Wheat Nitrogen Research Articles

Prokaryotic expression and purification of inorganic nitrogen transporters in wheat

The nitrate transporter (NRT) and ammonium transporter (AMT) are crucial transmembrane proteins involved in the absorption, transport, and distribution of inorganic nitrogen in wheat. Obtaining NRT/AMT and preparing corresponding antibodies are conducive to probing into their tissue localization and comprehending the nitrogen utilization process in wheat. In this study, four genes (TaNPF4.5, TaNPF8.3, TaNRT3.1, TaAMT1.2) with high expression levels were chosen and cloned from 405 genes of the TaNRT/TaNPF family and 23 genes of the TaAMT family identified previously. The transmembrane domains of the four transporters were predicted by HMMER to determine the putative expression segments, followed by prokaryotic expression and purification. Under the induction with 1 mmol/L IPTG at 37 ℃, the non-transmembrane segments of TaNPF4.5, TaNPF8.3, and TaNRT3.1 reached the highest expression levels (as inclusion bodies) after 4 h, while TaAMT1.2 was expressed at the highest level (as a soluble protein) after 3 h. TaNPF4.5, TaNPF8.3, and TaNRT3.1 were purified by a pH gradient. The purity of TaNPF4.5 and TaNPF8.3 reached about 87% and 85% at pH 2.0 and pH 3.0, respectively, both of which were suitable for antibody preparation. However, the purity of TaNRT3.1 did not reach 85%. TaAMT1.2 was purified by an imidazole gradient, reaching the purity of about 95% at 20 mmol/L imidazole, and the antibody was prepared successfully. The expression, purification, and antibody preparation of TaAMT1.2 not only provides insights into the expression, purification, and antibody preparation of membrane proteins including TaNPF4.5 and TaNPF8.3 but also lays a foundation for studying the expression and localization of membrane proteins in wheat.

TaNAR2.1 and TaNAR2.2 differ in influencing nitrogen uptake and growth of wheat (Triticum aestivum L.)

NAR2 (Nitrate assimilation related protein) is a protein chaperone involved in transporting nitrate across membranes. However, the expression pattern and function of NAR2 genes in wheat are still largely unknown. Here, we cloned two TaNAR2 genes (TaNAR2.1 and TaNAR2.2). To assess and compare the functional differences of TaNAR2.1 and TaNAR2.2, we analyzed the subcellular localization and expression pattern of the two genes in wheat under low nitrogen (LN) and high nitrogen (HN) conditions, as well as the nitrate influx and root system architecture of TaNAR2.1 and TaNAR2.2 overexpression wheat under LN and HN. Additionally, we investigated the effects of TaNAR2.1 and TaNAR2.2 overexpression on the growth phenotype, nitrogen uptake and yield of wheat throughout the growth period. There are significant differences in the expression patterns and functions of TaNAR2.1 and TaNAR2.2. TaNAR2.1 is located in the cytoplasm, nucleus and the plasma membrane, whereas TaNAR2.2 is a cytoplasm-specific protein. TaNAR2.1 appears to exhibit larger changes in expression levels and a higher capacity for nitrate influx than TaNAR2.2 under external nitrate supply. Overexpression of TaNAR2.1 significantly improves grain nitrogen use efficiency and increases grain yield, whereas overexpression of TaNAR2.2 enhances vegetative and reproductive growth of wheat roots. These findings indicate that TaNAR2.1 plays a crucial role in wheat nitrogen accumulation and yield, while TaNAR2.2 is pivotal for wheat root growth.

Effect of Delayed Irrigation at the Jointing Stage on Nitrogen, Silicon Nutrition and Grain Yield of Winter Wheat in the North China Plain.

