Showing papers in "Agronomy in 2019"
TL;DR: This review examines and summarises literature on biostimulant use on vegetable crops, focusing on their application to counteract the most common environmental stresses.
Abstract: Abiotic stresses strongly affect plant growth, development, and quality of production; final crop yield can be really compromised if stress occurs in plants’ most sensitive phenological phases. Additionally, the increase of crop stress tolerance through genetic improvements requires long breeding programmes and different cultivation environments for crop performance validation. Biostimulants have been proposed as agronomic tools to counteract abiotic stress. Indeed, these products containing bioactive molecules have a beneficial effect on plants and improve their capability to face adverse environmental conditions, acting on primary or secondary metabolism. Many companies are investing in new biostimulant products development and in the identification of the most effective bioactive molecules contained in different kinds of extracts, able to elicit specific plant responses against abiotic stresses. Most of these compounds are unknown and their characterization in term of composition is almost impossible; therefore, they could be classified on the basis of their role in plants. Biostimulants have been generally applied to high-value crops like fruits and vegetables; thus, in this review, we examine and summarise literature on their use on vegetable crops, focusing on their application to counteract the most common environmental stresses.
301 citations
TL;DR: Worldwide, MBS and MBF remain largely unexploited, such that this study highlights some of the current researches and future development priorities.
Abstract: Microalgae are attracting the interest of agrochemical industries and farmers, due to their biostimulant and biofertiliser properties. Microalgal biostimulants (MBS) and biofertilisers (MBF) might be used in crop production to increase agricultural sustainability. Biostimulants are products derived from organic material that, applied in small quantities, are able to stimulate the growth and development of several crops under both optimal and stressful conditions. Biofertilisers are products containing living microorganisms or natural substances that are able to improve chemical and biological soil properties, stimulating plant growth, and restoring soil fertility. This review is aimed at reporting developments in the processing of MBS and MBF, summarising the biologically-active compounds, and examining the researches supporting the use of MBS and MBF for managing productivity and abiotic stresses in crop productions. Microalgae are used in agriculture in different applications, such as amendment, foliar application, and seed priming. MBS and MBF might be applied as an alternative technique, or used in conjunction with synthetic fertilisers, crop protection products and plant growth regulators, generating multiple benefits, such as enhanced rooting, higher crop yields and quality and tolerance to drought and salt. Worldwide, MBS and MBF remain largely unexploited, such that this study highlights some of the current researches and future development priorities.
239 citations
TL;DR: In this article, a bibliometric assessment of scientific documents and patents related to wheat and barley through the Scopus database was conducted, where the number of documents published per year, their affiliation and corresponding scientific areas, publishing journals, document types and languages were metricized.
Abstract: Grain cereals such as wheat, barley, rice, and maize are the nutritional basis of humans and animals worldwide. Thus, these crop plants are essential in terms of global food security. We conducted a bibliometric assessment of scientific documents and patents related to wheat and barley through the Scopus database. The number of documents published per year, their affiliation and corresponding scientific areas, the publishing journals, document types and languages were metricized. The main keywords included in research publications concerning these crops were also analysed globally and clustered in thematic groups. In the case of keywords related to agronomy or genetics and molecular biology, we considered documents dated up to 1999, and from 2000 to 2018, separately. Comparison of the results obtained for wheat and barley revealed some remarkable different trends, for which the underlying reasons are further discussed.
231 citations
TL;DR: This review gives an overview of the importance and influence of different natural plant biostimulants on both the yield and quality of crops.
Abstract: Biostimulants are among the natural preparations that improve the general health, vitality, and growth of plants and protect them against infections. They can be successfully used in both agri- and horticultural crops. The main active substances used in such preparations are humic and fulvic acids, protein hydrolysates, compounds containing nitrogen, seaweed extracts, beneficial fungi, and bacteria. Biostimulant formulations may be single- or multi-component, but the synergic action of several different components has been observed. Many groups of biostimulants have been distinguished through their method of application (soil, foliar), the material from which they were produced (plant, animal), or the process by which they were created (hydrolysis, fermentation, extraction). Natural soil stimulants can induce the development of beneficial soil organisms that provide substrates for plant growth. The use of natural preparations that are not harmful to the environment is particularly important in connection with the progressive processes of soil degradation and atmospheric pollution. This review gives an overview of the importance and influence of different natural plant biostimulants on both the yield and quality of crops.
217 citations
TL;DR: While most vineyards in Europe are currently dry-farmed, irrigation may also be an option to grow sustainable yields under increasingly dry conditions but consideration must be given to associated impacts on water resources and the environment.
Abstract: Climate change will impose increasingly warm and dry conditions on vineyards. Wine quality and yield are strongly influenced by climatic conditions and depend on complex interactions between temperatures, water availability, plant material, and viticultural techniques. In established winegrowing regions, growers have optimized yield and quality by choosing plant material and viticultural techniques according to local climatic conditions, but as the climate changes, these will need to be adjusted. Adaptations to higher temperatures include changing plant material (e.g., rootstocks, cultivars and clones) and modifying viticultural techniques (e.g., changing trunk height, leaf area to fruit weight ratio, timing of pruning) such that harvest dates are maintained in the optimal period at the end of September or early October in the Northern Hemisphere. Vineyards can be made more resilient to drought by planting drought resistant plant material, modifying training systems (e.g., goblet bush vines, or trellised vineyards at wider row spacing), or selecting soils with greater soil water holding capacity. While most vineyards in Europe are currently dry-farmed, irrigation may also be an option to grow sustainable yields under increasingly dry conditions but consideration must be given to associated impacts on water resources and the environment.
