氮肥分期施用对机插稻产量构成及氮肥利用率的影响

通过田间试验,对分蘖肥、穗肥氮素一次和分次施用时机插水稻的产量构成、氮肥利用效率以及与二者紧密相关的茎蘖动态、高光效叶面积和叶片SPAD值进行了研究。结果表明:分蘖肥氮素分次施用对产量形成无显著影响,而穗肥氮素分次施用使产量增加6.1%~6.5%,氮肥利用率提高10.0%~11.6%。主要原因在于:分蘖肥氮素分次施用对水稻生育前期茎蘖动态和叶龄进程基本无影响。但是,穗肥氮素分次施用显著增加开花时倒一叶和倒二叶叶面积,较穗肥一次施用分别增长10.1%~13.7%和32.1%~39.9%,并减缓了开花后20 d内倒二叶SPAD值降解速率,为水稻后期光合物质累积提供良好物质基础,使水稻成穗率提高5.1%~6.1%,且大幅提高实粒数。因而,机插秧水稻分蘖肥一次施用,穗肥分次施用有利于增加产量,提高氮肥利用效率,同时一定程度降低劳动投入量。

Effects of N fertilizer application times on yield formation and N use efficiency of machine transplated rice

A field experiment was conducted to determine the effects of single N application and split N application as tiller fer-tilization and earing fertilization on rice yield and composition, N fertilizer use efficiency, as well as tiller dynamic, leaf areas of high photosynthetic efficiency and SPAD value of machine-transplanted rice, which were closely related to the yield and N fertilizer use efficiency in the mode of rice transplanting with machine. The results showed split N application as tiller fertiliza-tion had little effect on yield development. However, split N application as earing fertilization increased rice yield by 6. 1% ~6. 5%, and enhanced N fertilizer use efficiency by 10. 0% ~11. 6%. The main reasons were split N applications as tiller ferti-lization had no effect on tiller dynamic and leaf age. But, split N applications as earing fertilization increased leaves’ areas of top first leaf and top second leaf by 10. 1% ~13. 7% and 32. 1% ~39. 9%, respectively, which reached significant levels. Meanwhile, chlorophyll degradation rate within 20 days after flower was retarded under treatment of split N applications as ear-ing fertilization, which laid a good foundation for photosynthetic material accumulation during late growth stage, and then led to 5. 1% ~6. 1% of increase in spike rate, and greatly improved the filled grain number. In sum, single N application of tiller fertilization and split N applications of earing fertilization on rice transplanting with machine increased yield, raised N fertilizer use efficiency and slowed down labor shortage.