Agronomy

16 pages, 1173 KiB

Open AccessArticle

Development of an Integrated IoT-Based Greenhouse Control Three-Device Robotic System

by Vasileios Thomopoulos, Dionysios Bitas, Kyriakos-Nikos Papastavros, Dimitris Tsipianitis and Angeliki Kavga

Agronomy 2021, 11(2), 405; https://doi.org/10.3390/agronomy11020405 - 23 Feb 2021

Cited by 18 | Viewed by 5035

Abstract

The control of large greenhouse installations, especially those with hydroponics crops, is based on the analysis and use of data recorded by many sensors. At the same time, the size of such installations does not allow for their effective terrestrial surveillance, to detect [...] Read more.

The control of large greenhouse installations, especially those with hydroponics crops, is based on the analysis and use of data recorded by many sensors. At the same time, the size of such installations does not allow for their effective terrestrial surveillance, to detect problems promptly. In recent years, there has been an interest in the development of autonomous agbots equipped with agricultural sensors. Several ground-based AGV (automated guided vehicles) and UAV (unmanned aerial vehicles) systems have been developed for use in open-air plots. A key feature of all these innovative systems is spectroscopy, the development of which has been assisted by the surveillance capabilities and speed of modern-day UAVs (drones). However, there is a lag in the use of spectroscopy inside greenhouses since UAVs do not move freely indoors. In this paper, we propose as a solution a three-device (3DS) system. Full article

(This article belongs to the Special Issue Sensing and Perception Systems for Situational Awareness of Agricultural Robotic Vehicles)

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15 pages, 4204 KiB

Open AccessEditor’s ChoiceArticle

Novel Bacillus cereus Strain, ALT1, Enhance Growth and Strengthens the Antioxidant System of Soybean under Cadmium Stress

by Atlaw Anbelu Sahile, Muhammad Aaqil Khan, Muhammad Hamayun, Muhammad Imran, Sang-Mo Kang and In-Jung Lee

Agronomy 2021, 11(2), 404; https://doi.org/10.3390/agronomy11020404 - 23 Feb 2021

Cited by 27 | Viewed by 4049

Abstract

Cadmium stress significantly decreases agricultural productivity worldwide. Plant growth-promoting rhizobacteria (PGPR) are eco-friendly and inexpensive tool for mitigating heavy metal stress in crops. We isolated rhizospheric bacteria and screened them for various plant growth-promoting (PGP) traits as well as Cd tolerance. Only 6 [...] Read more.

Cadmium stress significantly decreases agricultural productivity worldwide. Plant growth-promoting rhizobacteria (PGPR) are eco-friendly and inexpensive tool for mitigating heavy metal stress in crops. We isolated rhizospheric bacteria and screened them for various plant growth-promoting (PGP) traits as well as Cd tolerance. Only 6 bacterial isolates out of 55 assessed showed multiple PGP traits in response to different Cd concentrations. The Bacillus cereus ALT1 strain showed high tolerance to increased Cd amounts in the culture medium, while secreting indole-3-acetic acid (IAA) and organic acids into the culture medium. High Cd concentrations (0.7 mM, 1.4 mM, and 2.1 mM) reduced soybean shoot and root length, root/shoot fresh and dry weight, as well as chlorophyll content; however, inoculation with the bacterial isolate ALT1 mitigated Cd stress and enhanced both soybean growth parameters and chlorophyll content. It also decreased abscisic acid (ABA) amounts, enhanced salicylic acid (SA) production, and promoted antioxidant response by increasing total proteins (TP) and superoxide dismutase (SOD), while decreasing glutathione (GSH) content, lipid peroxidation (LPO), peroxidase (POD), superoxide anion (SOA), and polyphenol oxidase (PPO) in soybean plants. In addition, inductively coupled plasma mass spectrometry (ICP-MS) showed that soybean plants treated with the bacterial isolate ALT1 enhanced K uptake and decreased Cd amounts in comparison to control plants. The present study reveals that Cd-tolerant bacterial isolate ALT1 can alleviate Cd toxicity on plants by increasing their growth, thus imposing itself as an eco-friendly bio-fertilizer under Cd stress. Full article

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18 pages, 1181 KiB

Open AccessEditor’s ChoiceArticle

Morphophysiology, Productivity and Quality of Soybean (Glycine max (L.) Merr.) cv. Merlin in Response to Row Spacing and Seeding Systems

by Marta Jańczak-Pieniążek, Jan Buczek, Dorota Bobrecka-Jamro, Ewa Szpunar-Krok, Renata Tobiasz-Salach and Wacław Jarecki

Agronomy 2021, 11(2), 403; https://doi.org/10.3390/agronomy11020403 - 23 Feb 2021

Cited by 18 | Viewed by 3745

Abstract

The appropriate row spacing and sowing density of soybeans are the basic non-input and pro-environmental agrotechnical factors. The optimal spacing of plants in the field can be crucial in terms of reducing competition between plants for water, nutrients and light, which is particularly [...] Read more.

The appropriate row spacing and sowing density of soybeans are the basic non-input and pro-environmental agrotechnical factors. The optimal spacing of plants in the field can be crucial in terms of reducing competition between plants for water, nutrients and light, which is particularly important for photosynthesis and maximizes the use of environmental resources. The field experiment was carried out in the years 2017–2019 at the Experimental Station for Cultivar Assessment in Przecław, Poland, on Merlin cv. soybean plants. The experimental factors were: row spacing of 15 and 30 cm and the sowing density of 70, 90 and 110 pcs. m⁻². During the research, the influence of row spacing and sowing density on yielding, seed quality, plant morphological features, nodulation and physiological processes in plants was assessed. The obtained soybean seed yield was not influenced by the experimental factors, but only by the weather conditions prevailing in the research years. The smaller row spacing and sowing density of 15/70 and 30/70 resulted in an increase in the parameters of the yield structure, the number and dry weight of root nodules, as well as the parameters of chlorophyll fluorescence (F_v/F_m, F_v/F₀ and PI). Greater plant density per area unit resulted in low yield structure parameters, lower number and dry weight of nodules, poorer parameters of chlorophyll fluorescence and higher protein content in seeds. With the increased sowing density, the plants were higher, the 1st. pod was placed higher and an LAI value was also higher. Full article

(This article belongs to the Special Issue Soybean Breeding, Agronomic Practices, and Production Systems)

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18 pages, 6813 KiB

Open AccessEditor’s ChoiceArticle

Impact of Integrated Agronomic Practices on Soil Fertility and Respiration on the Indo-Gangetic Plain of North India

by Rama Kant Dubey, Pradeep Kumar Dubey, Rajan Chaurasia, Ch Srinivasa Rao and Purushothaman Chirakkuzhyil Abhilash

Agronomy 2021, 11(2), 402; https://doi.org/10.3390/agronomy11020402 - 23 Feb 2021

Cited by 18 | Viewed by 3849

Abstract

Global agricultural production is accountable for the emission of ~30% of greenhouse gases. Therefore, the wide-scale adoptions of low-input, soil-friendly, and resource-conserving agronomic practices are imperative for the ‘planet healthy food production’ and also for reducing the carbon emissions from agricultural soil. In [...] Read more.