177 citations
TL;DR: In this article, the authors provide a comprehensive critical review of current developments in soilless culture, growing media, and future options of using different materials other than peat and rockwool.
Abstract: Decreasing arable land, rising urbanization, water scarcity, and climate change exert pressure on agricultural producers. Moving from soil to soilless culture systems can improve water use efficiency, especially in closed-loop systems with a recirculating water/nutrient solution that recaptures the drain water for reuse. However, the question of alternative materials to peat and rockwool, as horticultural substrates, has become increasingly important, due to the despoiling of ecologically important peat bog areas and a pervasive waste problem. In this paper, we provide a comprehensive critical review of current developments in soilless culture, growing media, and future options of using different materials other than peat and rockwool. Apart from growing media properties and their performance from the point of view of plant production, economic and environmental factors are also important. Climate change, CO2 emissions, and other ecological issues will determine and drive the development of soilless culture systems and the choice of growing media in the near future. Bioresources, e.g., treated and untreated waste, as well as renewable raw materials, have great potential to be used as growing media constituents and stand-alone substrates. A waste management strategy aimed at reducing, reusing, and recycling should be further and stronger applied in soilless culture systems. We concluded that the growing media of the future must be available, affordable, and sustainable and meet both quality and environmental requirements from growers and society, respectively.
156 citations
TL;DR: This review deals with the main mechanisms of action exerted by antagonistic bacteria, such as competition for space and nutrients, suppression via siderophores, hydrolytic enzymes, antibiosis, biofilm formation, and induction of plant resistance, which inhibit phytopathogen growth that affects postharvest fruit.
Abstract: This review deals with the main mechanisms of action exerted by antagonistic bacteria, such as competition for space and nutrients, suppression via siderophores, hydrolytic enzymes, antibiosis, biofilm formation, and induction of plant resistance. These mechanisms inhibit phytopathogen growth that affects postharvest fruit since quality and safety parameters are influenced by the action of these microorganisms, which cause production losses in more than 50% of fruit tree species. The use of synthetic fungicide products has been the dominant control strategy for diseases caused by fungi. However, their excessive and inappropriate use in intensive agriculture has brought about problems that have led to environmental contamination, considerable residues in agricultural products, and phytopathogen resistance. Thus, there is a need to generate alternatives that are safe, ecological, and economically viable to face this problem. Phytopathogen inhibition in fruit utilizing antagonist microorganisms has been recognized as a type of biological control (BC), which could represent a viable and environmentally safe alternative to synthetic fungicides. Despite the ecological benefit that derives from the use of controllers and biological control agents (BCA) at a commercial level, their application and efficient use has been minimal at a global level.
130 citations
TL;DR: The advantages are demonstrated of a powerful tool that applies real-time decisions from data such as variable rate irrigation, and selected parameters from field and weather conditions to provide the farmer with added value in the form of better decision making or more efficient exploitation operations and management.
Abstract: This paper has been partially supported by the European Union through the ERANETMED (Euromediterranean Cooperation through ERANET joint activities and beyond) project ERANETMED3-227 SMARTWATIR and by the "Ministerio de Ciencia, Innovacion y Universidades" through the "Ayudas para la adquisicion de equipamiento cientifico-tecnico, Subprograma estatal de infraestructuras de investigacion y equipamiento cientifico-tecnico (plan Estatal i+d+i 2017-2020)" (project EQC2018-004988-P).
129 citations
TL;DR: The analysis shows that besides case-specific optimization of irrigation and drainage management, combinations of soil amendments, conditioners, and residue management can contribute to significant reductions of soil salinity while significantly increasing crop yields and highlights that conservation agriculture can also achieve the higher yields required for upscaling and sustaining crop production.
Abstract: A major challenge of the Sustainable Development Goals linked to Agriculture, Food Security, and Nutrition, under the current global crop production paradigm, is that increasing crop yields often have negative environmental impacts. It is therefore urgent to develop and adopt optimal soil-improving cropping systems (SICS) that can allow us to decouple these system parameters. Soil salinization is a major environmental hazard that limits agricultural potential and is closely linked to agricultural mismanagement and water resources overexploitation, especially in arid climates. Here we review literature seeking to ameliorate the negative effect of soil salinization on crop productivity and conduct a global meta-analysis of 128 paired soil quality and yield observations from 30 studies. In this regard, we compared the effectivity of different SICS that aim to cope with soil salinization across 11 countries, in order to reveal those that are the most promising. The analysis shows that besides case-specific optimization of irrigation and drainage management, combinations of soil amendments, conditioners, and residue management can contribute to significant reductions of soil salinity while significantly increasing crop yields. These results highlight that conservation agriculture can also achieve the higher yields required for upscaling and sustaining crop production.
125 citations
TL;DR: Various techniques for plant phenotyping are presented together with applications of these techniques for breeding and cultivation and the key differences in the applications of such methods are highlighted.
