Microplastics are persistent contaminants of agricultural soils and may affect soil structure, microbial activity, nutrient cycling, crop growth, and the quality of plant-derived foods. Wheat (Triticum aestivum L.) deserves specific attention because it is a major staple crop, develops an extensive fibrous root system in cultivated soil, and produces grain that is consumed directly by humans. These characteristics create a close connection among soil contamination, rhizosphere processes, crop performance, and possible food-chain exposure. Unlike broader reviews of microplastics in crops, this review follows the pathway from particle entry into wheat-growing soils to transport, transformation, rhizosphere interactions, wheat responses, and possible contamination of edible grain. The movement and effects of microplastics depend on particle size, shape, polymer type, density, surface properties, aging, soil texture, mineral composition, organic matter, water movement, root activity, and soil organisms. Available studies show that plastic particles can alter root development, nutrient acquisition, oxidative balance, photosynthesis, biomass, and yield, although the direction and magnitude of these effects differ among experimental conditions. Evidence for root internalization and vascular transport is strongest for nanoplastics and submicrometer particles under controlled conditions. Direct field evidence for the accumulation of larger microplastics in mature wheat grain remains limited. Important research gaps include the scarcity of field measurements, the use of unrealistic exposure concentrations, poor separation of microplastic and nanoplastic evidence, uncertain root-to-grain transfer, and the lack of standardized analytical methods. Future research should combine realistic field exposure, aged and mixed-polymer particles, multi-season experiments, advanced particle tracing, and contamination-controlled analysis of wheat tissues and grain.

Strigolactones (SLs) are important regulators of shoot branching and environmental responses. However, how exogenous SLs spatiotemporally regulate tiller dynamics, systemic hormone networks, spikelet fertility, and yield formation in wheat (Triticum aestivum L.) remains unclear. In this study, the synthetic SL analogue GR24 was exogenously applied at the 5- and 7-leaf stages to investigate its effects on tiller development and yield formation. Application at the 5-leaf stage initially inhibited the 3rd tiller bud elongation while promoting leaf expansion in early 1st and 2nd tillers. Subsequent overwintering field investigation revealed a compensatory increase in the emergence rate of tillers at the 3rd node. However, by the jointing stage, the frequency of late-emerging tillers was significantly reduced under both 5- and 7-leaf GR24 treatments compared with the control. Hormone profiling revealed distinct tissue-specific responses. In the 3rd axillary bud, 5-leaf GR24 treatment reduced TZR, TZ, and ACC but increased GA7. In contrast, hormone changes in the 4th leaf involved reductions in several growth-related hormones, including ICA, SA, TZ, and Me-IAA. Conversely, 7-leaf treatment elevated IP, CZ, IAA, and ICA in the 5th axillary bud, while upregulating GA7, MT, IAA, Me-IAA, SAG, and ACC alongside lowered TZR and TZ in the 6th leaf. GR24 treatment increased fertile spikelet number and reduced sterile spikelets, resulting in higher spike number per plant, grain number per spike, and grain yield. Our findings demonstrate that exogenous GR24 application improves wheat population structure and reduces floret abortion through stage-dependent regulation of hormone profiles. These results highlight the potential of GR24-mediated tiller regulation for improving wheat yield formation.

The sustainability, crop production, and food safety of agriculture are increasingly challenged by microplastic pollution, as agricultural soils are the largest reservoirs and may serve as points of contact for plastic particles in the food chain. This review provides a comprehensive overview of plant materials, fate and uptake pathways, detection techniques, and the possible risks of microplastics in agriculture. Agroecosystems are also a source of microplastics, such as plastic mulch films, sewage sludge, compost and manure additives, wastewater irrigation, polymer-coated fertilizers, greenhouse materials, atmospheric deposition, and decomposition of discarded agricultural plastics. Their distribution and mobility in soil are controlled by polymer composition, particle size, morphology, density, surface ageing, soil texture, organic matter content, tillage practices, runoff, leaching, and soil biota. Recent data show that microplastics, especially smaller microplastics and nanoplastics, can attach to root surfaces, penetrate plants via cracks in roots, areas of lateral root development, and apoplastic pathways, and eventually move to tissues aboveground. Plant tissue detection is often accomplished by digestion of the sample, density separation, visual and fluorescence microscopy, Fourier-transform infrared spectroscopy, Raman spectroscopy, pyrolysis–gas chromatography mass spectrometry, and electron microscopy, but standardization of these methods remains a significant challenge. Microplastics can disrupt seed germination, root structure, nutrient absorption, photosynthesis, oxidative homeostasis, biomass buildup, yield development, and quality. Further, their capacity to transport additives, plasticizers, heavy metals, and persistent organic pollutants raises concerns about the transfer of contaminants to edible plant parts and their potential transfer to human diets. Further studies are needed focusing on field-realistic exposure conditions, long-term crop–soil interactions, nanoplastics behaviour, standardised analysis procedures, uptake and translocation pathways, edible crop risk assessments, and sustainable mitigation approaches to reduce microplastics in agroecosystems.

