Winter Wheat Yield Research Articles

Regional Winter Wheat Yield Prediction and Variable Importance Analysis Based on Multisource Environmental Data

Timely and accurate predictions of winter wheat yields are key to ensuring food security. In this research, winter wheat yield prediction models for six provinces were established using a random forest (RF) model. Two methods were employed to analyze feature variables. RF partial dependence plots were generated to demonstrate the nonlinear relationships between the feature variables and yield, and bivariate Moran’s I was considered to identify the spatial associations between variables. Results showed that when environmental data from key growth periods were used for prediction model establishment, the root mean square error (RMSE) varied between 200 and 700 kg/ha, and the coefficient of determination (R2) exceeded 0.5. Feature variable analysis results indicated that the longitude, latitude, topography and normalized difference vegetation index (NDVI) were important variables. Below the threshold, the yield gradually increased with increasing NDVI. Bivariate Moran’s I results showed that there was zonal distribution of meteorological elements. Within a large spatial range, the change in environmental variables due to the latitude and longitude should be accounted for in modeling, but the influence of collinearity between the feature variables should be eliminated via variable importance analysis.

Managing Residue Return Increases Soil Organic Carbon, Total Nitrogen in the Soil Aggregate, and the Grain Yield of Winter Wheat

Soil tillage and maize residues return are important practices for tackling and promoting soil quality and improving crop yield in the North China Plain (NCP), where winter wheat production is threatened by soil deterioration. Although maize residues incorporation with rotary tillage (RS) or deep plowing tillage (DS) is widespread in this region, only few studies have focused on rotation tillage. Four practices, namely RT (continuous rotary tillage without maize residues return), RS, DS, and RS/DS (rotary tillage every year and deep plowing interval of 2 years), were evaluated under field conditions lasting a period of 5 years. After a 5-year field experiment, the mean soil bulk density of the 0–30 cm soil layer decreased significantly with RS, DS, and RS/DS, i.e., by 4.19%, 6.33%, and 6.71% compared with RT, respectively. The treatments greatly improved the total soil porosity, soil aggregate size distribution, soil aggregate stability, and the root length density in the 0–30 cm soil layers. Residues return with DS and RS/DS treatments significantly increased the soil organic carbon (SOC) and total nitrogen (TN) storage in the 0–30 cm soil layer, mainly owed to the increases in the SOC and TN pool associated with the macro-aggregate. A positive trend in the grain yield was noted under both DS and RS/DS conditions, whereas a decreasing tendency was presented in continuous rotary treatments. In summary, RS/DS treatment significantly increased the amount of SOC and TN, improved the particle size distribution of soil aggregates, and thus improved the soil’s physicochemical properties, which is beneficial for wheat to achieve high yields. Our results suggested that RS/DS was a highly efficient practice to improve soil quality and increase crop production in the NCP.

Sustainability improvement of grain productivity of beet crop rotations in the foreststeppe of the Central Blackearth region

The purpose of the current study was to identify the effect of various crop rotations and rates of application of mineral fertilizers on productivity of winter wheat and spring barley, the productivity of crop rotations and the economic efficiency of cultivating crops. The study was carried out in a stationary field trial of the FSBSI “Kursk FARC” on typical heavy loamy blackearth (chernozem) in 2015–2023. Agricultural crops were grown in three crop rotations: 1 – grainrow fallow (black fallow, winter wheat, sugar beets, maize for silage, barley); 2 – grain-row green manure fallow (green manure fallow, winter wheat, sugar beets, maize for silage, barley); 3 – crop rotation (horse-bean for grain, winter wheat, sugar beets, white lupine for grain, barley). During the trial there have been compared two contrasting levels of mineral fertilizer application N30Р30К30 and N52Р52К52 per hectare of crop rotation area. The non-marketable portion of the harvest of all crops was used as fertilizer. Agricultural technology was generally conventional for the area. There has been established that, under all weather conditions, the highest yield of winter wheat at a low background of fertilization (N30Р30К300 per hectare of crop rotation area) is produced in green manure fallow, and at a high background of fertilization (N52Р52К52 per hectare of crop rotation area) in black fallow. There was found that the most favorable conditions for cultivating barley were created when cultivating with white lupine for grain. Fertilization increase led to productivity increase of the grain crops, but, at the same time, to a production profitability decrease. There has been determined that productivity of crop rotations with fallow forecrops is 14 % higher compared to crop rotations with a legume forecrop (horse-bean for grain). According to calculations, on average over the years of study, the most profitable was the winter wheat cultivation in black fallow, and spring barley cultivation in white lupine for grain. At the same time, the indicator of production profitability level decreased with an increase in the rate of mineral fertilizing, which results in production costs’ increase.

