Wheat Biomass Research Articles

Effects of sterilization and maturity of compost on soil bacterial and fungal communities and wheat growth

Composts are commonly used as soil amendments to sustain and improve the functionality of agricultural soil. Compost has abiotic (organic matter [OM], nutrients) and biotic characteristics (microorganisms) and both can influence the soil microbiome. The abiotic and biotic characteristics of compost, in turn, depend on properties of the compost such as maturity. Few studies have investigated the relative effects of abiotic and biotic components of compost on the soil microbial community and crop growth. To bridge this gap, we used a full-factorial design with sterile and live composts that differed in maturity (fresh, intermediate, mature) that were added to sterile and live soil to investigate the separate role of abiotic and biotic characteristics of composts on the resulting soil microbial community and on wheat growth. We found that the changes in the soil microbial community were mainly due to the input of compost with the presence of microorganisms rather than due to the abiotic properties of compost. The majority of the compost-associated microorganisms (more than 70% for bacteria and 90% for fungi) were detected in the soil in the presence of native soil microorganisms. Elimination of native soil microorganisms by sterilization enhanced the prevalence and abundance of compost-associated microorganisms. Adding fresh compost increased wheat biomass production, but the positive effects of compost on plant growth were strongest when sterile composts were used. Hence, our study reports that compost-associated microorganisms are essential to modify soil microbial community but may not benefit crop growth. This highlights the importance of understanding the role of abiotic and biotic properties of composts as common soil amendments on improving the functioning of agricultural soil.

Species-specific interaction affects organic nitrogen uptake during intercropping of four important crop species: A useful index for selecting appropriate intercropping combination

Intercropping has been an important practice for improving field production and its various aspects have been thoroughly investigated. However, only few studies have explored it from the perspective of organic nitrogen (N) uptake, especially under the rapid development of organic and no-tillage farming worldwide. In this study, two cereals (Triticum aestivum and Zea mays) and two legumes (Glycine max and Pisum sativum) were mono- and intercropped using microcosm experiments in a greenhouse, with a total of 10 combinations. The uptake pattern of in situ15N-labelled glycine by plants in each combination was investigated. The total biomass of wheat increased 1.6 times when intercropped with soybean, compared to its monoculture, but not at the expense of reduced soybean growth. Root:shoot ratios of maize increased 1.3 times when intercropped with pea compared with its monoculture. Intercropping with soybean decreased the uptake rates of 15N-labelled glycine by wheat compared to its monoculture. Although intercropping with other species increased the root:shoot in maize, it did not increase the glycine-derived 15N uptake rates. We conclude that interactions between agricultural plants are species-specific and can alter the uptake of N-derived from organic forms. These findings indicate that wheat-soybean intercropping can be a good choice for organic and no-tillage farming to improve production with the potential to reduce the application of synthetic N fertilizers.

Effects of Atmospheric CO2 and Temperature on Wheat and Corn Susceptibility to Fusarium graminearum and Deoxynivalenol Contamination.

This work details the impact of atmospheric CO2 and temperature conditions on two strains of Fusarium graminearum, their disease damage, pathogen growth, mycotoxin accumulation, and production per unit fungal biomass in wheat and corn. An elevated atmospheric CO2 concentration, 1000 ppm CO2, significantly increased the accumulation of deoxynivalenol in infected plants. Furthermore, growth in cool growing conditions, 20 °C/18 °C, day and night, respectively, resulted in the highest amounts of pathogen biomass and toxin accumulation in both inoculated wheat and corn. Warm temperatures, 25 °C/23 °C, day and night, respectively, suppressed pathogen growth and toxin accumulation, with reductions as great as 99% in corn. In wheat, despite reduced pathogen biomass and toxin accumulation at warm temperatures, the fungal pathogen was more aggressive with greater disease damage and toxin production per unit biomass. Disease outcomes were also pathogen strain specific, with complex interactions between host, strain, and growth conditions. However, we found that atmospheric CO2 and temperature had essentially no significant interactions, except for greatly increased deoxynivalenol accumulation in corn at cool temperatures and elevated CO2. Plants were most susceptible to disease damage at warm and cold temperatures for wheat and corn, respectively. This work helps elucidate the complex interaction between the abiotic stresses and biotic susceptibility of wheat and corn to Fusarium graminearum infection to better understand the potential impact global climate change poses to future food security.