The comprehensive understanding of root development under waterlogging stress is essential for high-yielding and waterlogging-tolerant wheat cultivars in the scenario of sustainable production in high-precipitation regions. A pot experiment was conducted to investigate the vertical distribution and physiology of root systems in the four commercial wheat cultivars (Yangmai24, Ningmai13, Ningmai9, and Yangmai25) which exhibit diverse grain yield and waterlogging tolerance. The results indicated that waterlogging stress caused a reduction of 21.5% in grain yield, 34.4% in root weight, and 34.5% in root length. Among the four cultivars, Yangmai25 exhibits both high yield and waterlogging tolerance, with only 11.8% grain yield reduction. Yangmai25 had the lowest shallow (0-20 cm) root weight percentage but the highest deep (60-100 cm) root weight percentage at maturity. These findings indicate that Yangmai25 maintained a numerous root system and balanced vertical growth pattern. Waterlogging stress inhibited the vitality and nitrogen assimilation efficiency in shallow roots, but high yield cultivars, Yangmai25 and Ningmai9, sustained significantly higher levels of these traits. Moreover, waterlogging significantly reduced the area and photosynthetic rate (Pn) of older leaves. Among the tested cultivars, Yangmai25 displayed the largest flag leaf area, potentially contributing to its strong photosynthetic capacity. Further analysis indicates that greater root weight and length significantly enhanced shoot biomass and grain yield, primarily through increased Pn of the top leaves. The Pn levels in the top two leaves mainly depended on the weight, length, vitality, nitrogen assimilation efficiency of shallow roots, and the 3rd leaf Pn was associated with an increased distribution of deep roots. This study indicated that improving the quantitative traits and nitrogen assimilation of shallow roots while maintaining an appropriate distribution of deep roots will be beneficial for photosynthesis capacity enhancement in leaves and the alleviation of waterlogging-induced yield losses, offering a novel perspective on achieving high and stable wheat production.

Elucidating the effects of waterlogging during internode elongation stage on stem growth and lodging resistance of wheat can provide comprehensive understanding of the mechanisms underlying waterlogging damage and lodging, which will benefit the stress-resistant and stable wheat production. We examined the effects of waterlogging stress on internode morphological and mechanical indicators at the flowering and milking stages of Yangmai 25. Waterlogging treatments were applied from the initiation of 1 cm elongation in the basal 1st (B1), 2nd (B2), 3rd (B3), 4th (B4), and 5th (B5) internodes, which lasted for 7 days each. The non-waterlogging treatment (CK) was used as the control. The results showed that waterlogging treatments significantly inhibited the elongation of undetermined internodes (internode not fully elongated to final length), and thus reduced plant height and center cgravity height at the milking stage. The B2 treatment resulted in the greatest decreases in plant height and center cgravity height, reaching 9.5% and 8.4%, respectively. Waterlogging significantly reduced the outer diameter and wall thickness of the 2nd, 3rd, 4th, and 5th internodes at both the flowering and milking stages, and decreased the filling degree of each internode at the flowering stage. Furthermore, waterlogging treatments significantly reduced the bending moment of each internode at the flowering and milking stages, and decreased the breaking resistance of internodes across stages. Specifically, B1 and B2 treatments significantly reduced the breaking resistance of all internodes, while B4 and B5 treatments mainly reduced the breaking resistance of upper internodes. The breaking resistance of the second internode (the main internode responsible for lodging) under different treatments followed the order: B2<B1<B3<B4<B5<CK. Treatments B1, B2, and B3 significantly increased the lodging index of the 1st, 2nd, and 3rd internodes, whereas no significant effects were found under B4 and B5 treatments. Linear correlation analysis of the morphology and lodging resistance of the basal 2nd internode indicated that improving the outer diameter and wall thickness of internodes could significantly enhance breaking resistance and reduce the lodging index. In summary, waterlogging stress during the internode elongation stage of wheat inhibited internode elongation, thickening, and wall development, thereby deteriorating internode structure, reducing breaking resistance, and increasing lodging risk. The most pronounced effects were observed during the elongation of the basal first and second internodes.

