Nitrogen optimization enhances grain filling and starch biosynthesis in japonica rice: physiological regulation of carbon-nitrogen metabolism and synthase activities

文献类型： 外文期刊

第一作者： Song, Yunsheng

作者： Song, Yunsheng;Jiang, Yi;Chen, Fei;Dong, Minghui;Gu, Junrong;Qiao, Zhongying;Jin, Xiuliang;Jin, Xiuliang;Hu, Yajie;Hu, Yajie;Wang, Yixiao

作者机构：

关键词： Nitrogen optimization; Grain filling; Starch biosynthesis; High-quality japonica rice; Carbon-nitrogen metabolism; Starch synthase activities

期刊名称：CEREAL RESEARCH COMMUNICATIONS （ 影响因子：1.9； 五年影响因子：1.7 ）

ISSN： 0133-3720

年卷期： 2025 年

页码：

收录情况： SCI

摘要： This study investigates the physiological mechanisms through which nitrogen (N) optimization enhances grain filling and starch biosynthesis in high-quality japonica rice, focusing on carbon-nitrogen (C-N) metabolic coordination and starch synthase regulation under varying N regimes in the Taihu Lake region, China. A two-year field experiment (2022-2023) employed six N treatments (0-400 kg ha-1) using the high-quality japonica cultivar 'Suxiangjing 100.' Grain yield, morphology, starch accumulation dynamics, and activities of key starch synthases were analyzed. Starch accumulation was modeled using the Richards equation, while enzyme activities were assayed spectrophotometrically. Optimal N application (240-320 kg ha-1) maximized grain yield (9237-9573 kg ha-1) and starch content (13.43 mg grain-1 in superior grains) by coordinating AGPase-initiated substrate supply with SSS/SBE-driven amylopectin crystallization. N240-N320 enhanced grain filling rates (1.57-1.73 mg grain-1 day-1), prolonged active filling duration (32-34 days), and increased starch synthase activities (AGPase: 0.42-0.45 mu mol grain-1 h-1; SSS: 0.21-0.23 mu mol grain-1 h-1; SBE: 441.9-452.9 grain-1 min-1). Superior grains (SG) exhibited 12.6% higher starch accumulation than inferior grains (IG) under optimal N, with SSS activity showing a near-perfect correlation to accumulation rates (r = 0.97-0.98). Excessive N (400 kg ha-1) suppressed late-stage enzyme activities by 15-22%, thus reducing grain density (1.29 vs. 1.38 g cm-3) and yield advantage (<= 9.0 t ha-1). N optimization at 240-320 kg ha-1 balances C-N metabolism to enhance starch biosynthesis and grain quality in japonica rice. Further research is needed to clarify the long-term soil impacts and to compare these findings with less-intensive management systems. Our results nonetheless underscore the importance of position-specific N management for achieving high-quality japonica grains.

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