Abstract: High-throughput field phenotyping has garnered major attention in recent years leading to the development of several new protocols for recording various plant traits of interest. Phenotyping of plants for breeding and for precision agriculture have different requirements due to different sizes of the plots and fields, differing purposes and the urgency of the action required after phenotyping. While in plant breeding phenotyping is done on several thousand small plots mainly to evaluate them for various traits, in plant cultivation, phenotyping is done in large fields to detect the occurrence of plant stresses and weeds at an early stage. The aim of this review is to highlight how various high-throughput phenotyping methods are used for plant breeding and farming and the key differences in the applications of such methods. Thus, various techniques for plant phenotyping are presented together with applications of these techniques for breeding and cultivation. Several examples from the literature using these techniques are summarized and the key technical aspects are highlighted.
120 citations
TL;DR: Multifaceted PGPRs are potential candidates for biofertilizer production to lessen the detrimental effects of drought stress on crops cultivated in arid regions and ways of augmenting their efficacy as bio-inoculants under field conditions are proffered.
Abstract: Abiotic stresses arising from climate change negates crop growth and yield, leading to food insecurity. Drought causes oxidative stress on plants, arising from excessive production of reactive oxygen species (ROS) due to inadequate CO2, which disrupts the photosynthetic machinery of plants. The use of conventional methods for the development of drought-tolerant crops is time-consuming, and the full adoption of modern biotechnology for crop enhancement is still regarded with prudence. Plant growth-promoting rhizobacteria (PGPR) could be used as an inexpensive and environmentally friendly approach for enhancing crop growth under environmental stress. The various direct and indirect mechanisms used for plant growth enhancement by PGPR were discussed. Synthesis of 1-aminocyclopropane−1-carboxylate (ACC) deaminase enhances plant nutrient uptake by breaking down plant ACC, thereby preventing ethylene accumulation, and enable plants to tolerate water stress. The exopolysaccharides produced also improves the ability of the soil to withhold water. PGPR enhances osmolyte production, which is effective in reducing the detrimental effects of ROS. Multifaceted PGPRs are potential candidates for biofertilizer production to lessen the detrimental effects of drought stress on crops cultivated in arid regions. This review proffered ways of augmenting their efficacy as bio-inoculants under field conditions and highlighted future prospects for sustainable agricultural productivity.
TL;DR: In this article, the influence of salicylic acid (1 mM), yeast extract (6 g L−1), and proline (10 mM) on the physiological and biochemical parameters of sweet pepper plants under saline conditions (2000 and 4000 ppm).
Abstract: Salinity stress occurs due to the accumulation of high levels of salts in soil, which ultimately leads to the impairment of plant growth and crop loss. Stress tolerance-inducing compounds have a remarkable ability to improve growth and minimize the effects of salinity stress without negatively affecting the environment by controlling the physiological and molecular activities in plants. Two pot experiments were carried out in 2017 and 2018 to study the influence of salicylic acid (1 mM), yeast extract (6 g L−1), and proline (10 mM) on the physiological and biochemical parameters of sweet pepper plants under saline conditions (2000 and 4000 ppm). The results showed that salt stress led to decreasing the chlorophyll content, relative water content, and fruit yields, whereas electrolyte leakage, malondialdehyde (MDA), proline concentration, reactive oxygen species (ROS), and the activities of antioxidant enzymes increased in salt-stressed plants. The application of salicylic acid (1 mM), yeast extract (6 g L−1), and proline (10 mM) markedly improved the physiological characteristics and fruit yields of salt-stressed plants compared with untreated stressed plants. A significant reduction in electrolyte leakage, MDA, and ROS was also recorded for all treatments. In conclusion, our results reveal the important role of proline, SA, and yeast extracts in enhancing sweet pepper growth and tolerance to salinity stress via modulation of the physiological parameters and antioxidants machinery. Interestingly, proline proved to be the best treatment.
TL;DR: It is evident that both CS and CNPs have tremendous potential against phytopathogens of tomato for further field screening towards crop protection.
Abstract: The present study was to prepare chitosan nanoparticles (CNPs) from chitosan (CS) to evaluate their in vitro antimicrobial activities against phytopathogens of tomato. We prepared and characterized CNPs for their particle size, polydispersity index, and structures. The antifungal properties of CS and CNPs against phytopathogenic fungi namely Colletotrichum gelosporidies, Phytophthora capsici, Sclerotinia sclerotiorum, Fusarium oxysporum, Gibberella fujikuori were investigated. CNPs showed the maximum growth inhibitory effects on mycelial growth of F. oxysporum followed by P. capsici. We also studied antibacterial activities against phytopathogenic bacteria, such as three strains of Erwinia carotovora subsp. carotovora and one strain of Xanthomonas campestris pv. vesicatoria. Our results showed that both CS and CNPs markedly inhibited the growth of the both Xanthomonas and Erwinia strains. From our study, it is evident that both CS and CNPs have tremendous potential against phytopathogens of tomato for further field screening towards crop protection.
TL;DR: Observations indicate that application of nano-silicon dioxide can limit the adverse anatomical and biochemical changes related to salt stress impacts on strawberry plants and that this is, in part, associated with epicuticular wax deposition.