Excessive application of conventional chemical nitrogen (N) fertilizers tends to cause a series of problems such as soil acidification and compaction, and restrict further yield gains. New-type fertilizers such as carbon-based fertilizer (CBF) and slow-release fertilizer (SRF) have been shown to improve soil fertility and increase wheat yield. However, systematic comparisons of their yield-enhancing potential and the mechanisms by which they improve soil properties remain limited. In this study, two CBFs (CBF1, N-P2O5-K2O=24%-12%-8%; CBF2, N-P2O5-K2O=24%-10%-10%), polymer-coated urea (PCU, 45% N), sulfur-coated urea (SCU, 37% N), and conventional urea (urea, 46% N) were used as materials to elucidate mechanistic differences among fertilizer types in the regulation of soil nitrate-N dynamics, soil physicochemical properties, and soil microbial community structure in wheat fields. Our objective was to identify fertilization strategies that simultaneously enhance wheat yield and improve soil quality. The results showed that CBF1 and CBF2 reduced the early peak concentrations of soil nitrate-N following basal and topdressing fertilization relative to Urea, while providing a more balanced nitrate-N supply across early and late wheat growth stages, which maintained higher soil nitrate-N levels than Urea from overwintering to jointing and from anthesis to maturity. Compared with CBF1, CBF2 showed higher soil nitrate-N from anthesis to maturity, which was similar to PCU. With an appropriate N supply, CBF2 facilitated coordinated yield formation, significantly increasing grains per spike and total grain number. Adequate nutrient availability post-anthesis in CBF2 also facilitated grain filling, resulting in 4.08% and 6.77% increases in grain yield compared with SCU and Urea, respectively. Compared with urea, CBFs application effectively mitigated soil pH decline, enhanced soil electrical conductivity, and modulated soil enzyme activities, as well as soil bacterial diversity and community composition. On the one hand, CBFs decreased the relative abundance of nitrifying bacteria (e.g., Nitrospirota_A), thereby suppressing soil nitrification, regulating soil nitrate concentrations, and consequently reducing the relative abundance of denitrifying bacteria such as Proteobacteria, Actinobacteriota, and Firmicutes_D, which decreased the potential risk of N₂O emissions. On the other hand, CBFs application altered the relative abundance of microbial groups involved in soil carbon cycling such as Bacteroidota and Gemmatimonadota, thereby enhancing soil nutrient availability and increasing the contents of soil organic matter, available P, and available K. In general, both CBF2 and PCU optimized soil nutrient supply and increased wheat yield, whereas CBF2 was more favorable for improving soil physicochemical properties and enhancing soil fertility, which is expected to promote the synergistic improvement of wheat production potential and soil quality.

Drought stress severely limits wheat growth, development and yield. Endophytic fungi play a crucial role in plant growth and drought resistance. In agricultural production, they hold significant application potential as biocontrol agents capable of mitigating drought-induced damage. However, the mechanisms underlying changes in endophytic fungal community structure under drought stress remain unclear. Our study employed amplicon sequencing to investigate the structure of endophytic fungal communities in wheat roots under different water treatments, comparing structural and functional changes between different treatments. Results revealed that drought stress led to the greatest accumulation of relative abundance in the phylum Ascomycota (86.4%). At the genus level, Stachybotrys (increase 994.2%), Fusarium (increase 94.6%) and Aspergillus (increase 295.6%) showed the most significant increases in relative abundance. Co-occurrence network and Sankey diagram analysis revealed that wheat roots formed a drought-specific endophytic fungal community centered around Stachybotrys, Fusarium and Aspergillus, which indirectly enhanced crop drought tolerance. Our findings provide a theoretical foundation for future agricultural strategies to improve crop drought resistance through precise regulation of microbial communities.