Water scarcity is a key limitation to winter wheat production in the North China Plain, and it is essential to explore the optimal timing of spring irrigation to optimize N and Si uptake as well as to safeguard yields. The aim of this study was to systematically study the effect mechanism of nitrogen and silicon absorption of winter wheat on yield under spring irrigation and to provide a scientific basis for optimizing irrigation strategy during the growth period of winter wheat. In this experiment, the winter wheat 'Heng 4399' was used. Five irrigation periods, i.e., 0 d (CK), 5 d (AJ5), 10 d (AJ10), 15 d (AJ15), and 20 d (AJ20) after the jointing stage, were set up to evaluate the nitrogen (N) and silicon (Si) absorption and grain yield (GY). The results showed that delayed irrigation for 5-10 days at the jointing stage had increased the GY. With the delay of irrigation time, the N/Si content of the entire plant at the maturity period increased first and then decreased; among that, the maximum N contents appeared in AJ15 and AJ5 in 2015 and 2020, respectively, while the Si concentrations appeared in AJ5 and AJ10 in sequence. Compared with AJ15 and AJ20, the N accumulation of vegetative organs in AJ5 increased by 3.05~23.13% at the flowering stage, 14.12~40.12% after the flowering stage, and a 1.76~6.45% increase in the N distribution rate at maturity stage. A correlation analysis revealed that the GY was significantly and positively correlated with the N/Si accumulation at the anthesis and N translocation after the anthesis stage. In conclusion, under limited irrigation conditions, delaying watering for 5 to 10 days at the jointing stage can improve the nitrogen and silicon absorption and nutrient status of wheat plants and increase wheat yield.

Impact of Bio-Organic Fertilizer Incorporation on Soil Nutrients, Enzymatic Activity, and Microbial Community in Wheat–Maize Rotation System

Excessive use of inorganic fertilizers disrupts soil nutrient balance and leads to soil degradation and a decrease in biodiversity. In contrast, bio-fertilizers enhance soil structure and fertility and promote plant growth and sustainable agriculture development. Therefore, this study focused on a rotation system of winter wheat and summer maize and aimed to explore the effects of applying chemical fertilizer (NPK) and bio-fertilizer (BF) in the winter wheat season on the sustainable soil development of current wheat and subsequent maize. Before sowing winter wheat four fertilization treatments were, respectively CK (100% NPK at 750 kg ha−1), A (60% NPK at 450 + 20% BF at 150 kg ha−1), B (60% NPK at 450 + 40% BF at 300 kg ha−1), and C (60% NPK at 450 + 60% BF at 450 kg ha−1), conducted. The results showed that treatment A (60% NPK + 20% BF) replacing the NPK at 300 kg ha−1 with BF at 150 kg ha−1 significantly soil nutrient contents, enzyme activity, and microbial metabolic activity. The study also found a positive correlation between soil parameters (total nitrogen, alkaline nitrogen, available phosphorus, organic matter, urease, and alkaline phosphatase in the winter wheat and maize cropping season). Furthermore, the soil microbial composition showed significant enrichment of Proteobacteria, Acidobacteria, Actinobacteria, and Firmicutes, and variations among treatments. Moreover, the application of biofertilizer enhanced the diversity of soil fungi species, particularly during the winter wheat season. This study highlights the importance of integrating biofertilizers with NPK fertilizer for agricultural system conversion and promoting agricultural production and sustainability.

Effects of irrigation and nitrogen topdressing on water and nitrogen use efficiency for winter wheat with micro-sprinkling hose irrigation in North China

In order to explore the efficient use of water and nitrogen for winter wheat under irrigation with micro-sprinkling hose, two-season field experiments were conducted to evaluate the effects of irrigation levels and nitrogen application rate on yield, water productivity (WP) and nitrogen partial factor productivity (NPFP). Three irrigation levels were 60 %, 65 %, and 70 % field capacity (FC) during the reviving to jointing stage, 65 %, 70 %, and 75 % FC after the jointing stage, referred to as W1, W2 and W3, respectively. The irrigating water quota is 30 mm. The five N topdressing period treatments were reviving period + booting stage (N1), jointing + booting stage (N2), reviving period (N3), jointing stage (N4), and booting stage (N5). The results showed that the water consumption, leaf area index, plant height, biomass, grain yield, and NPFP increased with an increase in irrigation amount, and the WP decreased with an increase in irrigation amount. Nitrogen applied during the reviving period was beneficial for increasing grain yield, WP, and NPFP under the irrigation level W1; nitrogen applied during the jointing period was beneficial for increasing grain yield, WP, and NPFP for winter wheat under the W2 and W3 irrigation levels. The W3N2 treatment resulted in the highest grain yield (8.98 t·ha−1), but it was not significant difference from W2N2 (average of 8.92 t·ha−1). After a comprehensive evaluation based on grain yield, WP and NPFP, the appropriate modes of irrigation and nitrogen is the treatment of W2N2 (65 % and 70 % FC irrigation treatments during the reviving to jointing stage and the stages after jointing stage, respectively; the nitrogen topdressing during jointing + booting stage) for winter wheat using micro-sprinkling hose irrigation in North China.

