Winter wheat is a key staple crop in Northwest China, yet optimizing its productivity and economic returns remains a challenge due to water constraints and suboptimal planting densities.  This study evaluates the combined effects of irrigation strategies and planting density (PD) on winter wheat yield, resource-use efficiency, and net economic benefits (NEB).  A two-year field experiment was conducted under four irrigation treatments (I1, no irrigation; I2, before winter and jointing; I3, jointing; I4, jointing and anthesis) and three PD treatments (PD1, 562.5×10⁴ plants ha^–1; PD2, 375 ×10⁴ plants ha^–1; PD3, 187.5×10⁴ plants ha^–1).  Through field trials, we identified optimal water-saving irrigation regimes and planting densities that maximize grain yield while enhancing water productivity.  Our results demonstrated that lower PD (187.5×10⁴ plants ha^–1) under reduced irrigation significantly improved dry matter accumulation (DMA), SPAD, and leaf area index (LAI), leading to higher grain yield.  Moderate irrigation at the jointing stage (I3) enhanced grain yield in higher planting densities by up to 18.42% compared to other irrigation regimes, while the highest overall yield (6,310 kg ha^–1) was achieved in medium PD under the I3 irrigation.  Water-use efficiency (WUE) was significantly improved by reducing irrigation at specific growth stages, mitigating excessive evapotranspiration.  PD3–I3 achieved the highest NEB, exceeding I1, I2, and I4 by 11.9, 18.4, and 16.4%, respectively, in 2022–2023 and by 15.1, 14.0, and 8.4%, respectively, in 2023–2024.  The findings provide practical insights for sustainable wheat production, ensuring higher profitability while conserving water resources.  Implementing optimized irrigation and PD strategies offers a strategic pathway to improving food security and farm income in the semi-arid regions of Northwest China.

Ensuring the provision of adequate and nutritious food for humans through sustainable agricultural development poses a major challenge.  Optimizing the nitrogen supply is one of the key factors for improving crop grain yield and quality.  Green manure is often used to optimize the nitrogen supply in crop production, but it is unclear whether green manure can maintain nutrient yield and quality of spring wheat under reduced chemical nitrogen input.  A split-plot field experiment of several varieties of green manure and mixed cropping with green manure was established in an arid area in 2018.  This study aimed to explore the feasibility of using mixed common vetch and hairy vetch, which could simultaneously maintain high nutrient production and grain quality of spring wheat under reduced chemical nitrogen input, and to reveal the mechanism of nitrogen metabolism.  The effects of green manure and reduced chemical nitrogen on nutrient yield, amino acid contents, vitamin B contents, mineral contents, and processing quality of spring wheat grain, as well as nitrogen accumulation, remobilization, and assimilation, were examined from 2020 to 2022.  Our results showed that a reduced chemical nitrogen input led to lower nutrient production, but green manure could increase the protein and starch yields of wheat grain.  HCVN2 (mixed hairy vetch and common vetch under 20% nitrogen reduction) displayed higher protein and starch yields, which increased by 35.9 and 16.2% compared to fallow after wheat harvest with conventional nitrogen application (FN3).  Meanwhile, reduced chemical nitrogen reduced the wheat grain quality, but green manure improved wheat grain quality.  HCVN2 had higher wheat grain qualities, which improved by 13.2 and 10.0% for essential amino acid and non-essential amino acid contents, by 20.0 and 22.2% for vitamin B and zinc contents, and by 14.0 and 8.6% for falling number and wet gluten compared to FN3, respectively.  HCVN2 could simultaneously improve the nutrient production and quality of wheat grain.  This was attributed to significantly increasing the nitrogen accumulation and distribution in grain; enhancing the contribution rates of leaf, stem-sheath, and cob-glume nitrogen to grain nitrogen; and promoting the activities of nitrate reductase and glutamine synthetase.  Therefore, mixed sown green manure under chemical nitrogen reduced by 20% is promising for improving the nutrient production and quality of spring wheat grain by promoting nitrogen accumulation, remobilization, and assimilation.