The aggravation of ozone (O3) pollution poses a significant threat to agricultural production. With China being the leading wheat producer of the world, contributing 17.8% to global output, the vulnerability of wheat to O3 is of particular concern. Despite extensive research on the impacts of O3 on wheat production and the ongoing development of new wheat cultivars over the years, a connection between yield loss and the released ages of wheat cultivars under O3 stress remains unestablished. Addressing this, the experiment was carried out at the Yangzhou Rice and Wheat Free-air Gas Concentration Enrichment (FACE) Testing Base in China, using 17 wheat cultivars developed since the 1970s as experimental materials. The elevated O3 concentration in the test was 1.5 times higher than that in a normal atmosphere. The results indicated that O3 led to a significant reduction in wheat yield of 18.19%. The yield of cultivars released in the 1970s, 1980s, 1990s, and after 2000, decreased by 24.9%, 23.3%, 19.8%, and 14.7%, respectively. Overall, the direct effect of 1,000-grain weight on yield was the most significant, followed by the number of grains per spike, whereas the number of spikes contributed least to the yield components. To enhance resistance to O3 stress in future breeding efforts, increasing the 1,000-grain weight should be a primary objective. Our findings also revealed that elevated O3 concentration led to higher sedimentation values and protein content while lowering bulk density, hardness, and starch content. As the release age approaches, the rate of decrease in bulk density diminishes gradually. In terms of hardness, sedimentation value, and starch content, varieties released in the 1990s exhibited less sensitivity, whereas those released after the 2000s experienced the most significant changes in protein content. It is worth noting that the impact on the nutritional quality of modern cultivars is particularly significant, particularly regarding starch and protein content. Stress indices indicate that the cultivars released after 2000 exhibit stronger resistance to yield loss. The Yangmai series cultivars appear to be promising parental lines for future breeding programs aimed at developing O3-resistant wheat.

In the lower and middle sections of the Yangtze River Basin Region (YRBR) in China, challenges posed by climate change and delayed harvesting of preceding crops have hindered the timely sowing of wheat, leading to an increasing prevalence of late-sown wheat fields. This trend has emerged as a significant impediment to achieving high and stable production of wheat in this area. During the growing seasons of 2022–2023 and 2023–2024, an unmanned aerial vehicle (UAV)-based multispectral camera was used to monitor different wheat materials at various growth stages under normal sowing treatment (M1) and late sowing with increased plant density (M2). By assessing yield loss, the wheat tolerance to late sowing was quantified and categorized. The correlation between the differential vegetation indices (D-VIs) and late sowing resistance was examined. The findings revealed that the J2-Logistic model demonstrated optimal classification performance. The precision values of stable type, intermediate type, and sensitive type were 0.92, 0.61, and 1.00, respectively. The recall values were 0.61, 0.92, and 1.00. The mean average precision (mAP) of the model was 0.92. This study proposes a high-throughput and low-cost evaluation method for wheat tolerance to late sowing, which can provide a rapid predictive tool for screening suitable varieties for late sowing and facilitating late-sown wheat breeding.

Late sowing and spring low temperatures have a great impact on the growth and maturation of wheat in the rice–wheat rotation region. In order to analyze the impacts of cold stress in February in early spring on yield formation and agronomic traits of wheat on different sowing dates, a controlled pot experiment was performed using the widely promoted and applied spring-type wheat variety Yangmai23 (YM23). The yield of wheat treated with late sowing date II (SDII, 21 November) and overly late sowing date III (SDIII, 9 December) were both lower than that of wheat sown on the suitable date I (SDI, 1 November). The yield of late-sown wheat decreased by 40.82% for SDII and by 66.77% for SDIII, compared with SDI, and these three treatments of wheat all grew under the natural conditions as the control treatments. The plant height, stem diameter of the internode below the ear, flag leaf length and area, and total awn length of the spike, as well as the spike length of late-sown wheat, were all significantly lower than those of wheat in SDI treatment. Early spring low temperatures exacerbated the decline in yield of wheat sown on different dates, to some extent. Despite showing higher net photosynthetic rate, stomatal conductance, and transpiration rate in flag leaves of the SDIII treatment under low-temperature stress than those of the other treatments at anthesis, overly late sowing led to minimal leaf area, shorter plant height, fewer tillers, and smaller ears, ultimately resulting in the lowest yield. Our study suggested that additional focus and some regulation techniques are needed to be studied further to mitigate the combined negative impacts of late sowing and low-temperature stress in early spring on wheat production.