Global agricultural production is accountable for the emission of ~30% of greenhouse gases. Therefore, the wide-scale adoptions of low-input, soil-friendly, and resource-conserving agronomic practices are imperative for the ‘planet healthy food production’ and also for reducing the carbon emissions from agricultural soil. In this context, the present study aimed to analyze the impacts of integrated agronomic interventions i.e., the application of arbuscular mycorrhizal fungi (AMF) + reduced tillage (RT), biochar + RT, and AMF + biochar + RT, on spatiotemporal variations in soil-quality and soil-sustainability indicators, including microbial and soil respiration, in the Indo-Gangetic Plain (IGP) of North India. For this, field experiments on the above-mentioned agronomic interventions were employed using three different staple crops (Zea mays, Vigna mungo, and Brassica juncea) growing in three different agro-climatic zones of IGP (Varanasi, Sultanpur, and Gorakhpur) in a randomized block design. Periodic data collection was done to analyze the changes in physiochemical, biological, and biochemical properties of the soil, and statistical analyses were done accordingly. Irrespective of the sites, the experimental results proved that the integrated application of AMF + biochar + RT in V. mungo resulted in the highest soil organic carbon (i.e., 135% increment over the control) and microbial biomass carbon (24%), whereas the same application (i.e., AMF + biochar + RT) in Z. mays had the maximum reduction in microbial (32%) and soil (44%) respiration. On the other hand, enhanced occurrence of glomalin activity (98%) was noted in Z. mays cropping for all the sites. Significant negative correlation between soil respiration and glomalin activity under AMF + biochar + RT (−0.85), AMF + RT (−0.82), and biochar + RT (−0.62) was an indication of glomalin’s role in the reduced rate of soil respiration. The research results proved that the combined application of AMF + biochar + RT was the best practice for enhancing soil quality while reducing respiration. Therefore, the development of suitable packages of integrated agronomic practices is essential for agricultural sustainability. Full article

(This article belongs to the Section Farming Sustainability)

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15 pages, 1025 KiB

Open AccessEditor’s ChoiceArticle

Ghanaian Cocoa (Theobroma cacao L.) Bean Shells Coproducts: Effect of Particle Size on Chemical Composition, Bioactive Compound Content and Antioxidant Activity

by Carmen Botella-Martínez, Raquel Lucas-Gonzalez, Carmen Ballester-Costa, José Ángel Pérez-Álvarez, Juana Fernández-López, Johannes Delgado-Ospina, Clemencia Chaves-López and Manuel Viuda-Martos

Agronomy 2021, 11(2), 401; https://doi.org/10.3390/agronomy11020401 - 23 Feb 2021

Cited by 34 | Viewed by 6337

Abstract

The worldwide cocoa bean shell (CBS) generation is estimated at around 900,000 tons. In their composition, this coproduct showed several bioactive compounds like methylxanthines or polyphenolic compounds. Thus, the aim of this work was to investigate the effects of different particle sizes on [...] Read more.

The worldwide cocoa bean shell (CBS) generation is estimated at around 900,000 tons. In their composition, this coproduct showed several bioactive compounds like methylxanthines or polyphenolic compounds. Thus, the aim of this work was to investigate the effects of different particle sizes on the chemical composition, physico-chemical, bioactive compounds content, and antioxidant properties of flours obtained from cocoa (Theobroma cacao L.) bean shells. The flours obtained from CBS with different particle sizes had high content of dietary fiber (61.18–65.58 g/100 g). The polyphenolic profile identified seven compounds being epicatechin and catechin (values ranged 4.56–6.33 and 2.11–4.56 mg/g, respectively) as the most abundant compounds. Additionally, the methylxanthines theobromine and caffeine were quantified with values ranging from 7.12 to 12.77 and 4.02 to 6.13 mg/g, respectively. For the fatty acid profile, the principal compounds identified were oleic, stearic and palmitic acids. CBS had antioxidant capacity with all methods assayed. For DPPH, ABTS and FRAP assays values ranged between 2.35–5.53, 3.39–11.55, and 3.84–7.62 mg Trolox equivalents/g sample, respectively. This study suggests that cocoa bean shells may constitute a valuable coproduct for the food industry due to its high content in valuable bioactive compounds. Full article

(This article belongs to the Special Issue Potential Strategies for Adding Value of Mediterranean and Exotic Fruits and Vegetables ByProducts)

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11 pages, 1451 KiB

Open AccessArticle

Exogenous Serotonin Improves Salt Tolerance in Rapeseed (Brassica napus L.) Seedlings

by Yue Liu, Xiaoyu Ding, Yan Lv, Yong Cheng, Chunsheng Li, Lei Yan, Shanshan Tian and Xiling Zou

Agronomy 2021, 11(2), 400; https://doi.org/10.3390/agronomy11020400 - 23 Feb 2021

Cited by 18 | Viewed by 2950

Abstract

Serotonin is a well-known agent that plays various roles in animals, and is little known in plants. In this study, the effect of exogenous serotonin was tested on Brassica napus L. (rapeseed) under salt stress. The results revealed that exogenous application of 200 [...] Read more.

Serotonin is a well-known agent that plays various roles in animals, and is little known in plants. In this study, the effect of exogenous serotonin was tested on Brassica napus L. (rapeseed) under salt stress. The results revealed that exogenous application of 200 µmol/L serotonin had the best protection under salinity. Exogenous serotonin effectively alleviated the growth inhibition of seedlings caused by salinity, and significantly promoted the accumulation of the fresh and dry weights of roots and shoots. Besides, although the H₂O₂ and malondialdehyde (MDA) contents were raised under salinity, they were reduced by exogenous serotonin. The chlorophyll content was decreased under salinity, and was increased by exogenous serotonin. Under salinity, serotonin effectively activated antioxidant enzyme system through improving the catalase (CAT), superoxide dismutase (SOD), and peroxidase (POD) activities, and the expression of POD7, CAT3 and Cu-SOD genes was also up-regulated. The results also revealed exogenous serotonin increased the solute content by promoting the accumulation of soluble sugar and protein. In conclusion, salinity caused a toxicity to seedlings through oxidative damage to chlorophyll and cell membrane integrity, and serotonin possessed the ability of scavenging reactive oxygen species, osmotic pressure regulation and promoting growth, thus alleviating salinity of rape seedlings. Full article

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19 pages, 2776 KiB

Open AccessArticle

Genotypic and Phenotypic Characterization of Two Triticum aestivum L.—Dasypyrum villosum Translocations Lines in the Same Wheat Genetic Background

by Baicui Wang, Xiaolan Ma, Xingguo Ye, Yilin Zhou, Youzhi Ma and Zhishan Lin

Agronomy 2021, 11(2), 399; https://doi.org/10.3390/agronomy11020399 - 23 Feb 2021

Cited by 3 | Viewed by 2389

Abstract

A wheat 660K chip was used to genotype two wheat-Dasypyrum villosum 6V#4S.6DL and 6V#2S.6AL translocation lines (A303 and B303) and their common wheat recurrent parent Wan7107. The results showed that these three lines have similar characteristics of base composition except for the [...] Read more.

A wheat 660K chip was used to genotype two wheat-Dasypyrum villosum 6V#4S.6DL and 6V#2S.6AL translocation lines (A303 and B303) and their common wheat recurrent parent Wan7107. The results showed that these three lines have similar characteristics of base composition except for the translocation chromosomes. The alien translocation chromosomes have fewer homozygous and more heterozygous genotypes with more invalid probes. Distributions of SNPs between the translocation lines and Wan7107 were mainly dense on the regions of 6AS or 6DS as expected, but unexpectedly also on near the telomere of 2BS, and some regions of other wheat chromosomes. Meanwhile, the translocation lines A303 and B303 have 99.44% and 98.81% identical genotypes to Wan7107, respectively. Under the same genetic background, A303 and B303 showed different reactions to Blumeria graminis f. sp. tritici (Bgt) strains of powdery mildew. Both translocation lines have higher grain weight and plant height, and B303 has fewer spikelets compared to Wan7107. These results provide us a new insight into the genomic variation between the backcross generation plant and the recurrent parent, which is valuable information for understanding the relationship between wheat and the 6VS chromosome of D. villosum as well as the application potential of the alien chromosome arms. Full article

(This article belongs to the Special Issue Molecular Genetics, Genomics and Breeding of Cereal Crops)

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15 pages, 1856 KiB

Open AccessArticle

Soil Moisture Retrieval Model Design with Multispectral and Infrared Images from Unmanned Aerial Vehicles Using Convolutional Neural Network

by Min-Guk Seo, Hyo-Sang Shin and Antonios Tsourdos

Agronomy 2021, 11(2), 398; https://doi.org/10.3390/agronomy11020398 - 23 Feb 2021

Cited by 9 | Viewed by 3205

Abstract

This paper deals with a soil moisture retrieval model design with airborne measurements for remote monitoring of soil moisture level in large crop fields. A small quadrotor unmanned aerial vehicle (UAV) is considered as a remote sensing platform for high spatial resolutions of [...] Read more.