Winter wheat source‐sink relationships under various planting modes, complementary irrigation, and planting densities

AbstractVarious agronomic practices can affect the processes of aboveground dry matter accumulation (source) and grain filling (sink), resulting in yield differences. Improved source‐sink relationships can facilitate the production and accumulation of assimilates to increase the productivity of winter wheat (Triticum aestivum L.). A two‐season field experiment was undertaken on winter wheat during 2020–2021 and 2021–2022. In a split‐split‐plot design with three replicates (randomized blocks), we compared two planting modes (ridge‐furrow planting with plastic mulching [RFPM]; traditional flat planting [TF]), two complementary irrigation levels (I30+30: 30+30 mm; I0: no irrigation), and three planting densities (D1, D2, and D3: 240, 360, and 480 plants m−2). The results showed that RFPMI30+30 significantly increased maximum yield by 28.5% compared with TFI0. Although D3 increased the number of effective spikes per unit area and duration of grain filling compared to D2, it reduced the number of grains per spike, 1000‐grain weight, and average filling rate. Compared to TF and I0, RFPM and I30+30 improved the sink/source ratio by 5.3% and 6.5%, respectively. Grain yield peaked at D2 in the RFPM and at D3 in the TF. Medium planting density (D2) and complementary irrigation (I30+30) during the wintering and reviving periods under RFPM can achieve better source‐sink balance relationships and the maximum grain yield of winter wheat. Overall, we believe that in most cases, wheat yields are source‐limited and can be improved by ridge‐furrow planting with plastic mulching, complementary irrigation, and planting density regulation.

Soil mineral nitrogen and winter wheat nitrogen productivity influenced by summer cover crop and nitrogen fertilization

Cover crops and nitrogen (N) fertilization may affect soil mineral N, N uptake, and N productivity (grain yield per unit plant available N) in wheat (Triticum aestivum L.). We evaluated the effect of summer cover crops and N fertilization rates on soil mineral N and winter wheat grain yield, N uptake, and N productivity in the Loess Plateau of China. We measured cover crop aboveground biomass N, soil mineral N (0-20 cm), and winter wheat yield, N uptake, and N productivity for four seasons from 2017-2018 to 2020-2021. Cover crops were soybean (Glycine max L., SB), sudangrass (Sorghum sudanense [Piper] Stapf, SG], soybean and sudangrass mixture (SS), and no cover crop (CK) and N fertilization rates were 0, 60, and 120 kg N ha−1 applied to wheat. The SB increased cover crop biomass N and soil mineral N by 15 to 65%, but SS increased winter wheat yield, protein concentration, and N uptake by 25 to 55% compared to SG and CK at most N fertilization rates and years. Nitrogen fertilization rate had a variable effect on cover crop and wheat parameters. Wheat N productivity was 55 to 85% greater with CK than cover crops, but decreased with increased N fertilization rates. The N fertilizer equivalence of cover crops for wheat yield and N uptake ranged from 31 kg N ha−1 for SG to 150 kg N ha−1 for SS. Overall, SS with 60 kg N ha−1 can sustain winter wheat N uptake and N productivity compared to SG or CK with or without N fertilization.

