Agronomy

12 pages, 1394 KiB

Open AccessEditor’s ChoiceCommunication

Suitability of Black Soldier Fly Frass as Soil Amendment and Implication for Organic Waste Hygienization

by Thomas Klammsteiner, Veysel Turan, Marina Fernández-Delgado Juárez, Simon Oberegger and Heribert Insam

Agronomy 2020, 10(10), 1578; https://doi.org/10.3390/agronomy10101578 - 15 Oct 2020

Cited by 124 | Viewed by 15661

Abstract

Because of its nutritious properties, the black soldier fly has emerged as one of the most popular species in advancing circular economy through the re-valorization of anthropogenic organic wastes to insect biomass. Black soldier fly frass accumulates as a major by-product in artificial [...] Read more.

Because of its nutritious properties, the black soldier fly has emerged as one of the most popular species in advancing circular economy through the re-valorization of anthropogenic organic wastes to insect biomass. Black soldier fly frass accumulates as a major by-product in artificial rearing set-ups and harbors great potential to complement or replace commercial fertilizers. We applied frass from larvae raised on different diets in nitrogen-equivalent amounts as soil amendment, comparing it to NH₄NO₃ fertilizer as a control. While the soil properties did not reveal any difference between mineral fertilizer and frass, principal component analysis showed significant differences that are mainly attributed to nitrate and dissolved nitrogen contents. We did not find significant differences in the growth of perennial ryegrass between the treatments, indicating that frass serves as a rapidly acting fertilizer comparable to NH₄NO₃. While the abundance of coliform bacteria increased during frass maturation, after application to the soil, they were outcompeted by gram-negatives. We thus conclude that frass may serve as a valuable fertilizer and does not impair the hygienic properties of soils. Full article

(This article belongs to the Special Issue Smart Fertilizers and Innovative Organic Amendments for Sustainable Agricultural Systems)

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20 pages, 1209 KiB

Open AccessEditor’s ChoiceArticle

Zinc-Induced Effects on Productivity, Zinc Use Efficiency, and Grain Biofortification of Bread Wheat under Different Tillage Permutations

by Usman Zulfiqar, Saddam Hussain, Muhammad Ishfaq, Amar Matloob, Nauman Ali, Muhammad Ahmad, Mohammed Nasser Alyemeni and Parvaiz Ahmad

Agronomy 2020, 10(10), 1566; https://doi.org/10.3390/agronomy10101566 - 14 Oct 2020

Cited by 48 | Viewed by 5024

Abstract

Zinc (Zn) deficiency is a global concern for human health and causes a decrease in crop production and nutritional characteristics. A two-year field study was planned to evaluate comparative effects of various Zn application approaches in bread wheat under plough tillage (PT) and [...] Read more.

Zinc (Zn) deficiency is a global concern for human health and causes a decrease in crop production and nutritional characteristics. A two-year field study was planned to evaluate comparative effects of various Zn application approaches in bread wheat under plough tillage (PT) and zero tillage (ZT) system. Cultivation of wheat under ZT improved the soil organic carbon (17%), total soil porosity (11%), soil microbial biomass nitrogen (5%), and carbon (5%) in comparison to PT system averaged across the two years. Various efficiency indices were significantly influenced by Zn application methods during both years of experimentation. However, grain Zn contents were maximum with foliar-applied Zn in PT (31%) and soil-applied Zn under the ZT system (29.85%). Moreover, Zn use also enhanced the bioavailable Zn as lower phytate contents and phytate to Zn molar ratio were recorded. The highest bioavailable Zn was calculated for foliar (30%) and soil application (28%). Under both tillage systems, the maximum net benefits were obtained through Zn seed priming; nevertheless, ZT resulted in higher net benefits than PT due to low associated costs. In conclusion, Zn nutrition through different methods enhanced the productivity, profitability, and grain biofortification of wheat under PT and ZT systems. Full article

(This article belongs to the Special Issue Cereal Biofortification: Strategies, Challenges and Benefits)

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14 pages, 596 KiB

Open AccessEditor’s ChoiceArticle

Development of Pretreatment Strategies for the Fractionation of Hazelnut Shells in the Scope of Biorefinery

by Laura López, Sandra Rivas, Andrés Moure, Carlos Vila and Juan Carlos Parajó

Agronomy 2020, 10(10), 1568; https://doi.org/10.3390/agronomy10101568 - 14 Oct 2020

Cited by 12 | Viewed by 2432

Abstract

Hazelnut shells are an important waste from the hazelnut processing industry that could be valorized in a multi-product biorefinery. Individual or combined pretreatments may be integrated in processes enabling the integral fractionation of biomass. In this study, fractionation methods based on alkaline, alkaline-organosolv, [...] Read more.

Hazelnut shells are an important waste from the hazelnut processing industry that could be valorized in a multi-product biorefinery. Individual or combined pretreatments may be integrated in processes enabling the integral fractionation of biomass. In this study, fractionation methods based on alkaline, alkaline-organosolv, organosolv, or acid-catalyzed organosolv treatments were applied to raw or autohydrolyzed hazelnut shells. A comparative analysis of results confirmed that the highest lignin removal was achieved with the acid-catalyzed organosolv delignification, which also allowed limited cellulose losses. When this treatment was applied to raw hazelnut shells, 65.3% of the lignin was removed, valuable hemicellulose-derived products were obtained, and the cellulose content of the processed solids increased up to 54%. Autohydrolysis of hazelnut shells resulted in the partial solubilization of hemicelluloses (mainly in the form of soluble oligosaccharides). Consecutive stages of autohydrolysis and acid-catalyzed organosolv delignification resulted in 47.9% lignin removal, yielding solids of increased cellulose content (55.4%) and very low content of residual hemicelluloses. The suitability of selected delignified and autohydrolyzed-delignified hazelnut shells as substrates for enzymatic hydrolysis was assessed in additional experiments. The most susceptible substrates (from acid-catalyzed organosolv treatments) reached 74.2% cellulose conversion into glucose, with a concentration of 28.52 g glucose/L. Full article

(This article belongs to the Special Issue Pretreatment and Bioconversion of Crop Residues)

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16 pages, 3628 KiB

Open AccessEditor’s ChoiceArticle

Phosphorus Uptake and Growth of Wild-Type Barley and Its Root-Hairless Mutant Cultured in Buffered-and Non-Buffered-P Solutions

by Yucong Xie, Bala Rathinasabapathi, Bruce Schaffer, Rao Mylavarapu and Guodong Liu

Agronomy 2020, 10(10), 1556; https://doi.org/10.3390/agronomy10101556 - 13 Oct 2020

Cited by 3 | Viewed by 2674

Abstract

Root hairs play an important role in phosphorus (P) nutrition of plants. To better understand the relationship between root hairs and P acquisition efficiency (PAE) in barley, experiments were conducted with the wild-type barley (cv. ’Pallas’) and its root-hairless mutant (brb). [...] Read more.

Root hairs play an important role in phosphorus (P) nutrition of plants. To better understand the relationship between root hairs and P acquisition efficiency (PAE) in barley, experiments were conducted with the wild-type barley (cv. ’Pallas’) and its root-hairless mutant (brb). A hydroponic split-root system was used to supply P as Ca₃(PO₄)₂ (tri-calcium phosphate, TCP) to one-half and other nutrients to the other half of the root system. Using TCP as a sole P source can simulate a soil solution with buffered low P concentration in hydroponics to induce prolific root hair growth. Root morphology, plant growth, and P uptake efficiency were measured with 50 mg L⁻¹ TCP supplied to the roots in the split-root system and 0, 35, or 1000 μM NaH₂PO₄ in a non-split-root hydroponic system. The wild-type plants developed root hairs, but they did not contribute to the significant genotypic differences in the P uptake rate when a soluble P source was supplied in the non-split root system, indicating that root hair formation does not contribute to P uptake in a non-split root solution. On the other hand, when grown in a split-root system with one-half of the roots supplied with TCP, the wild-type showed 1.25-fold greater P uptake than the root hairless mutant. This study provides evidence that root hairs play an essential role in plant P uptake when P bioavailability is limited in the root zone. Full article

(This article belongs to the Section Soil and Plant Nutrition)

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13 pages, 1280 KiB

Open AccessEditor’s ChoiceArticle

Osmo-Priming with Seaweed Extracts Enhances Yield of Salt-Stressed Tomato Plants

by Emilio Di Stasio, Valerio Cirillo, Giampaolo Raimondi, Maria Giordano, Marco Esposito and Albino Maggio

Agronomy 2020, 10(10), 1559; https://doi.org/10.3390/agronomy10101559 - 13 Oct 2020

Cited by 36 | Viewed by 4650

Abstract

Salinization of agricultural land is an expanding phenomenon, which requires a multi-level strategy to counteract its deleterious effects on crop yield and quality. Plant biostimulants are increasingly used in agriculture with multiple purposes, including protection against abiotic stresses such as drought and salinity. [...] Read more.

Salinization of agricultural land is an expanding phenomenon, which requires a multi-level strategy to counteract its deleterious effects on crop yield and quality. Plant biostimulants are increasingly used in agriculture with multiple purposes, including protection against abiotic stresses such as drought and salinity. The complex nature of plant biostimulants, however, makes it difficult to establish a cause–effect relationship between the composition of the commercial product and its expected effects. Here, we demonstrate that field applications of two algal derivatives (Rygex, R and Super Fifty, SU) cause a 26% reduction in shoot biomass and a remodulation of the root-to-shoot ratio under moderately saline irrigation (6.3 dS m⁻¹). Moreover, plants treated with the two algal derivatives showed lower leaf water potential and improved water use efficiency under control conditions, suggesting an osmo-priming effect by these two products. These pre-adaptation responses increased tomato yield by 49% (R) and 70% (SU) regardless of the salinity level, with a remarkable reallocation of the biomass toward the fruits. Overall, our results suggest that the application of these two biostimulants can be useful in the open field to protect tomato plants from osmotic stress due to seasonal salinization, a phenomenon that typically occurs in arid and semi-arid environments. Full article

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14 pages, 1291 KiB

Open AccessEditor’s ChoiceArticle

Introgression of the Afila Gene into Climbing Garden Pea (Pisum sativum L.)

by Oscar Eduardo Checa, Marino Rodriguez, Xingbo Wu and Matthew Wohlgemuth Blair

Agronomy 2020, 10(10), 1537; https://doi.org/10.3390/agronomy10101537 - 10 Oct 2020

Cited by 9 | Viewed by 5180

Abstract

The pea (Pisum sativum L.) is one of the most important crops in temperate agriculture around the world. In the tropics, highland production is also common with multiple harvests of nearly mature seeds from climbing plant types on trellises. While the leafless [...] Read more.

The pea (Pisum sativum L.) is one of the most important crops in temperate agriculture around the world. In the tropics, highland production is also common with multiple harvests of nearly mature seeds from climbing plant types on trellises. While the leafless variant caused by the afila gene is widely used in developing row-cropped field peas in Europe, its use for trellised garden peas has not been reported. In this study we describe a pea breeding program for a high-elevation tropical environment in the Department of Nariño in Colombia, where over 16,000 hectares of the crop are produced. The most widespread climbing varieties in the region are ‘Andina’ and ‘Sindamanoy’, both of which have high-biomass architecture with abundant foliage. They are prone to many diseases, but preferred by farmers given their long production season. This plant type is expensive to trellis, with wooden posts and plastic strings used for vine staking constituting 52% of production costs. The afila trait could reduce these costs by creating interlocking plants as they do in field peas. Therefore, our goal for this research was to develop a rapid breeding method to introduce the recessive afila gene, which replaces leaves with tendrils, into the two commercial varieties used as recurrent parents (RPs) with three donor parents (DPs)—‘Dove’, ‘ILS3575′ and ‘ILS3568′—and to measure the effect on plant height (PH) and yield potential. Our hypothesis was that the afila gene would not cause linkage drag while obtaining a leafless climbing pea variety. Backcrossing was conducted without selfing for two generations and plants were selected to recover recurrent parent characteristics. Chi-square tests showed a ratio of 15 normal leaved to one afila leaved in the BC₂F₂ plants, and 31:1 in the BC₃F₂ generation. Selecting in the last of these generations permitted a discovery of tall climbing plants that were similar to those preferred commercially, but with the stable leafless afila. The method saved two seasons compared to the traditional method of progeny testing before each backcross cycle; the peas reached the BC₂F₂ generation in five seasons and the BC₃F₂ in seven seasons. This is advantageous with trellised peas that normally require half a year to reach maturity. Leafless garden peas containing the afila gene were of the same height as recurrent parents and, by the third backcross, were equally productive, without the high biomass found in the traditional donor varieties. The value of the afila gene and the direct backcrossing scheme is discussed in terms of garden pea improvement and crop breeding. Full article

(This article belongs to the Section Crop Breeding and Genetics)

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15 pages, 3317 KiB

Open AccessEditor’s ChoiceReview

A Review for Southern Highbush Blueberry Alternative Production Systems

by Yang Fang, Gerardo H. Nunez, Mariana Neves da Silva, Douglas A. Phillips and Patricio R. Munoz

Agronomy 2020, 10(10), 1531; https://doi.org/10.3390/agronomy10101531 - 9 Oct 2020

Cited by 43 | Viewed by 12621

Abstract

Southern highbush blueberry cultivation has expanded into non-traditional growing areas worldwide due to elite cultivars and improved horticultural practices. This article presents a comprehensive review of current production systems—alternatives to traditional open field production—such as production in protected environments, high-density plantings, evergreen production, [...] Read more.