Abstract: Silicon application can improve productivity outcomes for salt stressed plants. Here, we describe how strawberry plants respond to treatments including various combinations of salt stress and nano-silicon dioxide, and assess whether nano-silicon dioxide improves strawberry plant tolerance to salt stress. Strawberry plants were treated with salt (0, 25 or 50 mM NaCl), and the nano-silicon dioxide treatments were applied to the strawberry plants before (0, 50 and 100 mg L−1) or after (0 and 50 mg L−1) flowering. The salt stress treatments reduced plant biomass, chlorophyll content, and leaf relative water content (RWC) as expected. Relative to control (no NaCl) plants the salt treated plants had 10% lower membrane stability index (MSI), 81% greater proline content, and 54% greater cuticular transpiration; as well as increased canopy temperature and changes in the structure of the epicuticular wax layer. The plants treated with nano-silicon dioxide were better able to maintain epicuticular wax structure, chlorophyll content, and carotenoid content and accumulated less proline relative to plants treated only with salt and no nano-silicon dioxide. Analysis of scanning electron microscopic (SEM) images revealed that the salt treatments resulted in changes in epicuticular wax type and thickness, and that the application of nano-silicon dioxide suppressed the adverse effects of salinity on the epicuticular wax layer. Nano-silicon dioxide treated salt stressed plants had increased irregular (smoother) crystal wax deposits in their epicuticular layer. Together these observations indicate that application of nano-silicon dioxide can limit the adverse anatomical and biochemical changes related to salt stress impacts on strawberry plants and that this is, in part, associated with epicuticular wax deposition.
TL;DR: Understanding how rice blast is affected by environmental conditions at the cellular and genetic level will provide critical insight into incidence of the disease in future climates for effective decision-making and management.
Abstract: Rice blast is a serious fungal disease of rice (Oryza sativa L.) that is threatening global food security. It has been extensively studied due to the importance of rice production and consumption, and because of its vast distribution and destructiveness across the world. Rice blast, caused by Pyricularia oryzae Cavara 1892 (A), can infect aboveground tissues of rice plants at any growth stage and cause total crop failure. The pathogen produces lesions on leaves (leaf blast), leaf collars (collar blast), culms, culm nodes, panicle neck nodes (neck rot), and panicles (panicle blast), which vary in color and shape depending on varietal resistance, environmental conditions, and age. Understanding how rice blast is affected by environmental conditions at the cellular and genetic level will provide critical insight into incidence of the disease in future climates for effective decision-making and management. Integrative strategies are required for successful control of rice blast, including chemical use, biocontrol, selection of advanced breeding lines and cultivars with resistance genes, investigating genetic diversity and virulence of the pathogen, forecasting and mapping distribution of the disease and pathogen races, and examining the role of wild rice and weeds in rice blast epidemics. These tactics should be integrated with agronomic practices including the removal of crop residues to decrease pathogen survival, crop and land rotations, avoiding broadcast planting and double cropping, water management, and removal of yield-limiting factors for rice production. Such an approach, where chemical use is based on crop injury and estimated yield and economic losses, is fundamental for the sustainable control of rice blast to improve rice production for global food security.
TL;DR: In this paper, the use of combined nano-micronutrients to ameliorate salinity stress in potato plants (Solanum tuberosum L) was investigated.
Abstract: Salinity stress is a severe environmental stress that affects plant growth and productivity of potato, a strategic crop moderately sensitive to saline soils. Limited studies are available on the use of combined nano-micronutrients to ameliorate salinity stress in potato plants (Solanum tuberosum L.). Two open field experiments were conducted in salt-affected sandy soil to investigate plant growth, physiology, and yield of potato in response to soil salinity stress under single or combined application of Zn, B, Si, and Zeolite nanoparticles. It was hypothesized that soil application of nanoparticles enhanced plant growth and yield by alleviating the adverse impact of soil salinity. In general, all the nano-treatments applications significantly increased plant height, shoot dry weight, number of stems per plant, leaf relative water content, leaf photosynthetic rate, leaf stomatal conductance, chlorophyll content, and tuber yield, as compared to the untreated control. Furthermore, soil application of these treatments increased the concentration of nutrients (N, P, K, Ca, Zn, and B) in plant tissues, leaf proline, and leaf gibberellic acid hormone (GA3) in addition to contents of protein, carbohydrates, and antioxidant enzymes (polyphenol oxidase (PPO) and peroxidase (POD) in tubers. Compared to other treatments, the combined application of nanoparticles showed the highest plant growth, physiological parameters, endogenous elements (N, P, K, Ca, Zn, and B) and the lowest concentration of leaf abscisic acid (ABA) and transpiration rate. The present findings suggest that soil addition of the aforementioned nanoparticles can be a promising approach to improving crop productivity in salt-affected soils.
TL;DR: It is suggested that the combined soil application of B. amyloliquefaciens and BC more effectively mitigates drought stress and improves wheat productivity as compared to any of the individual soil applications tested in this study.