ИНТЕНСИВНОСТЬ УСВОЕНИЯ УГЛЕРОДА ПОЛЕВЫМИ КУЛЬТУРАМИ В ЗАВИСИМОСТИ ОТ ТЕХНОЛОГИИ ВОЗДЕЛЫВАНИЯ В УСЛОВИЯХ РЕСПУБЛИКИ ТАТАРСТАН

Carbon dioxide is absorbed by plants during photosynthesis and the intensity of this process depends on the solar radiation coming to this territory, the temperature regime, the availability of moisture and batteries. The amount of CO2 absorbed by plants is determined by the accumulated dry biomass or yield. The potential yield of field crops in production conditions is not always achieved. The paper presents the results of studies on the effect of calculated doses of mineral fertilizers on various types of soils with different moisture indicators on the formation of dry biomass by spring durum wheat. Field experiments were carried out on gray forest soils in 2005-2008, which occupy 43.7% of agricultural land in the Republic of Tatarstan and chernozems in 2001-2003, occupying 39.9%. The assimilation of mineral nutrition elements from soil and fertilizers by plants is influenced not only by the type of soil, but also by the availability of productive moisture. In the studies of 1984-1987, the effect of fertilizers and irrigation on the intensity of accumulation of dry biomass by spring durum wheat was studied. The use of calculated doses of mineral fertilizers on leached chernozems on average for 1984-1987 increased the accumulation of dry biomass of spring durum wheat by 45.6%, and in combination with irrigation by another 57.4%. In the experiments of 2001-2003, calculated doses of mineral fertilizers increased the accumulation of dry biomass by 20.7% on the chernozems of the Transcamian region of the Republic of Tatarstan, and by 13.6% on the gray forest soils of the Pre-Kama region in 2005-2008

Co-inoculation of Trichoderma gamsii A5MH and Trichoderma harzianum Tr906 in wheat suppresses in planta abundance of the crown rot pathogen Fusarium pseudograminearum and impacts the rhizosphere soil fungal microbiome

Wheat root endophytic strains Trichoderma gamsii A5MH and T. harzianum Tr906 were assessed for their abilities to suppress in planta abundance of the crown rot pathogen Fusarium pseudograminearum and increase growth of durum wheat. Fusarium crown rot suppressive assays were conducted in natural Kandosol and Chromosol wheat cropping soils with greater disease expression observed in the Chromosol. Rhizosphere abundance of T. gamsii A5MH, T. harzianum Tr906 and F. pseudograminearum were quantified by species-specific qPCR at plant maturity. Strains A5MH and Tr906 actively colonized the wheat rhizosphere and suppressed in planta pathogen abundance in both soil types, with both inoculants persisting in roots and soil to 84 days postemergence. Strain A5MH increased wheat biomass in both soils, whereas strain Tr906 only increased biomass of Chromosol-grown wheat. Metabolites of strains A5MH and Tr906 decreased in vitro growth of wheat pathogenic F. pseudograminearum, Rhizoctonia solani and Pythium irregulare, but did not inhibit either inoculant. Compared with individually inoculated strains, co-inoculation of A5MH and Tr906 did not affect rhizosphere niche abundance, in planta pathogen suppressive efficacies or wheat growth-benefits of either inoculant in Chromosol-grown wheat. Fusarium crown rot symptoms however, only decreased in the A5MH and co-inoculated treatments. Each Trichoderma treatment had distinct impacts on the structure (beta diversity) of the indigenous rhizosphere soil fungal community of Chromosol-grown wheat. Strain A5MH and co-inoculated treatments had the greatest overall effects on soil fungal community (alpha) diversity and structure. Community differentiation was primarily attributed to increased abundance of Trichoderma spp. in the inoculated treatments and associated decreases in plant pathogenic and predominantly saprophytic fungal genera.

Exogenous ascorbic acid application alleviates cadmium toxicity in seedlings of two wheat (Triticum aestivum L.) varieties by reducing cadmium uptake and enhancing antioxidative capacity.

