Abstract: A field experiment was conducted to study the effects of nitrogen （N） rate and plant density on grain yield and N use efficiency of hybrid rice Deyou 4727 with heavy panicle, and conventional rice Wushansimiao with light panicle, under four N application rate（0，120，165 and 210 kg/hm2, namely N0, N120, N165 and N210）and three plant densities （25.0, 19.1, 12.5 hills/m2, namely D1, D2 and D3）. The results showed that the 25.0 hills/m2 of planting density was the optimum planting density. When the planting density was 25.0 hills/m2, the grain yield of Deyou 4727 was increased with the increasing of N application rate at first and decreased after N application rate exceeding 165 kg/hm2, and the grain yield of Wushansimiao was increased with the increasing of N application rates. The highest grain yield of Deyou 4727（10.90 t/hm2） was in combination of N 165 kg/hm2 and 25.0 hills/m2. Wushansimiao obtained the highest grain yield（10.21 t/hm2）in the combination of N 210 kg/hm2 and 25.0 hills/m2. Under the same plant density, N use efficiency was decreased with the increasing of N application rates. Grain yield and N use efficiency was increased with the increasing of plant densities. It is a key technique for the high-yielding and high-efficiency cultivation of hybrid rice with heavy panicle. N application rate of 165 kg/ hm2 and plant density of 25.0 hills/m2 is the optimum combination.

Key words: nitrogen application rate, plant density, heavy panicle type, hybrid rice, grain yield, nitrogen use efficiency

摘要： 以重穗型杂交稻德优4727和轻穗型常规稻五山丝苗为材料，设置4个施氮量（0、120、165、210 kg/hm2，分别记为N0、N120、N165、N210）和3种移栽密度（25.0、19.1、12.5丛/m2，分别记为D1、D2、D3），于2016年在四川德阳进行大田试验，研究施氮量和移栽密度对重穗型杂交稻产量及氮肥利用率的影响。结果表明，参试水稻品种的适宜移栽密度均为25.0丛/m2，在此移栽密度下，重穗型杂交稻德优4727产量随施氮量的增加呈先增加后下降的趋势，以N165处理产量最高（10.90 t /hm2），轻穗型常规稻五山丝苗产量随施氮量的增加呈升高趋势，以N210处理产量最高（10.21 t /hm2）；相同移栽密度下，参试水稻品种氮肥利用率随施氮量的增加呈下降趋势；随移栽密度的增加，参试水稻品种产量和氮肥利用率呈增加趋势。可见，提高移栽密度，减少施氮量可兼顾水稻高产和氮肥高效利用，其最佳肥密组合为施氮量165 kg/hm2、移栽密度25丛/m2，即低氮密植可作为重穗型杂交稻高产高效栽培的关键技术。

关键词: 施氮量, 移栽密度, 重穗型, 杂交稻, 产量, 氮肥利用率