Agronomy, Volume 8, Issue 7 (July 2018) – 32 articles

The astonishing increase in temperature presents an alarming threat to crop production worldwide. As evident by huge yield decline in various crops, the escalating drastic impacts of heat stress (HS) are putting global food production as well as nutritional security at high risk. HS is a major abiotic stress that influences plant morphology, physiology, reproduction, and productivity worldwide. The physiological and molecular responses to HS are dynamic research areas, and molecular techniques are being adopted for producing heat tolerant crop plants. In this article, we reviewed recent findings, impacts, adoption, and tolerance at the cellular, organellar, and whole plant level and reported several approaches that are used to improve HS tolerance in crop plants. Omics approaches unravel various mechanisms underlying thermotolerance, which is imperative to understand the processes of molecular responses toward HS. Our review about physiological and molecular mechanisms may enlighten ways to develop thermo-tolerant cultivars and to produce crop plants that are agriculturally important in adverse climatic conditions. Full article

All living organisms perceive mechanical signals, regardless of their taxonomic classifications or life habits. Because of their immobility, plants are influenced by a variety of environmental stresses, such as mechanical stress, during their growth and development. Plants develop physiological behaviors to adapt to their environment for long-term development and evolution. Sound-induced stress—an abiotic stress factor—is an example of mechanical stress and is caused by sound waves generated by different sources. This stress has a negative effect on the development and growth of plants. The strawberry plants evaluated in this study were exposed to three different sound intensity levels (95, 100, 105 dB) at a constant frequency of 1000 Hz. In strawberry plants, stress induced by sound waves is thought to trigger increased production of secondary metabolites as a defense mechanism. To determine the effect of sound applications, the fresh and dry weights of the roots and shoots were measured in strawberry plants, and the pH, total soluble solids (Brix), titratable acidity, vitamin C, total sugar, total acid, and total phenols were analyzed in the fruits. Results show that the sound stress, which was produced at a constant frequency (1000 Hz) and different sound levels (95, 100, 105 dB), affects the growth parameters of the plant and several quality parameters of the fruit. Full article

Plant biostimulants (PBs) such as protein hydrolysates and seaweed extracts are attracting the increasing interest of scientists and vegetable growers for their potential toenhance yield and nutritional quality. The current study assessed crop productivity, leaf colorimetry, mineral profile and bioactive compounds of greenhouse spinach in response to the foliar application of three PBs: legume-derived protein hydrolysate [PH], extract of seaweed Ecklonia maxima or mixture of vegetal oils, herbal and seaweed Ascophyllum nodosum extracts. Plants were PB-treated at a rate of 3 mL L⁻¹ four times during their growth cycle at weekly intervals. Foliar PB applications enhanced fresh yield, dry biomass and leaf area of spinach in comparison with untreated plants. Improved yield performance with PB applications was associated with improved chlorophyll biosynthesis (higher SPAD index). The three PB treatments elicited an increase in bioactive compounds (total phenols and ascorbic acid), thus raised the functional quality of spinach. The application of PH enhanced K and Mg concentrations and did not result in increased nitrate accumulation as observed with the other two PB treatments. Our findings can assist vegetable farmers and the agro-food industry in adopting innovative and sustainable tools such as PB for complementing a high yield with premium quality. Full article

Low-carbon production is one of the dominating issues in the sustainable development of the food industry with high energy consumption, especially in the table grapes cold chain. The aim of this paper is to propose a profit maximization strategy of table grapes cold chain by integrating the carbon footprint to improve the low-carbon production and sustainability of the cold chain system. The carbon footprint was evaluated by life cycle assessment (LCA) in entire cold chain system of table grapes, and the economic order quantity (EOQ) model was used to develop the profit maximization model with minimal carbon footprint and to maintain the optimal balance between stock and cost. The profit optimization performance, the sensitivity performance and the influencing factors of the decay rate, the carbon emission price, and the distance and carbon emission coefficient in refrigerated transport were analyzed according to the profit maximization model and the inventory data in actual cold chain investigated. The sensitivity performance analysis illustrated that the selling price had the highest sensitivity, and the carbon emission coefficient in storage had the lowest sensitivity. The comprehensive analysis results indicated that there is an optimal combination point between the economy and environment in actual cold chain, which not only reduced the carbon emission, but also had minimal impact on the profit in cold chain. The enterprises should integrate the carbon footprint cost into the profit maximization once the carbon emission tax is levied. The proposed strategy of the profit maximization with carbon footprint constraint is also suitable for improving profit maximization of other low-carbon supply chain applications. Full article

Lucerne (alfalfa; Medicago sativa L.) is the key forage for grazing in dryland temperate regions around the world. While rotational grazing of lucerne is recommended, in southern Australia the intervals between grazing events are often chosen in an opportunistic manner, to meet livestock production targets and utilise excessive spring and summer growth. To assess whether the persistence of lucerne is sensitive to variations in rotational grazing management practice, we report on an experiment with four sheep grazing treatments that was conducted for 2.5 years, including three summers, in southern New South Wales. The grazing management treatments were a crash-grazing control, frequent grazing, feed-based rotational grazing and time-based rotational grazing, replicated four times. The number of grazing events, percentage of time under grazing, lucerne top dry matter (DM) at the beginning and end of grazing periods and plant density were measured. The results relating to number of grazing events, percentage of time grazing and DM removed during grazing indicated that four grazing practices had been achieved. The treatments all had significant periods of rest for at least 73% of time and were empirically different in their approach but resulted in similar grazing pressures, in terms of overall pasture removed during grazing. Nevertheless, there was little difference in lucerne densities between grazing treatments over the life of the experiment. We conclude that there is flexibility in the rotational management of grazed lucerne provided adequate rest periods are part of the management program. Full article