Trends in the yield response to nitrogen of winter wheat in Oklahoma

Trends in the yield response to nitrogen of winter wheat in Oklahoma

N Fertilizer in Combination with Straw Improves Soil Physicochemical Properties and Crop Productivity in Sub-Humid, Drought-Prone Areas

Straw returning may be an efficient strategy to maintain agricultural sustainability. However, which straw returning strategy can effectively improve soil properties and crop yield remain unclear. A five-year (2011–2016) field experiment in sub-humid, drought-prone areas of northwestern China with uneven rainfall distribution and irrigation was conducted to evaluate the effects of nitrogen fertilizer without straw mulching (CK), with regular straw mulching (LSM), and with ammoniated straw plowing (ALSP) on soil water, soil aggregates, soil organic carbon (SOC), total nitrogen (TN), and water use efficiency (WUE) in an annual winter wheat (Triticum aestivum L.)–summer maize (Zea mays L.) rotation system. The results demonstrate that ALSP had a greater soil water content than CK in the 0–60 cm soil layer. ALSP also had substantially more soil water than LSM in the 0–100 cm layer during the wet year (2011–2012) and two dry years (2014–2015 and 2015–2016). In the normal years (2012–2013 and 2013–2014), the soil water content in ALSP was significantly lower than in LSM in the 0–20 cm soil layer. ALSP was better able to alleviate soil drought in dry years and excessive humidity in wet years. Compared to CK, SOC in the 0–20 cm soil layer in 2016 increased by 8.3% in LSM and 11.7% in ALSP, and TN in the upper soil increased by 6.6% in LSM and 10.1% in ALSP. The equivalent wheat yield and WUE increased in ALSP by 15.6% and 17.5%, respectively, relative to CK, and by 6.79% and 5.97%, respectively, relative to LSM. Thus, we concluded that plowing ammoniated straw with N fertilization is a promising strategy for improving soil fertility and crop productivity in winter wheat–summer maize rotation systems in the sub-humid, drought-prone areas of northwestern China.

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.

Identification of Wheat Glutamate Synthetase Gene Family and Expression Analysis under Nitrogen Stress.

Nitrogen (N), as the main component of biological macromolecules, maintains the basic process of plant growth and development. GOGAT, as a key enzyme in the N assimilation process, catalyzes α-ketoglutaric acid and glutamine to form glutamate. In this study, six GOGAT genes in wheat (Triticum aestivum L.) were identified and classified into two subfamilies, Fd-GOGAT (TaGOGAT2s) and NADH-GOGAT (TaGOGAT3s), according to the type of electron donor. Subcellular localization prediction showed that TaGOGAT3-D was localized in mitochondria and that the other five TaGOGATs were localized in chloroplasts. Via the analysis of promoter elements, many binding sites related to growth and development, hormone regulation and plant stress resistance regulations were found on the TaGOGAT promoters. The tissue-specificity expression analysis showed that TaGOGAT2s were mainly expressed in wheat leaves and flag leaves, while TaGOGAT3s were highly expressed in roots and leaves. The expression level of TaGOGATs and the enzyme activity of TaGOGAT3s in the leaves and roots of wheat seedlings were influenced by the treatment of N deficiency. This study conducted a systematic analysis of wheat GOGAT genes, providing a theoretical basis not only for the functional analysis of TaGOGATs, but also for the study of wheat nitrogen use efficiency (NUE).

Coupled one-off alternate furrow irrigation with nitrogen topdressing at jointing optimizes soil nitrate-N distribution and wheat nitrogen productivity in dryland.

