我们的试验结果表明,杂交水稻后期同样用4.5公斤尿素,施于粒肥的比施促花肥的增产14.7％,比施保花肥的增产5.76％,比后期不施肥的,亩净增稻谷58.4公斤,增产10.2％。从试验和10来年施肥实践中得知,杂交水稻施用穗粒肥,增产效果之所以显著,主要原因是: 杂交水稻按库源特征分类,属增源增产型,即库源是充足的,而叶片光合产物不能充分满足库源充实的需要,表现为源的不足。因为杂交水稻幼穗分化时间较长,单株颖花数比常规水稻大大增多,强弱势花灌浆高峰值差20天左右。表现为对源的争夺力强。虽然杂交水稻营养生长旺盛,根系发达,吸肥力强,茎鞘物质输出率31.82％与转换率22.42％,均大大高于其他水稻,而转入生殖生长后期,生长优势弱,远不能满足穗分化和籽实形成的需要,产生需求矛盾大,易于出现脱肥现象。因此,常常表现为“分蘖有余而穗数不足,穗大有余而结实不 Our results showed that the same hybrid rice with 4.5 kg of urea, applied to the grain fertilizer than the Shi Hua Fa yield 14.7%, than the Shi Hua Fa yield 5.76%, no fertilizer than the late, Mu net increase of 58.4 kg of rice, 10.2% increase Based on the experiment and the fertilization practice in the next 10 years, it is known that the effect of yield increase is obvious when the hybrid rice is treated with grain-enduring fertilizer. The main reason is that hybrid rice is classified as source-source and yield-increasing type, that is, Photosynthetic products can not fully meet the needs of enrichment of the source, the performance of the lack of source. Because hybrid rice panicle differentiation time longer, the number of plants per plant significantly increased the number of spikes, strong potential weak flower grouting peak difference of about 20 days. The performance of the competition for the source of strong. Although hybrid rice had strong vegetative growth, developed root system and strong absorption of fertilizers, the output of stem and sheath materials was 31.82% and the conversion rate was 22.42%, which were much higher than other rice plants. However, the growth of hybrid rice was weak and could not meet the ear differentiation And the formation of seed needs, resulting in contradictions in demand, easy to appear fattening phenomenon. Therefore, often manifested as "more than enough tillers spike, spike large but not strong