不同密度和氮肥用量对水稻产量、构成因子及氮肥利用率的影响

针对水稻生产中氮肥用量过高、劳动力成本上涨及移栽密度越来越低的现状,设置氮肥、密度互作试验,研究施氮量和移栽密度及其互作效应对水稻产量和氮肥利用率的影响,以期为水稻节氮、省工合理栽培及高效施肥提供理论依据。结果表明,氮肥用量和密度均可显著影响水稻产量,互作效应显著。施氮(N82.5、N165.0、N247.5)后平均分别增产30.6%、47.8%、44.6%;密度为21万蔸/hm2时,籽粒产量最高。有效穗数随施氮量和移栽密度的增加而增加,提高密度后实粒数、结实率和千粒重则出现降低。氮肥利用率随施氮量增加而下降,随密度增加先上升后下降。在资源短缺、环境污染及生产成本上涨的形势下,低氮水平时应适当增加密度,提高移栽密度时则应控制氮肥用量。在本试验条件中,移栽密度为22.1万蔸/hm2的基础上施氮194.9 kg/hm2是实现水稻高产高效、节氮、省工栽培的合理组合。

Effects of Nitrogen Application Rate and Planting Density on Grain Yields, Yield Components and Nitrogen Use Efficiencies of Rice

An experiment was carried out to study the interactive effect of nitrogen(N) fertilizer rate and planting density on rice yield and N use efficiency in order to provide a basis for rational cultivation management. The results indicated that the N rate and planting density had significant effects on grain yield of rice and the interactive effect was also significant. Compared with the no N treatment, the average yields of the treatments with N rates of 82.5, 165.0 and 247.5 kg/hm2 increased by 30.6%, 47.8% and 44.6%, respectively. The plant density was 21×104 seedlings/hm2 for the highest grain yield. Increasing the N rate and planting density significantly increased the number of spikes per unit. However, grains per spike, seed setting rate and thousand grain weight decreased with the increase of planting density. N use efficiency decreased at the higher N application rate, but increased first and then dropped with the increase of planting density. Planting density also had significant effects on grain yields of rice, increasing density promoted rice yield under the condition of low N rate (0 and 82.5 kg/hm2), but for the high density treatment, higher N rate significantly decreased the yield. In this study, the appropriate nitrogen application rate and plant density of rice were 194.9 kg/hm2 and 22.1×104 seedlings/hm2, respectively.