In this study, an Artificial Neural Network (ANN) model was developed in order to classify varieties belonging to grain species. Varieties of bread wheat, durum wheat, barley, oat and triticale were utilized. 11 physical properties of grains were determined for these varieties as follows: thousand kernel weight, geometric mean diameter, sphericity, kernel volume, surface area, bulk density, true density, porosity and colour parameters. It was found that these properties had been statistically significant for the varieties. An Artificial Neural Network was developed for classifying varieties. The structure of the ANN model developed was designed to have 11 inputs, 2 hidden and 2 output layers. Thousand kernel weight, geometric mean diameter, sphericity, kernel volume, surface area, bulk density, true density, porosity and colour were used as input parameters; and species and varieties as output parameters. While classifying the varieties by the ANN model developed, R², RMSE and mean error were found to be 0.99, 0.000624 and 0.009%, respectively. In classifying the species, these values were found to be 0.99, 0.000184 and 0.001%, respectively. It has shown that all the results obtained from the ANN model had been in accordance with the real data. Full article

Achieving high yields is a challenge for sugarcane producers due to the diverse environmental conditions to which the crop is subjected. In tropical and subtropical regions, where sugarcane is typically cultivated, crop diseases are common. This necessitates the development of disease management techniques. Among these techniques, chemical control is of particular significance due to the development of new antifungal agents, such as pyraclostrobin. For some crops, pyraclostrobin has a positive influence on yield due to its effects on plant physiology. The aim of this study was to evaluate the physiological responses and yield of three sugarcane cultivars treated with the fungicide, pyraclostrobin. The experiment was performed in a randomized block design (RBD) with a split-plot arrangement; the variables analyzed were the application or non-application of fungicide in the plots and, in the subplots, the evaluation times after fungicide application. Both the rate of photosynthesis and the antioxidant enzyme (Superoxide Dismutase, Catalase and Ascorbate Peroxidades) activity increased in plants treated with fungicide in comparison to untreated plants, and in the RB855156 cultivar the stomatal conductance, transpiration, and nocturnal respiratory rate were increased. Furthermore, application of pyraclostrobin increased stalk yield and the green biomass index in the RB855156 and RB86751 sugarcane cultivars. In certain cultivars of sugarcane, application of pyraclostrobin leads to an increased yield. Full article

Increased nutrient withdrawal by rapidly expanding intensive cropping systems, in combination with imbalanced fertilization, is leading to potassium (K) depletion from agricultural soils in Asia. There is an urgent need to better understand the soil K-supplying capacity and K-use efficiency of crops to address this issue. Maize is increasingly being grown in rice-based systems in South Asia, particularly in Bangladesh and North East India. The high nutrient extraction, especially K, however, causes concerns for the sustainability of maize production systems in the region. The present study was designed to estimate, through a plant-based method, the magnitude, and variation in K-supplying capacity of a range of soils from the maize-growing areas and the K-use efficiency of maize in Bangladesh. Eighteen diverse soils were collected from several upazillas (or sub-districts) under 11 agro-ecological zones to examine their K-supplying capacity from the soil reserves and from K fertilization (100 mg K kg⁻¹ soil) for successive seven maize crops grown up to V10–V12 in pots inside a net house. A validation field experiment was conducted with five levels of K (0, 40, 80, 120 and 160 kg ha⁻¹) and two fertilizer recommendations based on “Nutrient Expert for Maize-NEM” and “Maize Crop Manager-MCM” decision support tools (DSSs) in 12 farmers’ fields in Rangpur, Rajshahi and Comilla districts in Bangladesh. Grain yield and yield attributes of maize responded significantly (p < 0.001) to K fertilizer, with grain yield increase from 18 to 79% over control in all locations. Total K uptake by plants not receiving K fertilizer, considered as potential K-supplying capacity of the soil in the pot experiment, followed the order: Modhukhali > Mithapukur > Rangpur Sadar > Dinajpur Sadar > Jhinaidah Sadar > Gangachara > Binerpota > Tarash > Gopalpur > Daudkandi > Paba > Modhupur > Nawabganj Sadar > Shibganj > Birganj > Godagari > Barura > Durgapur. Likewise, in the validation field experiment, the K-supplying capacity of soils was 83.5, 60.5 and 57.2 kg ha⁻¹ in Rangpur, Rajshahi, and Comilla, respectively. Further, the order of K-supplying capacity for three sites was similar to the results from pot study confirming the applicability of results to other soils and maize-growing areas in Bangladesh and similar soils and areas across South Asia. Based on the results from pot and field experiments, we conclude that the site-specific K management using the fertilizer DSSs can be the better and more efficient K management strategy for maize. Full article

