研究表明，减少生育前期１／３左右的氮或氮、钾施用量对两系杂交稻Ｎ３１Ｓ／Ｐ４０（Ｆ_１）穗粒数影响很小．但增加生育后期的氮或氮、钾追施比例可明显提高结实期的叶片光合速率、根系活力和干物质生产，结实率、千粒重和谷产量也明显提高。后期追施氮、钾比单施氮的效果更好。 Studies have shown that reducing the nitrogen or nitrogen and potassium application rate of about 1/3 of the first half of the reproductive cycle has little effect on the spike grain number of two-line hybrid rice N31S / P40 (F_1). However, increasing the ratio of topdressing nitrogen, nitrogen and potassium during late growth could significantly increase the photosynthetic rate of leaf during the grain-filling stage. The root vigor and dry matter production, seed setting rate, 1000-grain weight and grain yield were also significantly increased. Nitrogen and potassium in the later chase is better than nitrogen alone.