Southern highbush blueberry cultivation has expanded into non-traditional growing areas worldwide due to elite cultivars and improved horticultural practices. This article presents a comprehensive review of current production systems—alternatives to traditional open field production—such as production in protected environments, high-density plantings, evergreen production, and container-based production. We discuss the advantages and disadvantages of each system and compare their differences to open field production. In addition, we provide potential solutions for some of the disadvantages. We also highlight some of the gaps existing between academic studies and production in industry, providing a guide for future academic research. All these alternative systems have shown the potential to produce high yields with high-quality berries. Alternative systems, compared to field production, require higher establishment investments and thus create an entry barrier for new producers. Nevertheless, with their advantages, alternative productions have the potential to be profitable. Full article

(This article belongs to the Section Horticultural and Floricultural Crops)

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21 pages, 2799 KiB

Open AccessEditor’s ChoiceArticle

Estimating Organ Contribution to Grain Filling and Potential for Source Upregulation in Wheat Cultivars with a Contrasting Source–Sink Balance

by Carolina Rivera-Amado, Gemma Molero, Eliseo Trujillo-Negrellos, Matthew Reynolds and John Foulkes

Agronomy 2020, 10(10), 1527; https://doi.org/10.3390/agronomy10101527 - 8 Oct 2020

Cited by 25 | Viewed by 4793

Abstract

Grain filling may be limited by the joint source and sink capacity in modern wheat cultivars, indicating a need to research the co-limitation of yield by both photosynthesis and the number and potential size of grains. The extent to which the post-anthesis source [...] Read more.

Grain filling may be limited by the joint source and sink capacity in modern wheat cultivars, indicating a need to research the co-limitation of yield by both photosynthesis and the number and potential size of grains. The extent to which the post-anthesis source may be limiting final grain size can be estimated by partial degraining of spikes, while defoliation and shading treatments can be useful to estimate if any excess photosynthetic capacity exists. In the current study, degraining was applied to a set of 26 elite spring wheat cultivars from the International Maize and Wheat Improvement Center (CIMMYT)’s core germplasm (CIMCOG) panel, while lamina defoliation and shading through stem-and-leaf-sheath covering treatments were applied to a subset of the same cultivars. Responses to source treatments in grain weight, pre-anthesis reserve contribution to grain weight, dry-matter translocation efficiency, and flag-leaf and spike photosynthetic rate were measured and compared to an unmanipulated control treatment. Grain weight responses to degraining among cultivars ranged from no response to increases of 28%, suggesting a range of responses from sink limitation, to probable source and sink co-limitation of grain growth. Grain weight’s response to degraining increased linearly with the years of cultivar release from 1966 to 2009, indicating that the current highest yield potential CIMMYT spring wheats have a co-limitation of grain growth by source and sink. This may have been due to an increase in grain sink strength with years of cultivar release with no commensurate increase in post-anthesis source capacity. The relatively low decreases in grain weight with defoliation compared to decreases in light interception by defoliation indicated that sink limitation was still likely predominating in the cultivars with co-limitation. The stem-and-leaf-sheath covering treatment decreased grain weight by nearly 10%, indicating that stem-and-leafsheath photosynthesis plays a key role in grain growth during grain filling. In addition, pre-anthesis reserve contribution to grain weight was increased by ca. 50% in response to lamina defoliation. Our results showed that increasing the post-anthesis source capacity, through increases in stem-and-leaf-sheath photosynthetic rate during grain filling and pre-anthesis reserve contribution to grain weight, is an important objective in enhancing yield potential in wheat through maintaining a source–sink balance. Full article

(This article belongs to the Special Issue Photosynthetic Performance and Water-Use-Efficiency in Grasses)

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15 pages, 1033 KiB

Open AccessEditor’s ChoiceArticle

Screening of Popcorn Genotypes for Drought Tolerance Using Canonical Correlations

by Samuel Henrique Kamphorst, Gabriel Moreno Bernardo Gonçalves, Antônio Teixeira do Amaral Júnior, Valter Jário de Lima, Jhean Torres Leite, Kátia Fabiane Medeiros Schmitt, Divino Rosa dos Santos Junior, Juliana Saltires Santos, Fábio Tomaz de Oliveira, Caio Cézar Guedes Corrêa, Weverton Pereira Rodrigues and Eliemar Campostrini

Agronomy 2020, 10(10), 1519; https://doi.org/10.3390/agronomy10101519 - 6 Oct 2020

Cited by 12 | Viewed by 3433

Abstract

Getting around the damage caused by drought is a worldwide challenge, particularly in Brazil, given that economy is based on agricultural activities, including popcorn growing. The purpose of this study was to evaluate popcorn inbred lines under water stressed (WS) and well-watered (WW) [...] Read more.

Getting around the damage caused by drought is a worldwide challenge, particularly in Brazil, given that economy is based on agricultural activities, including popcorn growing. The purpose of this study was to evaluate popcorn inbred lines under water stressed (WS) and well-watered (WW) conditions regarding agronomic attributes, root morphology, and leaf “greenness” index (SPAD index), besides investigating the viability of indirect selection by canonical correlations (CC) of grain yield (GY) and popping expansion (PE). Seven agronomic, six morphological root traits were evaluated and SPAD index at five different dates during grain filling. The WS (−29% less water than WW) affected significantly the GY (−55%), PE (−28%), increased the brace and crown root density, and more vertically oriented the brace and crown angles. Higher SPAD index is associated with a higher yield, and these measures were the only ones with no significant genotype × water condition interaction, which may render concomitant selection for WS and WW easier. For associating the corrections of the different traits, CC proved to have better potential than simple correlations. Thus, the evaluation of SPAD index at 29 days after the anthesis showed the best CC, and based on the previous results of SPAD index, may be used regardless of the water condition. Full article

(This article belongs to the Special Issue Optimizing Plant Water Use Efficiency for a Sustainable Environment)

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16 pages, 20952 KiB

Open AccessEditor’s ChoiceArticle

Chlorophyll-a Fluorescence Analysis Reveals Differential Response of Photosynthetic Machinery in Melatonin-Treated Oat Plants Exposed to Osmotic Stress

by Onoud Alyammahi and Mayank Anand Gururani

Agronomy 2020, 10(10), 1520; https://doi.org/10.3390/agronomy10101520 - 6 Oct 2020

Cited by 29 | Viewed by 3491

Abstract

In this study, the effects of melatonin-induced enhancement on the principal photosynthetic parameters and antioxidant machinery were investigated in Avena sativa (oat) plants exposed to polyethylene glycol (PEG)-induced osmotic stress. The parameters of growth, chlorophyll content, stomatal conductance, proline accumulation, lipid peroxidation, and [...] Read more.

In this study, the effects of melatonin-induced enhancement on the principal photosynthetic parameters and antioxidant machinery were investigated in Avena sativa (oat) plants exposed to polyethylene glycol (PEG)-induced osmotic stress. The parameters of growth, chlorophyll content, stomatal conductance, proline accumulation, lipid peroxidation, and electrolyte leakage showed noteworthy improvements between the groups. Melatonin treatment caused upregulation of the genes that encode the three major antioxidant enzymes: ascorbate peroxidase (APX), superoxide dismutase (SOD) and catalase (CAT). Chlorophyll-a fluorescence kinetic analyses revealed that melatonin treatment improved performance indices (PI_ABS and PI_total), quantum yields, and efficiencies of photosystem II (PSII) in oat plants subjected to PEG-induced osmotic stress. Furthermore, upregulation of five genes (PsbA, PsbB, PsbC, PsbD, and PsbO) that encode the core proteins of PSII implied melatonin exerted a positive influence on photosynthesis under conditions of osmotic stress. Full article

(This article belongs to the Section Crop Breeding and Genetics)

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24 pages, 2331 KiB

Open AccessEditor’s ChoiceArticle

Alleviation of Salt Stress by Plant Growth-Promoting Bacteria in Hydroponic Leaf Lettuce

by Alessandra Moncada, Filippo Vetrano and Alessandro Miceli

Agronomy 2020, 10(10), 1523; https://doi.org/10.3390/agronomy10101523 - 6 Oct 2020

Cited by 49 | Viewed by 6841

Abstract

Mediterranean areas with intensive agriculture are characterized by high salinity of groundwater. The use of this water in hydroponic cultivations can lead to nutrient solutions with an electrical conductivity that overcomes the tolerance threshold of many vegetable species. Plant growth-promoting rhizobacteria (PGPR) were [...] Read more.

Mediterranean areas with intensive agriculture are characterized by high salinity of groundwater. The use of this water in hydroponic cultivations can lead to nutrient solutions with an electrical conductivity that overcomes the tolerance threshold of many vegetable species. Plant growth-promoting rhizobacteria (PGPR) were shown to minimize salt stress on several vegetable crops but the studies on the application of PGPR on leafy vegetables grown in hydroponics are rather limited and have not been used under salt stress conditions. This study aimed to evaluate the use of plant growth-promoting bacteria to increase the salt tolerance of leaf lettuce grown in autumn and spring in a floating system, by adding a bacterial biostimulant (1.5 g L⁻¹ of TNC Bactorr^S13 a commercial biostimulant containing 1.3 × 10⁸ CFU g⁻¹ of Bacillus spp.) to mineral nutrient solutions (MNS) with two salinity levels (0 and 20 mM NaCl). Leaf lettuce plants showed a significant reduction of growth and yield under salt stress, determined by the reduction of biomass, leaf number, and leaf area. Plants showed to be more tolerant to salinity in autumn than in spring. The inhibition of lettuce plant growth due to salt stress was significantly alleviated by the addition of the bacterial biostimulant to the MNS, which had a positive effect on plant growth and fresh and dry biomass accumulation of the unstressed lettuce in both cultivation seasons, and maintained this positive effect in brackish MNS, with similar or even significantly higher values of morphologic, physiologic, and yield parameters than those recorded in control unstressed plants. Full article

(This article belongs to the Special Issue Effects of Abiotic Stresses and Their Control on Quality of Horticultural Products)

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9 pages, 2023 KiB

Open AccessEditor’s ChoiceArticle

Confirmation and Characterization of the First Case of Acetolactate Synthase (ALS)-Inhibitor—Resistant Wild Buckwheat (Polygonum convolvulus L.) in the United States

by Balaji Aravindhan Pandian, Abigail Friesen, Martin Laforest, Dallas E. Peterson, P. V. Vara Prasad and Mithila Jugulam

Agronomy 2020, 10(10), 1496; https://doi.org/10.3390/agronomy10101496 - 1 Oct 2020

Cited by 3 | Viewed by 3454

Abstract

Wild buckwheat (Polygonum convolvulus L.) is a problem weed and ALS-inhibitors (e.g., chlorsulfuron) are commonly used for its management. Recently, a population of wild buckwheat (KSW-R) uncontrolled with ALS-inhibitors was found in a wheat field in Kansas, USA. The objectives of this [...] Read more.