The aggravation of soil cadmium (Cd) pollution is a serious threat to human food health and safety. To reduce Cd uptake and alleviate Cd toxicity in staple food of wheat, a completely random experiment was performed to investigate the effect of exogenous ascorbic acid (AsA) on Cd toxicity in two wheat varieties (L979 and H27). In this study, the treatments with combinations of Cd (0, 5, and 10µmol L-1) and AsA (0, 50, and 200µmol L-1) were applied in a hydroponic system. Toxicity induced by Cd inhibited biomass accumulation; decreased wheat growth, photosynthesis, and chlorophyll content; increased lipid peroxidation; and reduced activity of superoxide dismutase (SOD), but stimulated catalase (CAT) and peroxidase (POD). The addition of AsA significantly improved the growth status by increasing the wheat biomass, chlorophyll content, photosynthetic rate, protein concentrations, and antioxidant enzyme activity. Besides, AsA significantly decreased Cd concentration of shoot and root by 14.1-53.9% and 20.8-59.5% in L979 and 23.7-58.8% and 22.1-58.1% in H27 under Cd5, and 23.7-53.6% and 16.6-57.1% in L979 and 21.5-51.6% and 15.3-54.0% in H27 under Cd10, respectively. Malondialdehyde (MDA) accumulation was decreased remarkably with the addition of AsA by 31.2-32.9% in L979 and 27.1-45.2% in H27 under Cd10, respectively. Overall, exogenous application of AsA alleviated the Cd toxicity in wheat plants by improving the wheat growth, soluble protein content, photosynthesis, and antioxidant defense systems, and decreasing MDA accumulation.

Coupling Remote Sensing Data and AquaCrop Model for Simulation of Winter Wheat Growth under Rainfed and Irrigated Conditions in a Mediterranean Environment

The coupling of remote sensing technology and crop growth models represents a promising approach to support crop yield prediction and irrigation management. In this study, five vegetation indices were derived from the Copernicus-Sentinel 2 satellite to investigate their performance monitoring winter wheat growth in a Mediterranean environment in Lebanon’s Bekaa Valley. Among those indices, the fraction of canopy cover was integrated into the AquaCrop model to simulate biomass and yield of wheat grown under rainfed conditions and fully irrigated regimes. The experiment was conducted during three consecutive growing seasons (from 2017 to 2019), characterized by different precipitation patterns. The AquaCrop model was calibrated and validated for different water regimes, and its performance was tested when coupled with remote sensing canopy cover. The results showed a good fit between measured canopy cover and Leaf Area Index (LAI) data and those derived from Sentinel 2 images. The R2 coefficient was 0.79 for canopy cover and 0.77 for LAI. Moreover, the regressions were fitted to relate biomass with Sentinel 2 vegetation indices. In descending order of R2, the indices were ranked: Fractional Vegetation Cover (FVC), LAI, the fraction of Absorbed Photosynthetically Active Radiation (fAPAR), the Normalized Difference Vegetation Index (NDVI), and the Enhanced Vegetation Index (EVI). Notably, FVC and LAI were highly correlated with biomass. The results of the AquaCrop calibration showed that the modeling efficiency values, NSE, were 0.99 for well-watered treatments and 0.95 for rainfed conditions, confirming the goodness of fit between measured and simulated values. The validation results confirmed that the simulated yield varied from 2.59 to 5.36 t ha−1, while the measured yield varied from 3.08 to 5.63 t ha−1 for full irrigation and rainfed treatments. After integrating the canopy cover into AquaCrop, the % of deviation of simulated and measured variables was reduced. The Root Mean Square Error (RMSE) for yield ranged between 0.08 and 0.69 t ha−1 before coupling and between 0.04 and 0.42 t ha−1 after integration. This result confirmed that the presented integration framework represents a promising method to improve the prediction of wheat crop growth in Mediterranean areas. Further studies are needed before being applied on a larger scale.