Abstract: Drought stress retards wheat plant’s vegetative growth and physiological processes and results in low productivity. A stressed plant synthesizes ethylene which inhibits root elongation; however, the enzyme 1-Aminocyclopropane-1-Carboxylate (ACC) deaminase catabolizes ethylene produced under water stress. Therefore, the ACC deaminase producing plant growth promoting rhizobacteria (PGPR) can be used to enhance crop productivity under drought stress. Biochar (BC) is an organically active and potentially nutrient-rich amendment that, when applied to the soil, can increase pore volume, cation exchange capacity and nutrient retention and bioavailability. We conducted a field experiment to study the effect of drought tolerant, ACC deaminase producing PGPR (with and without timber waste BC) on plant growth and yield parameters under drought stress. Two PGPR strains, Agrobacterium fabrum or Bacillus amyloliquefaciens were applied individually and in combination with 30 Mg ha−1 BC under three levels of irrigation, i.e., recommended four irrigations (4I), three irrigations (3I) and two irrigations (2I). Combined application of B. amyloliquefaciens and 30 Mg ha−1 BC under 3I, significantly increased growth and yield traits of wheat: grain yield (36%), straw yield (50%), biological yield (40%). The same soil application under 2I resulted in greater increases in several of the growth and yield traits: grain yield (77%), straw yield (75%), above- and below-ground biomasses (77%), as compared to control; however, no significant increases in chlorophyll a, b or total, and photosynthetic rate and stomatal conductance in response to individual inoculation of a PGPR strain (without BC) were observed. Therefore, we suggest that the combined soil application of B. amyloliquefaciens and BC more effectively mitigates drought stress and improves wheat productivity as compared to any of the individual soil applications tested in this study.
TL;DR: The results reveal that Si mitigates LP stress by improving photosynthetic capacity, antioxidant potential, and nutrient homeostasis and that it can be used for agronomic management of vegetable crops in P-deficient soils.
Abstract: Phosphorus (P) deficiency in soils is a major problem for sustainable crop production worldwide. Silicon (Si) is a beneficial element that can promote plant growth, development and responses to stresses. However, the effect of Si on tomato (Solanum lycopersicum L.) growth, photosynthesis and mineral uptake under P deficit conditions and underlying mechanisms remain unclear. Here, we showed that low P (LP) supply inhibited tomato growth as revealed by significantly decreased fresh and dry weights of shoots and impaired root morphological traits. LP-induced growth inhibition was associated with decreased photosynthetic pigment content, net photosynthetic rate (Pn), stomatal conductance, transpiration rate and water use efficiency. However, exogenous Si application alleviated LP-induced decreases in growth and physiological parameters. In particular, Si increased Pn by 65.2%, leading to a significantly increased biomass accumulation. Biochemical quantification and in situ visualization of reactive oxygen species (ROS) showed increased ROS (O2−· and H2O2) accumulation under LP stress, which eventually elevated lipid peroxidation. Interestingly, exogenous Si decreased ROS and malondialdehyde levels by substantially increasing the activity of antioxidant enzymes, including superoxide dismutase, peroxidase, and catalase. In addition, Si increased concentrations of osmoregulatory substances, such as proline, soluble sugar, soluble proteins, free amino acids, and organic acids under LP stress. Analysis of major element concentrations revealed that exogenous Si application under LP stress not only increased Si uptake but also enhanced the concentrations of most essential elements (K, Na, Ca, Mg, Fe, and Mn) in different tissues (roots, leaves, and stems). These results reveal that Si mitigates LP stress by improving photosynthetic capacity, antioxidant potential, and nutrient homeostasis and that it can be used for agronomic management of vegetable crops in P-deficient soils.
TL;DR: There is, currently, much interest in the development of efficient strategies to mitigate the risks associated to the application of organic amendments to agricultural soil, while benefiting from their numerous advantages.
Abstract: The use of organic amendments in agriculture is a common practice due to their potential to increase crop productivity and enhance soil health. Indeed, organic amendments of different origin and composition (e.g., animal slurry, manure, compost, sewage sludge, etc.) can supply valuable nutrients to the soil, as well as increase its organic matter content, with concomitant benefits for soil health. However, the application of organic amendments to agricultural soil entails a variety of risks for environmental and human health. Organic amendments often contain a range of pollutants, including heavy metals, persistent organic pollutants, potential human pathogens, and emerging pollutants. Regarding emerging pollutants, the presence of antibiotic residues, antibiotic-resistant bacteria, and antibiotic-resistance genes in agricultural amendments is currently a matter of much concern, due to the concomitant risks for human health. Similarly, currently, the introduction of microplastics to agricultural soil, via the application of organic amendments (mainly, sewage sludge), is a topic of much relevance, owing to its magnitude and potential adverse effects for environmental health. There is, currently, much interest in the development of efficient strategies to mitigate the risks associated to the application of organic amendments to agricultural soil, while benefiting from their numerous advantages.
TL;DR: In this article, the authors investigated how bioenergy cropping systems can become more social-ecologically sustainable in future and brought together expert opinions from the fields of agronomy, economics, meteorology, and geography.
Abstract: The growing bioeconomy will require a greater supply of biomass in the future for both bioenergy and bio-based products. Today, many bioenergy cropping systems (BCS) are suboptimal due to either social-ecological threats or technical limitations. In addition, the competition for land between bioenergy-crop cultivation, food-crop cultivation, and biodiversity conservation is expected to increase as a result of both continuous world population growth and expected severe climate change effects. This study investigates how BCS can become more social-ecologically sustainable in future. It brings together expert opinions from the fields of agronomy, economics, meteorology, and geography. Potential solutions to the following five main requirements for a more holistically sustainable supply of biomass are summarized: (i) bioenergy-crop cultivation should provide a beneficial social-ecological contribution, such as an increase in both biodiversity and landscape aesthetics, (ii) bioenergy crops should be cultivated on marginal agricultural land so as not to compete with food-crop production, (iii) BCS need to be resilient in the face of projected severe climate change effects, (iv) BCS should foster rural development and support the vast number of small-scale family farmers, managing about 80% of agricultural land and natural resources globally, and (v) bioenergy-crop cultivation must be planned and implemented systematically, using holistic approaches. Further research activities and policy incentives should not only consider the economic potential of bioenergy-crop cultivation, but also aspects of biodiversity, soil fertility, and climate change adaptation specific to site conditions and the given social context. This will help to adapt existing agricultural systems in a changing world and foster the development of a more social-ecologically sustainable bioeconomy.
