Water-saving and drought-resistant rice (WDR) under dry direct-seeded rainfed (DDSR) cultivation is a key technology to alleviate water scarcity and labor shortages, yet cultivar-specific nitrogen (N) management for coordinated yield-quality improvement remains unresolved. Field experiments were conducted in 2023–2024 with five N rates (0–360 kg N ha -1 ) to evaluate yield, dry matter translocation, nitrogen use efficiency, and grain quality in two hybrids (WHLY25, LHLY21) and one inbred (LH639) WDR variety. Grain yield peaked at N3 (270 kg N ha -1 ) for all varieties, while excessive N (N4, 360 kg N ha -1 ) reduced yield by 22.39%–37.27% compared with N3 due to proliferated unproductive tillers and impaired dry matter translocation from stems to panicles. Hybrids outyielded the inbred variety by 13.42%–16.39% with stronger N responsiveness and higher partial factor productivity of N, attributable to their larger sink size and superior dry matter remobilization capacity. Stems served as the dominant pre-anthesis carbon reserve, contributing 11.31%–27.73% of panicle weight. Quality parameters exhibited differential responses: grain size, milling quality, and amylose content followed quadratic N responses, whereas chalkiness degree and protein content increased linearly with N. Most RVA profile parameters peaked at N3. The modest reduction in amylose content under high N could not offset the negative effect of elevated protein content, which deteriorated cooking and eating quality. Based on a weighted comprehensive evaluation model combined with principal component analysis, cultivar-specific optimal N rates balancing yield and quality were 185 kg N ha -1 for WHLY25, 186 kg N ha -1 for LHLY21, and 214 kg N ha -1 for LH639, with sensitivity analysis revealing pronounced yield-quality trade-offs across the N gradient. These findings highlight that cultivar-specific precision N management is crucial for simultaneous yield-quality improvement in DDSR-based WDR systems. • Hybrids required less N input per unit grain yield than the inbred variety. • Hybrids exhibited higher yield and dry-matter remobilization capacity owing to a larger sink size. • Increasing N rate increased grain PC and deteriorated appearance quality. • Milling quality, AC, and RVA parameters showed quadratic responses to N rate. • Comprehensive evaluation showed an optimal N rate of 185–214 kg ha -1 for yield–quality synergy in WDR under DDSR conditions.
Zhen et al. (Fri,) studied this question.