Characterizing the N uptake and utilization of different maize hybrids is essential for optimizing N application and increasing the profits from maize production.  Research trials were conducted with controlled-release urea (CRU) as a base fertilizer (TC) and urea split application in one (T1), two (T2), or three (T3) stages to evaluate the effects on N uptake, N use efficiency (NUE), and yield using the ¹⁵N tracer technique and two maize hybrids: DH518 (a mid-early-maturing hybrid) and DH605 (a late-maturing hybrid).  According to the results, compared with urea, CRU as a base fertilizer and urea split applications in two and three stages significantly increased grain yield and NUE while reducing environmental N loss.  Compared with T1, the grain yields of the TC, T2, and T3 treatments were respectively increased by 11.1, 9.8, and 11.7% in DH518 and by 16.4, 15.7, and 22.9% in DH605.  Regression analysis showed that the grain yield of DH518 displayed a bilinear trend with an initial rapid increase and then a slow increase with increases in post-anthesis N accumulation, total N accumulation, N recovery efficiency, and N nutrition index (NNI).  By contrast, DH605 consistently showed a linear regression relationship with a rapid increase.  The crop recovery N efficiency (CRN) values in the T3 treatment for urea applied at the sowing stage and as topdressing at the 9th-leaf stage (V9) in DH518 were 60.0 and 62.4% higher than under topdressing at the tasseling stage (VT) stage, respectively, while the CRN values of urea topdressing at the V9 and VT stages in DH605 were 37.7 and 37.1% higher than when applied at the sowing stage, respectively.  The higher pre-anthesis N demand and shorter growth period of DH518 maintained the N supply–demand balance, resulting in the NNI (NNI≥0.988) falling within the range of a low yield increase under the T2 and TC treatments, while the N status of DH605 plants only reached optimal levels in the T3 treatment.  Therefore, a three-stage split application of urea or applying CRU as a base fertilizer and topdressing with urea in the later growth stages is recommended for obtaining an optimal yield in mid-late-maturing hybrids.  In addition, for mid-early-maturing hybrids, applying CRU or reducing the number of split applications, e.g., a two-stage split application, can ensure an adequate N supply in the later growth stages and increase production, and thus profits.

Improving nitrogen utilization efficiency is not only beneficial for increasing maize yield, but it can also mitigate the environmental impact of excessive nitrogen fertilizer use.  Numerous studies have evaluated the impacts of plant growth retardants and plant density on plant lodging resistance and nitrogen uptake.  However, the influence of plant growth retardants on nitrogen utilization efficiency (NUtE) under varying plant densities has been rarely reported.  A field experiment conducted in 2020–2021 involved spraying EC (an ethephon and cycocel compound) at the 7th-leaf stage of maize with dosages of 0 (CK), 450, and 900 mL ha⁻¹ at plant densities of 4.5, 6.0, 7.5, and 9.0 plants m⁻².  Compared to CK, the application of EC (especially the high dosage) significantly reduced plant height and dry matter, while increasing stem diameter, the plant horizontal-vertical ratio (PHVR, a new index which we define as the ratio of stem diameter of the basal first internode above the ground to plant height), and the number and area of vascular bundles.  PHVR and vascular bundle morphology had significantly positive correlations with individual plant dry matter remobilization amount and its contribution to grain yield.  Therefore, despite the reduced dry matter weight observed in the EC treatment, the greater dry matter remobilization enhanced the harvest index (HI).  However, nitrogen uptake efficiency was not improved with the enhancement of PHVR and vascular bundle morphology, due to a reduction in dry matter accumulation.  In contrast, the improved PHVR and vascular bundle were beneficial for accelerating nitrogen translocation, thus increasing NUtE significantly by 4.3–31.1% compared with CK across the plant densities.  Increasing density simultaneously improved nitrogen uptake and utilization efficiency.  Consequently, a high dosage application of EC under high density could not only significantly enhance lodging resistance but also improve NUtE and HI significantly by promoting the transport of dry matter and nitrogen. 