Wild buckwheat (Polygonum convolvulus L.) is a problem weed and ALS-inhibitors (e.g., chlorsulfuron) are commonly used for its management. Recently, a population of wild buckwheat (KSW-R) uncontrolled with ALS-inhibitors was found in a wheat field in Kansas, USA. The objectives of this research were to determine the level and mechanism of resistance to chlorsulfuron and cross resistance to other ALS-inhibitors in the KSW-R population. In response to chlorsulfuron rates ranging from 0 to 16x (x = 18 g ai/ha), the KSW-R wild buckwheat was found >100-fold more resistant compared to a known ALS-inhibitor susceptible (KSW-S) wild buckwheat. Also, >90% of KSW-R plants survived field recommended rates of sulfonylurea but not imidazolinone family of ALS-inhibitors. A portion of the ALS gene covering all previously reported mutations known to bestow resistance to ALS-inhibitors was sequenced from both KSW-R and KSW-S plants. The Pro-197-Ser substitution that confers resistance to the sulfonylurea herbicides was found in KSW-R plants. Our results support the evolution of high level of chlorsulfuron resistance as a result of a mutation in the ALS-gene in KSW-R buckwheat. This is the first case of resistance to any herbicides in wild buckwheat in the US. Full article

(This article belongs to the Special Issue Herbicide Resistance in Weed Management)

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24 pages, 1300 KiB

Open AccessEditor’s ChoiceArticle

Identification of Opportunities for Applying the Circular Economy to Intensive Agriculture in Almería (South-East Spain)

by José A. Aznar-Sánchez, Juan F. Velasco-Muñoz, Daniel García-Arca and Belén López-Felices

Agronomy 2020, 10(10), 1499; https://doi.org/10.3390/agronomy10101499 - 1 Oct 2020

Cited by 48 | Viewed by 7746

Abstract

The use of intensive high-yield agricultural systems has proved to be a feasible alternative to traditional systems as they able to meet the objective of guaranteeing long-term sustainability in the supply of food. In order to implement these systems, it is necessary to [...] Read more.

The use of intensive high-yield agricultural systems has proved to be a feasible alternative to traditional systems as they able to meet the objective of guaranteeing long-term sustainability in the supply of food. In order to implement these systems, it is necessary to replace the traditional model of “extract-use-consume-dispose” with a model based on the principles of the Circular Economy (CE), optimizing the use of resources and minimizing the generation of waste. Almería has become a paradigm of this type of high-yield agricultural system, with the largest concentration of greenhouses in the world. This study analyses the opportunities that the CE can offer the intensive agriculture sector in Almería in order to obtain long-term sustainability. The results show a wide variety of alternatives, both on an agricultural exploitation level and in the case of the product packaging and wholesale centers. The priority areas of action are waste management, the prevention of product waste and the improvement in the efficiency of the use of water and energy. The principal limitations for adopting circular practices are the large investment required, the limited transfer of knowledge between the different users and the lack of sufficient support from the government and the sector. Full article

(This article belongs to the Special Issue Greenhouse Technology)

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4 pages, 192 KiB

Open AccessEditor’s ChoiceEditorial

Climate Change: A New Challenge for the Winemaking Sector

by Helder Fraga

Agronomy 2020, 10(10), 1465; https://doi.org/10.3390/agronomy10101465 - 25 Sep 2020

Cited by 21 | Viewed by 4536

Abstract

Viticulture and winemaking have a strong socio-economic importance worldwide. Weather and climate represent key forcing factors for grapevine development, yields, and quality. Hence, climate change is expected to pose a strong impact on this crop, threatening the sustainability of the winemaking sector. Recent-past [...] Read more.

Viticulture and winemaking have a strong socio-economic importance worldwide. Weather and climate represent key forcing factors for grapevine development, yields, and quality. Hence, climate change is expected to pose a strong impact on this crop, threatening the sustainability of the winemaking sector. Recent-past trends show noticeable warming in the grapevine growing season, as well as changes in the precipitation patterns in many renowned winemaking regions worldwide. Furthermore, climate projections point to enhanced stress conditions for grapevine growth under future scenarios. The strong evidence for a significant warming and drying in the upcoming decades urges adaptation measures to be taken by the winemaking sector. The aim of this editorial is to provide an updated overview of the adaptation measures that can be used by sector stakeholders to mitigate the negative impacts of climate change. A recent review article, which highlights several adaptation strategies to ensure the future sustainability of this important sector, is hereby analyzed. Full article

(This article belongs to the Section Horticultural and Floricultural Crops)

29 pages, 2791 KiB

Open AccessEditor’s ChoiceArticle

Effect of Some Citrus Essential Oils on Post-Harvest Shelf Life and Physicochemical Quality of Strawberries during Cold Storage

by Said A. Shehata, Emad A. Abdeldaym, Marwa R. Ali, Reda M. Mohamed, Rwotonen I. Bob and Karima F. Abdelgawad

Agronomy 2020, 10(10), 1466; https://doi.org/10.3390/agronomy10101466 - 25 Sep 2020

Cited by 93 | Viewed by 9485

Abstract

Utilization of essential oils alone or incorporation with edible films is an appropriate technique to conserve the quality attributes and reduce post-harvest deterioration in fresh vegetables and fruits. Strawberries, being perishable fruits have a short shelf life, and using essential oils is considered [...] Read more.

Utilization of essential oils alone or incorporation with edible films is an appropriate technique to conserve the quality attributes and reduce post-harvest deterioration in fresh vegetables and fruits. Strawberries, being perishable fruits have a short shelf life, and using essential oils is considered one of the most suitable methods to prolong their shelf life during storage. The current study assessed the impact of different essential oils, including lemon oil (L), orange oil (O) and mandarin oil (M) on the physicochemical and microbial load of strawberries (Fragaria × ananassa cv. Festival) stored at 2 ± 1 °C and 95% relative humidity (RH) for 18 days. The differences in the physicochemical and microbial properties of strawberries were assessed by determining the following parameter changes: weight loss, decay percentage, firmness, soluble solids content, titratable acidity, color, anthocyanins, vitamin C, total phenol, total antioxidant, catalase activity, polyphenol oxidase activity, sensory evaluation, microbial content, total coliforms, molds, and yeasts. The results of this study indicated that the fruits treated with all essential oils treatments (L, O and M) had higher total antioxidant content and physicochemical properties than untreated fruits, due to protection against the microbial growth of molds, and yeasts. At the end of the storage period, the treated fruits showed a greater acceptance and sensory attributes than the untreated fruits. Furthermore, the correlation study showed a significant and negative relationship between the total antioxidant of treated fruits and following quality attributes including, weight loss, decay percentage, respiration rate soluble solids content, polyphenol oxidase activity, molds, and yeasts. It is noteworthy that all the essential oil treatments extended the shelf-life of strawberries and delayed their deterioration up to 18 days. Full article

(This article belongs to the Special Issue Postharvest Storage Techniques and Quality Evaluation of Fruits and Vegetables)

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10 pages, 246 KiB

Open AccessEditor’s ChoiceEditorial

Toward a Sustainable Agriculture Through Plant Biostimulants: From Experimental Data to Practical Applications

by Youssef Rouphael and Giuseppe Colla

Agronomy 2020, 10(10), 1461; https://doi.org/10.3390/agronomy10101461 - 24 Sep 2020

Cited by 131 | Viewed by 11851

Abstract

Modern agriculture increasingly demands an alternative to synthetic chemicals (fertilizers and pesticides) in order to respond to the changes in international law and regulations, but also consumers’ needs for food without potentially toxic residues. Microbial (arbuscular mycorrhizal and plant growth promoting rhizobacteria: Azotobacter [...] Read more.

Modern agriculture increasingly demands an alternative to synthetic chemicals (fertilizers and pesticides) in order to respond to the changes in international law and regulations, but also consumers’ needs for food without potentially toxic residues. Microbial (arbuscular mycorrhizal and plant growth promoting rhizobacteria: Azotobacter, Azospirillum and Rizhobium spp.) and non-microbial (humic substances, silicon, animal- and vegetal-based protein hydrolysate and macro- and micro-algal extracts) biostimulants represent a sustainable and effective alternative or complement for their synthetic counterparts, bringing benefits to the environment, biodiversity, human health and economy. The Special Issue “Toward a sustainable agriculture through plant biostimulants: from experimental data to practical applications” compiles 34 original research articles, 4 review papers and 1 brief report covering the implications of microbial and non-microbial biostimulants for improving seedling growth and crop performance, nutrient use efficiency and quality of the produce as well as enhancing the tolerance/resistance to a wide range of abiotic stresses in particular salinity, drought, nutrient deficiency and high temperature. The present compilation of high standard scientific papers on principles and practices of plant biostimulants will foster knowledge transfer among researchers, fertilizer and biostimulant industries, stakeholders, extension specialists and farmers, and it will enable a better understanding of the physiological and molecular mechanisms and application procedure of biostimulants in different cropping systems. Full article

(This article belongs to the Special Issue Toward a Sustainable Agriculture Through Plant Biostimulants: From Experimental Data to Practical Applications)

45 pages, 1271 KiB

Open AccessEditor’s ChoiceReview

Sprouts and Microgreens: Trends, Opportunities, and Horizons for Novel Research

by Angelica Galieni, Beatrice Falcinelli, Fabio Stagnari, Alessandro Datti and Paolo Benincasa

Agronomy 2020, 10(9), 1424; https://doi.org/10.3390/agronomy10091424 - 19 Sep 2020

Cited by 94 | Viewed by 21389

Abstract

Sprouts and microgreens have attracted tremendous interest across multiple disciplines in recent years. Here, we critically review the most recent advances to underscore research prospects and niches, and related challenges, not yet addressed or fully pursued. In particular, we report a number of [...] Read more.

Sprouts and microgreens have attracted tremendous interest across multiple disciplines in recent years. Here, we critically review the most recent advances to underscore research prospects and niches, and related challenges, not yet addressed or fully pursued. In particular, we report a number of themes that merit special attention as a result of their relevance to plant science, nutrition, health, and zootechnics: (1) species not yet or inadequately investigated, such as wild plants, and fruit tree strains; (2) abiotic and biotic factors, and biostimulants, for elicitation strategies and metabolic engineering; (3) sanitization and processing technologies to obtain high-quality products; (4) digestive fate and impact of bioactive elements, antinutrients, and allergens on human nutrition; (5) experimental challenges to researching health benefits; (6) the opportunity to generate natural product libraries for drug discovery; and (7) sprouts in animal feeding to improve both animal health and the nutritional value of animal products for the human diet. The convergence of different themes involving interdisciplinary competencies advocate fascinating research pursuits, for example, the elicitation of metabolic variants to generate natural product collections for identification and selection of bioactive chemicals with a role as nutraceuticals, key constituents of functional foods, or interactive partners of specific drugs. Full article

(This article belongs to the Special Issue Sprouts, Microgreens and Edible Flowers as Novel Functional Foods)

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17 pages, 2760 KiB

Open AccessEditor’s ChoiceArticle

Impact of Water Stress on Microbial Community and Activity in Sandy and Loamy Soils

by Sylwia Siebielec, Grzegorz Siebielec, Agnieszka Klimkowicz-Pawlas, Anna Gałązka, Jarosław Grządziel and Tomasz Stuczyński

Agronomy 2020, 10(9), 1429; https://doi.org/10.3390/agronomy10091429 - 19 Sep 2020

Cited by 71 | Viewed by 5654

Abstract

Prolonged drought and extreme precipitation can have a significant impact on the activity and structure of soil microbial communities. The aim of the study was to assess the impact of drought length on the dynamics of mineral nitrogen, enzyme activities and bacterial diversity [...] Read more.

Prolonged drought and extreme precipitation can have a significant impact on the activity and structure of soil microbial communities. The aim of the study was to assess the impact of drought length on the dynamics of mineral nitrogen, enzyme activities and bacterial diversity in two soils of different texture (sand and silt loam, according to USDA classification). An additional objective was to evaluate the effect of compost on the alleviation of soil microbial responses to stress conditions, i.e. alternating periods of drought and excessive soil moisture. The pot study was carried out in a greenhouse under controlled conditions. Compost was added at an amount equal to 3% of soil to the sandy soil, which was characterised by a significantly lower water retention capacity. Specific levels of water stress conditions were created through application of drought and soil watering periods. For each soil, four levels of moisture regimes were set-up, including optimal conditions kept at 60% of field water holding capacity, and three levels of water stress: The low level—2 week period without watering; the medium level—1 month drought period followed by watering to full but short-term soil saturation with water; and the high level—2 month drought period followed by full and long-term saturation with the same total amount of water, as in other variants. The soil water regime strongly modified the activities of dehydrogenases and acid and alkaline phosphatase, as well as the bacterial diversity. Loamy soil exhibited greater resistance to the inhibition of soil enzymatic activity. After irrigation, following both a 1 month and 2 month drought, the enzyme activities and nitrification largely recovered in soil with a loamy texture. Drought induced substantial shifts in the functional diversity of bacterial communities. The use of such C substrates, as carboxylic and acetic acids, was strongly inhibited by water deficit. Water deficit induced changes in the relative abundances of particular phyla, for example, an increase in Acidobacteria or a decrease in Verrucomicrobia. The study clearly proves the greater susceptibility of microbial communities to drought in sandy soils and the important role of exogenous organic matter in protecting microbial activity in drought periods. Full article

(This article belongs to the Special Issue Climate Change, Agriculture, and Food Security)

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19 pages, 1375 KiB

Open AccessEditor’s ChoiceArticle

Nitrogen Fertilizer Equivalence of Black Soldier Fly Frass Fertilizer and Synchrony of Nitrogen Mineralization for Maize Production

by Dennis Beesigamukama, Benson Mochoge, Nicholas Korir, Martha W. Musyoka, Komi K. M. Fiaboe, Dorothy Nakimbugwe, Fathiya M. Khamis, Sevgan Subramanian, Thomas Dubois, Sunday Ekesi and Chrysantus M. Tanga

Agronomy 2020, 10(9), 1395; https://doi.org/10.3390/agronomy10091395 - 15 Sep 2020

Cited by 46 | Viewed by 8823

Abstract

The use of black soldier fly frass fertilizer (BSFFF) is being promoted globally. However, information on nitrogen (N) fertilizer equivalence (NFE) value and synchrony of N mineralization for crop production remains largely unknown. Comparative studies between BSFFF and commercial organic fertilizer (SAFI) were [...] Read more.