Nitrogen (N) input is crucial for increasing soil nutrients and improving crop root architecture. Slow-release N fertilizer has been expected to regulate soil nutrient supply in the middle and later growth stage of wheat, but its effect on root architecture and soil nutrients and their interactions remains unclear. The self-made root canal-soil column system was used to investigate the effects of sulfur-coated urea (SCU), urea (U) and compound fertilizer (CF) on the vertical distribution of wheat root and soil nutrients. The vertical distributions of root length, length density and dry weight in 0 − 90 cm soil layer increased first and then decreased after booting. Compared with U and CF treatment, SCU treatment increased the total root length by 26.16

The delayed sowing date and basal internode lodging caused by climate change are major constraints on wheat productivity. To investigate the effects of varying sowing dates and fertilization application regimes on wheat yield and lodging resistance, a two-year field experiment was conducted with two sowing dates and five fertilization application regimes. Results revealed that the T2 sowing period caused grain yield reductions of 43.82% and 29.82% over two consecutive years, accompanied by shortened second basal internode length and decreased plant height, although lignin content increased significantly. Among fertilization treatments, S4 effectively enhanced the mechanical strength of the second basal internode, achieving both higher yield and superior lodging resistance. We propose combining controlled-release nitrogen fertilizer (CRNF) with urea across different sowing dates to optimize productivity and stem stability. These strategies tackle climate-driven sowing delays and lodging while maximizing yield potential.

BACKGROUND:Ozone (O3), a widespread air pollutant, significantly impairs crop growth and development, with wheat, the second largest crop by planting area of the world, being especially vulnerable. This study, conducted under Free Air Concentration Enrichment (FACE) conditions, focused on four wheat cultivars from the middle and lower reaches of the Yangtze River, investigating the effects of elevated O3 on wheat growth, physiology and quality. RESULTS:Elevated O3 levels impaired assimilate accumulation and mobilization in wheat grains, reducing pre-anthesis nitrogen accumulation and causing an 8.21% decline in post-anthesis nitrogen translocation amount (NT), while increasing post-anthesis nitrogen translocation efficiency (NTE) by 3.83% and nitrogen harvest index (NHI) by 3.43%. Over 2 years, elevated O3 raised grain protein content by 6.6-6.7% but significantly reduced protein accumulation by 10.4-10.7%, driven by declines in gliadin and glutenin. Total free amino acids and key nitrogen metabolizing enzymes also decreased. Among the four cultivars, YN19 was the most sensitive, showing the largest protein accumulation reductions. CONCLUSION:This study demonstrates that elevated O3 disrupts wheat nitrogen accumulation and protein synthesis by reducing pre-anthesis nitrogen accumulation, accelerating post-anthesis senescence, and suppressing nitrogen translocation due to rapid leaf area index (LAI) decline. The decline in nitrogen accumulation and nitrogen metabolizing enzyme activity is a critical factor contributing to reduced grain protein accumulation. Notably, YN19 exhibited the highest O3 sensitivity, underscoring the need to develop O3-resilient wheat cultivars to sustain grain quality under rising O3 levels. © 2025 Society of Chemical Industry.