Effects of Straw Return and Nitrogen Application Rates on Soil Ammonia Volatilization and Yield of Winter Wheat

This study investigates the impact of corn straw return and nitrogen application rates on ammonia volatilization and yield enhancement under field conditions, in order to reduce emissions while increasing crop yield. During the winter wheat season, a fissure area design was implemented, comprising three levels of straw return in the main area and three distinct nitrogen fertilizer levels in the subsidiary area, for a total of nine treatments. The results can be summarized as follows: (1) The ammonia emissions flux initially increased followed by a decrease, and was primarily concentrated within the first 14 days after fertilization, with a peak observed at 4–5 days before decreasing. Notably, nitrogen fertilizer significantly affected the cumulative ammonia emissions, ranging from 0.019 to 1.786 kg·hm−2·d−1 and 0.013 to 1.693 kg·hm−2·d−1 across the two seasons. (2) The soil with a higher nitrogen application rate exhibited elevated levels of inorganic nitrogen content and urease activity under the same straw return level. Maintaining a consistent nitrogen application level, the return of straw to the field increased the cumulative ammonia discharge, inorganic nitrogen content, and urease activity. (3) The interaction between straw return and nitrogen fertilizer substantially affected crop yield. Specifically, during the winter wheat season, the optimal combination for reducing ammonia emissions and enhancing yield was observed under straw return (both half or full) combined with 180 kg·hm−2 nitrogen application. Notably, the reduction of soil emissions and winter wheat yield augmentation were feasible through appropriate corn straw return in the preceding season.

The effect of green manure on the agrochemical properties of soil in winter wheat crops, yield and grain quality

The effect of green manure on the agrochemical properties of soil in winter wheat crops, yield and grain quality

Drought stimulus enhanced stress tolerance in winter wheat (Triticum aestivum L.) by improving physiological characteristics, growth, and water productivity

The impact of drought events on the growth and yield of wheat plants has been extensively reported; however, limited information is available on the changes in physiological characteristics and their effects on the growth and water productivity of wheat after repeated drought stimuli. Moreover, whether appropriate drought stimulus can improve stress resistance in plants by improving physiological traits remains to be explored. Thus, in this study, a pot experiment was conducted to investigate the effects of intermittent and persistent mild [65%–75% soil water-holding capacity (SWHC)], moderate (55%–65% SWHC), and severe drought (45%–55% SWHC) stress on the growth, physiological characteristics, yield, and water-use efficiency (WUE) of winter wheat. After the second stress stimulus, persistent severe drought stress resulted in 30.98%, 234.62%, 53.80%, and 31.00% reduction in leaf relative water content, leaf water potential, photosynthetic rate (Pn), and indole-3-acetic acid content (IAA), respectively, compared to the control plants. However, abscisic acid content, antioxidant enzyme activities, and osmoregulatory substance contents increased significantly under drought stress, especially under persistent drought stress. After the second rehydration stimulus (ASRR), the actual and maximum efficiency of PSII and leaf water status in the plants exposed to intermittent moderate drought (IS2) stress were restored to the control levels, resulting in Pn being 102.56% of the control values; instantaneous WUE of the plants exposed to persistent severe drought stress was 1.79 times that of the control plants. In addition, the activities of superoxide dismutase, peroxidase, catalase, and glutathione reductase, as well as the content of proline, under persistent mild drought stress increased by 52.98%, 33.47%, 51.95%, 52.35%, and 17.07% at ASRR, respectively, compared to the control plants, which provided continuous antioxidant protection to wheat plants. This was also demonstrated by the lower H2O2 and MDA contents after rehydration. At ASRR, the IAA content in the IS2 and persistent moderate drought treatments increased by 36.23% and 19.61%, respectively, compared to the control plants, which favored increased aboveground dry mass and plant height. Compared to the control plants, IS2 significantly increased wheat yield, WUE for grain yield, and WUE for biomass, by 10.15%, 32.94%, and 33.16%, respectively. Collectively, IS2 increased grain growth, yield, and WUE, which could be mainly attributed to improved physiological characteristics after drought-stimulated rehydration.