The use of black soldier fly frass fertilizer (BSFFF) is being promoted globally. However, information on nitrogen (N) fertilizer equivalence (NFE) value and synchrony of N mineralization for crop production remains largely unknown. Comparative studies between BSFFF and commercial organic fertilizer (SAFI) were undertaken under field conditions to determine synchrony of N release for maize uptake. The BSFFF, SAFI, and urea fertilizers were applied at the rates of 0, 30, 60, and 100 kg N ha⁻¹. The yield data from urea treated plots were used to determine the NFE of both organic inputs. Results showed that maize from BSFFF treated plots had higher N uptake than that from SAFI treated plots. High N immobilization was observed throughout the active growth stages of maize grown in soil amended with BSFFF, whereas soil treated with SAFI achieved net N release at the silking stage. Up to three times higher negative N fluxes were observed in SAFI amended soils as compared with BSFFF treated plots at the tasseling stage. The BSFFF applied at 30 and 60 kg N ha⁻¹ achieved significantly higher NFE than all SAFI treatments. Our findings revealed that BSFFF is a promising and sustainable alternative to SAFI or urea for enhanced maize production. Full article

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16 pages, 483 KiB

Open AccessEditor’s ChoiceReview

From Old-Generation to Next-Generation Nematicides

by Yuji Oka

Agronomy 2020, 10(9), 1387; https://doi.org/10.3390/agronomy10091387 - 14 Sep 2020

Cited by 82 | Viewed by 10621

Abstract

The phaseout of methyl bromide and the ban on, or withdrawal of, other toxic soil fumigants and non-fumigant nematicides belonging to the organophosphate and carbamate groups are leading to changes in nematode-control strategies. Sustainable nematode-control methods are available and preferred, but not always [...] Read more.

The phaseout of methyl bromide and the ban on, or withdrawal of, other toxic soil fumigants and non-fumigant nematicides belonging to the organophosphate and carbamate groups are leading to changes in nematode-control strategies. Sustainable nematode-control methods are available and preferred, but not always effective enough, especially for cash crops in intensive agriculture. A few non-fumigant nematicides, which have a relatively high control efficacy with a low toxicity to non-target organisms, have been released to the market or are in the process of being registered for use. Fluensulfone, fluopyram, and fluazaindolizine are the three main and most promising next-generation nematicides. In this paper, several aspects of these non-fumigant nematicides are reviewed, along with a brief history and problems of old-generation nematicides. Full article

(This article belongs to the Special Issue Effects of Nematodes on Crops)

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14 pages, 1417 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Cover Crop for a Sustainable Viticulture: Effects on Soil Properties and Table Grape Production

by Concetta Eliana Gattullo, Giuseppe Natale Mezzapesa, Anna Maria Stellacci, Giuseppe Ferrara, Giuliana Occhiogrosso, Giuseppe Petrelli, Mirko Castellini and Matteo Spagnuolo

Agronomy 2020, 10(9), 1334; https://doi.org/10.3390/agronomy10091334 - 5 Sep 2020

Cited by 42 | Viewed by 5986

Abstract

Cover crops are increasingly adopted in viticulture to enhance soil quality and balance the vegetative and reproductive growth of vines. Nevertheless, this sustainable practice has been only recently used for table grape viticulture, with results often contrasting. The aim of this study was [...] Read more.

Cover crops are increasingly adopted in viticulture to enhance soil quality and balance the vegetative and reproductive growth of vines. Nevertheless, this sustainable practice has been only recently used for table grape viticulture, with results often contrasting. The aim of this study was to assess the effect of a fescue (Festucaarundinacea Schreb.) cover crop on soil quality, yield, and grape qualitative parameters in a table grape vineyard (cv “Italia”) located in southern Italy, comparing results with the conventional tillage. Soil organic carbon (C), total nitrogen (N), microbial biomass C (MBC), β-glucosidase (BGLU) and alkaline phosphomonoesterase (APME) activities were assessed during three growing seasons (2012–2014) and three phenological stages. The trend of soil chemical and microbiological properties was jointly influenced by the soil management system, growing season and phenological stage. Compared to conventional tillage, cover crops increased, on average, soil organic C, total N, MBC, BGLU and APME by 136%, 93%, 112%, 100% and 62%, respectively. Slight or no effects of cover crops were observed on grape quality and yield, except for 2012 (the driest season), when a yield reduction occurred. This study reveals that cover crops strongly enhance soil quality in the short-term, with potential advantages for grape production in the long-term. Full article

(This article belongs to the Special Issue Agroecology and Organic Agriculture for Sustainable Crop Production)

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28 pages, 2535 KiB

Open AccessEditor’s ChoiceReview

Implications of Abscisic Acid in the Drought Stress Tolerance of Plants

by Shahid Ali, Kashif Hayat, Amjad Iqbal and Linan Xie

Agronomy 2020, 10(9), 1323; https://doi.org/10.3390/agronomy10091323 - 4 Sep 2020

Cited by 105 | Viewed by 13373

Abstract

Drought is a severe environmental constraint, which significantly affects plant growth, productivity, and quality. Plants have developed specific mechanisms that perceive the stress signals and respond to external environmental changes via different mitigation strategies. Abscisic acid (ABA), being one of the phytohormones, serves [...] Read more.

Drought is a severe environmental constraint, which significantly affects plant growth, productivity, and quality. Plants have developed specific mechanisms that perceive the stress signals and respond to external environmental changes via different mitigation strategies. Abscisic acid (ABA), being one of the phytohormones, serves as an important signaling mediator for plants’ adaptive response to a variety of environmental stresses. ABA triggers many physiological processes, including bud dormancy, seed germination, stomatal closure, and transcriptional and post-transcriptional regulation of stress-responsive gene expression. The site of its biosynthesis and action must be clarified to understand the signaling network of ABA. Various studies have documented multiple sites for ABA biosynthesis, their transporter proteins in the plasma membrane, and several components of ABA-dependent signaling pathways, suggesting that the ABA response to external stresses is a complex networking mechanism. Knowing about stress signals and responses will increase our ability to enhance crop stress tolerance through the use of various advanced techniques. This review will elaborate on the ABA biosynthesis, transportation, and signaling pathways at the molecular level in response to drought stress, which will add a new insight for future studies. Full article

(This article belongs to the Special Issue Application of Plant Growth Promoting Microorganism and Plant Growth Regulators in Agricultural Production and Research)

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18 pages, 1431 KiB

Open AccessEditor’s ChoiceArticle

Isolation and Characterization of Plant Growth Promoting Endophytic Bacteria from Desert Plants and Their Application as Bioinoculants for Sustainable Agriculture

by Muneera D. F. ALKahtani, Amr Fouda, Kotb A. Attia, Fahad Al-Otaibi, Ahmed M. Eid, Emad El-Din Ewais, Mohamed Hijri, Marc St-Arnaud, Saad El-Din Hassan, Naeem Khan, Yaser M. Hafez and Khaled A. A. Abdelaal

Agronomy 2020, 10(9), 1325; https://doi.org/10.3390/agronomy10091325 - 4 Sep 2020

Cited by 145 | Viewed by 14972

Abstract

Desert plants are able to survive under harsh environmental stresses inherent to arid and semiarid regions due to their association with bacterial endophytes. However, the identity, functions, and the factors that influence the association of bacterial endophytes with desert plants are poorly known. [...] Read more.

Desert plants are able to survive under harsh environmental stresses inherent to arid and semiarid regions due to their association with bacterial endophytes. However, the identity, functions, and the factors that influence the association of bacterial endophytes with desert plants are poorly known. These bacterial endophytes can be used as an untapped resource to favor plant growth and development in agro-ecosystems of arid regions. The present study is therefore focused on the isolation and identification of bacterial endophytes from two native medicinal plants (Fagonia mollis Delile and Achillea fragrantissima (Forssk) Sch. Bip.) growing spontaneously in the arid region of the South Sinai (Egypt), and characterization of their plant growth promoting (PGP) traits. Thirteen putative bacterial endophytes were isolated from the leaves of both plant species and characterized for their plant growth promoting abilities using molecular and biochemical approaches, as well as greenhouse trials. Selected endophytic bacterial strains were applied to maize plants (Zea mays L. var. Single cross Pioneer 30K08) to further evaluate their PGP abilities under greenhouse conditions. Isolated bacterial strains have variable plant growth promoting activities. Among these activities, isolated bacterial endophytes have the efficacy of phosphate solubilizing with clear zones ranging from 7.6 ± 0.3 to 9.6 ± 0.3 mm. Additionally, the obtained bacterial endophytes increased the productivity of indole acetic acid (IAA) in broth media from 10 to 60 µg·mL⁻¹ with increasing tryptophan concentration from 1 to 5 mg·mL⁻¹. Bacillus and Brevibacillus strains were frequently isolated from the leaves of both plant species, and had significant positive effects on plant growth and shoot phosphorus (P) and nitrogen (N) contents. Results suggest that these endophytes are good candidates as plant growth promoting inoculants to help reduce chemical input in conventional agricultural practices and increase nutrient uptake and stress resilience in plant species. Full article

(This article belongs to the Special Issue Application of Plant Growth Promoting Microorganism and Plant Growth Regulators in Agricultural Production and Research)

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22 pages, 3499 KiB

Open AccessEditor’s ChoiceArticle

On the Use of Multivariate Analysis and Land Evaluation for Potential Agricultural Development of the Northwestern Coast of Egypt

by Mohamed El Sayed Said, Abdelraouf. M. Ali, Maurizio Borin, Sameh Kotb Abd-Elmabod, Ali A. Aldosari, Mohamed M. N. Khalil and Mohamed K. Abdel-Fattah

Agronomy 2020, 10(9), 1318; https://doi.org/10.3390/agronomy10091318 - 3 Sep 2020

Cited by 37 | Viewed by 4941

Abstract

The development of the agricultural sector is considered the backbone of sustainable development in Egypt. While the developing countries of the world face many challenges regarding food security due to rapid population growth and limited agricultural resources, this study aimed to assess the [...] Read more.

The development of the agricultural sector is considered the backbone of sustainable development in Egypt. While the developing countries of the world face many challenges regarding food security due to rapid population growth and limited agricultural resources, this study aimed to assess the soils of Sidi Barrani and Salloum using multivariate analysis to determine the land capability and crop suitability for potential alternative crop uses, based on using principal component analysis (PCA), agglomerative hierarchical cluster analysis (AHC) and the Almagra model of MicroLEIS. In total, 24 soil profiles were dug, to represent the geomorphic units of the study area, and the soil physicochemical parameters were analyzed in laboratory. The land capability assessment was classified into five significant classes (C1 to C5) based on AHC and PCA analyses. The class C1 represents the highest capable class while C5 is assigned to lowest class. The results indicated that about 7% of the total area was classified as highly capable land (C1), which is area characterized by high concentrations of macronutrients (N, P, K) and low soil salinity value. However, about 52% of the total area was assigned to moderately high class (C2), and 29% was allocated in moderate class (C3), whilst the remaining area (12%) was classified as the low (C4) and not capable (C5) classes, due to soil limitations such as shallow soil depth, high salinity, and increased erosion susceptibility. Moreover, the results of the Almagra soil suitability model for ten crops were described into four suitability classes, while about 37% of the study area was allocated in the highly suitable class (S2) for wheat, olive, alfalfa, sugar beet and fig. Furthermore, 13% of the area was categorized as highly suitable soil (S2) for citrus and peach. On the other hand, about 50% of the total area was assigned to the marginal class (S4) for most of the selected crops. Hence, the use of multivariate analysis, mapping land capability and modeling the soil suitability for diverse crops help the decision makers with regard to potential agricultural development. Full article

(This article belongs to the Special Issue Sustainable Agricultural Practices—Impact on Soil Quality and Plant Health)

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17 pages, 2675 KiB

Open AccessEditor’s ChoiceArticle

Efficiency of Nitrogen Fertilization of Winter Wheat Depending on Sulfur Fertilization

by Monika Tabak, Andrzej Lepiarczyk, Barbara Filipek-Mazur and Aneta Lisowska

Agronomy 2020, 10(9), 1304; https://doi.org/10.3390/agronomy10091304 - 2 Sep 2020

Cited by 46 | Viewed by 5565

Abstract

Optimization of fertilization enables to obtain a yield of high quality and quantity, brings economic profits, and reduces environmental threats. The aim of the three-year field experiment was to determine the efficiency of fertilization with a new fertilizer available on the Polish market [...] Read more.

