【目的】结实期田间穗部冠层小气候是水稻生长发育最直接的微环境因子,水分和氮肥运筹通过影响水稻群体构建进而影响水稻田间冠层小气候,研究水氮互作对直播稻结实期冠层小气候及稻米品质的影响,可以丰富和完善直播稻水氮管理技术。【方法】以杂交稻F优498为试材,通过淹灌(W₁)、干湿交替(W₂)、旱种(W₃)3种灌水方式及底肥:蘖肥:穗肥质量比分别为5:3:2(N₁)、3:3:4(N₂)、3:1:6(N₃)3种氮肥运筹模式,研究水氮互作对直播稻灌浆结实期冠层温度、光照强度及稻米品质的影响;并探讨水氮互作下直播稻灌浆结实期穗部冠层小气候特征与米质的关系。【结果】水氮互作对稻米加工、外观及食味品质均存在显著或极显著的影响。各灌水方式在150 kg/hm²施氮量下,氮肥后移比例均以占总施氮量的20%最优,且与W₂处理耦合可进一步改善稻米品质。各灌溉方式下,氮肥后移比例增加到总量的60%时,会导致直播稻灌浆结实期温差、总温差、积温、有效积温、光照强度及米质下降。水氮互作下穗部冠层小气候与加工品质及蒸煮食味品质关系密切,温度对整精米率的影响大于光照强度,且有效积温与整精米率相关性最高;光照强度与稻米蒸煮食味品质的外观、口感以及综合评分关系最密切【结论】初步探明,水氮互作会通过改变直播稻冠层小气候进而影响稻米品质。可为直播稻提质丰产增效提供理论依据与实践基础。

【Objective】Field canopy microclimate is the most direct environment factor for rice growth and development. The management of water and nitrogen fertilizer affects the growth of rice and thus affect the canopy microclimate of paddy field. Studying the effect of water and nitrogen interaction on the canopy microclimate during the seed-filling stage and rice quality of directly seeded rice can enrich and improve water and nitrogen management of the directly seeded rice. 【Method】With hybrid rice F You 498 as material, three irrigation treatments were designed including flooding (W₁), dry-wet alternate (W₂) and drying (W₃) as well as three N fertilizer application methods with basal fertilizer: fertilizer for tillering: topdressing for panicle initiation 5:3:2(N₁), 3:3:4(N₂) and 3:1:6(N₃), The effect of water and nitrogen interaction on canopy temperature, light intensity and rice quality of directly-seeded rice were analyzed during grain filling stage. The relationship between canopy microclimate and rice quality was also discussed. 【Result】The results showed that irrigation mode and N fertilization interactions had a significant or extremely significant effect on milling quality, appearance quality, and cooking and palatability of directly seeded rice. Under the conditions of 150 kg/hm² N application rate for each irrigation method, the most suitable panicle N-fertilizer level should account for 20% of total N. Coupled with W₂, it can further improve rice quality. The ratio of N-fertilizer for panicle initiation increased to 60%, leading to the decrease of daily temperature difference, total temperature difference, accumulated temperature, effective accumulated temperature, daily average light intensity and rice quality of directly seeded rice under irrigation. Under the interaction of water and N, the canopy microclimate in the field exerted the greatest impact on milling quality, and cooking and palatability of directly seeded rice. The effect of temperature on the head milled rice rate was greater than the light intensity, and the effective accumulated temperature had the highest correlation with head milled rice rate. Light intensity was the most closely related to the appearance, taste and comprehensive score of rice cooking and palatability quality. 【Conclusion】It is preliminarily proved that the interaction between water and nitrogen affects rice quality by changing the microclimate of the direct-seeded rice canopy. The results will lay a theoretical and practical basis for improvement of the quality and yield of direct-seeded rice.