generations. Further MNU applications should be examined to induce the uniparental inheritance of other salinity tolerant genes such as OsCPK17, OsRMC, OsNHX1, OsHKT1;5 to target rice cultivars. However, the mechanism of inducing this novel uniparental inheritance for salinity tolerance by MNU application needs elaboration. Full article
(This article belongs to the Special Issue Climate Change, Agriculture, and Food Security)
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Article
Alterations of the Chemical Compositions, Surface Functionalities, and Nitrogen Structures of Cage Layer Chicken Manure by Carbonization to Improve Nitrogen Bioavailability in Soil
Agronomy 2020, 10(7), 1031; https://0-doi-org.brum.beds.ac.uk/10.3390/agronomy10071031 - 16 Jul 2020
Cited by 1 | Viewed by 888
Abstract
Carbonization of cage layer chicken manure (CLCM) can improve its bio-recalcitrance which might improve nitrogen (N) bioavailability in soil. However, temperature(s) to exhibit appropriate variations in the chemical makeup of the manure during carbonization in order to achieve this objective is unknown. In [...] Read more.
Carbonization of cage layer chicken manure (CLCM) can improve its bio-recalcitrance which might improve nitrogen (N) bioavailability in soil. However, temperature(s) to exhibit appropriate variations in the chemical makeup of the manure during carbonization in order to achieve this objective is unknown. In this study, we investigated the alterations in chemical compositions, surface functionalities, and N speciation initiated by different carbonization temperatures (350, 500, and 650 °C) and the effects of these alterations on N bioavailability in soil. The objective was to identify suitable temperature condition(s) for the conversion of CLCM into a carbonized product of appropriate bio-recalcitrance that is capable of improving N bioavailability in soil more than the un-carbonized CLCM. The results showed an increased bio-recalcitrance of the manure with increasing carbonization temperatures due to drastic changes in the chemical makeup and accumulation of heterocyclic aromatic N structures. Subsequently, these alterations in the chemical makeup and state of the organic N species in the manure affected N bioavailability in soil. Notably, N bioavailability of CLCM and benefits on plants were improved when soil was supplied with CLCM that was altered at 350 °C. With these observations, we concluded that alterations in chemical and surface structural compositions and N speciation at 350 °C are optimum for instituting the required bio-recalcitrance to CLCM in order to improve N bioavailability in soil for plants. Full article
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Article
Effect of Salt-Tolerant Bacterial Inoculations on Rice Seedlings Differing in Salt-Tolerance under Saline Soil Conditions
Agronomy 2020, 10(7), 1030; https://0-doi-org.brum.beds.ac.uk/10.3390/agronomy10071030 - 16 Jul 2020
Cited by 15 | Viewed by 1441
Abstract
Salt-tolerant plant growth-promoting rhizobacteria (PGPR) could be an alternative to alleviate salinity problems in rice plants grown in the coastal areas. This study was conducted to isolate and characterize salt-tolerant PGPR and observe their effects on the physiological and biochemical properties of rice [...] Read more.
Salt-tolerant plant growth-promoting rhizobacteria (PGPR) could be an alternative to alleviate salinity problems in rice plants grown in the coastal areas. This study was conducted to isolate and characterize salt-tolerant PGPR and observe their effects on the physiological and biochemical properties of rice plants grown under non-saline and saline glasshouse conditions. Three strains were selected based on their salt-tolerance and plant growth-promoting properties under in vitro saline conditions. These strains were identified as Bacillus tequilensis (UPMRB9), Bacillus aryabhattai (UPMRE6), and Providencia stuartii (UPMRG1) using a 16S rRNA technique. The selected strains were inoculated to three different rice varieties, namely BRRI dhan67 (salt-tolerant), Putra-1 (moderate salt-tolerant), and MR297 (salt-susceptible) under glasshouse conditions. Results showed that the MR297 rice variety inoculated with UPMRB9 produced the highest total chlorophyll content, with an increment of 28%, and lowest electrolyte leakage of 92%. The Putra-1 rice variety also showed a 156% total dry matter increase with the inoculation of this bacterial strain. The highest increase of relative water content and reduction of Na/K ratio were found upon inoculation of UPMRE6 and UPMRB9, respectively. The biggest significant effects of these bacterial inoculations were on relative water content, electrolyte leakage, and the Na/K ratio of the BRRI dhan67 rice variety under saline conditions, suggesting a synergistic effect on the mechanisms of plant salt-tolerance. This study has shown that the application of locally-isolated salt-tolerant PGPR strains could be an effective long-term and sustainable solution for rice cultivation in the coastal areas, which are affected by global climate change. Full article
(This article belongs to the Special Issue Effects of Biostimulants and Bioeffectors on Plant Growth)
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Article
Effect of Water Stress on the Physiological Characteristics of Five Basil (Ocimum basilicum L.) Cultivars
Agronomy 2020, 10(7), 1029; https://0-doi-org.brum.beds.ac.uk/10.3390/agronomy10071029 - 16 Jul 2020
Cited by 3 | Viewed by 1151
Abstract
Water stress in one of the most important abiotic stresses that affects the productivity of many crop species worldwide. In addition, the climate change creates new challenges for crop adaptation especially as water resources become limited and the increase in water stress becomes [...] Read more.