The hypothesis that application of starter nitrogen (N) fertilizer to cowpea may increase grain and fodder yields and profitability was tested in the Guinea and Sudan savanna zones of northern Ghana. Two cowpea varieties (Apagbaala: grain-type and Padi-Tuya: dual purpose) and three N fertilizer rates (0-30-30, 15-30-30 and 30-30-30 N-P₂O₅-K₂O kg/ha) were evaluated using a 2 × 3 factorial treatments arrangement in a randomized complete block design with three replicates. Grain and fodder yields, 100 seed weight (SW) and net return of Padi-Tuya increased significantly compared with Apagbaala in both zones. Application of starter N fertilizer increased grain yield, fodder yield, N use efficiency (NUE) and net return by more than 30% compared with the control in both zones. Padi-Tuya cowpea with 15 kg/ha N fertilizer was risk efficient at all risk aversion levels when only grain was considered, but Padi-Tuya with 30 kg/ha N fertilizer becomes the most risk efficient option when the value of fodder was included. The results suggest that small-scale farmers could apply starter N fertilizer at either 15 kg/ha N for grain only or 30 kg/ha N for both grain and fodder yields improvement of cowpea in West Africa and similar ecologies. Full article

Humans have domesticated hundreds of plant and animal species as sources of food, fiber, forage, and tools over the past 12,000 years, with manifold effects on both human society and the genetic structure of the domesticated species. The outcomes of crop domestication were shaped by selection driven by human preferences, cultivation practices, and agricultural environments, as well as other population genetic processes flowing from the ensuing reduction in effective population size. It is obvious that any selection imposes a reduction of diversity, favoring preferred genotypes, such as nonshattering seeds or increased palatability. Furthermore, agricultural practices greatly reduced effective population sizes of crops, allowing genetic drift to alter genotype frequencies. Current advances in molecular technologies, particularly of genome sequencing, provide evidence of human selection acting on numerous loci during and after crop domestication. Population-level molecular analyses also enable us to clarify the demographic histories of the domestication process itself, which, together with expanded archaeological studies, can illuminate the origins of crops. Domesticated plant species are found in 160 taxonomic families. Approximately 2500 species have undergone some degree of domestication, and 250 species are considered to be fully domesticated. The evolutionary trajectory from wild to crop species is a complex process. Archaeological records suggest that there was a period of predomestication cultivation while humans first began the deliberate planting of wild stands that had favorable traits. Later, crops likely diversified as they were grown in new areas, sometimes beyond the climatic niche of their wild relatives. However, the speed and level of human intentionality during domestication remains a topic of active discussion. These processes led to the so-called domestication syndrome, that is, a group of traits that can arise through human preferences for ease of harvest and growth advantages under human propagation. These traits included reduced dispersal ability of seeds and fruits, changes to plant structure, and changes to plant defensive characteristics and palatability. Domestication implies the action of selective sweeps on standing genetic variation, as well as new genetic variation introduced via mutation or introgression. Furthermore, genetic bottlenecks during domestication or during founding events as crops moved away from their centers of origin may have further altered gene pools. To date, a few hundred genes and loci have been identified by classical genetic and association mapping as targets of domestication and postdomestication divergence. However, only a few of these have been characterized, and for even fewer is the role of the wild-type allele in natural populations understood. After domestication, only favorable haplotypes are retained around selected genes, which creates a genetic valley with extremely low genetic diversity. These “selective sweeps” can allow mildly deleterious alleles to come to fixation and may create a genetic load in the cultivated gene pool. Although the population-wide genomic consequences of domestication offer several predictions for levels of the genetic diversity in crops, our understanding of how this diversity corresponds to nutritional aspects of crops is not well understood. Many studies have found that modern cultivars have lower levels of key micronutrients and vitamins. We suspect that selection for palatability and increased yield at domestication and during postdomestication divergence exacerbated the low nutrient levels of many crops, although relatively little work has examined this question. Lack of diversity in modern germplasm may further limit our capacity to breed for higher nutrient levels, although little effort has gone into this beyond a handful of staple crops. This is an area where an understanding of domestication across many crop taxa may provide the necessary insight for breeding more nutritious crops in a rapidly changing world. Full article

In recent years, it has become readily accepted among interdisciplinary agriculturalists that the current global crop yield to land capability ratio is significantly insufficient to achieve food security for the predicted population of 9.5 billion individuals by the year 2050. This issue is further compounded by the: (1) food versus biofuel debate; (2) decreasing availability of arable land; (3) required reductions to the extensive and ongoing environmental damage caused by either poor agricultural practices or agriculture expansion, and; (4) increasingly unfavorable (duration and severity) crop cultivation conditions that accompany man-made climate change, driven by ever-expanding urbanization and its associated industrial practices. Mounting studies are repeatedly highlighting the critical importance of linking genotypes to agronomically beneficial phenotypes and/or using a molecular approach to help address this global crisis, as “simply” clearing the remaining natural ecosystems of the globe for the cultivation of additional, non-modified crops is not efficient, nor is this practice sustainable. The majority of global food crop production is sourced from a small number of members of the Poaceae family of grasses, namely; maize (Zea mays L.), wheat (Triticum aestivum L.) and rice (Oryza sativa L.). It is, therefore, of significant concern that all three of these Poaceae grass species are susceptible to a range of abiotic stresses, including drought and salt stress. Highly conserved among monocotyledonous and dicotyledonous plant species, microRNAs (miRNAs) are now well-established master regulators of gene expression, influencing all aspects of plant development, mediating defense responses against pathogens and adaptation to environmental stress. Here we investigate the variation in the abundance profiles of six known abiotic stress-responsive miRNAs, following exposure to salt and drought stress across these three key Poaceae grass crop species as well as to compare these profiles to those obtained from the well-established genetic model plant species, Arabidopsis thaliana (L.) Heynh. Additionally, we outline the variables that are the most likely primary contributors to instances of differential miRNA abundance across the assessed species following drought or salt stress exposure, specifically; (1) identifying variations in the experimental conditions and/or methodology used to assess miRNA abundance, and; (2) the distribution of regulatory transcription factor binding sites within the putative promoter region of a MICRORNA (MIR) gene that encodes the highly conserved, stress-responsive miRNA. We also discuss the emerging role that non-conserved, species-specific miRNAs play in mediating a plant’s response to drought or salt stress. Full article