This paper deals with a soil moisture retrieval model design with airborne measurements for remote monitoring of soil moisture level in large crop fields. A small quadrotor unmanned aerial vehicle (UAV) is considered as a remote sensing platform for high spatial resolutions of airborne images and easy operations. A combination of multispectral and infrared (IR) sensors is applied to overcome the effects of canopies convering the field on the sensor measurements. Convolutional neural network (CNN) is utilized to take the measurement images directly as inputs for the soil moisture retrieval model without loss of information. The procedures to obtain an input image corresponding to a certain soil moisture level measurement point are addressed, and the overall structure of the proposed CNN-based model is suggested with descriptions. Training and testing of the proposed soil moisture retrieval model are conducted to verify and validate its performance and address the effects of input image sizes and errors on input images. The soil moisture level estimation performance decreases when the input image size increases as the ratio of the pixel corresponding to the point to estimate soil moisture level to the total number of pixels in the input image, whereas the input image size should be large enough to include this pixel under the errors in input images. The comparative study shows that the proposed CNN-based algorithm is advantageous on estimation performance by maintaining spatial information of pixels on the input images. Full article

(This article belongs to the Special Issue Machine Learning Applications in Digital Agriculture)

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21 pages, 353 KiB

Open AccessArticle

The Impact of Carbon Dioxide Concentrations and Low to Adequate Photosynthetic Photon Flux Density on Growth, Physiology and Nutrient Use Efficiency of Juvenile Cacao Genotypes

by Virupax C. Baligar, Marshall K. Elson, Alex-Alan F. Almeida, Quintino R. de Araujo, Dario Ahnert and Zhenli He

Agronomy 2021, 11(2), 397; https://doi.org/10.3390/agronomy11020397 - 23 Feb 2021

Cited by 11 | Viewed by 3396

Abstract

Cacao (Theobroma cacao L.) was grown as an understory tree in agroforestry systems where it received inadequate to adequate levels of photosynthetic photon flux density (PPFD). As atmospheric carbon dioxide steadily increased, it was unclear what impact this would have on cacao [...] Read more.

Cacao (Theobroma cacao L.) was grown as an understory tree in agroforestry systems where it received inadequate to adequate levels of photosynthetic photon flux density (PPFD). As atmospheric carbon dioxide steadily increased, it was unclear what impact this would have on cacao growth and development at low PPFD. This research evaluated the effects of ambient and elevated levels carbon dioxide under inadequate to adequate levels of PPFD on growth, physiological and nutrient use efficiency traits of seven genetically contrasting juvenile cacao genotypes. Growth parameters (total and root dry weight, root length, stem height, leaf area, relative growth rate and net assimilation rates increased, and specific leaf area decreased significantly in response to increasing carbon dioxide and PPFD. Increasing carbon dioxide and PPFD levels significantly increased net photosynthesis and water-use efficiency traits but significantly reduced stomatal conductance and transpiration. With few exceptions, increasing carbon dioxide and PPFD reduced macro–micro nutrient concentrations but increased uptake, influx, transport and nutrient use efficiency in all cacao genotypes. Irrespective of levels of carbon dioxide and PPFD, intraspecific differences were observed for growth, physiology and nutrient use efficiency of cacao genotypes. Full article

(This article belongs to the Special Issue Advances in Understanding Physiological Processes of the Cacao Tree)

18 pages, 2703 KiB

Open AccessArticle

Delayed Development of Resistance to QoI Fungicide in Venturia inaequalis in Israeli Apple Orchards and Improved Apple Scab Management Using Fungicide Mixtures

by Lior Gur, Keren Levy, Amotz Farber, Omer Frenkel and Moshe Reuveni

Agronomy 2021, 11(2), 396; https://doi.org/10.3390/agronomy11020396 - 23 Feb 2021

Cited by 7 | Viewed by 3374

Abstract

Quinone outside inhibitors (QoI) fungicides group were introduced for commercial use against apple scab (Venturia inaequalis) in Israel in 1997. Unlike other regions in the world, in which resistance of V. inaequalis to QoI fungicides was observed within 3–5 years of use, [...] Read more.

Quinone outside inhibitors (QoI) fungicides group were introduced for commercial use against apple scab (Venturia inaequalis) in Israel in 1997. Unlike other regions in the world, in which resistance of V. inaequalis to QoI fungicides was observed within 3–5 years of use, in Israel it only occurred after 14 years of use. Field trials conducted between 2007 and 2017 showed a significant reduction in susceptibility to QoIs in northern Israel only since 2011. The delay in the development of resistance is related to limited fungicidal sprays resulting from unfavorable conditions for the pathogen. Of the 28 isolates collected from infected leaves or fruits of commercial orchards in northern Israel, 27 were resistant to the QoI fungicide Kresoxim-methyl. Amplification of the CYTB gene and sequencing of the G143A mutation region confirmed the resistance of all 27 isolates to QoIs. Resistance is demonstrated in the orchard, in vitro and molecular-based study, which forced the growers to avoid using QoIs against apple scab. We show that foliar applications of tank mixtures of systemic fungicides plus captan or prepacked fungicidal mixtures improved efficacy and can be used as a strategic approach in fungicide resistance management, including in orchards in which resistance to QoIs has been detected. Full article

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

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14 pages, 298 KiB

Open AccessArticle

Evaluation of Humic Fertilizers Applied at Full and Reduced Nitrogen Rates on Kentucky Bluegrass Quality and Soil Health

by Alex J. Lindsey, Adam W. Thoms, Marshall D. McDaniel and Nick E. Christians

Agronomy 2021, 11(2), 395; https://doi.org/10.3390/agronomy11020395 - 23 Feb 2021

Cited by 5 | Viewed by 2622

Abstract

Soil health and sustainable management practices have garnered much interest within the turfgrass industry. Among the many practices that enhance soil health and sustainability are applying soil additives to enhance soil biological activity and reducing nitrogen (N) inputs—complimentary practices. A two-year study was [...] Read more.

Soil health and sustainable management practices have garnered much interest within the turfgrass industry. Among the many practices that enhance soil health and sustainability are applying soil additives to enhance soil biological activity and reducing nitrogen (N) inputs—complimentary practices. A two-year study was conducted to investigate if reduced N fertilizer rates applied with humic substances could provide comparable turfgrass quality as full N rates, and whether humic fertilizers would increase biological aspects of soil health (i.e., microbial biomass and activity). Treatments included synthetic fertilizer with black gypsum (SFBG), poly-coated humic-coated urea (PCHCU; two rates), urea + humic dispersing granules (HDG; two rates), urea, stabilized nitrogen, HDG, and a nontreated control. Reduced rates of N with humic substances maintained turfgrass quality and cover, and reduced clipping biomass compared to full N rates. There were no differences in soil physical and chemical properties besides soil sulfur (S) concentration. SFBG resulted in the highest soil S concentration. Fertilizer treatments had minimal effect on microbial biomass and other plant-available nutrients. However, PCHCU (full rate) increased potentially mineralizable carbon (PMC) and N (PMN) by 68% and 59%, respectively, compared to the nontreated control. Meanwhile SFBG and stabilized nitrogen also increased PMC and PMN by 77% and 50%, and 65% and 59%, respectively. Overall, applications of reduced N fertilizer rates with the addition of humic substances could be incorporated into a more sustainable and environmentally friendly turfgrass fertilizer program. Full article

15 pages, 1024 KiB

Open AccessArticle

Suspension Cell Culture of Dioscorea deltoidea—A Renewable Source of Biomass and Furostanol Glycosides for Food and Pharmaceutical Industry

by Maria V. Titova, Elena V. Popova, Svetlana V. Konstantinova, Dmitry V. Kochkin, Igor M. Ivanov, Andrey G. Klyushin, Elena G. Titova, Elena A. Nebera, Ekaterina R. Vasilevskaya, Galina S. Tolmacheva, Elena A. Kotenkova, Alexandr M. Nosov and Kee-Yoeup Paek

Agronomy 2021, 11(2), 394; https://doi.org/10.3390/agronomy11020394 - 23 Feb 2021

Cited by 16 | Viewed by 3918

Abstract

Dioscorea deltoidea is a medicinal plant valued for its high content of steroidal glycosides (SG)—bioactive compounds with cardioprotective and immunomodulation actions, also used to treat reproductive system disorders. To overcome the limitations of natural resources of this species, a suspension cell culture of [...] Read more.