Estimation of winter wheat yield in Hebi city based on crop models and remote sensing data assimilation

Abstract Assimilating remote sensing data with crop models is an effective approach to improve the accuracy of crop model applications at the regional scale. Sobol global sensitivity analysis and Markov Chain Monte Carlo methods were used to calibrate parameters in the WOFOST and WheatSM models within a gridded model framework in the study area. Time series data reconstruction techniques were employed to correct MODIS LAI and ET data. Four assimilation scenarios were tested, including assimilation of only leaf area index (LAI), assimilation of only evapotranspiration (ET), simultaneous assimilation of LAI and ET and a control scenario without assimilation. These scenarios were applied to model winter wheat yields in Hebi City, China, from 2013 to 2018. Statistical validation demonstrated that assimilating ET or LAI individually significantly improved model accuracy compared to the control scenario with similar levels of improvement. The highest model accuracy was achieved when assimilating both ET and LAI simultaneously, showing the highest correlation coefficients and the lowest root mean square errors among the four scenarios. This research provides a basis for selecting assimilation variables when applying crop models at the regional scale. The coupling of crop growth models with remote sensing data empowers governments and agricultural producers to devise more effective agricultural strategies, allocate resources efficiently, and implement disaster response measures. This enhances scientific management within the agricultural sector, promotes increased food production and elevates farmers’ incomes.

The Effect of Different Cultivation Technologies on the Agromeliorative Condition of the Soil and the Crop Yield of Winter Wheat

The Effect of Different Cultivation Technologies on the Agromeliorative Condition of the Soil and the Crop Yield of Winter Wheat

AN INTEGRATED APPROACH TO STABILIZING THE PHYTOSANITARY CONDITION OF WINTER WHEAT CROPS IN THE SOUTH OF RUSSIA

The main condition for obtaining high yields of winter wheat is agricultural productivity: the use of high-yielding varieties, the selection of predecessors, the best sowing dates, careful soil cultivation, as well as the use of mineral fertilizers and protective equipment. At the moment, a situation has developed in agriculture in the south of Russia that is important for the phytosanitary condition of grain crops and forms a certain composition of harmful organisms. Winter wheat occupies a large part in the structure of sown areas; repeated crops are often observed. A definitely important place is occupied by technological methods of cultivation in the formation of a harmful component of the grain field. Therefore, when cultivating winter wheat, fungal diseases become of great importance, which cause thinning of crops, lead to growth inhibition, disrupt the dynamics of plant organogenesis, impair the formation of crop structure elements, causing a significant decrease in the qua-lity of the resulting product. Surveys to identify the phytosanitary state of winter wheat crops are aimed at creating a system of effective measures that can ensure the containment of pathogenic organisms. The research is aimed at analyzing the factors influencing the formation of the phytosanitary state of grain crops, including winter wheat, to study the effectiveness of both individual control methods and their effective combinations.A set of methods that can effectively curb the development of pests includes: selection of zoned resistant varieties, compliance with crop rotation and selection of predecessors. An integral part of the technology for cultivating grain crops is the implementation of protective extermination measures to obtain high yields of high-quality products.

GRAIN YIELD AND SIDERAL MASS OF FIELD CROPS IN CROP ROTATIONS OF THE LOWER VOLGA REGION

Background. For the first time in the abiotic conditions of the Lower Volga region on light chestnut soils, new methods of biologization of soil fertility preservation and specialized field crop rotations based on the replacement of pure steam with sideral steam with little–studied crops for green fertilizer – biennial yellow clover, oats and phacelia were developed and studied; the structure of sown areas includes cultures of various biological groups, including cereals, legumes, oilseeds, rowed and perennial legumes; in addition to siderates, organic fertilizers are used in the form of straw and crop –root residues of cultivated crops. The purpose of the work is the influence of pure and sideral steam on the yield of field crops Materials and methods. The study of the influence of sideral masses on the yield of grain crops in field crop rotations in the conditions of the Lower Volga region. Results. According to the conducted research, it has been established that biologized crop rotations are the first major stage in the transition to organic farming in the Volgograd region. The best option for the soils of the dry-steppe zone of chestnut subzones of light chestnut soils of the Lower Volga region is a four-field biologized field crop rotation and a five-field crop rotation with sideral steam (donnik). Conclusion. Data analysis showed that the best indicators of winter wheat yield were obtained for pure and sideral (sweet clover) pairs - 1.8 t/ha, chickpeas for the predecessor winter wheat in the five–field crop rotation - 0.87 t/ha and spring barley for the predecessor chickpeas – 1.48 t/ha.

