移栽密度及氮肥投入量对水稻氮素利用效率的协同效应

Synergistic effects of planting density and nitrogen application rate on the nitrogen use efficiency of rice

采用大田小区试验,以"南粳9108"为供试水稻品种,在D_(1)(90×10^(4)株·hm^(-2))、D_(2)(120×10^(4)株·hm^(-2))、D_(3)(150×10^(4)株·hm^(-2))等3个移栽密度下,分别设置N_(1)(0 kg·hm^(-2))、N_(2)(240 kg·hm^(-2))、N_(3)(270 kg·hm^(-2))、N_(4)(300 kg·hm^(-2))等4个施氮量水平,研究水稻氮素利用效率对移栽密度和氮肥投入量的协同响应。结果表明:在N_(2)D_(3)处理下,水稻每穗粒数较少,结实率也较低,但N_(2)D_(3)处理有效穗数比N_(2)D_(1)和N_(2)D_(2)平均提高29.3%,较高的水稻有效穗数保证了其产量不减。N_(2)D_(3)处理生物产量比N_(2)D_(1)和N_(2)D_2平均提高17.0%,明显提高的生物产量为水稻获得高产提供了基础条件。密植减氮的N_(2)D_(3)处理水稻N素累积量提高13.8%,N素干物质生产效率提高7.1%,N素籽粒生产效率变化不大,N素收获指数则降幅显著;与N_(2)D_(1)和N_(2)D_(2)处理相比较,N_(2)D_(3)处理使水稻N肥吸收利用率、偏生产力、农学利用率和生理利用率分别平均提高了32.4%、13.8%、54.6%和17.1%。当氮肥投入量较高时,稻田土壤速效氮含量在不同移栽密度下均较高;当氮肥投入量较低时,稻田土壤速效氮含量在较高移栽密度下能保持较高水平。在常规施氮水平300 kg·hm^(-2)的基础上,通过增加水稻移栽密度至150×10^(4)株·hm^(-2),降低20%的氮肥投入量,在保证水稻产量的同时,使水稻的氮肥吸收量和氮素利用效率均得到明显提高,并能保持稻田土壤肥力不减。

A field experiment was carried out to study the synergistic effects of transplanting den-sity and nitrogen application rate on yield formation and nitrogen use efficiency of rice(cultivarNanjing 9108).We set up three basic seedling densities of D_(1)(90×10^(4)ind·hm^(-2)),D_(2)(120×10^(4)ind·hm^(-2)),and D_(3)(150×10^(4)ind·hm^(-2)),and four nitrogen application rates of N_(1)(0 kg·hm^(-2)),N_(2)(240 kg·hm^(-2)),N_(3)(270 kg·hm^(-2)),and N_(4)(300 kg·hm^(-2)).The resultsshowed that under treatment N_(2)D_(3),spikelets per panicle and filled grain percentage of rice wererelatively small,but the effective panicle number was 29.3%higher than that of N_(2)D_(1)and N_(2)D_(2),which indicated that the higher number of effective panicles of rice resulted in unchanged yield.The biomass yield of N2D3was 17.0%higher than that of N_(2)D_(1)and N_(2)D_(2),and such obviousenhancement of biomass yield ensure the high yield of rice.N2D3treatment significantly increasedrice nitrogen accumulation by 13.8%and nitrogen dry matter production efficiency by 7.1%.There was no variation in nitrogen use efficiency of grain yield of rice,but the nitrogen harvestindex significantly decreased under the treatment of N_(2)D_(3).Compared with N_(2)D_(1)and N_(2)D_(2),N_(2)D_(3)treatment increased the N fertilizer absorption and utilization rate,partial productivity,agronomic utilization rate,and physiological utilization rate by 32.4%,13.8%,54.6%and 17.1%,respec-tively.Higher nitrogen application rate ensured the higher available nitrogen content in soil underdifferent transplanting densities.When the input of nitrogen fertilizer was low,soil available nitro-gen content could maintain a high level under high transplanting density.In conclusion,on thebasis of conventional nitrogen application rate of 300 kg·hm^(-2),by increasing planting density ofrice and 20%reduction of nitrogen fertilization rate,the D3N2treatment could ensure rice yield,improve N absorption and N use efficiency of rice,and maintain soil fertility of paddy field.