Silage maize (Zea mays L.) is the dominating energy crop for biogas production due to its high biomass yield potential, but alternatives are currently being discussed to avoid environmental problems arising from maize grown continuously. This study evaluates the productivity and resource use efficiency of different bioenergy crops and cropping systems using experimental and simulation modelling derived data. The field experiment consisted of two years, two sites differing in soil texture and soil water availability, different cropping systems and increasing nitrogen (N) supply. Continuous (two years) perennial ryegrass and two crop rotations including winter cover crops (double cropping system) and combining C4 and C3 crops were compared with continuous maize (maize–maize). The productivity of the crops and cropping systems in terms of dry matter (DM) yield was analyzed with respect to the fraction of light interception and light use efficiency (LUE). In addition, water use and water use efficiency (WUE), N uptake, and N use efficiency (NUE) were quantified. DM yield of the double cropping system was similar to that of continuous maize, due to a prolonged leaf area duration, compensating for the intrinsic lower LUE of C3 crops. Perennial ryegrass was less productive than the other crops/cropping systems. Nitrogen uptake and consequently N demand of perennial ryegrass and the C3 crops of the crop rotations were higher than for maize–maize. Groundwater recharge was mainly site-dependent, but was at both sites higher for maize than for the crop rotations or the perennial ryegrass system. Our results indicate that, in terms of biomass productivity, optimized rotations are feasible alternatives to maize–maize, but trade-offs exist in terms of water and N use efficiency. Full article

Those engaged in agriculture possess a definite but unexamined moral confidence or certainty about the correctness of what they do. The basis of the moral confidence is not obvious to those who have it, or to the public. In fact, the moral confidence that pervades agriculture is potentially harmful because it is unexamined. It is necessary that those engaged in agriculture analyze what it is about agriculture in society that favors, inhibits, or limits agriculture. All should strive to nourish and strengthen the aspects of agriculture that are beneficial and change those that are not. To do this all must be confident to study ourselves, our institutions, and be dedicated to the task of modifying the values and goals of both. Full article

Developing biomarkers and bio-indicators that will better indicate stress tolerance is crucial for plant breeding to increase crop resilience and productivity. However, complex interactions between water availability, light intensity, and temperature fluctuations make it difficult to develop standardised properties to monitor performance under field conditions. Sugar alcohols have been shown to function as stress metabolites, demonstrating considerable promise for use as bio-indicators of stress tolerance. This experiment monitored the accumulation of metabolites, including that of the sugar alcohol D-pinitol, in 3 chickpea genotypes grown under field conditions during reproductive stages of development. Further, compound specific carbon isotope abundance (δ¹³C) of these compounds was quantified to investigate the influence on predictions of water use efficiency. It was found that the magnitude of water deficit did not instigate significant responses in metabolite abundance, however, concentrations of D-pinitol increased significantly over reproductive stages, indicating the accumulation of this sugar alcohol may be under significant developmental control. Significant differences in the δ¹³C of D-pinitol compared to other metabolites indicate this compound imparts a substantial effect over concentration-weighted predictions of water use efficiency obtained from the soluble fraction of leaves, especially as its proportion in the soluble fraction increases with plant development. Full article

Despite a high abundance and diversity of natural plant pathogens, plant disease susceptibility is rare. In agriculture however, disease epidemics often occur when virulent pathogens successfully overcome immunity of a single genotype grown in monoculture. Disease epidemics are partially controlled by chemical and genetic plant protection, but pathogen populations show a high potential to adapt to new cultivars or chemical control agents. Therefore, new strategies in breeding and biotechnology are required to obtain durable disease resistance. Generating and exploiting a genetic loss of susceptibility is one of the recent strategies. Better understanding of host susceptibility genes (S) and new breeding technologies now enable the targeted mutation of S genes for genetic plant protection. Here we summarize biological functions of susceptibility factors and both conventional and DNA nuclease-based technologies for the exploitation of S genes. We further discuss the potential trade-offs and whether the genetic loss of susceptibility can provide durable disease resistance. Full article