Water stress in one of the most important abiotic stresses that affects the productivity of many crop species worldwide. In addition, the climate change creates new challenges for crop adaptation especially as water resources become limited and the increase in water stress becomes more pronounced even in areas where there is adequate water supply. The objective of the present study was to determine the effect of water stress on physiological characteristics of five cultivars of basil under field conditions. Water stress affected leaf temperature, dry herb yield, leaf water potential, assimilation rate and gas exchange parameters, quantum yield, instantaneous water use efficiency (WUE), and essential oil content. From the physiological characteristics water potential and assimilation rate can be used for the selection of basil cultivars tolerant to water stress. In addition, essential oil content was lower under water stress indicating that essential oil content is correlated with water availability. From the present study it is obvious that there are tolerant basil cultivars to water stress and can be found using physiological traits such as water potential and assimilation rate and can be used to save and use water more sustainable and also conserve the water resources. Full article
(This article belongs to the Special Issue Irrigation Strategies in Sustainable Agriculture)
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Article
Analysis of Proteomic Profile of Contrasting Phosphorus Responsive Rice Cultivars Grown under Phosphorus Deficiency
Agronomy 2020, 10(7), 1028; https://0-doi-org.brum.beds.ac.uk/10.3390/agronomy10071028 - 16 Jul 2020
Cited by 3 | Viewed by 893
Abstract
Phosphorus (P) deficiency is one of the major limiting factors for crop productivity. The yield of rice (Oryza sativa L.) is severely limited by phosphorus deficiency. An attempt has been made in this study to identify P deficiency responsive differentially expressed proteins [...] Read more.
Phosphorus (P) deficiency is one of the major limiting factors for crop productivity. The yield of rice (Oryza sativa L.) is severely limited by phosphorus deficiency. An attempt has been made in this study to identify P deficiency responsive differentially expressed proteins of rice through analysis of leaf proteome of contrasting P-responsive rice cultivars under P deficiency conditions because genetic variability has been found in the rice cultivars for adaptive response to P deficiency and a controlled regulatory system is involved in the P deficiency adaptation response. Phosphorus-efficient (cv. Panvel) and P-inefficient (cv. Nagina 22) rice cultivars were hydroponically grown in the nutrient medium under control environmental conditions at low-P level (2.0 µM) and optimum-P level (320 µM) treatments. Expression patterns of the proteins of the leaves of both the cultivars were analyzed in 30-day-old plants. The identification of these proteins through mass spectrometry and MASCOT software (Matrix Science Inc., Boston, USA) revealed that these differentially expressed proteins were homologous to known functional proteins involved in energy metabolism, biosynthesis, photosynthesis, signaling, protein synthesis, protein folding, phospholipid metabolism, oxidative stress, transcription factors, and phosphorus metabolism. It has been observed that rice cultivars responded differently to low-P treatment through modification in protein expressions pattern to maintain the growth of the plants. Therefore, the expression patterns of proteins were different in both of the cultivars under low-P treatment. Higher potential of protein stability, stress tolerance, osmo-protection, and regulation of phosphorus uptake was observed in cv. Panvel than cv. Nagina 22. This study could help to unravel the complex regulatory process that is involved in adaptation to P deficiency in rice. Full article
(This article belongs to the Special Issue Analysis of Crop Genetic and Germplasm Diversity)
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Article
Real-Time Detection of Strawberry Powdery Mildew Disease Using a Mobile Machine Vision System
Agronomy 2020, 10(7), 1027; https://0-doi-org.brum.beds.ac.uk/10.3390/agronomy10071027 - 16 Jul 2020
Cited by 4 | Viewed by 1723
Abstract
Strawberry cropping system relies heavily on proper disease management to maintain high crop yield. Powdery mildew, caused by Sphaerotheca macularis (Wall. Ex Fries) is one of the major leaf diseases in strawberry which can cause significant yield losses up to 70%. Field scouts [...] Read more.
Strawberry cropping system relies heavily on proper disease management to maintain high crop yield. Powdery mildew, caused by Sphaerotheca macularis (Wall. Ex Fries) is one of the major leaf diseases in strawberry which can cause significant yield losses up to 70%. Field scouts manually walk beside strawberry fields and visually observe the plants to monitor for powdery mildew disease infection each week during summer months which is a laborious and time-consuming endeavor. The objective of this research was to increase the efficiency of field scouting by automatically detecting powdery mildew disease in strawberry fields by using a real-time machine vision system. A global positioning system, two cameras, a custom image processing program, and a ruggedized laptop computer were utilized for development of the disease detection system. The custom image processing program was developed using color co-occurrence matrix-based texture analysis along with artificial neural network technique to process and classify continuously acquired image data simultaneously. Three commercial strawberry field sites in central Nova Scotia were used to evaluate the performance of the developed system. A total of 36 strawberry rows (~1.06 ha) were tested within three fields and powdery mildew detected points were measured manually followed by automatic detection system. The manually detected points were compared with automatically detected points to ensure the accuracy of the developed system. Results of regression and scatter plots revealed that the system was able to detect disease having mean absolute error values of 4.00, 3.42, and 2.83 per row and root mean square error values of 4.12, 3.71, and 3.00 per row in field site-I, field site-II, and field site-III, respectively. The slight deviation in performance was likely caused by high wind speeds (>8 km h−1), leaf overlapping, leaf angle, and presence of spider mite disease during field testing. Full article
(This article belongs to the Section Precision and Digital Agriculture)
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