为筛选出五丰优T025在红壤稻田上的合理氮肥用量和种植密度，本试验以天优998为对照品种，在典型的红壤性水稻土设置了氮肥用量与种植密度试验，系统研究了不同氮密互作条件下五丰优T025的茎蘖动态和产量变化。结果表明，氮密互作下五丰优T025和天优998的分蘖消长动态基本一致，在移栽后60 d（齐穗期），五丰优T025每m2有效分蘖328个，天优998为349个；不同氮肥用量的分蘖数不存在显著差异，但不同种植密度之间的分蘖数均存在显著差异，与低密度处理（D21）相比，五丰优T025 D26和D32处理每m2分蘖数分别增加了13.8%~33.1%、6.4%~11.1%，天优998分别增加30.1%~34.9%、5.7%~12.1%；五丰优T025和天优998均以N180D32处理产量最高，分别为10 719.0 kg/hm2和9 682.7 kg/hm2；与天优998相比，五丰优T025的有效穗数和每穗粒数明显要高，由于有效穗数与产量成显著的正相关关系，表明五丰优T025主要是通过增加有效穗数来实现水稻增产。在南方红壤稻田上，五丰优T025的合理氮密配比为N 180 kg/hm2、栽插密度32万丛/ hm2。

Field experiment was carried out to find better amount of N (nitrogen) fertilizer and planting density of Wufengyou T025 in red paddy soil. The tillering dynamics and yield were analyzed under different N ratio and density compared with Tianyou 998. The results showed that the tillering dynamics of Wufengyou T025 was similar to Tianyou 998. The effective tillers of Wufengyou T025 were 328/m2 in 60 days after transplanting, and Tianyou 998 were 349/m2. There was no significant difference among different N rate. However, the tillers per square meter of Wufengyou T025 in D32 and D26 treatment were increased by 13.8%~33.1% and 6.4%~11.1% compared with D21. The tillers per square meter of Tianyou 998 were increased by 30.1%~34.9% and 5.7%~12.1%. The grain yield of N180D32 was highest in all treatments, where Wufengyou T025 and Tianyou 998 were 10 719.0 and 9 682.7 kg/hm2, respectively. The effective panicles and grain numbers per panicle of Wufengyou T025 were higher than Tianyou 998, and the effective panicles were significantly positively correlated with the yield. Therefore, reasonable increase in planting density was mainly increased the effective panicles and achieved high yield. The better ratios of N fertilizer and density were N 180 kg/hm2 and 320 000 hill/hm2.