Optimization of fertilization enables to obtain a yield of high quality and quantity, brings economic profits, and reduces environmental threats. The aim of the three-year field experiment was to determine the efficiency of fertilization with a new fertilizer available on the Polish market and containing nitrogen (N) and sulfur (S) in proportions designed for cereals cultivation (30% N and 6% S as ammonium nitrate and ammonium sulfate). Other treatments included no fertilization; fertilization with ammonium nitrate (34% N); fertilization with standard nitrogen and sulfur fertilizer with N supplementation with ammonium nitrate. Nitrogen doses were 150, 200, and 250 kg N ha⁻¹. Sulfur was applied in doses of 30, 40, and 50 kg S ha⁻¹. A beneficial effect of using fertilizer containing N and S in proportions designed for cereals cultivation was observed. The highest mean optimal nitrogen dose and maximum winter wheat yield were recorded for the new fertilizer (217 kg N ha⁻¹ and 8251 kg ha⁻¹, respectively). Sulfur supplementation with the new fertilizer significantly increased apparent nitrogen recovery (mean values 48.9%, 44.6%, and 40.6% for doses 150, 200, and 250 kg N ha⁻¹, respectively), agronomic efficiency (11.1 and 8.6 kg kg⁻¹ N for doses 200 and 250 kg N ha⁻¹, respectively), and physiological efficiency (24.7 kg kg⁻¹ N for dose 200 kg N ha⁻¹). Full article

(This article belongs to the Special Issue Soil Healthy in Agro-ecosystems)

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18 pages, 5200 KiB

Open AccessEditor’s ChoiceArticle

Bacillus velezensis PEA1 Inhibits Fusarium oxysporum Growth and Induces Systemic Resistance to Cucumber Mosaic Virus

by Ahmed Abdelkhalek, Said I. Behiry and Abdulaziz A. Al-Askar

Agronomy 2020, 10(9), 1312; https://doi.org/10.3390/agronomy10091312 - 2 Sep 2020

Cited by 43 | Viewed by 5538

Abstract

Bacillus velezensis manifests robust biocontrol activity against fungal plant pathogens; however, its antiviral activity has rarely been investigated. Bacillus velezensis strain PEA1 was isolated, characterized, and evaluated for antifungal and antiviral activities against Fusarium oxysporum MT270445 and cucumber mosaic virus (CMV) MN594112. Our [...] Read more.

Bacillus velezensis manifests robust biocontrol activity against fungal plant pathogens; however, its antiviral activity has rarely been investigated. Bacillus velezensis strain PEA1 was isolated, characterized, and evaluated for antifungal and antiviral activities against Fusarium oxysporum MT270445 and cucumber mosaic virus (CMV) MN594112. Our findings proved that strain PEA1 had intense antagonist activity against F.oxysporum. Under greenhouse conditions, the antiviral activities (protective, curative, and inactivation) of PEA1-culture filtrate (CF) on Datura stramonium plants were assayed, using a half-leaf method. The inactivation treatment exhibited the highest inhibition rate (97.56%) and the most considerable reduction of CMV-CP accumulation levels (2.1-fold) in PEA1-CF-treated plants when compared with untreated plants (26.9-fold). Furthermore, PEA1-CF induced systemic resistance with significantly elevated transcriptional levels of PAL, CHS, HQT, PR-1, and POD genes in D. stramonium leaves after all treatments. Gas chromatography‒mass spectrometry analysis showed that pyrrolo[1,2-a]pyrazine-1,4-dione is the main compound in the PEA1-CF ethyl acetate extract, which may act as an elicitor molecule that induces plant systemic resistance and inhibits both fungal growth and viral replication. Consequently, B. velezensis can be considered as a potential source for the production of bioactive compounds for the management of plant diseases. To our knowledge, this is the first report of the antiviral activity of B. velezensis against plant viral infection. Full article

(This article belongs to the Section Pest and Disease Management)

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21 pages, 1278 KiB

Open AccessEditor’s ChoiceReview

Gene Pyramiding for Sustainable Crop Improvement against Biotic and Abiotic Stresses

by Richard Dormatey, Chao Sun, Kazim Ali, Jeffrey A. Coulter, Zhenzhen Bi and Jiangping Bai

Agronomy 2020, 10(9), 1255; https://doi.org/10.3390/agronomy10091255 - 26 Aug 2020

Cited by 67 | Viewed by 13735

Abstract

Sustainable agricultural production is endangered by several ecological factors, such as drought, extreme temperatures, excessive salts, parasitic ailments, and insect pest infestation. These challenging environmental factors may have adverse effects on future agriculture production in many countries. In modern agriculture, conventional crop-breeding techniques [...] Read more.

Sustainable agricultural production is endangered by several ecological factors, such as drought, extreme temperatures, excessive salts, parasitic ailments, and insect pest infestation. These challenging environmental factors may have adverse effects on future agriculture production in many countries. In modern agriculture, conventional crop-breeding techniques alone are inadequate for achieving the increasing population’s food demand on a sustainable basis. The advancement of molecular genetics and related technologies are promising tools for the selection of new crop species. Gene pyramiding through marker-assisted selection (MAS) and other techniques have accelerated the development of durable resistant/tolerant lines with high accuracy in the shortest period of time for agricultural sustainability. Gene stacking has not been fully utilized for biotic stress resistance development and quality improvement in most of the major cultivated crops. This review emphasizes on gene pyramiding techniques that are being successfully deployed in modern agriculture for improving crop tolerance to biotic and abiotic stresses for sustainable crop improvement. Full article

(This article belongs to the Section Crop Breeding and Genetics)

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15 pages, 670 KiB

Open AccessEditor’s ChoiceArticle

Stability of Fruit Quality Traits of Different Strawberry Varieties under Variable Environmental Conditions

by Lucía Cervantes, María Teresa Ariza, Luis Miranda, David Lozano, Juan Jesús Medina, Carmen Soria and Elsa Martínez-Ferri

Agronomy 2020, 10(9), 1242; https://doi.org/10.3390/agronomy10091242 - 23 Aug 2020

Cited by 40 | Viewed by 5281

Abstract

Strawberry fruit quality traits can be affected by genotype–environment interactions, determining the final consumer acceptance of fruits. Trait stability under varying environments is necessary to ensure the fruit quality of strawberries selected by breeding programs. Hence, inter- and intra-annual variation of organoleptic and [...] Read more.

Strawberry fruit quality traits can be affected by genotype–environment interactions, determining the final consumer acceptance of fruits. Trait stability under varying environments is necessary to ensure the fruit quality of strawberries selected by breeding programs. Hence, inter- and intra-annual variation of organoleptic and functional fruit quality parameters of five strawberry varieties throughout four consecutive cropping seasons was analyzed to assess their relative stability. In most varieties, organoleptic parameters showed higher inter-annual stability but greater variability throughout the season, while the reverse was true for the functional quality parameters. Relative humidity and mean and minimum temperatures partially accounted for fruit quality variation but other factors along with the genotype may also have an influence. Among the varieties, ‘Splendor’ displayed greater year-on-year stability in organoleptic parameters, and ‘Sabrina’ and Candonga^® showed higher inter- and intra-annual stability on functional fruit quality, respectively. Environmental variation did not affect fruit quality parameters similarly in all strawberry varieties. In ‘Sabrina’ and Candonga^® antioxidant capacity (TEAC) was greater and stable throughout the cropping season, underlining TEAC as a tool for varietal selection, and suggesting these two varieties as parents for breeding programs that seek healthy features and high-quality fruits that meet consumer demands. Full article

(This article belongs to the Special Issue Genotype× Environment Interactions in Crop Breeding)

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4 pages, 199 KiB

Open AccessEditor’s ChoiceEditorial

Microalgae: New Source of Plant Biostimulants

by Giuseppe Colla and Youssef Rouphael

Agronomy 2020, 10(9), 1240; https://doi.org/10.3390/agronomy10091240 - 22 Aug 2020

Cited by 72 | Viewed by 8276

Abstract

Biostimulant manufacturers have developed innovative products targeting specific agronomic needs, hence attracting the attention of the scientific community, extension specialists, and industry stakeholders including policymakers and crop producers. Microalgae acquire a broad economic value in the production of nutrient dense food and supplementary [...] Read more.

Biostimulant manufacturers have developed innovative products targeting specific agronomic needs, hence attracting the attention of the scientific community, extension specialists, and industry stakeholders including policymakers and crop producers. Microalgae acquire a broad economic value in the production of nutrient dense food and supplementary diet produce, in addition to their high importance in biofuel production and wastewater bioremediation. Recently, microalgae, which comprise blue-green algae (eukaryotic and prokaryotic cyanobacteria), have gained prominence as biostimulant products due to their potential to increase germination, seedling growth, plant growth, productivity, nutrient use efficiency, as well as tolerance to a wide range of abiotic stresses (salinity, drought, sub- and supra-optimal temperatures, and heavy metals contamination). Although it is well established that green and blue-green algae produce several bioactive and signaling molecules active on horticultural and agronomic crops, their targeted applications in plant science are still in their infancy stage. The aim of this editorial paper is to provide an updated overview of this far-reaching new category of plant biostimulants and the possible physiological and molecular mechanisms behind the biostimulatory action based on the recent scientific literature. Finally, this editorial paper identifies the main bottlenecks that hamper market introduction and farmers from reaping the full benefit of microalgae-based biostimulants; it also pinpoints the future relevant areas of microalgae research to enhance the biostimulant action of microalgal extracts in agriculture. Full article

(This article belongs to the Section Horticultural and Floricultural Crops)

21 pages, 2871 KiB

Open AccessEditor’s ChoiceReview

Use of Spent Mushroom Substrate in New Mushroom Crops to Promote the Transition towards A Circular Economy

by Diego Cunha Zied, Jose Ernesto Sánchez, Ralph Noble and Arturo Pardo-Giménez

Agronomy 2020, 10(9), 1239; https://doi.org/10.3390/agronomy10091239 - 21 Aug 2020

Cited by 59 | Viewed by 20387

Abstract

The use of spent mushroom substrate (SMS) in new cultivation cycles has already been reported due to its economic and environmental viability. When considering the application of the circular economy concept in the production of edible mushrooms, the re-use of the SMS within [...] Read more.

The use of spent mushroom substrate (SMS) in new cultivation cycles has already been reported due to its economic and environmental viability. When considering the application of the circular economy concept in the production of edible mushrooms, the re-use of the SMS within the same process is highly attractive, because it allows a better use of the biomass and the energy involved in the process and, therefore, tends to improve energy efficiency and resource conservation. However, this alternative generates important challenges, which derive from maintaining the quality standards of the mushrooms produced and, at the same time, not incurring excessive costs that are detrimental to the process itself. In our opinion, the main difficulty of the process in achieving success is regarding the biological and agronomic parameters that involve the production of the mushroom. It is useless to apply SMS in new cycles if the mushroom harvest is impaired and farms become non-viable. However, numerous examples are reported here where SMS was recycled into new substrates for either the same or different mushroom species without negatively affecting yield compared with using substrates prepared from 100% fresh raw materials. Thus, we suggest that each farm has its own specific technological study, since a small variation in the raw material of the compost, and mushroom cultivation practices and casing layer used, can influence the entire viability of the mushroom circular economy. Full article

(This article belongs to the Special Issue Production and Development of Mushrooms)

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15 pages, 782 KiB

Open AccessEditor’s ChoiceArticle

Application of Single Superphosphate with Humic Acid Improves the Growth, Yield and Phosphorus Uptake of Wheat (Triticum aestivum L.) in Calcareous Soil

by Muhammad Izhar Shafi, Muhammad Adnan, Shah Fahad, Fazli Wahid, Ahsan Khan, Zhen Yue, Subhan Danish, Muhammad Zafar-ul-Hye, Martin Brtnicky and Rahul Datta

Agronomy 2020, 10(9), 1224; https://doi.org/10.3390/agronomy10091224 - 19 Aug 2020

Cited by 122 | Viewed by 8732

Abstract

In calcareous soil, the significant portion of applied phosphorus (P) fertilizers is adsorbed on the calcite surface and becomes unavailable to plants. Addition of organic amendments with chemical fertilizers can be helpful in releasing the absorbed nutrients from these surfaces. To check out [...] Read more.