Dioscorea deltoidea is a medicinal plant valued for its high content of steroidal glycosides (SG)—bioactive compounds with cardioprotective and immunomodulation actions, also used to treat reproductive system disorders. To overcome the limitations of natural resources of this species, a suspension cell culture of D. deltoidea was developed as a renewable and ecologically sustainable source of raw biomass and SG. Cell culture demonstrated stable and intensive growth in the laboratory (20 L) and industrial (630 L) bioreactors operated under a semi-continuous regime (specific growth rate 0.11–1.12 day⁻¹, growth index 3.5–3.7). Maximum dry weight accumulation (8.5–8.8 g/L) and SG content (47–57 mg/g DW) were recorded during the stationary phase. Bioreactor-produced cell biomass contained inorganic macro (K, Ca, Mg, Na) and micro (Zn, Mn, Fe, B, Al, Cu, Cr, Se, Co, Ni) elements in concentrations within the safe range of dietary recommendations. Acute toxicity test showed no or insignificant changes in organ weight, hematological panel and blood biochemistry of laboratory animals fed with 2000 and 5000 mg/kg dry biomass. The results suggest that cell culture of D. deltoidea grown in bioreactors has great potential to be used as functional foods and a component of specialized dietary supplements in complex therapy of reproductive system disorders and mineral deficiency. Full article

(This article belongs to the Special Issue Role of Plant Tissue Culture in Agricultural Research and Production)

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11 pages, 1027 KiB

Open AccessArticle

Can Hydromulch Reduce the Emergence of Perennial Weeds?

by Maria Teresa Mas, Gabriel Pardo, Jorge Pueyo, Antoni M. C. Verdú and Alicia Cirujeda

Agronomy 2021, 11(2), 393; https://doi.org/10.3390/agronomy11020393 - 23 Feb 2021

Cited by 9 | Viewed by 2629

Abstract

Herbicide weed control is difficult in the first years of perennial crop establishment or in minor crops, and plastic sheet mulches can leave persistent residues. Liquid spray-on mulch (hydromulch) might be a solution in these cases. To test three hydromulch formulations on perennial [...] Read more.

Herbicide weed control is difficult in the first years of perennial crop establishment or in minor crops, and plastic sheet mulches can leave persistent residues. Liquid spray-on mulch (hydromulch) might be a solution in these cases. To test three hydromulch formulations on perennial weed emergence, greenhouse assays were conducted for two years in two localities to evaluate their rhizome sprouting and shoot emergence. Data, obtained from a completely randomized block design, were analyzed by means of generalized linear mixed models with binomial distribution and logit link function; the effects of hydromulch, species, and their interaction were considered fixed, while the other sources of variation (i.e., locality, year, block and rhizome length) were considered random. All three hydromulches, based on wheat straw, rice husk, and used substrate for mushroom cultivation, were capable of reducing rhizome sprouting of all four species tested when compared to the non-mulched treatment. Many rhizomes sprouted but were trapped under the mulch layer, especially those of Paspalum dilatatum (87%), Cynodon dactylon, and Sorghum halepense (around 50%), while Cyperus rotundus was least affected by the hydromulch treatments (16%). All three blends showed promising results in the reduction of perennial weed emergence, warranting field trials to test combined weed management strategies. Full article

(This article belongs to the Special Issue Weed Management & Sustainable Agriculture)

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17 pages, 2553 KiB

Open AccessEditor’s ChoiceArticle

Cladosporium sp. Isolate as Fungal Plant Growth Promoting Agent

by Iuliana Răut, Mariana Călin, Luiza Capră, Ana-Maria Gurban, Mihaela Doni, Nicoleta Radu and Luiza Jecu

Agronomy 2021, 11(2), 392; https://doi.org/10.3390/agronomy11020392 - 23 Feb 2021

Cited by 38 | Viewed by 8575

Abstract

Cladosporium species are active in protecting plants against different biotic and abiotic stresses. Since these species produced a wide range of secondary metabolites responsible for the adaptation to new habitats, plant health and performance, they are of great interest, especially for biostimulants in [...] Read more.

Cladosporium species are active in protecting plants against different biotic and abiotic stresses. Since these species produced a wide range of secondary metabolites responsible for the adaptation to new habitats, plant health and performance, they are of great interest, especially for biostimulants in agriculture. Cladosporium sp. produces protein hydrolysates (PHs), a class of biostimulants, by cultivation on medium with keratin wastes (feathers) as carbon and energy sources. The aim of this study was to select a Cladosporium isolate with potential to be used as plant growth promoting agent. The characteristics of Cladosporium isolates as plants biostimulants were evaluated through several tests, such as: antagonism versus plants pathogens, effect on plant growth of secreted volatiles produced by isolates, secretion of hydrolytic enzymes, production of 3-indole acetic acid, zinc and phosphorous solubilization, capacity to promote tomato seedlings growth (pot experiments). Cladosporium isolate T2 presented positive results to all tests. Encouraging results were obtained treating tomato seedlings with PHs from isolate Cladosporium T2 cultured on medium supplemented with 1% (w/w) chicken feathers, for which growth parameters, such as stem weight, stem height, and root weight were significantly higher by 65%, 32%, and 55%, respectively, compared to those treated with water. Full article

(This article belongs to the Special Issue Effects of Biostimulants and Bioeffectors on Plant Growth)

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18 pages, 3248 KiB

Open AccessArticle

Variation among Tanzania Rice Germplasm Collections Based on Agronomic Traits and Resistance to Rice Yellow Mottle Virus

by William Titus Suvi, Hussein Shimelis, Mark Laing, Isack Mathew and Admire I. T. Shayanowako

Agronomy 2021, 11(2), 391; https://doi.org/10.3390/agronomy11020391 - 22 Feb 2021

Cited by 5 | Viewed by 2817

Abstract

Rice (Oryza species) is a commercial crop worldwide. Across Africa, the potential yield and quality of rice is diminished by a lack of high performance, locally adapted varieties, and the impact of rice yellow mottle virus (RYMV). The objective of this study [...] Read more.