Application of vermiculture products as an innovative direction of organic production

An important strategy for diversifying agricultural production is the use of vermicomposting and the production of new products from vermicompostfor their further widespread use. Objective. To investigate the effectiveness of the use of vermicompost and the biological product ‘Nanoverm’ obtained from it as a high-quality complex environmentally friendly organic fertiliser for application to grain crops. Methods. The research was conducted at LIGA COLAP LLC, the Department of General and Applied Ecology and Zoology of Zaporizhzhia National University (Zaporizhzhia) and farms of the Vilnyansky and Orikhivsky districts of Zaporizhzhia region in two stages. At the first stage, the effect of vermicompost at a dose of 1.0-1.5 l/t and Nanoverm at a dose of 1.0-1.5 l/t on the first stages of winter wheat ontogeny of Podolyanka variety was studied. At the second stage, the effect of the biological product ‘Nanoverm’ on the formation of biometric growth parameters and yield of winter wheat was studied. Plants of the control group were grown without fertilizers, and the experimental group was treated with Nanoverm biofertilizer at a dose of 1.5 l/t. Results. It was found that pre-sowing treatment of winter wheat seeds with vermicompost provided an increase in seed germination energy by 3.7-4.0 % compared to the control, and laboratory germination by 5.3 %. When seeds were treated with Nanoverm biological product at a dose of 1 l/t, germination energy increased by 4.7 %, and laboratory germination increased by 6.0 %. With an increase in the dose of the preparation to 1.5 l/t, these indicators increased by 5.0 and 7.3 %, respectively. Pre-sowing treatment of seeds with the studied preparations also had a positive effect on such indicators as the length of the coleoptile and roots of winter wheat seedlings. The analysis of biometric parameters of winter wheat growth and yield after harvesting showed that in the experimental variant, such indicators as grain weight, number of grains per ear and yield were significantly higher. With almost the same plant height and a slight increase in the length of the ear, the stimulating effect of feeding winter wheat in the earing phase with Nanoverm was expressed in an increase in the number of grains per ear by 15.3 %, and the weight of grain per ear by 22.2 % (p<0.001). As a result, the grain yield in the experimental group was 8.3 c/ha higher than in the control group (p<0.001). Conclusions. It was found that pre-sowing treatment of seeds with vermigum or biological product ‘Nanoverm ’ improves all the indicators that characterise the first stages of ontogeny of winter wheat variety Podolyanka. Fertilising winter wheat in the earing phase with Nanoverm at a dose of 1.5 l/ha led to the activation ofgrowth processes and contributed to the formation of higher productivity. As a result of a significant increase in the number and weight of grains in the ear, the yield increased by 22.3 % and amounted to 47.2 c/ha. Keywords: california worms, vermicompost, Nanoverm, winter wheat, Podolianka, growth, yield.

Dependency of Long-Term Soil Quality Controls on Summer Fallow Tillage and Soil Layers for Dryland Winter Wheat in Loess Plateau

The capacity for winter wheat to produce sufficient yield may be influenced by soil tillage practices and soil quality. However, determining how to quantify the impact of long-term tillage on soil quality is crucial. Here, we address this issue by comparing soil properties and wheat yield under four tillage systems during summer fallow in the Loess Plateau. Twenty-two soil properties were explored to estimate soil quality. Results showed that a rotational tillage (PT/ST) during summer fallow decreased soil bulk density (ρb) and improved soil gravimetric water content (θg), soil organic carbon (SOC), soil capillary porosity (Pc), and total porosity (Pt) in 0–50 cm soil layers. A minimum dataset (MDS) of thirteen indicators was selected to calculate soil quality index (SQI). Treatment of PT/ST had higher SQI value in soil layers of 0–10 cm and 20–50 cm, and PT/ST showed a significant increase in yield since the third year. No tillage (NT) during summer fallow decreased soil physical and chemical indicators, thus decreasing soil quality. These findings suggest that a rotation tillage of PT/ST during summer fallow could enhance soil chemical and biological properties concurrently, and PT/ST may provide a promising management strategy to sustain soil quality and grain yield for dryland winter wheat in the Loess Plateau.

