Hongjian Cheng

Henan Province, the foremost wheat-producing region in China, frequently experiences drought stress during the wheat seedling stage. Innovating the evaluation methods for drought resistance at this stage and identifying drought-resistant varieties are crucial for the effective utilization of germplasm. This study utilized 55 wheat varieties that have been bred and promoted in Henan Province in recent years as experimental materials. A 15% PEG-6000 solution was employed to simulate drought stress, and the primary morphological indicators of seedlings, relative chlorophyll content (SPAD), and various chlorophyll fluorescence parameters were assessed. The comprehensive drought resistance scores (D values) for each variety were determined by calculating the drought resistance coefficients for each index, employing principal component analysis, and conducting membership function analysis. Based on the cluster analysis of D values, 55 varieties were categorized into four groups: high drought resistance (10), medium drought resistance (28), low drought resistance (16), and drought-sensitive (1). Seven indicators—SPAD, fresh root weight, seedling height, fresh weight of the aboveground part, Fv/Fm, PItotal, and Mo—were selected as evaluation metrics for the drought resistance of wheat through stepwise regression analysis. The comprehensive evaluation system developed in this study, which is based on morphological and photosynthetic fluorescence characteristics, can swiftly and accurately assess the drought resistance of wheat seedlings. The key indicators identified for highly drought-resistant varieties may serve as valuable references for drought-resistant wheat breeding in Henan Province.

Nitrogen (N) is a key nutrient influencing wheat growth, grain yield, and quality. A long-term field experiment was conducted using cultivar Zhengmai 1860 to clarify the effects of N topdressing on grain protein composition, starch accumulation, and yield. Treatments included a basal N application of 150 kg ha⁻¹ (N1) combined with four topdressing rates at jointing: 37.5, 75, 112.5, and 150 kg ha⁻¹ (N1 + 37.5, N1 + 75, N1 + 112.5, N1 + 150). Nitrogen topdressing significantly affected the physiological and biochemical characteristics of grains at different spike positions. Amylopectin, globulin, soluble starch (SS), and soluble starch synthase (SSS) accumulated most under 75–112.5 kg ha⁻¹, with N1 + 75 showing the strongest response in basal and middle spike grains. Amylose and granule-bound starch synthase (GBSS) peaked at the middle spike under N1 + 112.5. Protein component (gliadin, glutelin, albumin), amino acids, glutamate synthase (GOGAT), and glutamine synthetase (GS) increased progressively with higher N rates, with maximum accumulation at N1 + 150. Nitrogen topdressing also enhanced spike number (5.05–37.13%), grains per spike (3.86–16.22%), and 1000-grain weight (2.72–5.79%), with the highest yield (9451.7 kg ha⁻¹) at N1 + 112.5. These results highlight the critical role of optimized N management in improving grain composition and yield in wheat.

Increasing species richness through rotation is considered a promising measure to enhance agroecosystem functions and services. However, the legacy effects of introducing legumes into a wheat–maize rotation in the North China Plain on soil microecology, especially the soil metabolome, in the succeeding wheat season have not been elucidated. This study established three cropping systems: (1) a continuous winter wheat–summer maize rotation (M), (2) a winter wheat–summer peanut (summer maize) rotation (PM), and (3) a winter wheat–summer soybean (summer maize) rotation (SM). The soil physicochemical properties, microbial communities, and metabolomes were analyzed at the stage of the succeeding wheat crop. Introducing peanuts or soybeans into a wheat–maize rotation significantly reduced the soil bacterial abundance and increased the soil fungal Shannon index. This rotation adjustment had a substantial impact on the structure and taxa composition of the soil microbial community. Crop diversification increased the number of total edges, the average degree, and the average number of neighbors in the soil microbial co-occurrence network. Different crop rotations significantly affected the soil metabolic profiles in the positive and negative ion modes. Crop diversification significantly reduced the abundance of coumarin and coumaric acid in the soils. In conclusion, introducing peanuts or soybeans into a wheat–maize rotation could increase the soil fungal community diversity, change the soil microbial community structure and taxa composition, increase the complexity of the soil microbial ecological network, and reduce the abundance of soil allelochemicals. Our study demonstrated the continuity of the impact of crop rotation on soil ecology, and revealed the ecological advantages of crop diversification from the perspective of soil microbiology and metabolomics.

Appropriate deep sowing holds significant potential in enhancing wheat production, particularly in dry and low-rainfall regions. Henan Province is a major winter wheat-producing area in China; evaluating the adaptability of wheat varieties to deep sowing through scientific methods is crucial to improve wheat production. This study investigates 26 wheat cultivars in Henan. By assessing key traits of seeds and seedlings at various sowing depths, we analyzed the effects of sowing depth on seed germination and seedlings. A comprehensive index for deep sowing tolerance was established using principal component analysis (PCA) and the membership function method, followed by the classification of the varieties according to their tolerance to deep sowing. The results indicated that, with increased sowing depth, seedling emergence time, coleoptile length, and coleoptile internode length increased, while seedling emergence rate, seedling height, leaf area, and shoot dry weight per unit area decreased. Based on PCA and membership function values, the 26 wheat varieties were classified into three categories: deep sowing tolerant, moderately tolerant, and intolerant, comprising 3, 19, and 4 varieties. This study provides valuable insights for optimizing wheat variety selection and improving sowing practices in Henan Province, offering both theoretical and practical contributions to local wheat production.