Rice (Oryza species) is a commercial crop worldwide. Across Africa, the potential yield and quality of rice is diminished by a lack of high performance, locally adapted varieties, and the impact of rice yellow mottle virus (RYMV). The objective of this study was to assess the performance of a diverse collection of rice germplasm for RYMV resistance and agronomic traits, and to select promising lines for breeding for Tanzanian conditions. Fifty-four rice genotypes were field evaluated in two important rice production sites (Ifakara and Mkindo) in Tanzania, which are recognized as RYMV hotspots, using a 6 × 9 alpha lattice design with two replications. There was significant (p < 0.05) genotypic variation for agronomic traits and RYMV susceptibility in the tested germplasm. Seven genotypes with moderate to high RYMV resistance were identified, including Salama M-57, SSD1, IRAT 256, Salama M-55, Mwangaza, Lunyuki, and Salama M-19, which were identified as new sources of resistance genes. Positive and significant correlations were detected between grain yield and number of panicles per plant (NPP), panicle length (PL), number of grains per panicle (NGP), percentage-filled grains (PFG), and thousand-grain weight (TGW), which are useful traits for simultaneous selection for rice yield improvement. A principal component analysis allocated five principal components, accounting for 79.88% of the total variation present in the assessed germplasm collection. Traits that contributed most to variability included NPP, number of tillers/plant (NT), PL, grain yield (GY), and days to 50% flowering (DFL). The genotypes Rangimbili, Gigante, and SARO possess complementary agronomic traits and RYMV resistance, and can be recommended for further evaluation, genetic analysis, and breeding. Full article

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12 pages, 1049 KiB

Open AccessEditor’s ChoiceArticle

Zinc Uptake by Plants as Affected by Fertilization with Zn Sulfate, Phosphorus Availability, and Soil Properties

by Ramiro Recena, Ana M. García-López and Antonio Delgado

Agronomy 2021, 11(2), 390; https://doi.org/10.3390/agronomy11020390 - 22 Feb 2021

Cited by 48 | Viewed by 4785

Abstract

Zinc (Zn) deficiency constrains crop yield and quality, but soil factors influencing Zn availability to plants and reactions of applied Zn fertilizer are not fully understood. This work is aimed at studying Zn availability in soil and the use efficiency of Zn fertilizers [...] Read more.

Zinc (Zn) deficiency constrains crop yield and quality, but soil factors influencing Zn availability to plants and reactions of applied Zn fertilizer are not fully understood. This work is aimed at studying Zn availability in soil and the use efficiency of Zn fertilizers by plants as affected by soil properties and particularly by soil available P. We performed a pot experiment involving four consecutive crops fertilized with Zn sulfate using 36 soils. The cumulative Zn uptake and dry matter yield in the four crops increased with increased initial diethylenetriamine pentaacetic acid extraction of Zn (DTPA-Zn) (R² = 0.75 and R² = 0.61; p < 0.001). The initial DTPA-Zn increased with increased Olsen P (R² = 0.41; p < 0.001) and with increased ratio of Fe in poorly crystalline to Fe in crystalline oxides (R² = 0.58; p < 0.001). DTPA-Zn decreased with increased cumulative Zn uptake, but not in soils with DTPA-Zn < 0.5 mg kg⁻¹. Overall, the available Zn is more relevant in explaining Zn uptake by plants than applied Zn sulfate. However, in Zn-deficient soils, Zn fertilizer explained most of the Zn uptake by crops. Poorly crystalline Fe oxides and P availability exerted a positive role on Zn availability to plants in soil. Full article

(This article belongs to the Special Issue Phosphorus and Micronutrient Interactions in Soils)

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20 pages, 1157 KiB

Open AccessArticle

Crop Establishment and Weed Control Options for Sustaining Dry Direct Seeded Rice Production in Eastern India

by Sanjoy Saha, Sushmita Munda, Sudhanshu Singh, Virender Kumar, Hemant Kumar Jangde, Ashirbachan Mahapatra and Bhagirath S. Chauhan

Agronomy 2021, 11(2), 389; https://doi.org/10.3390/agronomy11020389 - 22 Feb 2021

Cited by 19 | Viewed by 4071

Abstract

Dry direct seeded rice (DSR) has emerged as an economically viable alternative to puddled transplanted rice to address emerging constraints of labor and water scarcity and the rising cost of cultivation. However, wide adoption of DSR is seriously constrained by weed management trade-off. [...] Read more.

Dry direct seeded rice (DSR) has emerged as an economically viable alternative to puddled transplanted rice to address emerging constraints of labor and water scarcity and the rising cost of cultivation. However, wide adoption of DSR is seriously constrained by weed management trade-off. Therefore, the availability of effective weed control options is critical for the success and wide-scale adoption of DSR. A field study was conducted at ICAR-National Rice Research Institute, Cuttack, India, in the dry seasons of 2015 and 2016 to evaluate the performance of three crop establishment methods and five weed control practices on weed management, productivity, profitability and energetics of dry DSR. The results demonstrated that weed density and weed dry weight was lower in drill seeding than broadcast seeding by 26–36% and manual line-seeding by 16–24%, respectively, at 30 and 60 days after crop emergence (DAE). Among herbicides, post-emergence application (17 DAE) of azimsulfuron was most effective in controlling weeds compared to early post application of bispyribac-sodium and bensulfuron-methyl+pretilachlor. Weed competition in the weedy check treatment resulted 58% reduction in rice yield. Among establishment methods, drill-seeding was most profitable with US $ 685 ha⁻¹ higher net income than broadcast seeding primarily due to higher yield. Among weed control treatments, azimsulfuron was most profitable resulting in US $ 160 and 736 ha⁻¹ higher net income than weed free and weedy check, respectively. The specific energy was lowest for drill seeding among establishment method and azimsulfuron among weed control practices, suggesting lowest energy consumed in producing per unit of grain yield. Full article

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17 pages, 765 KiB

Open AccessEditor’s ChoiceArticle

Species Interactions and Nitrogen Use during Early Intercropping of Intermediate Wheatgrass with a White Clover Service Crop

by Shoujiao Li, Erik Steen Jensen, Nan Liu, Yingjun Zhang and Linda-Maria Dimitrova Mårtensson

Agronomy 2021, 11(2), 388; https://doi.org/10.3390/agronomy11020388 - 22 Feb 2021

Cited by 11 | Viewed by 3155

Abstract

Perennial grain crops intercropped with legumes are expected to use nitrogen (N) resources efficiently. A pot experiment using the ¹⁵N isotope dilution method demonstrated interspecific competition and use of N from the soil and N₂ fixation in intermediate wheatgrass (Thinopyrum [...] Read more.

Perennial grain crops intercropped with legumes are expected to use nitrogen (N) resources efficiently. A pot experiment using the ¹⁵N isotope dilution method demonstrated interspecific competition and use of N from the soil and N₂ fixation in intermediate wheatgrass (Thinopyrum intermedium (Host) Barkworth & D.R. Dewey, IWG) and white clover (Trifolium repens L., WC) intercrops at five species-relative frequencies and four levels of inorganic N fertilizer in a replacement series design. The proportion of N in WC derived from the atmosphere increased from 39.7% in a sole crop to 70.9% when intercropped with IWG, and 10.1% N in IWG transferred from WC. Intermediate wheatgrass showed high fitness with maintained high total dry matter production at low relative frequencies. Decreasing IWG-relative frequency only increased dry matter and N accumulation of WC, resulting in increased amounts of N₂ fixed. Increased levels of N fertilization increased the proportion of N acquired from the fertilizer in IWG and WC but decreased the N fixed by WC and N absorbed by IWG from the soil. Our study indicates that WC supply sufficient fixed N₂ for IWG intercrop biomass yields under appropriate levels of soil N fertility and species-relative frequencies. Full article

(This article belongs to the Special Issue Assessing Breeding Technologies and Ecosystem Services in Perennial Agriculture and Novel Farming Systems)

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15 pages, 2011 KiB

Open AccessEditor’s ChoiceArticle

Cover Crop Contributions to Improve the Soil Nitrogen and Carbon Sequestration in Almond Orchards (SW Spain)

by Miguel A. Repullo-Ruibérriz de Torres, Manuel Moreno-García, Rafaela Ordóñez-Fernández, Antonio Rodríguez-Lizana, Belén Cárceles Rodríguez, Iván Francisco García-Tejero, Víctor Hugo Durán Zuazo and Rosa M. Carbonell-Bojollo

Agronomy 2021, 11(2), 387; https://doi.org/10.3390/agronomy11020387 - 22 Feb 2021

Cited by 21 | Viewed by 5125

Abstract

Almond (Prunus dulcis Mill. [D.A. Webb]) is the third most widely spread crop in Spain and has traditionally been cultivated in marginal areas and shallow soils under rainfed conditions. However, it recently has been progressively introduced in flat irrigated areas. The implementation [...] Read more.