Maize producers transitioning to an organic cropping system must grow crops organically without price premiums for 36 months before certification. We evaluated conventional and organic maize with recommended and high seeding and N rates in New York to identify the best organic management practices during the transition. Conventional versus organic maize management differences included a treated (fungicide/insecticide) Genetically Modified (GM) hybrid versus a non-treated non-GM isoline; side-dressed synthetic N versus pre-plow composted manure; and Glyphosate versus mechanical weed control, respectively. Organic versus conventional maize yielded 32% lower as the entry crop (no previous green manure crop). Grain N% and weed densities explained 72% of yield variability. Organic and conventional maize, following wheat/red clover in the second year, yielded similarly. Organic maize with high inputs following wheat/red clover and conventional maize with high inputs following soybean in the third year yielded the highest. Grain N% and maize densities explained 54% of yield variability. Grain crop producers in the Northeast USA who do not have on-farm manure and forage equipment should plant maize after wheat/red clover with additional N (~56 kg N/ha) at higher seeding rates (~7%) during the transition to insure adequate N status and to offset maize density reductions from mechanical weed control. Full article

The New York table beet industry is expanding and has unique challenges to minimize crop loss in both conventional and organic production. Diseases may reduce plant population density and increase heterogeneity in a stand, reduce the duration of time foliage is healthy, and decrease the yield of marketable roots. Rhizoctonia solani Kuhn and Pythiumultimum Trow are dominant in the pathogen complex affecting crop stand and root health. Cercospora leaf spot (CLS) caused by the fungus, Cercospora beticola Sacc., is a highly destructive disease affecting foliar health. In conventional table beet production, fungicides are applied in-furrow and at emergence for early season and root disease control, and applied to foliage periodically thereafter for foliar disease control. Resistance within C. beticola populations to single-site mode-of-action fungicides poses the most significant threat to the resilience of conventional disease management. An integrated approach to reduce pesticide application when not economically warranted (i.e., a false positive) is urgently required. For foliar disease, improved scheduling of fungicides may reduce usage without loss of disease control. For soilborne diseases, pre-plant quantification of soilborne inoculum may support the selection of fields with lower inoculum densities to minimize risk of early season and root disease. For organic production, some approved products have moderate efficacy for foliar disease control, but strategies to reduce inoculum and select fields at lowest risk of disease will be paramount. Crop rotation has shown promise for disease management, but broad host range of several of the major soilborne pathogens limits the utility of this method in the production region. Enhanced knowledge of cultivar susceptibility to local populations of fungal pathogens responsible for foliar and root diseases is paramount, and adoption of commercially acceptable cultivars with improved resistance to CLS and Rhizoctonia crown and root rot has potential to transform disease management strategies for the New York table beet industry. Full article

Vegetable production in greenhouses is preferred when soil quality is degraded by high salinity or incidence of pests and diseases. In these soils with abiotic and biotic issues, it is a challenge to increase the yield and quality of fruits. The use of rootstocks and organic substrates are effective and environmentally friendly techniques to solve that challenge. The objective was to study the effect of rootstocks on yields and quality in bell peppers (Capsicum annuum L.) grown in either soil or coconut fiber substrate, in greenhouses. Using a randomized block design with three repetitions, the resulting treatment groups consisted of three rootstocks (Foundation-F1, Yaocali-F1, CLX-PTX991-F1 (Ultron), and non-grafted controls) with four hybrids as scions (Lamborghini, Bambuca, DiCaprio, and Ucumari). The yield of fruit per plant (YFP) and number of fruit per plant (NFP) obtained in coconut fiber were 85% and 55% greater, respectively, than in soil. The CLX-PTX991-F1 rootstock was superior to the hybrids without rootstock (p ≤ 0.05) in YFP and NPF (30% and 19.5%, respectively). The Lamborghini hybrid had significantly greater YFP and NFP than the Ucumari. We concluded that the use of coconut fiber significantly improves the yields of bell pepper and that the use of rootstock improves plant vigor and plant yield. Full article

Grain yield in maize responds to N fertility in a linear-plateau fashion with nitrogen use efficiency (NUE) higher under lower N fertilities and less as grain yield plateaus. Field experiments were used to identify plant parameters relative for improved NUE in maize and then experiments were performed under controlled conditions to elucidate metabolism controlling these parameters. Field experiments showed reproductive parameters, including R1 ear-weight, predictive of N response under both high and low NUE conditions. R1 ear-weight could be changed by varying nitrate concentrations early during reproductive development but from V12 onward R1 ear-weight could be changed little by increasing or decreasing nitrate fertility. Ammonia, on the other hand, could rescue R1 ear-weight as late as V15 suggesting nitrate assimilation (NA) limits ear development response to N fertility since bypassing NA can rescue R1 ear-weight. Nitrate reductase activity (NRA (in vitro)) increases linearly with nitrate fertility but in vivo nitrate reductase activity (NRA (in vivo)) follows organic N accumulation, peaking at sufficient levels of nitrate fertility. The bulk of the increase in total plant N at high levels of nitrate fertility is due to increased plant nitrate concentration. Increasing NADH levels by selective co-suppression of ubiquinone oxidoreductase 51 kDa subunit (Complex I) was associated with improved grain yield by increasing ear size, as judged by increased kernel number plant⁻¹ (KNP), and increased NRA (in vivo) without a change in NRA (in vitro). These results support NUE is limited in maize by NA but not by nitrate uptake or NRA (in vitro). Full article