In calcareous soil, the significant portion of applied phosphorus (P) fertilizers is adsorbed on the calcite surface and becomes unavailable to plants. Addition of organic amendments with chemical fertilizers can be helpful in releasing the absorbed nutrients from these surfaces. To check out this problem, a field experiment was conducted for two years to determine the effect of P fertilizers and humic acid (HA) in enhancing P availability in soil and their ultimate effect on growth, yield and P uptake of wheat in calcareous soils. The experiment was comprised of five levels of P (0, 45, 67.5, 90 and 112.5 kg P₂O₅ ha⁻¹) as a single superphosphate (SSP) and 2 levels of locally produced humic acid (with and without HA) arranged in a two factorial randomized complete block design (RCBD) with three replications. Wheat plant height, spike length, number of grains per spike, 1000-grain weight, grain, straw and biological yield were significantly improved by the addition of HA with SSP. Very often, the performance of 67.5 kg P₂O₅ ha⁻¹ with HA were either similar or better than 90 or even 112.5 kg P₂O₅ ha⁻¹ applied without HA. Post-harvest soil organic matter, AB-DTPA extractable and water-soluble P, plant P concentration and its uptake were also significantly improved by the addition of HA with SSP compared to sole SSP application. It was evident that P efficiency could be increased with HA addition and it has the potential to improve crop yield and plants P uptake in calcareous soils. Full article

(This article belongs to the Special Issue Smart Fertilizers and Innovative Organic Amendments for Sustainable Agricultural Systems)

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13 pages, 2942 KiB

Open AccessEditor’s ChoiceArticle

The Effects of Alkaline Pretreatment on Agricultural Biomasses (Corn Cob and Sweet Sorghum Bagasse) and Their Hydrolysis by a Termite-Derived Enzyme Cocktail

by Mpho. S. Mafa, Samkelo Malgas, Abhishek Bhattacharya, Konanani Rashamuse and Brett I. Pletschke

Agronomy 2020, 10(8), 1211; https://doi.org/10.3390/agronomy10081211 - 18 Aug 2020

Cited by 34 | Viewed by 5820

Abstract

Sweet sorghum bagasse (SSB) and corncob (CC) have been identified as promising feedstocks for the production of second-generation biofuels and other value-added chemicals. In this study, lime (Ca(OH)₂) and NaOH pretreatment efficacy for decreasing recalcitrance from SSB and CC was investigated, [...] Read more.

Sweet sorghum bagasse (SSB) and corncob (CC) have been identified as promising feedstocks for the production of second-generation biofuels and other value-added chemicals. In this study, lime (Ca(OH)₂) and NaOH pretreatment efficacy for decreasing recalcitrance from SSB and CC was investigated, and subsequently, the pretreated biomass was subjected to the hydrolytic action of an in-house formulated holocellulolytic enzyme cocktail (HEC-H). Compositional analysis revealed that SSB contained 29.34% lignin, 17.75% cellulose and 16.28% hemicellulose, while CC consisted of 22.51% lignin, 23.58% cellulose and 33.34% hemicellulose. Alkaline pretreatment was more effective in pretreating CC biomass compared to the SSB biomass. Both Ca(OH)₂ and NaOH pretreatment removed lignin from the CC biomass, while only NaOH removed lignin from the SSB biomass. Biomass compositional analysis revealed that these agricultural feedstocks differed in their chemical composition because the CC biomass contained mainly hemicellulose (33–35%), while SSB biomass consisted mainly of cellulose (17–24%). The alkaline pretreated SSB and CC samples were subjected to the hydrolytic action of the holocellulolytic enzyme cocktail, formulated with termite derived multifunctional enzymes (referred to as MFE-5E, MFE-5H and MFE-45) and exoglucanase (Exg-D). The HEC-H hydrolysed NaOH pretreated SSB and CC more effectively than Ca(OH)₂ pretreated feedstocks, revealing that NaOH was a more effective pretreatment. In conclusion, the HEC-H cocktail efficiently hydrolysed alkaline pretreated agricultural feedstocks, particularly those which are hemicellulose- and amorphous cellulose-rich, such as CC, making it attractive for use in the bioconversion process in the biorefinery industry. Full article

(This article belongs to the Special Issue Pretreatment and Bioconversion of Crop Residues)

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19 pages, 3360 KiB

Open AccessEditor’s ChoiceArticle

Regulation of Agronomic Traits, Nutrient Uptake, Osmolytes and Antioxidants of Maize as Influenced by Exogenous Potassium Silicate under Deficit Irrigation and Semiarid Conditions

by Mohamed F. M. Ibrahim, Gomaa Abd El-Samad, Hatem Ashour, Ahmed M. El-Sawy, Mohamed Hikal, Amr Elkelish, Hany Abd El-Gawad, Ahmed Abou El-Yazied, Wael N. Hozzein and Reham Farag

Agronomy 2020, 10(8), 1212; https://doi.org/10.3390/agronomy10081212 - 18 Aug 2020

Cited by 49 | Viewed by 4570

Abstract

Understanding the link between the protective role of potassium silicate (K₂SiO₃) against water shortage and the eventual grain yield of maize plants is still limited under semiarid conditions. Therefore, in this study, we provide insights into the underlying metabolic [...] Read more.

Understanding the link between the protective role of potassium silicate (K₂SiO₃) against water shortage and the eventual grain yield of maize plants is still limited under semiarid conditions. Therefore, in this study, we provide insights into the underlying metabolic responses, mineral nutrients uptake and some nonenzymatic and enzymatic antioxidants that may differ in maize plants as influenced by the foliar application of K₂SiO₃ (0, 1 and 2 mM) under three drip irrigation regimes (100, 75 and 50% of water requirements). Our results indicated that, generally, plants were affected by both moderate and severe deficit irrigation levels. Deficit irrigation decreased shoot dry weight, root dry weight, leaf area index (LAI), relative water content (RWC), N, P, K, Ca, Fe, Zn, carotenoids, grain yield and its parameters, while root/shoot ratio, malondialdehyde (MDA), proline, soluble sugars, ascorbic acid, soluble phenols, peroxidase (POD), catalase (CAT), polyphenol oxidase (PPO), and ascorbate peroxidase (APX) were improved. The foliar applications of K₂SiO₃ relatively alleviated water stress-induced damage. In this respect, the treatment of 2 mM K₂SiO₃ was more effective than others and could be recommended to mitigate the effect of deficit irrigation on maize plants. Moreover, correlation analysis revealed a close link between yield and the most studied traits. Full article

(This article belongs to the Special Issue Optimizing Plant Water Use Efficiency for a Sustainable Environment)

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26 pages, 5418 KiB

Open AccessEditor’s ChoiceReview

Flavonoids in Agriculture: Chemistry and Roles in, Biotic and Abiotic Stress Responses, and Microbial Associations

by Ateeq Shah and Donald L. Smith

Agronomy 2020, 10(8), 1209; https://doi.org/10.3390/agronomy10081209 - 17 Aug 2020

Cited by 162 | Viewed by 14436

Abstract

The current world of climate change, global warming and a constantly changing environment have made life very stressful for living entities, which has driven the evolution of biochemical processes to cope with stressed environmental and ecological conditions. As climate change conditions continue to [...] Read more.

The current world of climate change, global warming and a constantly changing environment have made life very stressful for living entities, which has driven the evolution of biochemical processes to cope with stressed environmental and ecological conditions. As climate change conditions continue to develop, we anticipate more frequent occurrences of abiotic stresses such as drought, high temperature and salinity. Living plants, which are sessile beings, are more exposed to environmental extremes. However, plants are equipped with biosynthetic machinery operating to supply thousands of bio-compounds required for maintaining internal homeostasis. In addition to chemical coordination within a plant, these compounds have the potential to assist plants in tolerating, resisting and escaping biotic and abiotic stresses generated by the external environment. Among certain biosynthates, flavonoids are an important example of these stress mitigators. Flavonoids are secondary metabolites and biostimulants; they play a key role in plant growth by inducing resistance against certain biotic and abiotic stresses. In addition, the function of flavonoids as signal compounds to communicate with rhizosphere microbes is indispensable. In this review, the significance of flavonoids as biostimulants, stress mitigators, mediators of allelopathy and signaling compounds is discussed. The chemical nature and biosynthetic pathway of flavonoid production are also highlighted. Full article

(This article belongs to the Special Issue Application of Plant Growth Promoting Microorganism and Plant Growth Regulators in Agricultural Production and Research)

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24 pages, 9293 KiB

Open AccessEditor’s ChoiceArticle

Stomata and Xylem Vessels Traits Improved by Melatonin Application Contribute to Enhancing Salt Tolerance and Fatty Acid Composition of Brassica napus L. Plants

by Ibrahim A. A. Mohamed, Nesma Shalby, Ali M. A. El-Badri, Muhammad Hamzah Saleem, Mohammad Nauman Khan, Muhammad A. Nawaz, Meng Qin, Ramadan A. Agami, Jie Kuai, Bo Wang and Guangsheng Zhou

Agronomy 2020, 10(8), 1186; https://doi.org/10.3390/agronomy10081186 - 13 Aug 2020

Cited by 78 | Viewed by 5861

Abstract

Salinity stress is a limiting factor for the growth and yield quality of rapeseed. The potentiality of melatonin (MT; 0, 25, 50, and 100 µM) application as a seed priming agent in mediating K⁺/Na⁺ homeostasis and preventing the salinity stress [...] Read more.

Salinity stress is a limiting factor for the growth and yield quality of rapeseed. The potentiality of melatonin (MT; 0, 25, 50, and 100 µM) application as a seed priming agent in mediating K⁺/Na⁺ homeostasis and preventing the salinity stress mediated oxidative damage and photosynthetic inhibition was studied in two rapeseed cultivars. We found that 50 µM MT treatment imparted a very prominent impact on growth, metabolism of antioxidants, photosynthesis, osmolytes, secondary metabolites, yield, and fatty acids composition. Days required for appearance of first flower and 50% flowering were decreased by MT application. Exogenous MT treatment effectively decreased the oxidative damage by significantly declining the generation of superoxide and hydrogen peroxide under saline and non-saline conditions, as reflected in lowered lipid peroxidation, heightened membrane stability, and up-regulation of antioxidant enzymes (catalase, superoxide dismutase, and ascorbate peroxidase). Furthermore, MT application enhanced the chlorophyll content, photosynthetic rate, relative water content, K⁺/Na⁺ homeostasis, soluble sugars, and proline content. Moreover, MT application obviously improved the oil quality of rapeseed cultivars by reducing glucosinolates, saturated fatty acids (palmitic and arachidic acids), and enhancing unsaturated fatty acids (linolenic and oleic acids except erucic acid were reduced). Yield related-traits such as silique traits, seed yield per plant, 1000 seeds weight, seed oil content, and yield biomass traits were enhanced by MT application. The anatomical analysis of leaf and stem showed that stomatal and xylem vessels traits are associated with sodium chloride tolerance, yield, and seed fatty acid composition. These results suggest the supportive role of MT on the quality and quantity of rapeseed oil yield. Full article

(This article belongs to the Special Issue Biostimulants and Micronutrients: Innovative Tools to Increase Crop Quality and Abiotic Stress Tolerance in Plants)

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14 pages, 3811 KiB

Open AccessEditor’s ChoiceArticle

Water-Soluble Carbon Nanoparticles Improve Seed Germination and Post-Germination Growth of Lettuce under Salinity Stress

by Hanna Baz, Matthew Creech, Jianjun Chen, Haijun Gong, Kent Bradford and Heqiang Huo

Agronomy 2020, 10(8), 1192; https://doi.org/10.3390/agronomy10081192 - 13 Aug 2020

Cited by 75 | Viewed by 6330

Abstract

Seed germination is a critical developmental phase for seedling establishment and crop production. Increasing salinity stress associated with climatic change can pose a challenge for seed germination and stand establishment of many crops including lettuce. Here, we show that water soluble carbon nanoparticles [...] Read more.