Almond (Prunus dulcis Mill. [D.A. Webb]) is the third most widely spread crop in Spain and has traditionally been cultivated in marginal areas and shallow soils under rainfed conditions. However, it recently has been progressively introduced in flat irrigated areas. The implementation of cover crops in the inter-rows of woody crops has been proven as a suitable strategy to reduce the runoff and soil erosion but they also can boost soil quality and health. A field experiment was conducted during two-monitoring seasons to examine the soil nitrogen and carbon sequestration potential of three seeded cover crops [barley (Hordeum vulgare L.), hairy vetch (Vicia villosa Roth), and a mixture of 65% barley and 35% vetch] and a control of spontaneous flora in irrigated almond orchards (SW Spain). Here, we show that barley provided the highest biomass amount, followed by mixture covers, vetch, and the control treatment. Also, vetch covered the soil faster in the growing stage, but its residues were decomposed easier than barley and mixture treatments during the decomposition period after mowing, providing less soil protection when the risk of water erosion with autumn rainfall is high. On the other hand, vetch improved soil nitrate content by over 35% with respect to barley and mixture treatments at 0–20 cm soil depth throughout the studied period. In addition, a greater carbon input to the soil was determined in the barley plot. That is, the mixture and barley cover crops had higher potential for carbon sequestration, augmenting the soil organic carbon by more than 1.0 Mg ha⁻¹ during the study period. Thus, taking into consideration the findings of the present experiment, the establishment of a seeded cover crop would be more advisable than spontaneous flora to mitigate soil erosion, enhancing soil fertility and carbon sequestration in irrigated almond plantations in Mediterranean semi-arid regions. Full article

(This article belongs to the Special Issue Conservation Agriculture as a Key Challenge for Sustainable Agroecosystems in Climate Change Mitigation and Adaptation)

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24 pages, 295 KiB

Open AccessArticle

A Swarm of Injustice: A Sociopolitical Framework for Global Justice in the Management of the Desert Locust

by Jeffrey A. Lockwood and Michael Christopher Sardo

Agronomy 2021, 11(2), 386; https://doi.org/10.3390/agronomy11020386 - 21 Feb 2021

Cited by 6 | Viewed by 3054

Abstract

In recent years, scientists and managers have advocated for the integration of the social sciences (particularly political science and economics) and the humanities (particularly moral philosophy) with the natural sciences (particularly entomology and ecology) in developing a full understanding of locust-management programs. In [...] Read more.

In recent years, scientists and managers have advocated for the integration of the social sciences (particularly political science and economics) and the humanities (particularly moral philosophy) with the natural sciences (particularly entomology and ecology) in developing a full understanding of locust-management programs. In this paper, we pursue such a synthesis by using the desert locust (Schistocerca gregaria) as an exemplar case. After an overview of this insect’s biology, ecology, and management, we provide a brief summary of the standard, moral theories (utilitarianism, deontology, and virtue ethics) and consider their shortcomings with regard to developing a framework for understanding the socioeconomic complexity of locust management. Next, we address some of the models of global justice and focus on two fundamental questions: Who is a moral agent with regard to desert locust management, and how should we justly distribute the responsibilities among agents during preventive and reactive modes? After identifying the agents, we use a fourfold set of principles to construct a framework for locust management consistent with global justice and apply this conceptual system to two hypothetical scenarios. We conclude with some observations from political philosophy that offer progress toward a comprehensive and applicable theory for locust management in the context of global justice. Full article

(This article belongs to the Special Issue How to Manage Migratory Pests and Potential Food Crises: Locusts Plagues in the 2020’s)

17 pages, 2729 KiB

Open AccessArticle

Comparison of Methods to Evaluate Rice (Oryza sativa) Germplasm for Tolerance to Low Temperature at the Seedling Stage

by Nirmal Sharma, Russell Reinke and Erik J. Sacks

Agronomy 2021, 11(2), 385; https://doi.org/10.3390/agronomy11020385 - 21 Feb 2021

Cited by 10 | Viewed by 3283

Abstract

Low temperature stress at the seedling stage is a major constraint to rice (Oryza sativa) production. Previously developed screening protocols typically germinate seed and establish seedlings under warm constant-temperature conditions that are optimal for growth, prior to initiating a constant low-temperature [...] Read more.

Low temperature stress at the seedling stage is a major constraint to rice (Oryza sativa) production. Previously developed screening protocols typically germinate seed and establish seedlings under warm constant-temperature conditions that are optimal for growth, prior to initiating a constant low-temperature challenge. We developed three controlled-environment protocols mimicking extreme cold boro (winter) seasons based on 25 years weather data from Bangladesh to test the hypothesis that by more closely replicating field conditions, greater information about cultivars could be obtained compared to standard protocols. Root and shoot growth after germination in a Petri dish at 20 °C for three weeks gave similar results as visual scores of transplanted seedlings in a standard five-week protocol. Moreover, transplanted seedlings at the end of the nine-week mimic protocols showed large differences in height and dry biomass, whereas for the standard protocols, growth during the warm pre-treatment substantially masked these genotypic differences. Thus, initial screening of large rice germplasm panels can be most efficiently accomplished with a short-duration germination test at low temperature. However, more effective differentiation of cultivars can be accomplished by measuring transplanted seedling growth from the newly-developed mimic protocols. These results will facilitate the development of improved rice cultivars. Full article

(This article belongs to the Special Issue The Adaptation of Agriculture to Climatic Change)

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11 pages, 2383 KiB

Open AccessArticle

Evaluation of Autosteer in Rough Terrain at Low Ground Speed for Commercial Wild Blueberry Harvesting

by Travis J. Esau, Craig B. MacEachern, Aitazaz A. Farooque and Qamar U. Zaman

Agronomy 2021, 11(2), 384; https://doi.org/10.3390/agronomy11020384 - 20 Feb 2021

Cited by 10 | Viewed by 3036

Abstract

Assessment of Global Navigation Satellite Signal (GNSS) autosteering is a critical step in the progression towards full wild blueberry (vaccinium angustifolium) harvester automation. The objective of the study was to analyze John Deere’s universal Auto-Trac 300 autosteer, 4640 display, and Starfire 6000 receiver [...] Read more.

Assessment of Global Navigation Satellite Signal (GNSS) autosteering is a critical step in the progression towards full wild blueberry (vaccinium angustifolium) harvester automation. The objective of the study was to analyze John Deere’s universal Auto-Trac 300 autosteer, 4640 display, and Starfire 6000 receiver with both the SF1 and SF3 signal levels for their pass-to-pass accuracy as well as how they compared versus a manual harvester operator. Incorporation of GNSS autosteer in wild blueberry harvesting has never been assessed as the slow harvester travel speeds and small working width caused the implementation to be too challenging. The results of this study concluded that there were no significant differences in pass-to-pass accuracy based on travel speeds of 0.31 m s⁻¹, 0.45 m s⁻¹, and 0.58 m s⁻¹ (p = 0.174). Comparing the signal levels showed significantly greater accuracy of the SF3 system (p < 0.001), which yielded an absolute mean pass-to-pass accuracy 22.7 mm better than SF1. Neither the SF1 nor SF3 signal levels were able to reach the levels of accuracy advertised by the manufacturer. That said, both signal levels performed better than a manual operator (p < 0.001). This result serves to support the idea that in the absence of skilled operators, an autosteer system can provide significant support for new operators. Further, an autosteer system can allow any operator to focus more of their attention on operating the harvester head and properly filling storage bins. This will lead to higher quality berries with less debris and spoilage. The results of this study are encouraging and represent a significant step towards full harvester automation for the wild blueberry crop. Full article

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23 pages, 781 KiB

Open AccessReview

Micronutrients and Soil Microorganisms in the Suppression of Potato Common Scab

by Jan Kopecky, Daria Rapoport, Ensyeh Sarikhani, Adam Stovicek, Tereza Patrmanova and Marketa Sagova-Mareckova

Agronomy 2021, 11(2), 383; https://doi.org/10.3390/agronomy11020383 - 20 Feb 2021

Cited by 13 | Viewed by 4832

Abstract

Nature-friendly approaches for crop protection are sought after in the effort to reduce the use of agrochemicals. However, the transfer of scientific findings to agriculture practice is relatively slow because research results are sometimes contradictory or do not clearly lead to applicable approaches. [...] Read more.