TL;DR: The hypothesis that the use of microbial consortia can increase the efficiency and reproducibility of BS-assisted strategies for crop production, particularly under challenging environmental conditions is supported.
Abstract: The use of biostimulants with plant growth-promoting properties, but without significant input of nutrients, is discussed as a strategy to increase stress resistance and nutrient use efficiency of crops. However, limited reproducibility under real production conditions remains a major challenge. The use of combination products based on microbial and non-microbial biostimulants or microbial consortia, with the aim to exploit complementary or synergistic interactions and increase the flexibility of responses under different environmental conditions, is discussed as a potential strategy to overcome this problem. This study aimed at comparing the efficiency of selected microbial single-strain inoculants with proven plant-growth promoting potential versus consortium products under real production conditions in large-scale tomato cultivation systems, exposed to different environmental challenges. In a protected greenhouse production system at Timisoara, Romania, with composted cow manure, guano, hair-, and feather-meals as major fertilizers, different fungal and bacterial single-strain inoculants, as well as microbial consortium products, showed very similar beneficial responses. Nursery performance, fruit setting, fruit size distribution, seasonal yield share, and cumulative yield (39–84% as compared to the control) were significantly improved over two growing periods. By contrast, superior performance of the microbial consortia products (MCPs) was recorded under more challenging environmental conditions in an open-field drip-fertigated tomato production system in the Negev desert, Israel with mineral fertilization on a high pH (7.9), low fertility, and sandy soil. This was reflected by improved phosphate (P) acquisition, a stimulation of vegetative shoot biomass production and increased final fruit yield under conditions of limited P supply. Moreover, MCP inoculation was associated with selective changes of the rhizosphere-bacterial community structure particularly with respect to Sphingobacteriia and Flavobacteria, reported as salinity indicators and drought stress protectants. Phosphate limitation reduced the diversity of bacterial populations at the root surface (rhizoplane) and this effect was reverted by MCP inoculation, reflecting the improved P status of the plants. The results support the hypothesis that the use of microbial consortia can increase the efficiency and reproducibility of BS-assisted strategies for crop production, particularly under challenging environmental conditions.
TL;DR: Results showed that across the seasons, treatment T6 increased the net photosynthesis rate, total biomass, grain yield, and amylose content by 23%, 90%, 95%, and 10%, respectively, compared with control, which provided a sustainable nutrient management strategy to improve crop yield with high nutrient use efficiency.
Abstract: The current farming system is heavily reliant on chemical fertilizers, which negatively affect soil health, the environment, and crop productivity. Improving crop production on a sustainable basis is a challenging issue in the present agricultural system. To address this issue, we assumed that the combined use of organic manure and inorganic nitrogen (N) fertilizers can improve rice grain yield and soil properties without the expense of the environment. This study explores the combined effects of cattle manure (CM), poultry manure (PM), and chemical fertilizer (CF) on soil properties, rice growth, physiology, and grain yield and quality. Six treatments in the following combinations were included: T1—no N fertilizer; T2—100% CF; T3—60% CM + 40% CF; T4—30% CM + 70% CF; T5—60% PM + 40% CF; and T6—30% PM + 70% CF. Results showed that across the seasons, treatment T6 increased the net photosynthesis rate, total biomass, grain yield, and amylose content by 23%, 90%, 95%, and 10%, respectively, compared with control. This increment in net photosynthetic rate and growth was the result of 24%, 14%, 19%, and 20% higher total root length, root surface area, root volume, and root diameter, respectively. Improvements in these attributes further enhanced the grain yield and nitrogen use efficiency of rice. No significant difference between T4 and T6 was observed. The correlation analysis also confirmed that root morphological traits were positively correlated with grain yield, N uptake, and biomass accumulation. Similarly, improvement in grain yield and NUE was also associated with improved soil properties, i.e., bulk density, soil porosity, soil organic carbon, and total N under combined organic and inorganic N fertilizers treatment. Conclusively, the integration of 30% N from PM or CM with 70% N from CF (urea) is a promising option not only for higher grain yield and quality of rice but also for improved soil health. This study provides a sustainable nutrient management strategy to improve crop yield with high nutrient use efficiency.
TL;DR: This review concludes with a discussion on the pros and cons of this technology, along with a brief outlook into future areas of research regarding UAS technology in agriculture.
Abstract: Numerous sensors have been developed over time for precision agriculture; though, only recently have these sensors been incorporated into the new realm of unmanned aircraft systems (UAS). This UAS technology has allowed for a more integrated and optimized approach to various farming tasks such as field mapping, plant stress detection, biomass estimation, weed management, inventory counting, and chemical spraying, among others. These systems can be highly specialized depending on the particular goals of the researcher or farmer, yet many aspects of UAS are similar. All systems require an underlying platform—or unmanned aerial vehicle (UAV)—and one or more peripherals and sensing equipment such as imaging devices (RGB, multispectral, hyperspectral, near infra-red, RGB depth), gripping tools, or spraying equipment. Along with these wide-ranging peripherals and sensing equipment comes a great deal of data processing. Common tools to aid in this processing include vegetation indices, point clouds, machine learning models, and statistical methods. With any emerging technology, there are also a few considerations that need to be analyzed like legal constraints, economic trade-offs, and ease of use. This review then concludes with a discussion on the pros and cons of this technology, along with a brief outlook into future areas of research regarding UAS technology in agriculture.
