不同水分条件下缓/控释氮肥对水稻干物质量和氮素吸收、运转及分配的影响

为探究缓/控释肥在不同水分条件下提高氮素利用率及增产机制。本研究以杂交中稻F优498为试验材料，在180 kg hm^-2施氮量基础上，采用两因素裂区设计: 主区设控灌、干湿交替灌溉、传统灌水灌溉3种水分管理方式，副区设尿素一道清、尿素常规运筹、硫包膜缓释肥、树脂包膜控释肥4种氮肥种类，研究缓/控释肥和水分管理方式对水稻干物质量和氮素吸收、运转、分配和产量的影响及其互作效应。结果表明, 缓/控释肥和水分管理方式对水稻主要生育期干物质量和氮吸收、转运、分配及产量具显著影响及互作效应，产量构成因素与氮素在结实期转运总量及其分配呈显著正相关。干湿交替灌溉和缓/控释肥均能提高干物质量、氮素吸收及产量并表现出显著互作效应，施用缓/控释肥氮素表观利用率达42%~53%，相较于尿素一道清和传统的尿素常规运筹，氮肥偏生产力提高6%~23%，氮素农学利用率提高26%~71%，增产8%~19%。控灌条件下，缓/控释肥处理氮素有效性高，保证足穗、促进重穗；干湿交替灌溉条件下缓/控释肥处理能保持氮素的高效释放，有利于高产群体的形成，从而提高稻株氮素积累、协调氮素分配；淹水灌溉条件下，缓/控释肥处理无效分蘖减少，氮素入渗、淋溶降低，成穗率提高。综合产量与氮素吸收、运转的表现，干湿交替灌溉条件下施用缓控释肥为本试验最佳处理，能有效提高氮素利用率，促进高产形成。

Effects of Water Management and Slow/Controlled Release Nitrogen Fertilizers on Biomass,Nitrogen Accumulation,Translocation, and Distribution in Rice

Slow/controlled release nitrogen fertilizers, providing a gradual nutrient supply for a long time period, improve nitrogen fertilizer use efficiency and reduce nitrogen leaching losses. However, the effectiveness of slow/controlled release nitrogen fertilizers will be strongly affected by the environmental conditions, especially by water conditions, in the planting region. Alternate wetting and drying (AWD) irrigation has been widely adopted to replace continuous flooding irrigation for saving water and increasing water use efficiency (WUE) in irrigated rice(Oryza sativa L.) systems. However, little attention has been paid to the performance of slow/controlled release nitrogen fertilizers and its mechanism of realizing high yield under different water managements. A field experiment was conducted to investigate the effects of slow/controlled release nitrogen fertilizers on biomass and nitrogen accumulation, translocation and distribution in rice, together with the mechanism, with a split-split design in 2012 and 2013. The main plot treatment was different water managements, including controlled irrigation (W₁), alternate wetting and drying irrigation (W₂) and flooding irrigation (W₃), and the subplot treatment contained urea single basal application (F₁), urea applying with ratio of base : tillering : earring = 5:3:2 (F₂), sulfur coated N fertilizer single basal application (F₃) and resin coated N fertilizer single basal application (F₄). Results showed that there was a significant interactive effect between water management and slow/controlled release nitrogen fertilizers application on biomass, nitrogen accumulation, translocation and distribution and rice yield in the main growth period. Moreover, there existed significantly positive correlations between yield component factors and nitrogen increasing in panicle, nitrogen translocation and distribution at heading stage. In addition, AWD and slow/controlled release nitrogen fertilizers had a significant interactive effect, enhancing biomass, nitrogen accumulation and yield in rice. Nitrogen use efficiency, partial factor productivity of applied nitrogen, nitrogen agronomic efficiency and yield increased by 42%–53%, 6%–23%, 26%–71%, and 8%–19% respectively in F₃, as compared with F₁ and F₂ treatments. Different types of nitrogen fertilizer and water condition affected rice yield mainly through affecting available spike number and grain number per spike. The application of slow/controlled release nitrogen fertilizers enhanced nitrogen use efficiency and maintained heavy and adequate panicles under controlled irrigation condition. Under alternate wetting and drying irrigation, the beneficial effect of using slow/controlled release nitrogen fertilizers was attributed to better nitrogen accumulation capacity and more coordinated nitrogen distribution in rice plant, which results from slowing the release of nitrogen into the soil relative to regular fertilizer and water conditions, and improving synchronization with crop N requirements during crop growth. Under flooding irrigation condition, slow/controlled release nitrogen fertilizers reduced ineffective tillering and nitrogen losses of leaching and penetrating, resulting in high earbearing tiller percentage. In conclusion, applying slow/controlled release nitrogen fertilizers under alternate wetting and drying irrigation condition can enhance nitrogen use efficiency and realize high yield.