Root system size is a key trait for improving water and nitrogen uptake efficiency in wheat (Triticum aestivum L.). This study aimed (i) to characterize the root system and shoot traits of five wheat cultivars with apparent differences in root system size; (ii) to evaluate whether the apparent differences in root system size observed at early vegetative stages in a previous semi-hydroponic phenotyping experiment are reflected at later phenological stages in plants grown in soil using large rhizoboxes. The five wheat cultivars were grown in a glasshouse in rhizoboxes filled to 1.0 m with field soil. Phenology and shoot traits were measured and root growth and proliferation were mapped to quantify root length density (RLD), root length per plant, root biomass and specific root length (SRL). Wheat cultivars with large root systems had greater root length, more root biomass and thicker roots, particularly in the top 40 cm, than those with small root systems. Cultivars that reached anthesis later had larger root system sizes than those that reached anthesis earlier. Later anthesis allowed more time for root growth and proliferation. Cultivars with large root systems had 25% more leaf area and biomass than those with small root systems, which presumably reflects high canopy photosynthesis to supply the demand for carbon assimilates to roots. Wheat cultivars with contrasting root system sizes at the onset of tillering (Z2.1) in a semi-hydroponic phenotyping system maintained their size ranking at booting (Z4.5) when grown in soil. Phenology, particularly time to anthesis, was associated with root system size. Full article

The biological pattern of plants’ nitrous oxide (N₂O) generation is not well understood because plant cells cannot form N₂O from nitric oxide (NO) reduction. Hypothetically, we consider that plant-endophytic co-denitrification is potentially capable of making up for the functional loss of NO reduction in the plant cell and is thus the source of plant-derived N₂O. In order to test the above hypothesis, field-cultured soybean seedlings and aseptic-cultured seedlings were used to establish plant holobionts with differentially established endophytes. The N₂O fluxes, copies of the bacterial NO reductase encoding gene, and a diversity of endophytic denitrifying bacteria of these holobionts were observed by gas chromatography, real-time PCR, and 16s rDNA sequencing. The flux of N₂O by the field seedlings was significantly higher than the fluxes of the aseptic seedlings and bulk soil. The N₂O flux of the soybean seedlings was significantly correlated to the abundance of the bacterial NO reductase encoding gene. Eleven genera of denitrifying bacteria were observed in the soybean seedlings, and among them, two genera of aerobic denitrifying bacteria were specifically associated with colonizing plant samples. In this work we have also showed that plant N₂O emission is affected by the abundance of total endophytic denitrifying bacteria. We conclude that plant sourced N₂O is cooperatively generated by the plant-endophyte symbiotic system in which endophytic denitrifying bacteria help plants to emit N₂O by taking over the NO–N₂O reduction process. Full article

Wild emmer wheat (Triticum turgidum ssp. dicoccoides) is the wild ancestor of all cultivated tetraploid and hexaploid wheats and harbors a large amount of genetic diversity. This diversity is expected to display eco-geographical patterns of variation, conflating gene flow, and local adaptation. As self-replicating entities comprising the bulk of genomic DNA in wheat, retrotransposons are expected to create predominantly neutral variation via their propagation. Here, we have examined the genetic diversity of 1 Turkish and 14 Israeli populations of wild emmer wheat, based on the retrotransposon marker methods IRAP and REMAP. The level of genetic diversity we detected was in agreement with previous studies that were performed with a variety of marker systems assaying genes and other genomic components. The genetic distances failed to correlate with the geographical distances, suggesting local selection on geographically widespread haplotypes (‘weak selection’). However, the proportion of polymorphic loci correlated with the population latitude, which may reflect the temperature and water availability cline. Genetic diversity correlated with longitude, the east being more montane. Principal component analyses on the marker data separated most of the populations. Full article

Amino acid substitutions that confer herbicide-resistance may cause fitness costs in mutant plants at unfavorable levels in contrast to wild-species. The fitness costs in three Lolium rigidum populations (AH3 (Ile-2041-Asn) and BO2 (Ile-1781-Leu) as resistant (R) to clodinafop-propargyl, an ACCase (acetyl-CoAcarboxylase) inhibitor, carrying the mutations 1781 and 2041, respectively, and HF as susceptible (S)) were studied during 2014 and 2016. The germination rates and percentages of the three L. rigidum populations, and competition between them and Triticum aestivum using substitution series experiments were assessed. The BO2 and AH3 populations showed resistance to clodinafop-propargyl due to mutations in their ACCase genes. The germination rate for L. rigidum decreased as the sowing depth increased, with the lowest germination rate being found at 8 cm. AH3 and HF populations presented higher seed germination under water and NaCl salinity stress, but no fitness cost variations were observed among these R populations under optimal growth conditions. Diverse germination responses to light conditions were observed between the S and R L. rigidum populations. The highest germination percentage was observed in the HF population at the two-week lighting + two-week darkness regime. The comparison of relative yield total and relative crowding coefficient showed that T. aestivum was more competitive than L. rigidum. However, among ACCase-resistant L. rigidum populations, AH3 population was the most competitive presenting no fitness costs. This R population was more competitive than the S (HF) one under competitive conditions. These results show that fitness costs in the R L. rigidum populations vary according to the specific mutation at the ACCase gene that confers resistance to clodinafop-propargyl. In conclusion, mutations occurring at the 2041 position in the ACCase gene caused fitness costs, but those occurring at the 1781 position did not generate fitness costs for L. rigidum. Therefore, non-chemical methods should be considered unfavorable for resistant populations of this species. Full article