Microplastic contamination in agricultural soils is emerging as a significant environmental challenge due to its detrimental effects on soil health, nitrogen cycling, and crop productivity. This review paper synthesizes current knowledge on the impacts of various microplastics, specifically polyethylene (PE), polyvinyl chloride (PVC), and polypropylene (PP), on agricultural systems, with a particular focus on their interactions with nitrogen dynamics and ammonia volatilization processes. Microplastics enter agricultural soils through multiple sources, including plastic mulching, irrigation, and application of biosolids, leading to alterations in soil physical and chemical properties, nutrient availability, and microbial activity. These changes negatively influence critical soil processes such as nitrogen mineralization, nitrification, and denitrification, thereby reducing nitrogen use efficiency (NUE) and increasing ammonia volatilization. Consequently, these disturbances manifest in reduced crop growth and productivity, particularly affecting crops such as wheat. This review also explores biochar as a promising remediation strategy, highlighting its potential to mitigate microplastic-induced disruptions in soil ecosystems by improving soil structure, enhancing nitrogen retention, and reducing ammonia emissions. However, the paper identifies significant knowledge gaps, including the need for standardized methodologies and long-term field studies to understand the cumulative impacts of microplastics comprehensively. To address microplastic pollution effectively, integrated approaches combining scientific research, sustainable agricultural practices, and robust policy frameworks are recommended. This will ensure agricultural sustainability, soil fertility, and food security amidst growing environmental concerns.

Rice-wheat and maize-wheat rotations are major cropping systems in the middle and lower reaches of Yangtze River in China, where high nitrogen (N) inputs and low N efficiency often exacerbate resource waste and environmental pollution. Due to the changes in factors such as soil properties and moisture content, the N fate and the N utilization characteristics of wheat in different rotations are significantly different. Efficient N management strategies are thus urgently required for promoting maximum wheat yield in different rotation systems while reducing N loss. A 2-year field experiment using isotopic (15N) tracer technique was conducted to evaluate the fate of 15N-labeled urea in wheat fields and the distribution characteristics of N derived from different sources. The wheat yield and N use efficiency under various N rates (180 and 240 kg ha−1, abbreviated as N180 and N240) and preceding crops (rice and maize, abbreviated as R-wheat and M-wheat) were also investigated. The results showed that N240 increased N uptake and grain yield by only 8.77−14.97% and 2.51−4.49% compared with N 180, but decreased N agronomic efficiency (NAE) and N physiological efficiency (NPE) by 14.78−18.79% and 14.06−31.35%. N240 also decreased N recovery in plants by 2.8% on average compared with N180, and increased N residue in soil and N loss to the environment. Compared with that of basal N, the higher proportion of topdressing N was absorbed by wheat rather than lost to the environment. In addition, the accumulation of topdressing N in grain was much higher than that of basal N. Compared with that in R-wheat treatment, plants in M-wheat treatment trended to absorb more 15N and reduce unaccounted N loss, resulting in higher yield potential. Moreover, the M-wheat treatment increased N recovery in 0−20 cm soil but decreased 80−100 cm soil compared with R-wheat treatment, indicating a lower risk of N loss in deeper soil. Collectively, reducing N application rate and increasing the topdressing ratio is an effective way to balance sustainable crop yield for a secure food supply and environmental benefit, which is more urgent in rice-wheat rotation.

The rhizosheath, the layer of soil tightly attached to the roots, protects plants against abiotic stress and other adverse conditions by providing a bridge from the plant root system to the soil. It reduces the formation of air gaps between the root and soil and facilitates the transportation of water at the root–soil interface. It also serves as a favourable niche for plant-growth-promoting rhizobacteria in the surrounding soil, which facilitate the absorption of soil water and nutrients. This review compares the difference between the rhizosheath and rhizosphere, and summarises the molecular and physiological mechanisms of rhizosheath formation, and identifying the causes of rhizosheath formation/non-formation in plants. We summarise the chemical and physical factors (root hair, soil-related factors, root exudates, and microorganisms) that determine rhizosheath formation, and focus on the important functions of the rhizosheath in plants under abiotic stress, especially in drought stress, phosphorus deficiency, aluminium stress, and salinity stress. Understanding the roles played by the rhizosheath and the mechanisms of its formation provides new perspectives for improving plant stress tolerance in the field, which will mitigate the increasing environmental stress conditions associated with on-going global climate change.