Effects of biochar amendment on wheat production, mycorrhizal status, soil microbial community, and properties of an Andisol in Southern Chile

Biochar (BC) production from agroforestry wastes and mycorrhizal fungi are potentially important agricultural practices for improving crops yields and increasing phosphorus (P) in volcanic soils. This study aimed to test the effect of BC application on wheat biomass and grain yield production, indigenous arbuscular mycorrhizal (AM) fungi propagules and soil microbial community and related to soil quality properties of an Andisol in Southern Chile. Biochars (BCs) were produced from oat hulls (OBC) and pine bark (PBC). Doses of 0, 5, 10, and 20 Mg ha−1 of BCs were applied on soil using wheat as the test crop. Wheat biomass (root and shoot portion) and grain yield, AM root colonization, spore, mycelium density, and glomalin content (glomalin related soil protein, EE-GRSP) were measured and related with soil quality properties such as bulk density, water-stable aggregates (WSA), and water holding capacity (WHC). The OBC had a significantly higher macronutrients content (N, P, K) than PBC. The highest dose of both BCs significantly improved shoot and root biomass and wheat grain yield. Application of 20 Mg ha−1 of OBC and PBC increased AM spore density and root colonization relative to control treatment. In the same way, the BC application significantly affects the AM mycelium density. The results showed that the application of higher BC dose changed the soil microbial community. The use of BCs in this volcanic soil is an effective strategy to increase wheat biomass, increase grain yield production, stimulate the indigenous AM fungi activity, enhance soil quality properties, and increase the sustainability levels of agricultural systems.

Prediction of Wheat Stripe Rust Occurrence with Time Series Sentinel-2 Images

Wheat stripe rust has a severe impact on wheat yield and quality. An effective prediction method is necessary for food security. In this study, we extract the optimal vegetation indices (VIs) sensitive to stripe rust at different time-periods, and develop a wheat stripe rust prediction model with satellite images to realize the multi-temporal prediction. First, VIs related to stripe rust stress are extracted as candidate features for disease prediction from time series Sentinel-2 images. Then, the optimal VI combinations are selected using sequential forward selection (SFS). Finally, the occurrence of wheat stripe rust in different time-periods is predicted using the support vector machine (SVM) method. The results of the features selected demonstrate that, before the jointing period, the optimal VIs are related to the biomass, pigment, and moisture of wheat. After the jointing period, the red-edge VIs related to the crop health status play important roles. The overall accuracy and Kappa coefficient of the prediction model, which is based on SVM, is generally higher than those of the k-nearest neighbor (KNN) and back-propagation neural network (BPNN) methods. The SVM method is more suitable for time series predictions of wheat stripe rust. The model obtained accuracy based on the optimal VI combinations and the SVM increased over time; the highest accuracy was 86.2%. These results indicate that the prediction model can provide guidance and suggestions for early disease prevention of the study site, and the method combines time series Sentinel-2 images and the SVM, which can be used to predict wheat stripe rust.

Agroecosystem Stability In Spring Wheat Crops With The Application Of Fertilizers And Microbial Biological Products

The formation of spring wheat biomass on sod-podzolic soil is carried out mainly due to soil nitrogen, the share of which reaches 1/3 of the total removal of the element when using mineral fertilizers. Inoculation of spring wheat seeds with biologics of rhizosphere microorganisms increases the nitrogen content of fertilizers to 7.3%, increases its immobilization by 5.9-6.7% and reduces losses by 7.4-13.9%. The stability of the agroecosystem is characterized by nitrogen flows. During the growing season of spring wheat with a hydrothermal coefficient of 1.55-1.72, the amount of mineralized nitrogen (mineralization (M)), depending on fertilizers, reaches 9.4-11.1 g/m2, while the reimobilized nitrogen (reimobilization (RI)) – 2.2-3.1 g/m2, net-mineralized (net-mineralization (N-M)) – 6.8 - 8.0 g/m2. The use of nitrogen fertilizers and biological products leads the agroecosystem to the resistance mode (the maximum permissible level of exposure) (RI : M = 27-28%, N-M : RI = 2.5-2.7).

Interaction of Inherited Microbiota from Cover Crops with Cash Crops

Cover crops (CC) provide important ecosystem services that are demanded to achieve more sustainable agrosystems. However, the legacy effects of CC on the microbial community structure and its interactions with the subsequent cash crops (CaC) are still poorly understood, especially when CC mixtures are involved. In this work, five CC (3 monocultures and 2 mixtures) were selected in an experiment under semi-controlled conditions to investigate if CC monocultures and mixtures differed in their effects on soil and crop variables and if the identity of the subsequent crop modulates these effects. The two most consumed crops worldwide, wheat and maize, were sown separately after CC. The legacy effects of CC on the studied microbial variables largely depended on the interaction with the CaC. The vetch and the barley-vetch mixture stood out by providing the microbial conditions that enhanced the absorption of macro- and micronutrients, to finally seek the highest wheat biomass (>80% more than the control). In maize, the effects of CC on soil microbiota were more limited. The soil microbial responses for CC mixtures were complex and contrasting. In wheat, the barley-vetch mixture behaved like barley monoculture, whereas in maize, this mixture behaved like vetch monoculture. In both CaC, the barley-melilotus mixture differed completely from its monocultures, mainly through changes in archaea, Glomeromycota, and F:B ratio. Therefore, it is necessary to deepen the knowledge on the CC-CaC-microbial interactions to select the CC that most enhance the sustainability and yield of each agrosystem.