The judicious management of water and nitrogen (N) is pivotal for augmenting crop productivity and N use efficiency, while also mitigating environmental concerns. With the advent of the High-Farmland Construction Program in China, one-off irrigation has become feasible for most dryland fields, presenting a novel opportunity to explore the synergistic strategies of water and N management. This study delves into the impact of one-off alternate furrow irrigation (AFI) and topdressing N fertilizer (TN) on soil nitrate-N distribution, and N productivity-including plant N accumulation, translocation, and allocation, and grain yield, protein content, N use efficiency of winter wheat (Triticum aestivum L.) in 2018-2019 and 2019-2020. Experimental treatments administered at the jointing stage comprised of two irrigation methods-every (EFI) and alternative (AFI) furrow irrigation at 75 mm, and two topdressing N rates-0 (NTN) and 60 (TN) kg N ha-1. Additionally, a conventional local farmer practice featuring no irrigation and no topdressing N (NINTN) was served as control. Compared to NINTN, EFINTN substantially increased aboveground N accumulation, grain yield, and protein yield, albeit with a reduction in grain protein content by 8.1%-10.6%. AFI, in turn, led to higher nitrate-N accumulation in the 60-160 cm soil depth at booting and anthesis, but diminished levels at maturity, resulting in a significant surge in N accumulation from anthesis to maturity and its contribution to grain, N fertilizer partial factor productivity (PFPN), and N uptake efficiency (NUPE), thereby promoting grain yield by 9.9% and preserving grain protein content. Likewise, TN enhanced soil nitrate-N at key growth stages, reflected in marked improvements in N accumulation both from booting to anthesis and from anthesis to maturity, as well as in grain yield, protein content, and protein yield. The combination of AFI and TN (AFITN) yielded the highest grain yield, protein content, with PFPN, NUPE, and N internal efficiency outstripping those of EFINTN, but not AFINTN. In essence, one-off AFI coupled with TN at the jointing stage is a promising strategy for optimizing soil nitrate-N and enhancing wheat N productivity in dryland where one-off irrigation is assured.

Combining spectrum, thermal, and texture features using machine learning algorithms for wheat nitrogen nutrient index estimation and model transferability analysis

The nitrogen nutrition index (NNI) has been extensively applied for the diagnosis of crop nitrogen status, providing insights into efficient nitrogen utilization and plant growth. In this study, we utilized a low-altitude unmanned aerial vehicle (UAV) platform, equipped with multispectral (MS), red–green–blue (RGB), and thermal infrared (TIR) cameras, to comprehensively capture wheat spectral information. The analysis of the relationship between NNI and relative yield revealed an initially linear relationship, which saturated for high NNI values. To enhance accuracy and minimize complexity, we employed a random forest (RF) – recursive feature elimination (RFE) method to select features as inputs for four machine learning (ML) models: back propagation neural network (BPNN), extreme learning machine (ELM), support vector regression (SVR), and Gaussian process regression (GPR). After feature selection, the prediction accuracies of single-sensor models were ranked as: MS > RGB > TIR. The R2 values for the four ML models were in the range of 0.54–0.75. Among multi-sensor combinations, the GPR with MS + RGB + TIR input features achieved the best results with R2 = 0.89 and RPD = 2.52. Further, the dataset was partitioned into six subsets based on location and cultivar variety to evaluate model transferability. The results showed that the transferability largely suffered during the bivariate conditions of different varieties at different locations; the transferability of the model was average improved by 11 % when GPR was combined with transfer component analysis (TCA). The accuracy and transferability of the NNI estimation models significantly improved, offering valuable guidance and methodological support for diagnosing the nitrogen nutrient status of wheat.

Optimizing Wheat Yield: A Comprehensive Study on the Impact of Inorganic Fertilizer Rates and Varietal Selection in Kofele, Ethiopia