Understanding the mechanisms that regulate plant root growth under soil drying is an important challenge in root biology. We observed that moderate soil drying promotes wheat root growth. To understand whether metabolic and hormonic changes are involved in this regulation, we performed transcriptome sequencing on wheat roots under well-watered and moderate soil drying conditions. The genes upregulated in wheat roots under soil drying were mainly involved in starch and sucrose metabolism and benzoxazinoid biosynthesis. Various plant hormone-related genes were differentially expressed during soil drying. Quantification of the plant hormones under these conditions showed that the concentrations of abscisic acid (ABA), cis-zeatin (CZ), and indole-3-acetic acid (IAA) significantly increased during soil drying, whereas the concentrations of salicylic (SA), jasmonic (JA), and glycosylated salicylic (SAG) acids significantly decreased. Correlation analysis of total root length and phytohormones indicated that CZ, ABA, and IAA are positively associated with wheat root length. These results suggest that changes in metabolic pathways and plant hormones caused by moderate soil drying help wheat roots grow into deeper soil layers.

Controlled-release nitrogen fertilizer (CRNF) has been expected to save labor input, reduce environmental pollution, and increase yield in crop production. However, the economic feasibility is still controversial due to its high cost. To clarify the suitable application strategy of CRNF in promoting the yield, nitrogen use efficiency and income on wheat grown in paddy soil, four equal N patterns were designed in 2017−2021 with polymer-coated urea (PCU) and common urea as material, including PCU applied once pre-sowing (M1), PCU applied 60% at pre-sowing and 40% at re-greening (M2), 30% PCU and 30% urea applied at pre-sowing, 20% PCU and 20% urea applied at re-greening (M3), and urea applied at four stage (CK, Basal:tillering:jointing:booting=50%:10%:20%:20%). In addition, M4−M6, which reduced N by 10%, 20% and 30% respectively based on M3, were designed in 2019−2021 to explore their potential for N-saving and efficiency-improving. The results showed that, compared with CK, M1 did not significantly reduce yield, but decreased the average N recovery efficiency (NRE) and benefits by 1.63% and 357.71 CNY ha−1 in the four years, respectively. M2 and M3 promoted tiller-earing, delayed the decrease of leaf area index (LAI) at milk-ripening stage, and increased dry matter accumulation post-anthesis, thereby jointly increasing spike number and grain weight of wheat, which significantly increased yield and NRE compared with CK in 2017−2021. Due to the savings in N fertilizer costs, M3 achieved the highest economic benefits. With the 20% N reduction, M5 increased NRE by 16.95% on average while decreasing yield and net benefit by only 6.39% and 7.40% respectively, compared with M3. Although NRE could continue to increase, but the yield and benefits rapidly decreased after N reduction exceeds 20%. These results demonstrate that twice-split application of PCU combined with urea is conducive to achieving a joint increase in yield, NRE, and benefits. More importantly, it can also significantly improve the NRE without losing yield and benefits while saving 20% N input.

High loss and low nitrogen (N) efficiency in agricultural production is severe. Also, ammonia volatilization and N leaching aggravated environmental pollution. The eutrophication of surface water and the emissions of N2O increased, hence green fertilization management urgently needs to be rationalized. Coordinating N supply from different sources has been shown to reduce environmental pollution. Therefore, this study was dedicated to clarifying the transport of N sources in the rice-wheat rotation system. The stable isotope tracer technology was used to label fertilizer (F), soil (T), and straw (J) with 15N, respectively. The utilization of N by crops (the N ratio in organs), as well as the residual N in soil and loss status, were measured. According to the potential of response to N, all the wheat cultivars were divided into groups with high (HNV) and low efficiency (LNV). The N contribution ratio showed that 43.28%~45.70% of total N accumulation was from T, while 30.11%~41.73% and 13.82%~24.19% came from F and J. The trend in soil N residue (T > F > J) was consistent with the above, while it was the opposite in N loss (T< F< J). The seasonal effectiveness showed that T achieved the highest N utilization efficiency (31.83%~44.69%), followed by F (21.05%~39.18%) and J (11.02%~16.91%). The post-season sustainability showed that T decreased the most in soil N residue (2.08%~12.53%), and F decreased the most in N accumulation (9.64%~18.13%). However, J showed an increase in N recovery rate (2.87%~5.89%). N translocation and distribution showed that N from different sources in grains was significantly higher than that in stems, glumes, and leaves. The ratio of HNV (75.14%~79.62%) was higher than that of LNV (71.90%~74.59%) in grain, while it was the opposite in other organs. Plant N accumulation, soil N supply, and straw N transformation were determined jointly by the three N sources, thus reducing N loss and N2O production. Therefore, the results will highlight the insights for constructing local N and emission reduction models.