The effects of microalgae-based fertilization of wheat on yield, soil microbiome and nitrogen oxides emissions

Overuse of agrochemicals is linked to nutrient loss, greenhouse gases (GHG) emissions, and resource depletion thus requiring the development of sustainable agricultural solutions. Cultivated microalgal biomass could provide such a solution. The environmental consequences of algal biomass application in agriculture and more specifically its effect on soil GHG emissions are understudied. Here we report the results of a field experiment of wheat grown on three different soil types under the same climatic conditions and fertilized by urea or the untreated biomass of fresh-water green microalga (Coelastrella sp.). The results show that neither soil type nor fertilization types impacted the aboveground wheat biomass, whereas, soil microbiomes differed in accordance with soil but not the fertilizer type. However, wheat grain nitrogen (N) content and soil N oxides emissions were significantly lower in plots fertilized by algal biomass compared to urea. Grain N content in the wheat grain that was fertilized by algal biomass was between 1.3%–1.5% vs. 1.6%–2.0% in the urea fertilized wheat. Cumulative soil nitric oxide (NO) emissions were 2–5 fold lower, 313–726 g N ha−1 season−1 vs. 909–3079 g N ha−1 season−1. Cumulative soil nitrous oxide (N2O) emissions were 2-fold lower, 90–348 g N ha−1 season−1 vs. 147–761 g N ha−1 season−1. The lower emissions resulted in a 4–11 fold lower global warming impact of the algal fertilized crops. This calculation excluded the CO2 cost from the algae biomass production. Once included algal fertilization had a similar, or 40% higher, climatic impact compared to the urea fertilization.

Mesotrione: a new preemergence herbicide option for wild radish (Raphanus raphanistrum) control in wheat

AbstractWild radish is the most problematic broadleaf weed in Australian grain production. The propensity of wild radish to evolve resistance to herbicides has led to high frequencies of multiple herbicide–resistant populations present in these grain production regions. The objective of this study was to evaluate the potential of mesotrione to selectively control wild radish in wheat. The initial dose response pot trials determined that at the highest mesotrione rate of 50 g ha−1 applied preemergence (PRE) was 30% more effective than when applied postemergence (POST) on wild radish. This same rate of mesotrione applied POST resulted in a 30% reduction in wheat biomass compared to 0% for the PRE application. Subsequent mesotrione PRE dose response trials identified a wheat selective rate range of >100 and <300 g ai ha−1 that provided greater than 85% wild radish control with less than 15% reduction in wheat growth. Field evaluations confirmed the efficacy of mesotrione at 100 to 150 g ai ha−1 in reducing wild radish populations by greater than 85% following PRE application and incorporation by wheat planting. Additionally, these field trials demonstrated the opportunity for season-long control of wild radish when mesotrione applied PRE was followed by bromoxynil applied POST. The sequential PRE application of mesotrione, a herbicide that inhibits p-hydroxyphenylpyruvate dioxygenase, followed by POST application of bromoxynil, a herbicide that inhibits photosystem II, has the potential to provide 100% wild radish control with no effect on wheat growth.