Wheat is one of the globally produced and marketed cereal crops which cover 15% of the total sowing areas of cereal crops in the world. The low productivity of wheat in Ethiopia is mainly attributed to lack of improved agronomic practices. Nitrogen and phosphorus are the major important elements for crop yield. But there is lack of information on optimum fertilizer rate for wheat production in this area (Kofele district of West Arsi zone). Therefore the objective of this research was to determine the optimum nitrogen and phosphorus fertilizer rate for wheat at Kofele district. This experiment was conducted for two consecutive years in 2016 and 2017 main cropping season. The treatment has two factors (three bread wheat varieties:- Digalu, Dendea and Didase and fertilizer rates: - 73kg/ha of nitrogen and 69kg /ha of P<sub>2</sub>O<sub>5</sub>, 109.5kg/ha of nitrogen and 103.5kg/ha of P<sub>2</sub>O<sub>5</sub>, 146kg/ha of nitrogen and 138kg/ha of P<sub>2</sub>O<sub>5 </sub>and 46kg/ha of nitrogen and 181kg/ha of NPS:-19:38:7). The analyzed data indicated that plant height and seeds per spike of bread wheat was highly significantly affected by main effect of variety. Highest plant height (128.33cm) and seeds per spike (42.1) were recorded from variety Dendea. Spike length was significantly affected by main effect of variety. The longest spike length (8.3) was recorded from variety Hidase. Wheat grain yield was significantly affected by interaction effect at (p<0.05). Variety Hidase produced the highest grain yield of 6904.4kg/ha at 146kg/ha of nitrogen and 138kg/ha of P<sub>2</sub>O<sub>5</sub>. Above ground dry weight of wheat was significantly affected by interaction effect. The highest above ground dry weight 18.9 ton/ha of wheat was produced from variety Digalu at 73kg/ha of nitrogen and 69kg/ha of P<sub>2</sub>O<sub>5</sub>. Therefore, to get the highest benefit farmers should grow variety Hidase by applying 146kg/ha of nitrogen and 138kg/ha of P<sub>2</sub>O<sub>5 </sub>at this area.

Effect of Seaweed Application on the Growth, Yield and Physiological Parameters in the Intercropping Farming System.

The present study demonstrates the application of biostimulants during the cultivation of wheat and chickpeas in intercropping farming. This study examined the effect of seaweed on the increasing amount of nitrogen, yield, and nutrient quality of wheat and chickpeas. In north India, rabi crops were grown for three seasons from 2019 to 2021 in the intercropping farming system. The main crop (wheat) was sown with chickpea (legumes) to enhance the yield of two crops in one season as chickpea also helps in nitrogen fixation in soil. There was a total of 36 rows each of 6 m, of which nine rows each were for wheat and chickpea and the other nine were for one row of wheat and another of chickpea. Results of the study, exhibit the significant effect of the amount of nitrogen which was a maximum of 4.33 mg/kg in intercropping treated with seaweed as compared to intercropping with control 4.23 mg/kg. AE (Agronomic Efficiency) in the intercropping with seaweed treatment was 3.27 kg/kg as compared to 3.23 kg/kg in the control. The yield and harvest index of seaweed with intercropping was higher than intercropping in control with chemical fertilizers like urea. Hence, biostimulants along with intercropping were found to be effective in increasing the yield and nutritional value of crops.

Nano calcium carbonate improves wheat nitrogen accumulation and grain yield by enhancing soil nitrogen supply and flag leaf photosynthetic characteristics

ContextOver-application of chemical fertilizers to attain optimal crop yields has resulted in an environmental issue of global concern. To mitigate this, reducing nitrogen (N) application and enhancing fertilizer use efficiency is crucial, and nano-fertilizers offer a promising solution. However, there is a paucity of studies examining the use of nano-fertilizers in fields. ObjectivesThis study aimed to assess the impact of different dosages of nano calcium carbonate (NCC) mixed with compound fertilizer (CF) on soil N supply, enzyme activity, microbial ecology, as well as photosynthetic characteristics, N accumulation and yield of wheat plants. MethodsThe effects were examined through a soil column leaching experiment and a two-year field experiment conducted from 2020 to 2022. Five treatment groups were established, namely CK (CF), T1 (CF + 0.15% NCC), T2 (CF + 0.30% NCC), T3 (CF + 0.45% NCC), and T4 (CF + 0.60% NCC), to determine the optimal ratio of NCC to CF. ResultsAll NCC treatments resulted in reduced leaching of soluble N. Nevertheless, the 0.45% and 0.60% NCC treatments (T3 and T4) posed a risk of migration through water runoff, leading to nutrient losses. The simultaneous application of NCC and CF increased the content of soil nitrate N (NO3--N), as well as the activity levels of urease and protease during the anthesis stage. Additionally, it elevated the abundance of various microbial communities, including Actinobacteria, Acidobacteria, Chloroflexi, Cyanobacteria, and Nitrospirae. NCC application reduced the content of Na+/K+ and malondialdehyde (MDA), while elevating the activities of flag leaf superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), nitrate reductase (NR), and glutamine synthetase (GS). Additionally, it increased stomatal conductance (Gs) and net photosynthetic rate (Pn). The 0.30% NCC treatment showed significantly higher N accumulation in the stem, leaf, and spike compared to CK at the maturity stage. Moreover, 0.30% NCC treatment exhibited a significant increase in the number of grains per spike and higher yields compared to CK. In particular, 0.30% and 0.45% NCC treatments accomplished yield boosts of 29.6–34.7% and 19.9–26.0%, respectively. ConclusionNCC enhanced wheat plant N accumulation and yield through regulation of N release rate and increased soil N content, enzyme activity, and microbial community diversity and abundance. Additionally, NCC boosted flag leaf photosynthesis rate during the anthesis to maturity stage of wheat. This research highlights the potential of NCC to improve wheat crop production. And 0.30% NCC is the optimal application concentration for NCC.