Genetic diversity is crucial to genetic research and crop breeding, and core collections are important resources for capturing this diversity.  Recently, the core germplasm of tea plants was constructed mainly based on phenotypic data or molecular markers; however, the effective construction of core germplasm resources for plant breeding programs requires consideration of multiple aspects.  In this study, we collected 320 tea germplasm resources and analyzed their single-nucleotide polymorphisms (SNPs) and metabolite data.  Abundant genetic diversity in tea plants was inferred from the mean values of observed heterozygosity (Ho=0.340), expected heterozygosity (He=0.327), minor allele frequency (MAF=0.229), and polymorphic information content (PIC=0.268), based on the data from 2,118,060 high-quality SNP markers.  A mean genetic diversity index (H´) value of 1.902 suggested significant metabolic variation.  The 320 tea samples were categorized into six groups based on phylogenetic analysis, reflecting the influence of geographical origins on genetic diversity.  Based on the genetic and metabolic data, a preliminary core collection of 106 accessions was developed to effectively represent most of the original panel’s molecular, metabolic, population, and regional diversity.  Genome-wide association studies of the core panel successfully replicated the marker-trait associations found in the original panel.  This study contributes to the conservation and management of tea plant germplasm.

Increasing the sucrose content of sugarcane, a major sugar crop, is a key breeding objective.  However, the complex genetic background of sugarcane affects development of sugarcane hybrids.  In this study, we sequenced 292 sugarcane germplasm accessions and identified 2,542,965 single nucleotide polymorphisms (SNPs) and insertions/deletions (InDels).  We performed a genome-wide association study (GWAS) for two important sugarcane traits: sucrose content and stem diameter.  Both traits followed a normal distribution and showed typical characteristics of quantitative traits.  Population structure analysis revealed four subpopulations with an average genetic distance of 0.236.  GWAS of the sucrose content detected 27 SNPs.  After annotating genes at or near significant loci, 17 candidate genes were screened.  For stem diameter, GWAS revealed 19 SNPs, from which 9 candidate genes were identified.  These results improve our understanding of genetic mechanisms affecting sucrose content in sugarcane, and identify important genetic resources to accelerate breeding of new sugarcane varieties with high sucrose content.

Anthocyanins play a crucial role in plant growth, development, reproduction, and stress response.  Additionally, anthocyanins enhance the quality of fruits and vegetables due to their antioxidant properties.  While numerous previous studies have been conducted on anthocyanins, limited information exists regarding their composition and the role of the anthocyanin pathway gene dihydroflavonol 4-reductase (DFR) in chili pepper leaves.  In this study, we used a purple leaf pepper cultivar H18 in which the anthocyanin content in leaves decreases with plant growth and development.  Targeted anthocyanin metabolite assays revealed that the contents of delphinidin, malvidin, and petunidin derivatives followed the same trend as the overall anthocyanin content, with delphinidin derivatives being the predominant component of H18 pepper leaves.  Transcriptome sequencing was performed on H18 leaves at four different stages.  The results showed that differentially expressed genes (DEGs) at various stages were primarily associated with biological processes and flavonoid metabolic pathways.  Through phylogenetic tree and expression analysis, we identified three candidate genes involved in DFR function.  Substrate catalysis assays of CaDFRs demonstrated that only CaDFR1 was active, catalyzing dihydroquercetin (DHQ), dihydromyricetin (DHM), and dihydrokaempferol (DHK).  VIGS-mediated silencing of CaDFR1 resulted in a significant decrease in anthocyanin levels in H18 pepper leaves and stems, along with a reduction in the expression levels of other candidate functional genes in the anthocyanin metabolic pathway.  This study identifies the key anthocyanin components in the leaves of H18 peppers and validates the function of CaDFR1, providing a theoretical foundation for modifying anthocyanin content in pepper plants through molecular breeding.

