关键词: 小麦, 品种更替, 源库理论, 蛋白质含量, 淀粉含量, 加工品质

Abstract:

【Objective】This study aimed to investigate the coordinated evolution of source-sink traits and quality traits in winter wheat during cultivar replacement in the Haihe Plain, thereby providing a theoretical basis for breeding and agronomic management aimed at simultaneously achieving high yield and high quality.【Method】Thirty major winter wheat cultivars approved from the 1950s to the present were evaluated in field experiments conducted over three wheat-growing seasons (2022-2025) at the Xinji Experimental Station, Agricultural University of Hebei. Source traits (leaf area index and net photosynthetic rate), sink traits (grain number per unit area, grain-filling rate, and yield), and quality traits (protein fractions, starch properties, and processing quality) were measured. Carbon-to-nitrogen (C/N) ratios and the activities of enzymes associated with carbon and nitrogen metabolism were also determined. Linear mixed-effects models and Mantel tests were used to characterize the temporal trends in source-sink traits and quality traits and to assess their relationships.【Result】Cultivar replacement improved source-sink traits. Source activity (net photosynthetic rate) increased by 0.66 μmol·m^-2·s^-1 per decade, whereas sink size (grain number per unit area) and sink activity (average grain-filling rate) increased by 626.56 grains/m² and 0.03 mg/(grain·d) per decade, respectively, resulting in an increase in sink strength (grain yield) of 551.77 kg·hm^-2 per decade. However, this process induced a pronounced “carbon dilution effect”, disrupting the balance between yield and quality: amylopectin content increased significantly by 0.31% per decade, whereas total protein content decreased by 0.23% per decade. Processing-quality parameters, including sedimentation value and wet gluten content, decreased significantly by 0.96 mL and 0.71%, respectively, per decade. Moreover, protein-related traits were significantly negatively correlated with source activity and sink strength. The activities of enzymes involved in carbon and nitrogen metabolism showed that cultivar replacement significantly increased the activities of key enzymes, including sucrose synthase and glutamine synthetase, leading to a 1.44 per-decade increase in the grain C/N ratio, whereas the C/N ratios of stems and leaves decreased significantly. This further indicated that cultivar replacement altered patterns of carbon and nitrogen metabolic partitioning.【Conclusion】Modern high-yielding cultivars achieved substantial yield gains through coordinated source-sink improvement by enhancing source activity and expanding sink capacity; however, relatively insufficient nitrogen accumulation in grains made it difficult to improve yield and quality simultaneously. Agronomic practices, such as shifting nitrogen application to the flowering stage and regulating water supply during grain filling, combined with the breeding of cultivars with high nitrogen assimilation or remobilization efficiency, were recommended to alleviate the carbon dilution effect and achieve coordinated improvements in yield and quality. These findings provid a theoretical basis for breeding and agronomic management strategies that coordinate high yield with high quality and promote high-yield, high-efficiency wheat production.

Key words: wheat, cultivar replacement, source-sink theory, protein content, starch content, processing quality