Seed germination is a critical developmental phase for seedling establishment and crop production. Increasing salinity stress associated with climatic change can pose a challenge for seed germination and stand establishment of many crops including lettuce. Here, we show that water soluble carbon nanoparticles (CNPs) can significantly promote seed germination without affecting seedling growth. Twenty-seven varieties of lettuce (Lactuca sativa) were screened for sensitivity to germination in 150 and 200 mM NaCl, and six salt-sensitive varieties (Little Gem, Parris Island, Breen, Butter Crunch, Muir, and Jericho) were selected and primed with 0.3% soluble carbon nanoparticles. Pretreatment with CNPs significantly improved seed germination under 150 mM NaCl and high temperature. CNP treatment slightly inhibited the elongation of primary roots but promoted lateral root growth and accumulation of chlorophyll content of seedlings grown under salt stress. Despite different lettuce varieties exhibiting a distinct response to nanoparticle treatments, results from this study indicate that soluble nanoparticles can significantly improve lettuce seed germination under salinity stress, which provide fundamental evidence on the potential of nanoparticles in agricultural application to improve crop yield and quality under stressful conditions. Full article

(This article belongs to the Special Issue Seed Dormancy and Germination as Key for Crop Establishment and Food Production)

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20 pages, 4121 KiB

Open AccessEditor’s ChoiceArticle

Chlorophyll Fluorescence Parameters and Antioxidant Defense System Can Display Salt Tolerance of Salt Acclimated Sweet Pepper Plants Treated with Chitosan and Plant Growth Promoting Rhizobacteria

by Muneera D. F. ALKahtani, Kotb A. Attia, Yaser M. Hafez, Naeem Khan, Ahmed M. Eid, Mohamed A. M. Ali and Khaled A. A. Abdelaal

Agronomy 2020, 10(8), 1180; https://doi.org/10.3390/agronomy10081180 - 12 Aug 2020

Cited by 121 | Viewed by 7626

Abstract

Salinity stress deleteriously affects the growth and yield of many plants. Plant growth promoting rhizobacteria (PGPR) and chitosan both play an important role in combating salinity stress and improving plant growth under adverse environmental conditions. The present study aimed to evaluate the impacts [...] Read more.

Salinity stress deleteriously affects the growth and yield of many plants. Plant growth promoting rhizobacteria (PGPR) and chitosan both play an important role in combating salinity stress and improving plant growth under adverse environmental conditions. The present study aimed to evaluate the impacts of PGPR and chitosan on the growth of sweet pepper plant grown under different salinity regimes. For this purpose, two pot experiments were conducted in 2019 and 2020 to evaluate the role of PGPR (Bacillus thuringiensis MH161336 10^6–8 CFU/cm³) applied as seed treatment and foliar application of chitosan (30 mg dm⁻³) on sweet pepper plants (cv. Yolo Wonder) under two salinity concentrations (34 and 68 mM). Our findings revealed that, the chlorophyll fluorescence parameter (Fv/Fm ratio), chlorophyll a and b concentrations, relative water content (RWC), and fruit yield characters were negatively affected and significantly reduced under salinity conditions. The higher concentration was more harmful. Nevertheless, electrolyte leakage, lipid peroxidation, hydrogen peroxide (H₂O₂), and superoxide (O₂⁻) significantly increased in stressed plants. However, the application of B. thuringiensis and chitosan led to improved plant growth and resulted in a significant increase in RWC, chlorophyll content, chlorophyll fluorescence parameter (Fv/Fm ratio), and fruit yield. Conversely, lipid peroxidation, electrolyte leakage, O₂⁻, and H₂O₂ were significantly reduced in stressed plants. Also, B. thuringiensis and chitosan application regulated the proline accumulation and enzyme activity, as well as increased the number of fruit plant⁻¹, fruit fresh weight plant⁻¹, and total fruit yield of sweet pepper grown under saline conditions. Full article

(This article belongs to the Special Issue Application of Plant Growth Promoting Microorganism and Plant Growth Regulators in Agricultural Production and Research)

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27 pages, 789 KiB

Open AccessEditor’s ChoiceReview

Relevance of Plant Growth Promoting Microorganisms and Their Derived Compounds, in the Face of Climate Change

by Judith Naamala and Donald L. Smith

Agronomy 2020, 10(8), 1179; https://doi.org/10.3390/agronomy10081179 - 12 Aug 2020

Cited by 72 | Viewed by 12649

Abstract

Climate change has already affected food security in many parts of the world, and this situation will worsen if nothing is done to combat it. Unfortunately, agriculture is a meaningful driver of climate change, through greenhouse gas emissions from nitrogen-based fertilizer, methane from [...] Read more.

Climate change has already affected food security in many parts of the world, and this situation will worsen if nothing is done to combat it. Unfortunately, agriculture is a meaningful driver of climate change, through greenhouse gas emissions from nitrogen-based fertilizer, methane from animals and animal manure, as well as deforestation to obtain more land for agriculture. Therefore, the global agricultural sector should minimize greenhouse gas emissions in order to slow climate change. The objective of this review is to point out the various ways plant growth promoting microorganisms (PGPM) can be used to enhance crop production amidst climate change challenges, and effects of climate change on more conventional challenges, such as: weeds, pests, pathogens, salinity, drought, etc. Current knowledge regarding microbial inoculant technology is discussed. Pros and cons of single inoculants, microbial consortia and microbial compounds are discussed. A range of microbes and microbe derived compounds that have been reported to enhance plant growth amidst a range of biotic and abiotic stresses, and microbe-based products that are already on the market as agroinputs, are a focus. This review will provide the reader with a clearer understanding of current trends in microbial inoculants and how they can be used to enhance crop production amidst climate change challenges. Full article

(This article belongs to the Special Issue Application of Plant Growth Promoting Microorganism and Plant Growth Regulators in Agricultural Production and Research)

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14 pages, 1242 KiB

Open AccessEditor’s ChoicePerspective

Plant Defense Chemicals against Insect Pests

by Jessica P. Yactayo-Chang, Hoang V. Tang, Jorrel Mendoza, Shawn A. Christensen and Anna K. Block

Agronomy 2020, 10(8), 1156; https://doi.org/10.3390/agronomy10081156 - 8 Aug 2020

Cited by 65 | Viewed by 10798

Abstract

Insect pests cause significant global agricultural damage and lead to major financial and environmental costs. Crops contain intrinsic defenses to protect themselves from such pests, including a wide array of specialized secondary metabolite-based defense chemicals. These chemicals can be induced upon attack (phytoalexins) [...] Read more.

Insect pests cause significant global agricultural damage and lead to major financial and environmental costs. Crops contain intrinsic defenses to protect themselves from such pests, including a wide array of specialized secondary metabolite-based defense chemicals. These chemicals can be induced upon attack (phytoalexins) or are constitutive (phytoanticipins), and can have a direct impact on the pests or be used indirectly to attract their natural enemies. They form part of a global arms race between the crops and their insect pests, with the insects developing methods of suppression, avoidance, detoxification, or even capture of their hosts defensive chemicals. Harnessing and optimizing the chemical defense capabilities of crops has the potential to aid in the continuing struggle to enhance or improve agricultural pest management. Such strategies include breeding for the restoration of defense chemicals from ancestral varieties, or cross-species transfer of defense metabolite production. Full article

(This article belongs to the Special Issue The Chemical Defenses of Crops against Insect Pests)

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15 pages, 665 KiB

Open AccessEditor’s ChoiceArticle

Co-Inoculation of Rhizobacteria and Biochar Application Improves Growth and Nutrientsin Soybean and Enriches Soil Nutrients and Enzymes

by Dilfuza Jabborova, Stephan Wirth, Annapurna Kannepalli, Abdujalil Narimanov, Said Desouky, Kakhramon Davranov, R. Z. Sayyed, Hesham El Enshasy, Roslinda Abd Malek, Asad Syed and Ali H. Bahkali

Agronomy 2020, 10(8), 1142; https://doi.org/10.3390/agronomy10081142 - 6 Aug 2020

Cited by 89 | Viewed by 6747

Abstract

Gradual depletion in soil nutrients has affected soil fertility, soil nutrients, and the activities of soil enzymes. The applications of multifarious rhizobacteria can help to overcome these issues, however, the effect of co-inoculation of plant-growth promoting rhizobacteria (PGPR) and biochar on growth andnutrient [...] Read more.

Gradual depletion in soil nutrients has affected soil fertility, soil nutrients, and the activities of soil enzymes. The applications of multifarious rhizobacteria can help to overcome these issues, however, the effect of co-inoculation of plant-growth promoting rhizobacteria (PGPR) and biochar on growth andnutrient levelsin soybean and on the level of soil nutrients and enzymes needs in-depth study. The present study aimed to evaluate the effect of co-inoculation of multifarious Bradyrhizobium japonicum USDA 110 and Pseudomonas putida TSAU1 and different levels (1 and 3%) of biochar on growth parameters and nutrient levelsin soybean and on the level of soil nutrients and enzymes. Effect of co-inoculation of rhizobacteria and biochar (1 and 3%) on the plant growth parameters and soil biochemicals were studied in pot assay experiments under greenhouse conditions. Both produced good amounts of indole-acetic acid; (22 and 16 µg mL⁻¹), siderophores (79 and 87%SU), and phosphate solubilization (0.89 and 1.02 99 g mL⁻¹). Co-inoculation of B. japonicum with P. putida and 3% biochar significantly improved the growth and nutrient content ofsoybean and the level of nutrients and enzymes in the soil, thus making the soil more fertile to support crop yield. The results of this research provide the basis of sustainable and chemical-free farming for improved yields and nutrients in soybean and improvement in soil biochemical properties. Full article

(This article belongs to the Special Issue Application of Plant Growth Promoting Microorganism and Plant Growth Regulators in Agricultural Production and Research)

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21 pages, 1242 KiB

Open AccessEditor’s ChoiceArticle

Specific Adsorption of Heavy Metals in Soils: Individual and Competitive Experiments

by Claudia Campillo-Cora, Manuel Conde-Cid, Manuel Arias-Estévez, David Fernández-Calviño and Flora Alonso-Vega

Agronomy 2020, 10(8), 1113; https://doi.org/10.3390/agronomy10081113 - 1 Aug 2020

Cited by 40 | Viewed by 6473

Abstract

The partitioning between the soil solid phase and the soil solution determines the mobility of pollutants like heavy metals. If nonspecific sorption takes place, the reactions are easily reversible and heavy metals are released to soil solution increasing the probability of leaching through [...] Read more.

The partitioning between the soil solid phase and the soil solution determines the mobility of pollutants like heavy metals. If nonspecific sorption takes place, the reactions are easily reversible and heavy metals are released to soil solution increasing the probability of leaching through soil profile. Mobility and leaching are also favoured if other metals are in the system and competition for specific adsorption sites takes place. In this study, desorption equilibrium experiments were conducted after adsorption ones. The specific adsorption was evaluated through the amounts of the still adsorbed Cu, Pb, Cr, Ni and Zn after desorption experiments in ten different soils. In addition, competition adsorption and desorption binary experiments were conducted for evaluating the metal competition in three of the soils. Pb and Cu are the metals adsorbed and retained in higher amounts in all the studied soils. In slightly neutral soils, Cr is retained in lesser amounts while in acidic soils Zn is the metal less retained. Results showed that despite the high and variable amounts of organic matter in the soils, soil pH is the most important variable in neutral soils. In acidic soils, soil properties different than pH play important roles and specific sorption of Pb is related to the cationic exchange capacity of the soils while that of Zn to the clay content. Instead, the release of Cu during desorption experiments is probably due to the more soluble organic fraction of the soils. The individual retention of Cu, Zn, Ni and Pb is higher than when they are in competition, except if Cr is present. In this case, the amount of those four metals and that of Cr increased. Therefore, the presence of Cr together with cationic heavy metals favoured the adsorption of those metals in multi-metal polluted areas. Specific adsorption is also important during competition as soil affinities increase during competition experiments. Full article

(This article belongs to the Special Issue Fate, Transport and Effect of Trace Elements in Plants and Agroecosystems)

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33 pages, 6041 KiB

Open AccessEditor’s ChoiceReview

Implementing Sustainable Irrigation in Water-Scarce Regions under the Impact of Climate Change

by Georgios Nikolaou, Damianos Neocleous, Anastasis Christou, Evangelini Kitta and Nikolaos Katsoulas

Agronomy 2020, 10(8), 1120; https://doi.org/10.3390/agronomy10081120 - 1 Aug 2020

Cited by 129 | Viewed by 25956

Abstract

The sustainability of irrigated agriculture is threatening due to adverse climate change, given future projections that every one in four people on Earth might be suffering from extreme water scarcity by the year 2025. Pressurized irrigation systems and appropriate irrigation schedules can increase [...] Read more.