Effect of strip-till and cultivar on photosynthetic parameters and grain yield of winter wheat

Effect of strip-till and cultivar on photosynthetic parameters and grain yield of winter wheat

WSTĘPNE OKREŚLENIE MOŻLIWOŚCI REDUKCJI NAWOŻENIA AZOTOWEGO POD WPŁYWEM PREPARATÓW BAKTERYJNYCH W UPRAWIE TRITICUM AESTIVUM L.

The use of microorganisms in agriculture is attracting increasing interest. Thus, the state of knowledge on this issue and biotechnological advances are significantly increasing. A field research was conducted during the 2022–2023 growing season to evaluate the influence of the combined application of bacterial formulation and mineral nitrogen fertilization on grain and straw yield of winter wheat (Triticum aestivum L.) and the structure of the obtained yield. The factors of the conducted field experiment were bacterial formulations: control (no application of bacterial formulations), I – Azotobacter and Arthrobacter, II – Bacillus subtillis, Bacillus megaterium, Bacillus azotofixans, III – Bacillus azotofixans; B – mineral nitrogen fertilization: control (no mineral nitrogen fertilization), 43 kg N·ha−1, 86 kg N·ha−1, 130 kg N·ha−1. Research was conducted demonstrating the most favorable effects after applying a bacterial formulation containing Azotobacter and Arthrobacter bacteria. It was statistically significant increase in grain yield by an average of 17%, number of ears per m2 by 15%, ear length by 5% and thousand grain weight by 3% The application of other formulations also caused an increase in the analyzed traits, but they were lower than those given for Azotobacter and Arthrobacter bacteria. A gradual increase in the level of mineral nitrogen fertilization also had a positive effect on the analyzed traits. The research conducted in the field found a possible reduction in mineral nitrogen fertilization under the conditions of the conducted experiment by about 33% without yield losses when using a bacterial formulation containing Azotobacter and Arthrobacter. Thus, it is appropriate to recommend the use of these bacteria in winter wheat cultivation, but due to the possible variable effectiveness of application under different soil and climatic conditions, the presented research should be continued in different areas both in wheat and other crops.

The Effects of Different Sowing Dates on the Autumn Development and Yield of Winter Wheat in Central Lithuania

Sowing date is a particularly important management option to optimize yields as it determines proper wintering and productivity. During a seven-year field experiment, the response of winter wheat to five different sowing times was studied. The beginning of the dormancy period was determined, and the Growing Degree Day (GDD) requirements for the period from sowing to emergence and from emergence to dormancy were assessed. As the sowing date was delayed, the time from sowing to emergence increased. The minimum optimum temperature during the emergence period was about 12 °C, with a heat requirement of about 125–130 GDD for earlier sowings, ensuring that winter wheat germinated successfully and properly prepared for wintering. The heat requirement for later sowings was higher and reached about 180 GDD when the average temperature of this period was about 8 °C. For the late sowing, the period from emergence to dormancy was too short, so winter wheat did not accumulate the required amount of heat, which had a significant impact on yield. The accumulated temperature from emergence to dormancy must be greater than 100 GDD. The obtained values can be applied in other regions or to choose the appropriate wheat sowing time to reduce yield losses under climate change.

Effects of Nitrogen Application at Different Levels by a Sprinkler Fertigation System on Crop Growth and Nitrogen-Use Efficiency of Winter Wheat in the North China Plain.