Effects of Nitrogen Fertilizer on Photosynthetic Characteristics, Biomass, and Yield of Wheat under Different Shading Conditions

Fruit-wheat intercropping is an important way to resolve the land competition between fruit and grain and ensure food security. However, there is little research on the mechanism of wheat yield formation and its response to nitrogen fertilizer under long-term shading. From 2016 to 2017, wheat variety “Xindong 20” was selected, and four shading treatments were set: shading at jointing stage 10%-shading at heading stage 25% (S1), 20%–50% (S2), 30%–75% (S3), normal light (S0) and four nitrogen fertilizer (N0: 0 kg ha−1, N1: 103.5 kg ha−1, N2: 138 kg ha−1, N3: 172.5 kg ha−1). The results show that compared with S0, wheat leaf area index (LAI), chlorophyll a, b and a + b content under S1 increase by 14.9–57.4%, 2.9–24.5%, 16.5–28.9%, 7.8–25.5%, respectively, and they decrease significantly under S2 and S3. With the increase in the shading range, the net photosynthesis rate (Pn), transpiration rate (Tr), stomatal conductance (gs), and non-photochemical quentum coefficient (NPQ) decrease significantly, while the actual photochemical efficiency (ΦPSII) and the photochemical quenching coefficient (qP) increase significantly. Under S1, S2, and S3, the total dry matter accumulation (TDA), the dry matter accumulation of reproductive organs (DAR), and the yield decrease with the increase in shading range. Under the S0 and S1 conditions, compared with other nitrogen treatments, LAI, chlorophyll content, Pn, ΦPSII, qP, TDA, DAR, and yield of wheat under N2 treatment increase by 4.1–366.9%, 5.7–56.3%, 3.0–131.7%, 6.7–87.5%, 3.7–96.9%, 7.1–340.8%, 0.3–323.0%, 1.5–231.2%. Therefore, under jujube-wheat intercropping, and apricot-wheat and walnut-wheat with light shade in the early stage, photosynthetic capacity of wheat leaves and dry matter accumulation and transfer to grains can be regulated by proper nitrogen application, which is beneficial to compensate for the negative effects of insufficient light on wheat yield; under moderate or excessive shading conditions (apricot-wheat and walnut-wheat in full fruit period), the regulating effect of nitrogen application on wheat is reduced, and the nitrogen application should be moderately reduced.

Winter Wheat (Triticum aestivum L.) Tolerance to Mulch.

Mulch from cover crops can effectively suppress weeds in organic corn (Zea mays L.) and soybean (Glycine max L.) as part of cover crop-based rotational no-till systems, but little is known about the feasibility of using mulch to suppress weeds in organic winter small grain crops. A field experiment was conducted in central NY, USA, to quantify winter wheat (Triticum aestivum L.) seedling emergence, weed and crop biomass production, and wheat grain yield across a gradient of mulch biomass. Winter wheat seedling density showed an asymptotic relationship with mulch biomass, with no effect at low rates and a gradual decrease from moderate to high rates of mulch. Selective suppression of weed biomass but not wheat biomass was observed, and wheat grain yield was not reduced at the highest level of mulch (9000 kg ha−1). Results indicate that organic winter wheat can be no-till planted in systems that use mulch for weed suppression. Future research should explore wheat tolerance to mulch under different conditions, and the potential of no-till planting wheat directly into rolled-crimped cover crops.

Vertical distribution of phosphorus fractions and the environmental critical phosphorus level in acidic red soil under long‐term fertilizer and lime application in southern China

AbstractBackgroundPhosphorus (P) deficiency in acidic red soil restricts crop yield. However, long‐term application of phosphate fertilizer can cause potential environmental risks due to the accumulation of P in the soil.AimsOur aim was to determine the distribution characteristics of P fractions in acidic red soil profiles and the environmental risk of soil P losses after application of organic fertilizer and lime, and analyze the key factors driving P distribution in the soil profile of acidic red soil.MethodsBased on the long‑term applicationof fertilizers and quicklime in the acidic soil under wheat–maize rotation system, contents of soil Olsen‐P and CaCl2‐P, as well as pH, at multiple soil layers between 0 and 50 cm depths were monitored. The environmental critical P levels were determined using a two‐segment linear model.ResultsDuring 1990–2010 and 2011–2014, application of phosphate fertilizer or quicklime on acidic red soil significantly (p < 0.05) increased the annual average aboveground biomass of wheat and maize and P recovery efficiency. Soil Olsen‐P and CaCl2‐P contents increased with the application of phosphate fertilizer, especially in combination with manure, and the increase mainly concentrated at the 0–20‐cm soil layer. The environmental critical Olsen‐P content was 99.7 mg kg−1. The Olsen‐P contents at different soil layers were mainly affected by cumulative P and organic P inputs, but were less affected by soil pH.ConclusionsThe application of organic fertilizer and lime can prevent the acidification of red soil, and the application of organic fertilizer should reduce the total phosphate fertilizer input to prevent rapid accumulation of P and risk of P loss in leachate while still improving the crop utilization rate of P fertilizer. Thus, this strategy should help achieve the concomitant goals of high crop yield and environmental protection.