When applying an aided phytostabilization in trace-element-contaminated agricultural soil, the cultivation of forage crops instead of edible crops can reduce the trace elements transfer to humans while minimizing the income loss of farmers. The objectives of this study were to compare the effect of the type of forage crops at the “family” level (Poaceae and Leguminosae) on aided phytostabilization using physical (water stable aggregation), chemical (Mehlich-3 extraction), and biological assessments (dehydrogenase activity). Pig manure and acid mine drainage sludge were used as soil amendments, and four plant species (Loliummultiflorum Lam. var. italicum and Secalecereale L. [Poaceae representatives], Viciavillosa Roth, and Trifoliumpratense L. [Leguminosae representatives]) were cultivated after amendment treatments. Chemical assessment showed that the reduction in bioavailability of trace elements was partly observed in legume crops. The positive effects of plant cultivation were determined through physical assessment. The effectiveness of pig manure as an organic amendment was determined by biological assessment. In some treatments, the synergistic effect of the incorporation of chemical stabilization with both plant families was observed but it was difficult to identify a clear distinction between the two families. The translocation of trace elements from root to shoot was low in all plants, indicating that the cultivation of the plants used in this study is safe with regards to the spread of trace elements into the environment. The results suggest that forage crop cultivation in contaminated agricultural soil could ameliorate soil quality after chemical stabilization. Full article

Agricultural soils utilized for corn (Zea mays L.) and soybean (Glycine max [L.] Merr.) production in the Midwestern U.S. are often managed to have adequate surface soil pH for crop growth, but the presence of acidic subsoils may limit crop production. Subsoil acidity may inhibit root growth, leading to decreased drought tolerance and grain yields. Application of aglime can increase soil pH, improve soil structure, and provide calcium and magnesium to the soil, but surface amendments that often occur in no-till systems rarely affect the subsoil, resulting in potential chemical and physical barriers to root growth. The objective of this study was to determine the effects of surface and a new deep vertical lime placement practice, at three application rates, on corn and soybean plant growth and yields in a conservation tillage system. Field trials were conducted from 2012 to 2016 in Northeast Missouri on a poorly-drained claypan soil with treatments of lime (0, 3.4, and 6.7 Mg ha⁻¹) broadcast on the soil surface or applied as a deep vertical band to a depth of 51 cm. When precipitation was below average, compared to control plots, deep vertical placed lime at 6.7 Mg ha⁻¹ significantly raised corn yields by 1.3 Mg ha⁻¹ four years after treatment. In years with adequate precipitation, no significant increases in corn yield were observed with deep lime placement treatments compared to the control. Lime treatments had a greater effect on corn yield than soybean. Deep vertical placement of lime resulted in no significant increase in soybean yield compared to the controls for all trials. Longer observation time may be needed to fully evaluate the effects of these lime placement treatments. Full article

Heat shock transcription factor (Hsf) is one of the conserved gene families in plants, playing a crucial role in growth and development, as well as in response to diverse stresses. Although it has been systematically studied in many species, little is known about the Hsf gene family in Chenopodium quinoa, especially those involved in the regulatory network of stress processes. In this study, we identified 23 Hsf genes in quinoa (CqHsfs) through a genome-wide search method based on the latest available genome information. Phylogenetic analysis classified them into three groups, and group A was further divided into nine subgroups, which was supported by conserved domain organizations. Gene structure and multiple sequence alignment analysis revealed that all of the CqHsfs possessed a similar structure organization and were highly conserved in BDB domain. Interaction network analysis identified 13 CqHsfs involved in the network pathway to regulate diverse biological processes. Expression profiles of these CqHsfs were further investigated using the RNA-seq data, and tissue-specific and stress-responsive candidates were identified. Finally, four heat-responsive CqHsfs were selected to validate their expression level through semi-quantitative RT-PCR analysis. This study reported the organization, structure, and expression profiles of the Hsf gene family in quinoa, which will contributes to further functional analysis, and helps to better understand the roles and regulatory mechanism of heat shock factors playing in quinoa and beyond. Full article

Soil waterlogging resulting from extreme precipitation events creates anaerobic conditions that may inhibit plant growth and increase N losses. A three-year (2013–2015) field experiment was conducted in poorly-drained claypan soils to assess the effects of waterlogging [0 or 7-days waterlogging at V3 growth stage of corn (Zea mays L.)] and pre-plant application of different N fertilizer sources and post-waterlogging rescue N application (0 or 84 kg N ha⁻¹ of urea plus urease inhibitor (NCU + UI) at V7) on chlorophyll SPAD meter (CM) readings, stomatal conductance, ear leaf and silage N concentrations, N uptake and apparent N recovery efficiency (ARE) of two corn hybrids with varying amounts of flood tolerance. Pre-plant N fertilizer sources included a non-treated control (CO), urea (NCU), urea plus nitrification inhibitor (NCU + NI) and polymer coated urea (PCU) applied at 168 kg N ha⁻¹. In 7-days waterlogged plots, rescue N applications increased N uptake in PCU treatments 33% and 40% in 2013 and 2014, respectively, as well as in NCU by 48% in 2013. In 7-days waterlogged plots which received rescue N applications, NCU and PCU in 2013 resulted in higher N uptake than CO and NCU + NI by 47 to 77 kg ha⁻¹. PCU had higher N uptake than NCU and NCU + NI by 78 and 72 kg ha⁻¹ in 7-days waterlogged plots that received rescue N applications in 2014. Corn hybrid showed no differences in N uptake and ARE in our study. Our results indicate combining pre-plant N fertilizer source selection and rescue N applications may be a strategy to reduce possible decreases in corn N uptake caused by early season soil waterlogging in average rainfall years. Full article

