机插超级粳稻产量、品质及氮肥利用率对氮肥的响应

Response of yield,quality and nitrogen use efficiency to nitrogen fertilizer from mechanical transplanting super japonica rice

在大田机插条件下，以5个超级粳稻品种为材料，设置0、150、187.5、225、262.5、300、337.5 kg·hm-2等7种施氮水平，研究氮肥用量对超级粳稻产量、品质及氮肥利用率的影响，并比较机插条件下各超级粳稻最高产施氮量与经济最佳施氮量的差异.结果表明： 随氮肥用量的增加，超级粳稻产量均先增加后下降，5个超级稻品种均在300kg·hm-2施氮条件下获得最高产量，达10.33～10.60 t·hm-2.产量的增加主要取决于较高的群体颖花量，在300 kg·hm-2施氮条件下，各超级粳稻品种的群体颖花量均达到最大值.随氮肥用量的增加，5个超级粳稻品种的糙米率、精米率、整精米率及蛋白质含量均增加，337.5 kg·hm-2氮肥处理比不施氮处理分别高3.3%～4.2%、2.9%～6.0%、4.4%～33.7%和23.8%～44.3%；直链淀粉含量、胶稠度和食味值均下降，337.5 kg·hm-2氮肥处理比不施氮处理分别低12.4%～389%、10.3%～28.5%和20.3%～29.7%；垩白度呈现先增加后下降的趋势，而垩白率的变化因品种不同略有差异.随氮肥用量的增加，5个超级粳稻品种的氮肥吸收利用率、氮肥农学利用率和氮肥生理利用率下降，而籽粒吸氮量显著增加.根据水稻产量与氮肥用量的效应方程，5个超级稻的理论最高产量为9.99 t·hm-2，对应的施氮量为299 kg·hm-2；如果考虑氮肥的投入成本，则经济最佳施氮量为275.68 kg·hm-2，对应的产量为9.97 t·hm-2.因此，对于现有的超级水稻生产，可根据高产、优质、高效和低投入等不同目标分类进行氮肥的综合管理.

Five super japonica rice cultivars were grown by mechanical transplanting in field and seven N treatments with total N application rate of 0, 150, 187.5, 225, 262.5, 300 and 337.5 kg·hm-2 respectively were adopted to study the effects of N rate on rice yield, quality and N use efficiency. The differences between N requirement for obtaining the highest yield and for achieving the best economic benefit were compared. With the increase of N fertilizer rate, the yields of five super japonica rice cultivars increased firstly and then descended, achieving the highest yield at the N level of 300 kg·hm-2 ranging from 10.33-10.60 kg·hm-2. Yield increase mainly attributed to the large number of spikelet, for the total spikelet number of each rice cultivar reached the maximum value at the 300 kg·hm-2 N level. With the increase of N application, the rates of brown rice, milled rice, head milled rice and the protein content of the five super japonica rice cultivars were all increased, and the rates of brown rice, milled rice, head milled rice and the protein content were higher at 337.5 kg·hm-2 N level than at 0 kg·hm-2 N level by 3.3%-4.2%, 2.9%-6.0%, 4.4%-33.7% and 23.8%-44.3%, respectively. While the amylose content, gel consistency and taste value of the five rice cultivars were all decreased, and the amylose content, gel consistency and taste value were lower at 337.5 kg·hm-2 N level than at 0 kg·hm-2 N level by 12.4%-38.9%, 10.3%-28.5% and 20.3%-29.7%, respectively. The chalkiness increased firstly and then decreased while the change of chalky rate varied with the cultivars. With the increase of N application, the N use efficiency, agronomic N use efficiency and physiological N use efficiency decreased while the N uptake of grain increased significantly. If the cost of N fertilizer was taken into account, the N fertilizer amount to obtain the optimal economic benefits would be 275.68 kg·hm-2 with the corresponding yield of 9.97 t·hm-2. Therefore, in the existing super rice production, classified management of N fertilizer would be required to meet differentiated demands of high yield, good quality, high efficiency, low N fertilizer input and so on.