Chinese cabbage (Brassica rapa subsp. pekinensis) is an important leafy vegetable in the Brassica genus of the Brassicaceae family.  The size of its edible leaves is an essential trait that determines its economic and nutritional values.  However, the current understanding of leaf development in Chinese cabbage remains limited.  Here, through forward genetic analysis of the mutant mini24 with defective leaf and root development, we identified the BrRRG gene, which regulates cell division in Chinese cabbage by map-based cloning.  We demonstrated that BrRRG impacts leaf size by regulating the expression of E2Fa transcription factors and cell cycle-related genes in Chinese cabbage.  Furthermore, BrRRG was found to modulate Chinese cabbage’s response to auxin (indole-3-acetic acid, IAA) and cytokinins hormones, revealing a distinct regulatory mechanism by which BrRRG coordinates the development of underground roots and aboveground leaves.  Thus, these results indicate that mutation in BrRRG impairs the growth and development of Chinese cabbage.

Simultaneously enhancing plant growth and disease resistance is an ideal goal in agriculture.  Significant efforts have been made to promote plant growth or immunity through the use of biological reagents, such as the application of beneficial microbes and plant immunity inducers.  However, balancing plant immunity and growth remains a challenging task.  In this study, we engineered the plant growth-promoting bacterium Bacillus subtilis OKB105 to express a secreted microbial pattern, flg22, and assessed its activity in enhancing both plant growth and disease resistance.  The OKB105 (flg22) strain exhibited plant growth-promoting activity similar to the OKB105 strain containing an empty vector, OKB105 (EV).  Furthermore, the OKB105 (flg22) strain significantly enhanced plant resistance against two distinct pathogens, Pseudomonas syringae DC3000 ΔhopQ1-1 and Phytophthora parasitica, compared to OKB105 (EV), confirming that the engineered OKB105 (flg22) effectively enhances plant disease resistance.  Interestingly, root irrigation with OKB105 (flg22) also markedly boosted the plant’s aboveground resistance to pathogens compared to OKB105 (EV).  We further demonstrated that OKB105 (flg22) can be applied to confer resistance to pathogens in other plants that recognize flg22. Finally, RNA-Seq and qRT-PCR analyses illustrated that OKB105 (flg22) effectively induced the expression of defense-related genes in pattern-triggered immunity.  Our results prove that employing an engineered beneficial microbe expressing a microbial pattern is a promising strategy for simultaneously enhancing plant growth and immunity.

As the largest multifunctional and dynamic organelle in fungi, vacuoles are associated with different organelles through membrane contact sites and participate in various cellular processes.  Vacuole and mitochondria patch (vCLAMP), the membrane contact site that tethers vacuoles and mitochondria, is indispensable for reciprocal interplay between these two organelles.  The impairment of vacuoles and mitochondria significantly suppressed FB1 production in Fusarium verticillioides.  However, the understanding of how vCLAMP complex regulates fumonisin biosynthesis remained unknown.  Herein, the biological functions of vCLAMP component Vam6 were investigated in F. verticillioides. Our results showed that FvVam6 deletion mutant ΔFvVam6 exhibited palpable defects in fungal development, stresses responses and pathogenicity.  In addition, abnormal vacuolar morphology and significantly reduced FB1 production were observed in ΔFvVam6.  Furthermore, we demonstrated that two vacuolar sorting protein 39 (Vps39) domains and clathrin domain were critical for the biological functions of FvVam6, while clathrin and Vps39-2 domains played dominant roles in the regulation of virulence and FB1 production.  Taken together, our results advanced our understanding of vCLAMP in fumonisin biosynthesis in plant pathogenic fungus F. verticillioides