Nature-friendly approaches for crop protection are sought after in the effort to reduce the use of agrochemicals. However, the transfer of scientific findings to agriculture practice is relatively slow because research results are sometimes contradictory or do not clearly lead to applicable approaches. Common scab of potatoes is a disease affecting potatoes worldwide, for which no definite treatment is available. That is due to many complex interactions affecting its incidence and severity. The review aims to determine options for the control of the disease using additions of micronutrients and modification of microbial communities. We propose three approaches for the improvement by (1) supplying soils with limiting nutrients, (2) supporting microbial communities with high mineral solubilization capabilities or (3) applying communities antagonistic to the pathogen. The procedures for the disease control may include fertilization with micronutrients and appropriate organic matter or inoculation with beneficial strains selected according to local environmental conditions. Further research is proposed to use metagenomics/metabolomics to identify key soil–plant–microbe interactions in comparisons of disease-suppressive and -conducive soils. Full article

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11 pages, 270 KiB

Open AccessArticle

Response to Selection for Reduced Anthesis-Silking Interval in Four Algerian Maize Populations

by Maysoun Benchikh-Lehocine, Pedro Revilla, Rosa Ana Malvar and Abderahmane Djemel

Agronomy 2021, 11(2), 382; https://doi.org/10.3390/agronomy11020382 - 20 Feb 2021

Cited by 6 | Viewed by 2299

Abstract

Drought is the main constraint to maize production in the Mediterranean area. This is the first report of breeding temperate maize populations from the Algerian desert. The objective of this study was to evaluate response to selection for reduced anthesis-silking interval (ASI) in [...] Read more.

Drought is the main constraint to maize production in the Mediterranean area. This is the first report of breeding temperate maize populations from the Algerian desert. The objective of this study was to evaluate response to selection for reduced anthesis-silking interval (ASI) in Algerian maize under drought and control conditions. Three cycles of selection for reduced ASI were carried out in four populations under control and drought conditions, and the breeding program was evaluated under both conditions. Selection under drought was more efficient than under control conditions, particularly for the LOM and TAO populations. Selection for low ASI reduced ASI and days per cycle for BTM and IGS, respectively, under drought conditions. Selection for ASI reduced anthesis in BTM, when selected under drought and evaluated under control conditions. Significant yield increase was observed for BTM under optimal conditions. Significant genetic gain for yield was observed for the population LOM under drought. Therefore, the improved Algerian populations BTM and TAO could be a novel source for reducing ASI and for earlier flowering time as a mechanism for avoiding drought. Furthermore, we propose these populations as sources to develop tolerant inbred lines and to find quantitative trait loci for drought tolerance. Full article

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

19 pages, 5931 KiB

Open AccessArticle

Biochar Promotes Nitrogen Transformation and Tomato Yield by Regulating Nitrogen-Related Microorganisms in Tomato Cultivation Soil

by Lili Guo, Huiwen Yu, Wenquan Niu and Mourad Kharbach

Agronomy 2021, 11(2), 381; https://doi.org/10.3390/agronomy11020381 - 20 Feb 2021

Cited by 12 | Viewed by 3234

Abstract

Nitrogen (N) transformation in soil directly determines the effectiveness of N for plant growth. Biochar has received evermore attention because of its significant ability to improve soil. However, the effects of biochar on N-related microorganisms (Lycopersicon esculentum Mill.) in tomato cultivation [...] Read more.

Nitrogen (N) transformation in soil directly determines the effectiveness of N for plant growth. Biochar has received evermore attention because of its significant ability to improve soil. However, the effects of biochar on N-related microorganisms (Lycopersicon esculentum Mill.) in tomato cultivation soil, N transformation, utilisation of water and N fertiliser, and tomato yield remain unclear. The objective of this study was to investigate the responses of N-related microorganisms to biochar and N fertilisation in soil, along with the implications of biochar for altering N transformation, N uptake by tomatoes, and utilisation of water and N fertiliser. A two-year greenhouse experiment containing six biochar levels under drip irrigation (0, 10, 30, 50, 70, and 90 t ha⁻¹) and two N fertiliser application rates (190 and 250 kg ha⁻¹) was conducted in the northwest of China. The results showed that adding biochar significantly promoted urease activity, microbial biomass carbon (MBC), microbial biomass nitrogen (MBN), and the number of amoA-type nitrifiers in the soil. The MBC:N ratio and the number of nirS-type denitrifiers were significantly inhibited when the added amount of biochar was greater than or equal to 30 t ha⁻¹. Moreover, biochar can increase the water content in the soil and can reduce the N lost to leaching. The inorganic N (NO₃⁻ and NH₄⁺) in the soil could be better maintained in the rootzone and better absorbed by tomato plants when adding 30, 50, and 70 t ha⁻¹ of biochar. The amount of N fertiliser could be reduced by 24% without a significant loss of tomato yield when the amount of biochar added was over 30 t ha⁻¹. It was indicated that the yield of tomatoes and the net profits were quadratically related to the application rate of biochar. In the test area, 53 t ha⁻¹ of biochar with 190 kg ha⁻¹ of N and 44.6 t ha⁻¹ of biochar with 190 kg ha⁻¹ of N were calculated to be the best amounts from the perspectives of tomato yield and net profit, respectively. Thus, biochar promotes N transformation by regulating N-related microorganisms; hence, it increases the inorganic N in the roots of the plants, reduces N lost to leaching, and significantly promotes the N absorption of tomatoes. The results in this research are of great significance for the development of management strategies for tomato maintenance, environmental protection, and resource conservation. Full article

(This article belongs to the Special Issue Applications of Biochar and Other Organic Amendments within a Sustainable Agriculture and Circular Economy)

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18 pages, 4744 KiB

Open AccessEditor’s ChoiceArticle

Biostimulant Activity of Azotobacter chroococcum and Trichoderma harzianum in Durum Wheat under Water and Nitrogen Deficiency

by Silvia Silletti, Emilio Di Stasio, Michael James Van Oosten, Valeria Ventorino, Olimpia Pepe, Mauro Napolitano, Roberta Marra, Sheridan Lois Woo, Valerio Cirillo and Albino Maggio

Agronomy 2021, 11(2), 380; https://doi.org/10.3390/agronomy11020380 - 20 Feb 2021

Cited by 30 | Viewed by 4481

Abstract

Biostimulants hold great potential for developing integrated sustainable agriculture systems. The rhizobacteria Azotobacter chroococcum strain 76A and the fungus Trichoderma harzianum strain T22, with demonstrated biostimulant activity in previous systems, were evaluated in Triticum durum cv Creso for their ability to enhance growth [...] Read more.