TL;DR: Results show that plant growth significantly improved by applying L-methionine at the lowest concentrations of 0.2 mg/L and 0.02mg/L, which can, therefore, improve hydroponic production of lettuce and, accordingly, human nutrition.
Abstract: As natural plant growth stimulators, amino acids are widely used to improve the yield and quality of crops. Several studies have illustrated the effects of different amino acids on lettuce plant parts. However, the effects of applying single amino acids on root growth remain elusive. The objective of this study was to evaluate the effect of root application of L-methionine on the growth of lettuce. In this study, two successive experiments on butterhead lettuce were conducted under hydroponic conditions. Three amino acids, L-methionine (20 mg/L), L-glycine (210 mg/L), and L-tryptophan (220 mg/L), were applied separately. L-methionine significantly increased the growth performance by 23.60%, whereas growth using L-tryptophan and L-glycine decreased by 98.78% and 27.45%, respectively. Considering the results of the first experiment, a second experiment was established with different concentrations of L-methionine (2200 mg/L, 220 mg/L, 22 mg/L, 2.2 mg/L, 0.2 mg/L, and 0.02 mg/L). The plants were allowed to grow for four weeks. Leaf width, plant area, leaf area, chlorophyll contents, etc., were evaluated. The results show that plant growth significantly improved by applying L-methionine at the lowest concentrations of 0.2 mg/L and 0.02 mg/L, which can, therefore, improve hydroponic production of lettuce and, accordingly, human nutrition.
TL;DR: The intrinsic value of genome editing is revealed and the knowledge about the network of proteins for leaf rolling and drought avoidance in rice is expanded.
Abstract: Rice leaf morphology is an essential agronomic trait to develop drought-tolerant genotypes for adequate and stable crop production in drought-prone areas. Here, rolled leaf mutant plants were acquired by CRISPR/Cas9-based mutagenesis of Semi-rolled leaf1,2 (SRL1 and SRL2) genes, and isobaric tags for relative and absolute quantification (iTRAQ) based proteomic analysis was performed to analyze the subsequent proteomic regulation events. Homozygous mutants exhibit decreased chlorophyll content, transpiration rate, stomatal conductance, vascular bundles (VB), stomatal number, and agronomic traits with increased panicle number and bulliform cells (BCs). Under drought stress, mutant plants displayed lower malondialdehyde (MDA) content while higher survival rate, abscisic acid (ABA) content, superoxide dismutase (SOD), catalase (CAT) activities, and grain filling percentage compare with their wild type (WT). Proteomic results revealed that 270 proteins were significantly downregulated, and 107 proteins were upregulated in the mutant line compared with WT. Proteins related to lateral organ boundaries’ (LOB) domain (LBD) were downregulated, whereas abiotic stress-responsive proteins were upregulated in the CRISPR mutant. LBD proteins (Q5KQR7, Q6K713, Q7XGL4, Q8LQH4), probable indole-3-acetic acid-amido synthetase (Q60EJ6), putative auxin transporter-like protein 4 (Q53JG7), Monoculm 1 (Q84MM9) and AP2 (Apetala2) domain-containing protein (Q10A97) were found to be hub-proteins. The hybrids developed from mutant restorers showed a semi-rolled leaf phenotype with increased panicle number, grain number per panicle, and yield per plant. Our findings reveal the intrinsic value of genome editing and expand the knowledge about the network of proteins for leaf rolling and drought avoidance in rice.
TL;DR: This review presents the responses of green peas, snap beans, tomatoes and sweet corn to water stress based on their stomatal behaviour, canopy temperature, chlorophyll fluorescence and the chlorophyLL content of leaves.
Abstract: The frequency of drought periods influences the yield potential of crops under field conditions. The change in morphology and anatomy of plants has been tested during drought stress under controlled conditions but the change in physiological processes has not been adequately studied in separate studies but needs to be reviewed collectively. This review presents the responses of green peas, snap beans, tomatoes and sweet corn to water stress based on their stomatal behaviour, canopy temperature, chlorophyll fluorescence and the chlorophyll content of leaves. These stress markers can be used for screening the drought tolerance of genotypes, the irrigation schedules or prediction of yield.
TL;DR: Bradyrhizobium japonicum SAY3-7 plus Bradyrh Izobium elkanii BLY3-8 and Streptomyces griseoflavus are effective bacteria that can be used together as biofertilizer for the production of economically important leguminous crops, especially soybean and mung bean.