The sustainability of irrigated agriculture is threatening due to adverse climate change, given future projections that every one in four people on Earth might be suffering from extreme water scarcity by the year 2025. Pressurized irrigation systems and appropriate irrigation schedules can increase water productivity (i.e., product yield per unit volume of water consumed by the crop) and reduce the evaporative or system loss of water as opposed to traditional surface irrigation methods. However, in water-scarce countries, irrigation management frequently becomes a complex task. Deficit irrigation and the use of non-conventional water resources (e.g., wastewater, brackish groundwater) has been adopted in many cases as part of a climate change mitigation measures to tackle the water poverty issue. Protected cultivation systems such as greenhouses or screenhouses equipped with artificial intelligence systems present another sustainable option for improving water productivity and may help to alleviate water scarcity in these countries. This article presents a comprehensive review of the literature, which deals with sustainable irrigation for open-field and protected cultivation systems under the impact of climatic change in vulnerable areas, including the Mediterranean region. Full article

(This article belongs to the Special Issue Irrigation Strategies in Sustainable Agriculture)

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10 pages, 2378 KiB

Open AccessEditor’s ChoiceArticle

Prediction of Soybean Plant Density Using a Machine Learning Model and Vegetation Indices Extracted from RGB Images Taken with a UAV

by Predrag Ranđelović, Vuk Đorđević, Stanko Milić, Svetlana Balešević-Tubić, Kristina Petrović, Jegor Miladinović and Vojin Đukić

Agronomy 2020, 10(8), 1108; https://doi.org/10.3390/agronomy10081108 - 31 Jul 2020

Cited by 44 | Viewed by 6304

Abstract

Soybean plant density is an important factor of successful agricultural production. Due to the high number of plants per unit area, early plant overlapping and eventual plant loss, the estimation of soybean plant density in the later stages of development should enable the [...] Read more.

Soybean plant density is an important factor of successful agricultural production. Due to the high number of plants per unit area, early plant overlapping and eventual plant loss, the estimation of soybean plant density in the later stages of development should enable the determination of the final plant number and reflect the state of the harvest. In order to assess soybean plant density in a digital, nondestructive, and less intense way, analysis was performed on RGB images (containing three channels: RED, GREEN, and BLUE) taken with a UAV (Unmanned Aerial Vehicle) on 66 experimental plots in 2018, and 200 experimental plots in 2019. Mean values of the R, G, and B channels were extracted for each plot, then vegetation indices (VIs) were calculated and used as predictors for the machine learning model (MLM). The model was calibrated in 2018 and validated in 2019. For validation purposes, the predicted values for the 200 experimental plots were compared with the real number of plants per unit area (m²). Model validation resulted in the correlation coefficient—R = 0.87, mean absolute error (MAE) = 6.24, and root mean square error (RMSE) = 7.47. The results of the research indicate the possibility of using the MLM, based on simple values of VIs, for the prediction of plant density in agriculture without using human labor. Full article

(This article belongs to the Section Precision and Digital Agriculture)

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10 pages, 530 KiB

Open AccessEditor’s ChoiceArticle

Effect of Wheat Cover Crop and Split Nitrogen Application on Corn Yield and Nitrogen Use Efficiency

by Oladapo Adeyemi, Reza Keshavarz-Afshar, Emad Jahanzad, Martin Leonardo Battaglia, Yuan Luo and Amir Sadeghpour

Agronomy 2020, 10(8), 1081; https://doi.org/10.3390/agronomy10081081 - 27 Jul 2020

Cited by 54 | Viewed by 5419

Abstract

Corn (Zea mays L.) grain is a major commodity crop in Illinois and its production largely relies on timely application of nitrogen (N) fertilizers. Currently, growers in Illinois and other neighboring states in the U.S. Midwest use the maximum return to N [...] Read more.

Corn (Zea mays L.) grain is a major commodity crop in Illinois and its production largely relies on timely application of nitrogen (N) fertilizers. Currently, growers in Illinois and other neighboring states in the U.S. Midwest use the maximum return to N (MRTN) decision support system to predict corn N requirements. However, the current tool does not factor in implications of integrating cover crops into the rotation, which has recently gained attention among growers due to several ecosystem services associated with cover cropping. A two-year field trail was conducted at the Agronomy Research Center in Carbondale, IL in 2018 and 2019 to evaluate whether split N application affects nitrogen use efficiency (NUE) of corn with and without a wheat (Triticum aestivum L.) cover crop. A randomized complete block design with split plot arrangements and four replicates was used. Main plots were cover crop treatments (no cover crop (control) compared to a wheat cover crop) and subplots were N timing applications to the corn: (1) 168 kg N ha⁻¹ at planting; (2) 56 kg N ha⁻¹ at planting + 112 kg N ha⁻¹ at sidedress; (3) 112 kg N ha⁻¹ at planting + 56 kg N ha⁻¹ at sidedress; and (4) 168 kg N ha⁻¹ at sidedress along with a zero-N control as check plot. Corn yield was higher in 2018 than 2019 reflecting more timely precipitation in that year. In 2018, grain yield declined by 12.6% following the wheat cover crop compared to no cover crop control, indicating a yield penalty when corn was preceded with a wheat cover crop. In 2018, a year with timely and sufficient rainfall, there were no yield differences among N treatments and N balances were near zero. In 2019, delaying the N application improved NUE and corn grain yield due to excessive rainfall early in the season reflecting on N losses which was confirmed by lower N balances in sidedressed treatments. Overall, our findings suggest including N credit for cereals in MRTN prediction model could help with improved N management in the Midwestern United States. Full article

(This article belongs to the Special Issue Soil Healthy in Agro-ecosystems)

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25 pages, 3134 KiB

Open AccessEditor’s ChoiceReview

Soil Organic Carbon in Sandy Paddy Fields of Northeast Thailand: A Review

by Noppol Arunrat, Praeploy Kongsurakan, Sukanya Sereenonchai and Ryusuke Hatano

Agronomy 2020, 10(8), 1061; https://doi.org/10.3390/agronomy10081061 - 22 Jul 2020

Cited by 72 | Viewed by 9031

Abstract

Soil organic carbon (SOC) improvement has become a sustainable strategy for enhancing soil resilience and reducing greenhouse gas (GHG) emissions in the rice cropping system. For tropical soils, the SOC accumulation was limited by the unfavorable environment, likely the sandy soil area in [...] Read more.

Soil organic carbon (SOC) improvement has become a sustainable strategy for enhancing soil resilience and reducing greenhouse gas (GHG) emissions in the rice cropping system. For tropical soils, the SOC accumulation was limited by the unfavorable environment, likely the sandy soil area in Northeast (NE) Thailand. This review aims to quantify and understand SOC in sandy paddy fields of NE Thailand. The existing research gap for alternative management practices is also highlighted to increase ecological and agronomic values. We review previous studies to determine the factors affecting SOC dynamics in sandy paddy fields, in order to enhance SOC and sustain rice yields. High sand content, up to 50% sand, was found in 70.7% of the observations. SOC content has ranged from 0.34 to 31.2 g kg⁻¹ for the past four decades in paddy rice soil of NE Thailand. The conventional and alternative practice managements were chosen based on either increasing rice crop yield or improving soil fertility. The lack of irrigation water during the mild dry season would physically affect carbon sequestration as the soil erosion accelerates. Meanwhile, soil chemical and microbial activity, which directly affect SOC accumulation, would be influenced by nutrient and crop residue management, including chemical fertilizer, manure and green manure, unburned rice straw, and biochar application. Increasing SOC content by 1 g kg⁻¹ can increase rice yield by 302 kg ha⁻¹. The predicted carbon saturation varied tremendously, from 4.1% to 140.6% (52% in average), indicating that the sandy soil in this region has the potential for greater SOC sequestration. Our review also suggests that broadening the research of rice production influenced by sandy soil is still required to implement adaptive management for sustainable agriculture and future food security. Full article

(This article belongs to the Special Issue Effects of Agricultural Management on Soil Properties and Health)

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16 pages, 1828 KiB

Open AccessEditor’s ChoiceArticle

Crop Yield Prediction through Proximal Sensing and Machine Learning Algorithms

by Farhat Abbas, Hassan Afzaal, Aitazaz A. Farooque and Skylar Tang

Agronomy 2020, 10(7), 1046; https://doi.org/10.3390/agronomy10071046 - 20 Jul 2020

Cited by 141 | Viewed by 10948

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

(This article belongs to the Special Issue Remote Sensing Applications for Agriculture and Crop Modelling-Series Ⅱ)

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15 pages, 1898 KiB

Open AccessEditor’s ChoiceArticle

Sensory Attributes and Consumer Acceptability of 12 Microgreens Species

by Francesco Caracciolo, Christophe El-Nakhel, Maria Raimondo, Marios C. Kyriacou, Luigi Cembalo, Stefania De Pascale and Youssef Rouphael

Agronomy 2020, 10(7), 1043; https://doi.org/10.3390/agronomy10071043 - 19 Jul 2020

Cited by 51 | Viewed by 7501

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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41 pages, 4999 KiB

Open AccessEditor’s ChoiceReview

CRISPR-Cas9 System for Plant Genome Editing: Current Approaches and Emerging Developments

by Jake Adolf V. Montecillo, Luan Luong Chu and Hanhong Bae

Agronomy 2020, 10(7), 1033; https://doi.org/10.3390/agronomy10071033 - 17 Jul 2020

Cited by 65 | Viewed by 20037

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

(This article belongs to the Special Issue Molecular Genetics, Genomics and Biotechnology of Crop Plants Breeding - Series Ⅱ)

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20 pages, 1613 KiB

Open AccessEditor’s ChoiceReview

A Review of Metal and Metal-Oxide Nanoparticle Coating Technologies to Inhibit Agglomeration and Increase Bioactivity for Agricultural Applications

by Anthony Cartwright, Kyle Jackson, Christina Morgan, Anne Anderson and David W. Britt

Agronomy 2020, 10(7), 1018; https://doi.org/10.3390/agronomy10071018 - 15 Jul 2020

Cited by 77 | Viewed by 6388

Abstract

Coatings offer a means to control nanoparticle (NP) size, regulate dissolution, and mitigate runoff when added to crops through soil. Simultaneously, coatings can enhance particle binding to plants and provide an additional source of nutrients, making them a valuable component to existing nanoparticle [...] Read more.

Coatings offer a means to control nanoparticle (NP) size, regulate dissolution, and mitigate runoff when added to crops through soil. Simultaneously, coatings can enhance particle binding to plants and provide an additional source of nutrients, making them a valuable component to existing nanoparticle delivery systems. Here, the surface functionalization of metal and metal-oxide nanoparticles to inhibit aggregation and preserve smaller agglomerate sizes for enhanced transport to the rooting zone and improved uptake in plants is reviewed. Coatings are classified by type and by their efficacy to mitigate agglomeration in soils with variable pH, ionic concentration, and natural organic matter profiles. Varying degrees of success have been reported using a range of different polymers, biomolecules, and inorganic surface coatings. Advances in zwitterionic coatings show the best results for maintaining nanoparticle stability in solutions even under high salinity and temperature conditions, whereas coating by the soil component humic acid may show additional benefits such as promoting dissolution and enhancing bioavailability in soils. Pre-tuning of NP surface properties through exposure to select natural organic matter, microbial products, and other biopolymers may yield more cost-effective nonagglomerating metal/metal-oxide NPs for soil applications in agriculture. Full article

(This article belongs to the Special Issue Nanotechnology Applications in Agriculture System)

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19 pages, 6989 KiB

Open AccessEditor’s ChoiceArticle

Using YOLOv3 Algorithm with Pre- and Post-Processing for Apple Detection in Fruit-Harvesting Robot

by Anna Kuznetsova, Tatiana Maleva and Vladimir Soloviev

Agronomy 2020, 10(7), 1016; https://doi.org/10.3390/agronomy10071016 - 14 Jul 2020

Cited by 156 | Viewed by 14224

Abstract

A machine vision system for detecting apples in orchards was developed. The system was designed to be used in harvesting robots and is based on a YOLOv3 algorithm with special pre- and post-processing. The proposed pre- and post-processing techniques made it possible to [...] Read more.

A machine vision system for detecting apples in orchards was developed. The system was designed to be used in harvesting robots and is based on a YOLOv3 algorithm with special pre- and post-processing. The proposed pre- and post-processing techniques made it possible to adapt the YOLOv3 algorithm to be used in an apple-harvesting robot machine vision system, providing an average apple detection time of 19 ms with a share of objects being mistaken for apples at 7.8% and a share of unrecognized apples at 9.2%. Both the average detection time and error rates are less than in all known similar systems. The system can operate not only in apple-harvesting robots but also in orange-harvesting robots. Full article

(This article belongs to the Special Issue Precision Agriculture for Sustainability)

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