Nitrogen (N) is an essential macronutrient for crop growth; therefore, N deficit can greatly limit crop growth and production. In the North China Plain (NCP), winter wheat (Triticum aestivum L.) is one of the main food crops, and its yield has increased from approximately 4000 kg ha-1 to 6000 kg ha-1 in the last two decades. Determining the proper N application rates at different growth stages and in all seasons is very important for the sustainable and high production of wheat in the NCP. A field experiment with five N application rates (250, 200, 150, 100, and 40 kgN·ha-1, designated as N250, N200, N150, N100, and N40, respectively) was conducted during the 2017-2018 and 2018-2019 winter wheat seasons to investigate the effects of the N application rate on water- and fertilizer-utilization efficiency and on the crop growth and yield of winter wheat under sprinkler fertigation conditions. The results showed that in the N application range of 40-200 kg ha-1, crop yield and water- and fertilizer-use efficiencies increased as the N application rate increased; however, further increases in the N application rate (from N200 to N250) did not have additional benefits. The N uptake after regreening of winter wheat linearly increased with crop growth. Considering the wheat yield and N-use efficiency, the recommended optimal N application rate was 200 kg ha-1, and the best topdressing strategy was equal amounts of N applied at the regreening, jointing, and grain-filling stages. The results of this study will be useful for optimizing field N management to achieve high wheat yield production in the NCP and in regions with similar climatic and soil environment conditions.

Enhancing water-carbon fluxes and yield predictions of winter wheat using irrigation and data assimilation techniques in a land surface model

Croplands are essential to land–atmosphere interactions and have a great impact on water balance, carbon fluxes, regional weather and climate, and food supply. This study utilized the Noah-MP land surface model, enhanced by a dynamic crop growth process known as Noah-MP-Crop, and employed a multi-pass data assimilation scheme (MLDAS) to assimilate leaf area index, surface soil moisture, and solar-induced chlorophyll fluorescence into the model for refining model’s simulations of land state variables (soil moisture and leaf biomass) and optimize the model vegetation parameters [specific leaf area (SLA) and maximum carboxylation rate normalized to 25 °C (Vcmax25)]. In conjunction with the irrigation module in this model, four experiments were conducted at the local observation-site scale to estimate and validate water-carbon fluxes [actual evapotranspiration (ETa) and gross primary productivity (GPP)] and crop yield within the winter wheat growing phase, which included open-loop simulation with and without irrigation (OLirr and OL), data assimilation with and without irrigation (DAirr and DA), separately. In-situ observations from the Yucheng Station in 2006 were used to evaluate these four experiments. Results indicated that the combined experiment (DAirr) provided the best agreement with the observed ETa, GPP, and yield. This superior performance is mainly attributed to the accurate vegetation information and soil moisture profile provided by the combined experiments with the model. Results indicated that the DAirr experiment performed better than the OL experiment in ETa estimation, with a higher correlation coefficient (R) of 0.85 compared to 0.71, a reduced root mean square error (RMSE) from 1.51 to 1.06 mm day−1, a lower normalized RMSE (NRMSE) from 43.21 % to 23.39 %, and a decreased mean absolute error (MAE) from 1.16 to 0.78 mm day−1. Similarly, DAirr increased R from 0.71 to 0.87 and cut down RMSE (MAE) from 5.81 (4.32) to 3.48 (2.26) g m−2 day−1 and NRMSE from 70.39 % to 18.20 % for GPP estimation. Moreover, winter wheat yield from DAirr (770.9 g m−2) agreed better with ground measurements (819.7 g m−2) than that from OL (400.6 g m−2). Additionally, results revealed that assimilating all three variables simultaneously is superior to single-variable assimilation and significantly outperforms the OL approach. All in all, this study has provided initial insights into the feasibility of assimilating three variables at the site scale into the model for improving the estimation accuracy of water-carbon fluxes and winter wheat yield, which laid a foundation for subsequent regional simulations.

Multifunctional Effect of Triterpenoid-Based Growth Regulators on Wheat Plants

The information on the biological role of triterpenoids in plants, possible mechanisms of the phytoregulatory action of triterpenoids and their glycosides is summarized, the physiological and biochemical aspects of the action of plant growth regulators (PGR) based on tritepenoids: Silk, Biosil, Novosil, Alfastim, etc. on wheat plants in different phases of ontogenesis under normal conditions and under the action of stress factors are considered. Data on the effect of these PGR on the incidence of phytopathogens, yield and grain quality of winter and spring wheat are presented.