Water and nitrogen fertilizers have great impacts on rice production. Studies on the effects of water-nitrogen coupling on bioactive substances in colored rice have rarely been reported. Identifying the effects of water and nitrogen coupling on the grain yield and bioactive substance content of colored rice helps to develop rational water and nitrogen management strategies, reduce resource inputs and achieve high yields and quality of colored rice. A three-factor field experiment including two colored rice genotypes (Youxianghongdao and Suixiangheinuo), three water management practices (rainfed, alternating wet and dry irrigation, and flood irrigation), and four nitrogen application levels (0, 50, 100, and 150 kg ha) was conducted to evaluate the effects of different water and nitrogen management practices on the grain yield and bioactive substance content of colored rice. Results showed that the coupling between water and nitrogen management had significant effects on grain yield, anthocyanin content, flavonoid content, phytic acid content, and total antioxidant capacity of colored rice. Increasing irrigation tended to increase the grain yield of colored rice but was detrimental to the accumulation of bioactive substances. Increased nitrogen fertilizer application tended to increase the yield of colored rice and the accumulation of beneficial bioactive substances such as anthocyanin, flavonoid, total phenolic, and antioxidant substances, but decreased the accumulation of phytic acid. The comprehensive evaluation value of the colored rice grains decreased with increasing irrigation water content and increased with increasing nitrogen application rate. Among all the treatments, the rainfed with a nitrogen application of 150 kg ha treatment had the highest comprehensive evaluation value. There is a trade-off between grain yield and bioactive content of colored rice under various water and nitrogen coupled conditions. Results suggested that rainfed with a nitrogen application of 150 kg ha treatment had the best balance between grain yield and bioactive substance content. We conclude that the optimal combination of water and nitrogen management for colored rice production in areas with 380–510 mm of rainfall during the rice growth period is rainfed with a nitrogen application of 150 kg ha.

中文翻译：

---

水氮耦合条件下彩色米产量与生物活性物质含量的权衡

水和氮肥对水稻生产影响很大。水氮耦合对彩米生物活性物质影响的研究鲜有报道。明确水氮耦合对彩色水稻产量和生物活性物质含量的影响，有助于制定合理的水氮管理策略，减少资源投入，实现彩色水稻的高产优质。三因素田间试验，包括两种彩色水稻基因型（又香红稻和随香黑糯）、三种水分管理措施（雨养、干湿交替、漫灌）和四种施氮水平（0、50、100和150公斤） ha)旨在评价不同水氮管理措施对彩色稻米产量和生物活性物质含量的影响。结果表明，水氮耦合管理对彩色米产量、花色苷含量、黄酮含量、植酸含量和总抗氧化能力影响显着。增加灌溉量有利于提高彩色稻的产量，但不利于生物活性物质的积累。增加氮肥施用量有利于提高彩色水稻的产量和花青素、黄酮类、总酚、抗氧化物质等有益生物活性物质的积累，但会降低植酸的积累。彩色稻粒综合评价值随灌溉水量的增加而降低，随施氮量的增加而增加。各处理中，施氮150 kg·ha雨养处理的综合评价值最高。在不同的水氮耦合条件下，籽粒产量和彩色米的生物活性含量之间存在着权衡。结果表明，雨养施氮量150 kg·ha处理的籽粒产量和生物活性物质含量达到最佳平衡。我们得出的结论是，在水稻生育期降雨量380-510毫米的地区，彩色水稻生产的最佳水氮管理组合是雨养，施氮量为150千克公顷。