Biostimulants hold great potential for developing integrated sustainable agriculture systems. The rhizobacteria Azotobacter chroococcum strain 76A and the fungus Trichoderma harzianum strain T22, with demonstrated biostimulant activity in previous systems, were evaluated in Triticum durum cv Creso for their ability to enhance growth and tolerance to drought stress. Growth and drought tolerance were evaluated in conditions of low and high soil nitrogen, with two levels of water stress. T. harzianum increased plant growth (+16%) under control conditions and tolerance to moderate drought stress (+52%) under optimal fertilization, while A. chroococcum conferred a growth penalty (−28%) in well-watered conditions under suboptimal fertilization and increased tolerance only under extreme drought stress (+15%). This growth penalty was ameliorated by nitrogen fertilization. T. harzianum abundance was found to be positively correlated to extreme soil drying, whereas A. chroococcum-induced tolerance was dependent on soil nitrogen availability. These results indicate that while biostimulants may enhance growth and stress tolerance, nutrient availability soil and environmental conditions heavily influence these responses. These interactions should be considered when designing biostimulant products targeted to specific cultural conditions. Full article

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20 pages, 1070 KiB

Open AccessEditor’s ChoiceArticle

Nitrogen, Phosphorus, and Potassium Adsorption and Desorption Improvement and Soil Buffering Capacity Using Clinoptilolite Zeolite

by Perumal Palanivell, Osumanu Haruna Ahmed, Latifah Omar and Nik Muhamad Abdul Majid

Agronomy 2021, 11(2), 379; https://doi.org/10.3390/agronomy11020379 - 20 Feb 2021

Cited by 20 | Viewed by 3794

Abstract

The physical and chemical properties of clinoptilolite zeolite can be used to enhance soil nutrient availability for optimum crop use. Amending nitrogen, phosphorus, and potassium fertilizers with clinoptilolite zeolite could create a pool of negative charges to retain and release nutrients timely for [...] Read more.

The physical and chemical properties of clinoptilolite zeolite can be used to enhance soil nutrient availability for optimum crop use. Amending nitrogen, phosphorus, and potassium fertilizers with clinoptilolite zeolite could create a pool of negative charges to retain and release nutrients timely for crop use. Thus, we used clinoptilolite zeolite to enhance Typic Paleudults sorption (adsorption and desorption) of nitrogen, phosphorus, potassium, and this soil’s pH buffering capacity. The treatments evaluated were: (i) 250 g soil alone, (ii) 20 g clinoptilolite zeolite alone, (iii) 250 g soil + 20 g clinoptilolite zeolite, (iv) 250 g soil + 40 g clinoptilolite zeolite, and (v) 250 g soil + 60 g clinoptilolite zeolite. Clinoptilolite zeolite increased soil nitrogen and potassium adsorption, nitrogen desorption, and soil pH. Moreover, ability of the soil to resist drastic change in pH (pH buffering capacity) was improved. Additionally, phosphorus adsorption and desorption of phosphorus and potassium were reduced. Higher potassium adsorption with lower potassium desorption suggests that the clinoptilolite zeolite sorbs potassium effectively. The clinoptilolite zeolite nitrogen, phosphorus, and potassium contributed to the reduction in the adsorption these nutrients. The clinoptilolite zeolite improved nitrogen, phosphorus, and potassium availability and soil buffering capacity to prevent these nutrients from being fixed or lost through for example, leaching. Therefore, clinoptilolite zeolite application could contribute to improved use of nitrogen, phosphorus, and potassium fertilizers to prevent soil, air, and water pollution. Additionally, our intervention could improve nitrogen, phosphorus, and potassium use efficiency. Full article

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11 pages, 2165 KiB

Open AccessArticle

Active Control of Greenhouse Climate Enhances Papaya Growth and Yield at an Affordable Cost

by Irene Salinas, Juan José Hueso and Julián Cuevas

Agronomy 2021, 11(2), 378; https://doi.org/10.3390/agronomy11020378 - 20 Feb 2021

Cited by 10 | Viewed by 4121

Abstract

Papaya is a tropical fruit crop that in subtropical regions depends on protected cultivation to fulfill its climate requirements and remain productive. The aim of this work was to compare the profitability of different climate control strategies in greenhouses located in subtropical areas [...] Read more.

Papaya is a tropical fruit crop that in subtropical regions depends on protected cultivation to fulfill its climate requirements and remain productive. The aim of this work was to compare the profitability of different climate control strategies in greenhouses located in subtropical areas of southeast Spain. To do so, we compared papayas growing in a greenhouse equipped with active climate control (ACC), achieved by cooling and heating systems, versus plants growing in another greenhouse equipped with passive climate control (PCC), consisting of only natural ventilation through zenithal and lateral windows. The results showed that ACC favored papaya plant growth; flowering; fruit set; and, consequently, yields, producing more and heavier fruits at an affordable cost. Climate control strategies did not significantly improve fruit quality, specifically fruit skin color, acidity, and total soluble solids content. In conclusion, in the current context of prices, an active control of temperature and humidity inside the greenhouse could be a more profitable strategy in subtropical regions where open-air cultivation is not feasible. Full article

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

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27 pages, 1689 KiB

Open AccessEditor’s ChoiceReview

Using Regulatory Flexibility to Address Market Informality in Seed Systems: A Global Study

by Katrin Kuhlmann and Bhramar Dey

Agronomy 2021, 11(2), 377; https://doi.org/10.3390/agronomy11020377 - 20 Feb 2021

Cited by 26 | Viewed by 6624

Abstract

Seed rules and regulations determine who can produce and sell seeds, which varieties will be available in the market, the quality of seed for sale, and where seed can be bought and sold. The legal and regulatory environment for seed impacts all stakeholders, [...] Read more.

Seed rules and regulations determine who can produce and sell seeds, which varieties will be available in the market, the quality of seed for sale, and where seed can be bought and sold. The legal and regulatory environment for seed impacts all stakeholders, including those in the informal sector, through shaping who can participate in the market and the quality and diversity of seed available. This paper addresses a gap in the current literature regarding the role of law and regulation in linking the informal and formal seed sectors and creating more inclusive and better governed seed systems. Drawing upon insights from the literature, global case studies, key expert consultations, and a methodology on the design and implementation of law and regulation, we present a framework that evaluates how regulatory flexibility can be built into seed systems to address farmers’ needs and engage stakeholders of all sizes. Our study focuses on two key dimensions: extending market frontiers and liberalizing seed quality control mechanisms. We find that flexible regulatory approaches and practices play a central role in building bridges between formal and informal seed systems, guaranteeing quality seed in the market, and encouraging market entry for high-quality traditional and farmer-preferred varieties. Full article

(This article belongs to the Special Issue The Role of Policies in Plant Breeding—Rights and Obligations)

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28 pages, 2265 KiB

Open AccessEditor’s ChoiceReview

Modern Approaches for the Genetic Improvement of Rice, Wheat and Maize for Abiotic Constraints-Related Traits: A Comparative Overview

by Elena Benavente and Estela Giménez

Agronomy 2021, 11(2), 376; https://doi.org/10.3390/agronomy11020376 - 20 Feb 2021

Cited by 22 | Viewed by 7340

Abstract

After a basic description of the different sets of genetic tools and genomic approaches most relevant for modern crop breeding (e. g., QTL mapping, GWAS and genomic selection; transcriptomics, qPCR and RNA-seq; transgenesis and gene editing), this review paper describes their history and [...] Read more.

After a basic description of the different sets of genetic tools and genomic approaches most relevant for modern crop breeding (e. g., QTL mapping, GWAS and genomic selection; transcriptomics, qPCR and RNA-seq; transgenesis and gene editing), this review paper describes their history and the main achievements in rice, wheat and maize research, with a further focus on crop traits related to the improvement of plant responses to face major abiotic constrains, including nutritional limitations, drought and heat tolerance, and nitrogen-use efficiency (NUE). Remarkable differences have been evidenced regarding the timing and degree of development of some genetic approaches among these major crops. The underlying reasons related to their distinct genome complexity, are also considered. Based on bibliographic records, drought tolerance and related topics (i.e., water-use efficiency) are by far the most abundantly addressed by molecular tools among the breeding objectives considered. Heat tolerance is usually more relevant than NUE in rice and wheat, while the opposite is true for maize. Full article

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

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