Effect of Nitrogen Management Strategies on Yield, Quality and Nitrogen Uptake by Wheat (Triticum aestivum L.)

There is little knowledge among farmers on the rate of nitrogen-fertilizer application. Therefore, there is a need to determine optimal rate of nitrogen-fertilizer application on growth and yield of wheat. Accordingly, an field experiment was conducted during the winter (Rabi) season at Crop Research Centre the Sardar Vallabhbhai Patel University of Agriculture and Technology, Meerut, Uttar Pradesh, to study the impact of different nitrogen level and splitting modules on quality, yield and nitrogen uptake by wheat (Triticum aestivum L.) crop. The main object of investigation was to find out the optimum dose and splitting of nitrogen for wheat in irrigated system under integrated nitrogen management approach. The experiment consisting of four nitrogen levels viz. control i.e. 0 kg N ha-1 , 90 kg N ha-1, i.e 120 kg N ha-1 and 150 kg N ha-1 as main plots and four splitting modules M1- 50% N as basal through VC, + 25% at CRI + 25% booting stage through urea, M2-50 % N as basal through FYM + 25% at tillering + 25% at booting stage through urea, M3 -50% N as basal through VC+FYM (1:1), + 25% at tillering + 20% at booting stage and 5 % N as foliar spray at pre flowering stage through urea, M4 -50% N as basal through VC+FYM (1:1), rest based on SPAD reading through urea as sub-plots. The experimental results revealed that the plot which fertilized with 150 kg N ha-1 gave higher yield-attributing characters and yield (grain, straw and biological yield). The application of 150 kg N ha-1 resulted in 0.44, 15.25 and 80.8 per cent during 2016-17 and 0.41, 13.05 and 79.2 per cent during 2017-18 produced the higher grain yield over 120, 90 and 0 kg N ha-1. The content and uptake of nitrogen by grain, straw and total uptake as well as protein content and protein yield were obtained with 150 Kg N ha-1 but differences between 120 and 150 kg N ha-1 were non-significant, during both the year 2016-17 and 2017-18. Among different splitting modules M3 resulted significantly higher entire yield attributes, yield (grain and straw yield), nitrogen content and uptake by grain, straw and total uptake as well as content and yield of protein. The M3 module produced higher grain yield by 7.9, 14.7 and 24.8 per cent during 2016-17 and 8.1, 14.89 and 25.2 per cent during 2017-18 over M4, M1 and M2 splitting modules, respectively.

Effect of a QTL on wheat chromosome 5B associated with enhanced root dry mass on transpiration and nitrogen uptake under contrasting drought scenarios in wheat.