Spring wheat productivity and grain quality in the crop rotation of the foreststeppe of Western Siberia

Spring bread wheat is cultivated in the Omsk region, mainly in grain-fallow crop rotations, repeated and perma[1]nent crops, less in crop-changing rotations and occupies up to 73% of the grain share of Western Siberia. Soybean crops are growing in the region, but at the same time, there have not been sufficiently studied the peculiarities of the cultivation technology of spring wheat sown after this forecrop. The purpose of the current study was to establish the efficiency of agricultural cultivation technologies of spring wheat in the crop rotation sown after soybean in the southern forest-steppe of Western Siberia. The study was carried out in a stationary crop rotation with alternating crops (soy[1]beans – spring wheat – oil flax – barley) in the laboratory for resource-saving agricultural technologies of the Omsk Research Center on meadow-blackearth soil in 2011–2019. There has been established that the soil cultivation system and the means of intensification influenced the elements of fertility and the phytosanitary state of the agrophytocenosis of spring wheat sown after soybean. With subsurface plowing, in comparison with moldboard plowing, there was an increase in biomass and number of weeds on 21 and 43%, respectively. The use of chemicals resulted in a significant increase in spring wheat biomass (on 1.8 times) and a decrease in number of weeds (on 3.3 times), which had a noticeable effect on the productivity. Productivity of wheat sown after soybeans decreased with a decrease in tillage intensity from moldboard plowing to subsurface plowing on 16%. The intensive cultivation technology of spring wheat increased its productivity up to 3.32 t / ha, the protein and gluten content in grain on 16–18%. As for chemicals, the maximum grain number increase on 28.2% was provided by the use of fungicides compared to the control (1.46 t/ha).

Improving Biomass and Grain Yield Prediction of Wheat Genotypes on Sodic Soil Using Integrated High-Resolution Multispectral, Hyperspectral, 3D Point Cloud, and Machine Learning Techniques

Sodic soils adversely affect crop production over extensive areas of rain-fed cropping worldwide, with particularly large areas in Australia. Crop phenotyping may assist in identifying cultivars tolerant to soil sodicity. However, studies to identify the most appropriate traits and reliable tools to assist crop phenotyping on sodic soil are limited. Hence, this study evaluated the ability of multispectral, hyperspectral, 3D point cloud, and machine learning techniques to improve estimation of biomass and grain yield of wheat genotypes grown on a moderately sodic (MS) and highly sodic (HS) soil sites in northeastern Australia. While a number of studies have reported using different remote sensing approaches and crop traits to quantify crop growth, stress, and yield variation, studies are limited using the combination of these techniques including machine learning to improve estimation of genotypic biomass and yield, especially in constrained sodic soil environments. At close to flowering, unmanned aerial vehicle (UAV) and ground-based proximal sensing was used to obtain remote and/or proximal sensing data, while biomass yield and crop heights were also manually measured in the field. Grain yield was machine-harvested at maturity. UAV remote and/or proximal sensing-derived spectral vegetation indices (VIs), such as normalized difference vegetation index, optimized soil adjusted vegetation index, and enhanced vegetation index and crop height were closely corresponded to wheat genotypic biomass and grain yields. UAV multispectral VIs more closely associated with biomass and grain yields compared to proximal sensing data. The red-green-blue (RGB) 3D point cloud technique was effective in determining crop height, which was slightly better correlated with genotypic biomass and grain yield than ground-measured crop height data. These remote sensing-derived crop traits (VIs and crop height) and wheat biomass and grain yields were further simulated using machine learning algorithms (multitarget linear regression, support vector machine regression, Gaussian process regression, and artificial neural network) with different kernels to improve estimation of biomass and grain yield. The artificial neural network predicted biomass yield (R2 = 0.89; RMSE = 34.8 g/m2 for the MS and R2 = 0.82; RMSE = 26.4 g/m2 for the HS site) and grain yield (R2 = 0.88; RMSE = 11.8 g/m2 for the MS and R2 = 0.74; RMSE = 16.1 g/m2 for the HS site) with slightly less error than the others. Wheat genotypes Mitch, Corack, Mace, Trojan, Lancer, and Bremer were identified as more tolerant to sodic soil constraints than Emu Rock, Janz, Flanker, and Gladius. The study improves our ability to select appropriate traits and techniques in accurate estimation of wheat genotypic biomass and grain yields on sodic soils. This will also assist farmers in identifying cultivars tolerant to sodic soil constraints.