Abstract: The use of biofertilizers is important for sustainable agriculture, and the use of nodule bacteria and endophytic actinomycetes is an attractive way to enhance plant growth and yield. This study tested the effects of a biofertilizer produced from Bradyrhizobium strains and Streptomyces griseoflavus on leguminous, cereal, and vegetable crops. Nitrogen fixation was measured using the acetylene reduction assay. Under N-limited or N-supplemented conditions, the biofertilizer significantly promoted the shoot and root growth of mung bean, cowpea, and soybean compared with the control. Therefore, the biofertilizer used in this study was effective in mung bean, cowpea, and soybean regardless of N application. In this study, significant increments in plant growth, nodulation, nitrogen fixation, nitrogen, phosphorus, and potassium (NPK) uptake, and seed yield were found in mung beans and soybeans. Therefore, Bradyrhizobium japonicum SAY3-7 plus Bradyrhizobium elkanii BLY3-8 and Streptomyces griseoflavus are effective bacteria that can be used together as biofertilizer for the production of economically important leguminous crops, especially soybean and mung bean. The biofertilizer produced from Bradyrhizobium and S. griseoflavus P4 will be useful for both soybean and mung bean production.
TL;DR: The potential of releasing durum Wheat varieties adapted to all growing conditions of SSA, from the oases of the Sahara to the highlands of Ethiopia, indicates that the new breeding technologies offer great promise for expanding the area of durum wheat production in SSA but that this achievement remains primarily dependent on the market ability to purchase these grains at a higher price to stimulate farmer adoption.
Abstract: Durum wheat is an important food crop in the world and an endemic species of sub-Saharan Africa (SSA). In the highlands of Ethiopia and the oases of the Sahara this crop has been cultivated for thousands of years. Today, smallholder farmers still grow it on marginal lands to assure production for their own consumption. However, durum wheat is no longer just a staple crop for food security but has become a major cash crop. In fact, the pasta, burghul and couscous industry currently purchase durum grain at prices 10 to 20% higher than that of bread wheat. Africa as a whole imports over €4 billion per year of durum grain to provide the raw material for its food industry. Hence, African farmers could obtain a substantial share of this large market by turning their production to this crop. Here, the achievements of the durum breeding program of Ethiopia are revised to reveal a steep acceleration in variety release and adoption over the last decade. Furthermore, the variety release for Mauritania and Senegal is described to show how modern breeding methods could be used to deliver grain yields above 3 t ha−1 in seasons of just 92 days of length and in daytime temperatures always above 32 °C. This review describes the potential of releasing durum wheat varieties adapted to all growing conditions of SSA, from the oases of the Sahara to the highlands of Ethiopia. This indicates that the new breeding technologies offer great promise for expanding the area of durum wheat production in SSA but that this achievement remains primarily dependent on the market ability to purchase these grains at a higher price to stimulate farmer adoption. The critical importance of connecting all actors along the semolina value chain is presented in the example of Oromia, Ethiopia and that success story is then used to prompt a wider discussion on the potential of durum wheat as a crop for poverty reduction in Africa.
TL;DR: In this article, the effect of biochar size on the physical, chemical and hydrological properties in sandy and loamy tropical soils was evaluated with eight treatments (only soil, two soils (loamy and sandy soil), and three biochar sizes (2 mm).
Abstract: The application of biochar is promising for improving the physical, chemical and hydrological properties of soil. However, there are few studies regarding the influence of biochar particle size. This study was conducted to evaluate the effect of biochar size on the physical, chemical and hydrological properties in sandy and loamy tropical soils. For this purpose, an incubation experiment was conducted in the laboratory with eight treatments (control (only soil), two soils (loamy and sandy soil), and three biochar sizes ( 2 mm)). Analyses of water content, bulk density, total porosity, pore size distribution, total carbon (TC) and total N (TN) were performed after 1 year of soil–biochar-interactions in the laboratory. The smaller particle size 2 mm and in the sandy soil with the addition of 0.15–2 mm biochar. Porosity increased in both soils with the addition of biochar in the range of 0.15–2 mm. Smaller biochar particles shifted pore size distribution to increased macro and mesoporosity in both soils. Total carbon content increased mainly in sandy soil compared to control treatment; the highest carbon amount was obtained in the biochar size 0.15–2 mm in loamy soil and <0.15 mm in sandy soil, while the TN content and C:N ratio increased slightly with a reduction of the biochar particle size in both soils. These results demonstrate that biochar particle size is crucial for water retention, water availability, pore size distribution, and C sequestration.
TL;DR: It is concluded that nHA had nontoxic effects on the authors' model plant and therefore it could be used both as a P supplier and carrier of other elements and molecules.
Abstract: The Nutrient Use Efficiency in intensive agriculture is lower than 50% for macronutrients. This feature results in unsustainable financial and environmental costs. Nanofertilizers are a promising application of nanotechnology in agriculture. The use of nanofertilizers in an efficient and safe manner calls for knowledge about the actual effects of nanoproducts on the plant metabolism and eventually on the carrier release kinetics and nutrient accumulation. Hydroxyapatite (Ca10(PO4)6(OH)2) nanoparticles (nHA) have an interesting potential to be used as nanofertilizers. In this study, the effects of different nHA solutions stabilized with carboxymethylcellulose (CMC) were evaluated on germination, seedling growth, and metabolism of Solanum lycopersicum L., used as model species. Our observations showed that the percentage germination of S. lycopersicum is not influenced by increasing concentrations of nHa, while root elongation is strongly stimulated. Tomato plants grown in hydroponics in the presence of nHA have not suffered phytotoxic effects. We conclude that nHA had nontoxic effects on our model plant and therefore it could be used both as a P supplier and carrier of other elements and molecules.