A sufficient nitrogen supply is crucial for high-quality wheat yields. However, the use of nitrogen fertilization can also negatively influence ecosystems due to leaching or volatile atmospheric emissions. Drought events, increasingly prevalent in many crop production areas, significantly impact nitrogen uptake. Breeding more efficient wheat varieties is necessary to achieve acceptable yields with limited nitrogen and water. Crop root systems play a crucial role as the primary organ for absorbing water and nutrients. To investigate the impact of an enhanced root system on nitrogen and water use efficiency in wheat under various irrigation conditions, this study conducted two experiments using precision phenotyping platforms for controlled drought stress treatment. Experiment 1 involved four contrasting winter wheat genotypes. It included the Chinese variety Ning0604, carrying a quantitative trait locus (QTL) on chromosome 5B associated with a higher root dry biomass, and three elite German varieties, Elixer, Genius, and Leandrus. Experiment 2 compared near-isogenic lines (NIL) of the three elite varieties, each containing introgressions of the QTL on chromosome 5B linked to root dry mass. In both experiments, nitrogen partitioning was tracked via isotope discrimination after fertilization with 5 Atom % 15N-labeled KNO3-. In experiment 1 the quantification by 15N isotope discrimination revealed significantly (p < 0.05) higher nitrogen derived from fertilizer in the root organ for Ning0604 than those of the three German varieties. In experiment 2, two out of three NILs showed a significantly (p < 0.05) higher uptake of N derived from fertilizer than their respective recipient line under well-watered conditions. Furthermore, significantly lower transpiration rates (p < 0.1) were observed in one NIL compared to its respective recipient. The combination of the DroughtSpotter facility coupled with 15N tracer-based tracking of N uptake and remobilization extends the insight into the impact of genetically altered root biomass on wheat NUE and WUE under different water availability scenarios. The study shows the potential for how a modified genetic constitution of the locus on wheat chromosome 5B can reduce transpiration and enhance N uptake. The dependence of the observations on the recipient and water availability suggests a need for further research to investigate the interaction with genetic background traits.

Changes in microbial community structure and yield responses with the use of nano-fertilizers of nitrogen and zinc in wheat–maize system

The growing popularity of nano-fertilization around the world for enhancing yield and nutrient use efficiency has been realized, however its influence on soil microbial structure is not fully understood. The purpose of carrying out this study was to assess the combined effect of nano and conventional fertilizers on the soil biological indicators and crop yield in a wheat–maize system. The results indicate that the at par grain yield of wheat and maize was obtained with application of 75% of recommended nitrogen (N) with full dose of phosphorus (P) and potassium (K) through conventional fertilizers along with nano-N (nano-urea) or nano-N plus nano-Zn sprays and N100PK i.e. business as usual (recommended dose of fertilizer). Important soil microbial property like microbial biomass carbon was found statistically similar with nano fertilizer-based management (N75PK + nano-N, and N75PK + nano-N + nano-Zn) and conventional management (N100PK), during both wheat and maize seasons. The experimental data indicated that the application of foliar spray of nano-fertilizers along with 75% N as basal is a sustainable nutrient management approach with respect to growth, yield and rhizosphere biological activity. Furthermore, two foliar sprays of nano-N or nano-N + nano-Zn curtailed N requirement by 25%, furthermore enhanced soil microbial diversity and the microbial community structure. The specific microbial groups, including Actinobacteria, Bacteroidia, and Proteobacteria, were present in abundance and were positively correlated with wheat and maize yield and soil microbial biomass carbon. Thus, one of the best nutrient management approaches for sustaining productivity and maintaining sound microbial diversity in wheat–maize rotation is the combined use of nano-fertilizers and conventional fertilizers.

Effects of arbuscular mycorrhizal fungi on uptake, partitioning and use efficiency of nitrogen in wheat

Arbuscular mycorrhizal fungi (AMF) can promote the growth and yield of crops by increasing the use of nutrients. However, the influence of AMF on the uptake, utilization and partitioning of nitrogen (N) from different sources remain uncertain. Therefore, we investigated AMF inoculation on plant biomass, N-uptake (from fertilizers and soil), -partitioning and N use-efficiency (NUE) in two wheat cultivars using 15N isotope labeling in a field and pot experiment. Results showed that AMF inoculation increased both plant biomass and N accumulation, and altered N partitioning in wheat. AMF inoculation significantly increased root N concentration and decreased grain N concentration (GNC) and leaf N concentration. The decrease in GNC by the AMF was mainly attributed to the variations in pre-anthesis accumulated N in vegetative organs and a reduction in the amount of N translocation. AMF significantly increased root dry weight by 13.5–18.2%, N uptake of the root by 25.4–37.2%. The N partitioning ratio in roots increased, but decreased in grains. Further, AMF significantly increased plant uptake of top-dressed 15N-labeled fertilizer by 15.0–17.8%. AMF promoted grain N absorbed from fertilizer (basal and topdressing fertilizer) but reduced its uptake from soil. Importantly, fertilizer N recovery efficiency (FNRE), N utilization efficiency (NUtE) and NUE were higher in AMF than in the control (CK), demonstrating the benefits of AMF inoculation on growth in wheat. Therefore, using AMF as biofertilizers in field conditions may be an effective agronomic practice in order to ensure sustainable production.

