Abstract:

【Objective】It is of significance to study the effects of different water and nitrogen coupling on nitrogen absorption, utilization and yield of indica hybrid rice with wheat straw returning.【Method】The nitrogen decomposition rate, nitrogen absorption and utilization were analyzed under two water treatments, three N treatments and two straw returning treatments with F You 498 as material with wheat straw returning at main growth stages. The two water treatments were alternative dry-wet irrigation and submerged irrigation and the straw returning treatments were full-burying returning and no straw returning and the N treatments were 150 kg/hm² of N application rates with three N regimes—the ratio of the basal fertilizer, tillering fertilizer and panicle fertilizer were 3∶3∶4 (N1), 7∶3∶0 (N2) and 0 (N0), respectively.【Result】The results showed that the alternative dry-wet irrigation promoted the release of straw nitrogen, increased the aboveground nitrogen accumulation of rice after jointing by 4.85%－33.92%, improved the nitrogen transport capacity of stem and sheath at maturity, increased the nitrogen absorption of panicle by 10.73%－16.42%, finally leading to an increase in the number of effective panicles and grain yield by 2.51%－3.77%. Straw returning (S1) released nitrogen nutrition, increased the aboveground nitrogen accumulation of rice by 5.15%－53.21% and the nitrogen transport capacity of leaves at maturity, increased the nitrogen absorption of panicle by 4.93%－43.91%, and finally increased the yield by 9.62%－18.33%. Nitrogen application promoted the release of straw nutrients and improved the nitrogen absorption and transport capacity of rice plants, increased the number of effective panicles and significantly increased the yield by 16.21%－28.31%. Compared with the alternative dry-wet irrigation coupled with optimized nitrogen application (N1) mode, the flooding irrigation coupled with traditional nitrogen application (N2) mode promoted the release of straw nutrients, increased the aboveground nitrogen accumulation of rice by 1.17%－11.89%. It improved the aboveground nitrogen accumulation capacity and nitrogen transport capacity of stems, sheaths and leaves, and significantly improved the nitrogen recovery and utilization rate by 7.27%－26.06%.【Conclusion】Under the conditions of full burying of wheat straw and returning to the field, the alternative dry-wet irrigation coupled with optimized nitrogen application can promote the release of straw nitrogen, effectively improve the nitrogen accumulation and utilization capacity of rice, and improve the nitrogen recovery and utilization rate and water use efficiency. It is the most suitable water-fertilizer coupling model in this experiment.

Key words: indica hybrid rice, straw returning, water-nitrogen coupling, nitrogen use efficiency, yield

摘要：

【目的】研究麦秆还田下不同水氮耦合对麦茬杂交籼稻氮素吸收利用及产量的影响。【方法】以杂交稻F优498为材料，设置不同水分处理方式(干湿交替灌溉、淹水灌溉)、氮肥运筹 [总氮150 kg/hm²，基肥∶蘖肥∶穗肥分别为3∶3∶4(N1)、7∶3∶0(N2)、不施氮(N0)]和秸秆还田(秸秆全量翻埋还田、秸秆不还田)，测定还田秸秆氮素腐解率、水稻籽粒产量及主要生育时期各器官氮素吸收利用特征。【结果】干湿交替灌溉促进了秸秆氮素释放，使水稻在拔节期后的地上部氮素积累量提高4.85%~33.92%，提高成熟期茎鞘氮素转运能力，穗部氮素吸收量提高了10.73%~16.42%，最终提高有效穗数并增产2.51%~3.77%。秸秆还田释放氮素营养，提高拔节期后的水稻地上部氮素积累量5.15%~53.21%和成熟期叶片氮素转运能力，提高穗部氮素吸收量4.93%~ 43.91%，最终增产9.62%~18.33%。施氮促进了秸秆养分释放，提高了水稻植株氮素吸收与转运能力，增加了有效穗数并显著增产16.21%~28.31%。对比干湿交替灌溉耦合优化施氮(N1)模式与淹水灌溉耦合传统施氮(N2)模式，前者促进了各时期的秸秆养分释放，提高了地上部氮素积累能力和茎鞘及叶片的氮素转运能力，并显著提高了氮肥回收利用率7.27%~26.06%。【结论】麦秆全量翻埋还田条件下，干湿交替灌溉耦合优化施氮的水氮耦合模式可促进秸秆氮素释放，有效提高水稻氮素积累及利用能力，提高氮肥回收利用率与水分利用率，为本研究中最适水肥耦合模式。

关键词: 杂交籼稻, 秸秆还田, 水氮耦合, 氮肥利用率, 产量