Understanding the influences of rainfall and temperature on soil water and the grain production of winter wheat (Triticum aestivum L.), is of great importance to ensure the sustainability of food production on the Loess Plateau of China. Based on calibration and evaluation, the Environmental Policy Integrated Climate (EPIC) model was employed to determine the response of soil water and winter wheat to rainfall and temperature changing over the last 30 years in different regions. Results showed that (1) the EPIC model simulated soil water content well in 0–2 m soil, with a relative root mean square error (RRMSE) value of 6.0~14.0%, and the mean value of R² was 0.824, which was similar to the value of ME (0.815); (2) rainfall decreased 13.6–24.9% more from 2001 to 2010 than it did during 1961–2000, while its minimum and maximum temperature increased 1.00–1.55 °C and 0.30–0.84 °C respectively, in comparison with 1961–2000; (3) both the increase of maximum temperature and the decrease of rainfall were harmful to the production of winter wheat. Contrarily, the increase of minimum temperature was beneficial to the production of winter wheat on the Loess Plateau of China. Furthermore, due to rainfall decreasing, the winter wheat yield of Luochuan, Changwu, Yuncheng, and Yan’an decreased by 8.5%, 7.6%, 11.7%, and 12.3%, respectively. Because of the rising of the maximum temperature, winter wheat yield decreased 6.4%, 6.8%, 7.2%, and −3.0%, respectively. On the other hand, the increase of the minimum temperature raised the winter wheat yield of 8.8%, 10.2%, 1.5%, and 12.0%, respectively. Climate change, either precipitation reduction or temperature increase, decreased soil water in the dry land winter wheat field. Therefore, more water-saving technologies are needed to adapt to climate change, to store and use water sources more effectively in semi-arid regions. Though precipitation reduction and maximum temperature increase produced negative impacts on winter wheat yield, the uptrend in minimum temperature is better for increasing the winter wheat yield, which can be used by farmers and governments to adapt to climate change, by adjusting planting time properly. Full article

Adequate supply of micronutrients is important for the proper growth and yield of lentil, particularly in poorly fertile soil. This study was carried out to understand the effects of zinc (Zn), boron (B), and molybdenum (Mo) on the growth and yield of lentil, and how these elements can help manage soil fertility issues. In this regard, the morpho-physiological traits of lentils (BARI Masur-7) were collected from two experiments receiving the same treatments carried out during consecutive rabi seasons of 2015–2016 and 2016–2017. The experiments were laid out with a randomized complete block design having eight treatments, and was replicated thrice. The treatments were T₁ (Control), T₂ (Zn_2.0 kg ha⁻¹), T₃ (B_1.5 kg ha⁻¹), T₄ (Mo_1.0 kg ha⁻¹), T₅ (Zn_2.0B_1.5 kg ha⁻¹), T₆ (Zn_2.0Mo_1.0 kg ha⁻¹), T₇ (B_1.5Mo_1.0 kg ha⁻¹), and T₈ (Zn_2.0B_1.5Mo_1.0 kg ha⁻¹). The results revealed that the application of micronutrients either singly or in combination had significant effects on the plant height, number of branches per plant, number of pods per plant, number of seeds per pod, thousand seed weight, and the seed yield of lentil. The maximum seed production was, however, observed in plots receiving treatment T₈, i.e., the combined application of Zn, B, and Mo. Agronomic biofortification also had significantly increased protein content of lentil seeds while affecting the macro and micronutrient content of lentil seed. These results suggest that any micronutrient deficiencies might lead to a yield loss of lentil, and such a scenario could be avoided by a combined application of micronutrients at a proportionate level. Full article

Heat stress frequently imposes a strong negative impact on vegetative and reproductive development of plants leading to severe yield losses. Wheat, a major temperate crop, is more prone to suffer from increased temperatures than most other major crops. With heat waves becoming more intense and frequent, as a consequence of global warming, a decrease in wheat yield is highly expected. Here, we examined the impact of a short-term (48 h) heat stress on wheat imposed during reproduction at the pollen mitosis stage both, at the physiological and molecular level. We analyzed two sets of summer wheat germplasms from Australia (Kukri, Drysdale, Gladius, and RAC875) and Europe (Epos, Cornetto, Granny, and Chamsin). Heat stress strongly affected gas exchange parameters leading to reduced photosynthetic and transpiration rates in the European cultivars. These effects were less pronounced in Australian cultivars. Pollen viability was also reduced in all European cultivars. At the transcriptional level, the largest group of heat shock factor genes (type A HSFs), which trigger molecular responses as a result of environmental stimuli, showed small variations in gene expression levels in Australian wheat cultivars. In contrast, HSFs in European cultivars, including Epos and Granny, were strongly downregulated and partly even silenced, while the high-yielding variety Chamsin displayed a strong upregulation of type A HSFs. In conclusion, Australian cultivars are well adapted to moderate heat stress compared to European summer wheat. The latter strongly react after heat stress application by downregulating photosynthesis and transpiration rates as well as differentially regulating HSFs gene expression pattern. Full article