Growth, yield and arsenic accumulation by wheat grown in a pressmud amended salt-affected soil irrigated with arsenic contaminated water

The study assessed the influence of pressmud (PM) application on soil available phosphorus (P) content, growth, yield, and arsenic (As) accumulation in wheat grains on a salt-affected soil receiving irrigation of As-contaminated water. Wheat seeds (cv. Faisalabad-2008) were sown in pots containing saline soil (EC 11.72 dS m−1; pH 8.07; SAR 31.3 mmol1/2 L−1/2) amended with PM (0, 2.5, 10 and 15 g kg−1) and irrigated with As-contaminated water (0, 25 and 100 µg L−1). The pot experiments had two sets, one was harvested after 30-days of germination while the other at crop maturity. Pressmud application at 2.5, 10 and 15 g kg−1 improved biomass of 30-days old wheat seedlings by 44%, 86% and 90%, respectively compared to unamended soil. Irrigation with As-contaminated waters did not affect seedling biomass or grain yield of wheat. Plant height, fertile tillers, straw biomass and grain yield increased from 57-62 cm, 3–5 no. plant−1, 2.93–5.31 g plant−1 and 3.93–7.11 g plant−1, respectively by 15 g PM kg−1 soil. Moreover, PM application resulted in an 8-fold increase in soil available P content, which resulted in higher grain P uptake. Irrigation with water of 25 and 100 µg As L−1 increased soil available P by 7.6% and 11%, respectively, but its influence on the grain P concentration was non-significant. Pressmud application in combination with As-contaminated water increased accumulation of As in grains. By applying water of 25 and 100 µg L−1 As, accumulation of As in wheat grains increased from 3.12-42.4 and 49.58–91.85 µg kg−1, respectively compared with normal water. However, these concentrations of As in wheat grains were still below the permissible limit of 430 µg kg−1 prescribed for agronomic crops. In conclusion, PM is very effective in improving wheat productivity on salt-affected soils but it can aggravate As accumulation in wheat grains if applied in combination with As polluted water.

Effect of Seed Rates and Weeding Frequency on Yield and Yield Components of Bread Wheat (Triticum aestivum L.) on Vertisols in Toke Kutaye District

Bread wheat (Triticum aestivum L.) plays a crucial role in ensuring food security in Ethiopia. However, its production and productivity is constrained by weed infestation and inappropriate seed rate used. Hence, an experiment was conducted to determine the optimal seed rate and weeding frequency for bread wheat production on Vertisols in Toke Kutaye district during 2020 main cropping season. Treatments consisted of five levels of seed rates (75, 100, 125, 150, and 175kgha-1) and four levels of weeding frequency (zero weeding, once weeding (15DAE), twice weeding (15 and 45 DAE) and thrice weeding (15, 45 and 75 DAE). Experiment was laid out in Randomized Complete Block Design (RCBD) with factorial combination replicated thrice. Results of the study revealed that the interaction of seed rate and weeding frequency significantly (P≤ 0.05) influenced phenological and growth parameters except days reqired for 50% emergence and yield of bread wheat. Highest wheat biomass yield (11.03tha-1), grain yield (4.47tha-1) and straw yield (6.6tha-1)were obtained using 175kgha-1seed rate with thrice hand weeding. Highest relative yield loss (71.3%) was recorded from weedy plot with 75kgha-1seed rate, while the lowest loss (1.2%) was recorded at 175kgha-1seed rate with thrice hand weeding. Highest net benefit of ETB 73,170ha-1 , marginal rate of return 884.4% and value to cost ratio of ETB 8.34 per unit of investment was obtained from 175kgha-1 seed rate combined with thrice hand weeding. Therefore, use of 175kgha-1 seed rate with thrice hand weeding was found profitable, and recommended for bread wheat production in Toke Kutaye district.