Responses of root characteristics and nitrogen absorption and assimilation to different pH gradients of winter wheat at seedling stage.

Nitrogen (N) and rhizosphere pH are the two main factors restricting the growth of winter wheat (Triticum aestivum L.) in North China Plain. Soil nutrient availability is affected by soil acidity and alkalinity. In order to understand the effect of rhizosphere pH value on wheat nitrogen metabolism and the response of wheat growth to pH value at seedling stage, winter wheat varieties 'Aikang 58' (AK58) and 'Bainong 4199' (BN4199) were tested in hydroponics under three pH treatments (pH = 4.0, 6.5, and 9.0). The results showed that the accumulation of dry matter in root and above ground under pH 4.0 and pH 9.0 treatments was lower than that under pH 6.5 treatments, and the root/shoot ratio increased with the increase of pH value. Regardless of pH value, 'BN4199' had higher root dry weight, root length, root surface area, root activity and root tip than 'AK58'. Therefore, wheat that is tolerant to extreme pH is able to adapt to the acid-base environment by changing root characteristics. At pH 4.0, the net H+ outflow rate of wheat roots was significantly lower than that of the control group, and the net NO3- flux of wheat roots was also low. The net H+ outflow occurred at pH 6.5 and 9.0, and at the same time, the net NO3- flux of roots also increased, and both increased with the increase of pH. The activity of nitrate reductase (NR) in stem of pH 9.0 treatment was significantly higher than that of other treatments, while the activity of glutamine synthetase (GS) in root and stem of pH 6.5 treatment was significantly higher than that of other treatments. Under pH 4.0 and pH 9.0 treatments, the activities of NR and GS in 'BN4199' were higher than those in 'AK58', The root respiration of 'BN4199' was significantly higher than that of 'AK58' under pH 4.0 and pH 9.0 treatment, and 'BN4199' had higher NO3- net flux, key enzyme activity of root nitrogen metabolism and root respiration. Therefore, we believe that 'BN4199' has strong resistance ability to extreme pH stress, and high root/shoot ratio and strong root respiration can be used as important indicators for wheat variety screening adapted to the alkaline environment at the seedling stage.

Unraveling differential characteristics and mechanisms of nitrogen uptake in wheat cultivars with varied nitrogen use efficiency

Nitrogen uptake is crucial to wheat nitrogen use efficiency (NUE). The study's findings indicate that both high- and low-NUE cultivars exhibited highest nitrogen uptake efficiency (NupE) under 0.2 mM nitrogen. Under 2 mM nitrogen, their NupEs decrease significantly, while uptakes to NO3− were notably higher than that of NH4+. Strikingly, high-NUE cultivars exhibited a significantly higher NH4+ uptake rate than low NUE cultivars, resulting in a marked improvement in their ability to take up nitrogen. The NUEs of the cultivars with 5 mM nitrogen were almost half that of 2 mM nitrogen. NO3− uptake primarily occurred in the mature zone of roots, while NH4+ uptake took place in the root tip meristem and elongation zones. Notably, the NH4+ uptake in root tip meristematic zone of high-NUE cultivar was significantly higher than that of low NUE cultivar. Furthermore, the NO3− uptake of high-NUE cultivar in the root mature zone was significantly higher than that of low-NUE cultivar under 2 mM nitrogen. These findings were consistent with the significantly higher expression levels of TaAMT in root tip and of TaNRT in root mature area of high-NUE cultivar compared to low-NUE cultivar, respectively, enabling efficient absorption of NO3− and NH4+ and transport of NO3− to shoot. The high-NUE cultivars showed elevated expression of amino acid transporters further promoting nitrogen uptake, and conversion of nitrogen into ureides and amino acids further facilitated inorganic nitrogen uptake by roots. The differential findings offer valuable insights into novel variety breeding of high NUE in the future.