不同氮肥水平下早熟晚粳氮和磷的吸收利用特性及相互关系

采用大田试验，以长江中下游地区具有代表性的50个早熟晚粳品种为材料，研究7个氮肥水平(0、150.0、187.5、225.0、262.5、300.0、337.5 kg hm^-2纯氮)下水稻氮和磷积累量、吸收速率、利用效率的差异及其相互关系。结果表明：(1)在0~337.5 kg hm^-2纯氮范围内，随着氮肥水平的增加，早熟晚粳的植株含氮率和氮积累量在拔节、抽穗和成熟期均显著增加；植株含磷率和磷积累量在拔节和抽穗期显著增加，成熟期呈先增后减变化。(2)播种至拔节阶段氮和磷吸收速率随施氮量的增加而提高，差异极显著；拔节至抽穗阶段氮和磷吸收速率随施氮量的增加呈现先增加后降低的变化趋势；抽穗至成熟阶段的氮和磷吸收速率规律不明显。(3)在0~337.5 kg hm^-2纯氮范围内，随着施氮量的增加氮素籽粒生产效率和磷素籽粒生产效率均显著降低，随着施氮量的增加基因型之间的差异减小；随着施氮量的增加氮和磷收获指数都呈现抛物线关系，在施氮量为262.0 kg hm^-2纯氮时出现最大值。(4)早熟晚粳对氮和磷的吸收利用具有显著的协同效应，但随生育进程的推进这种效应减弱。水稻在播种至拔节、拔节至抽穗和抽穗至成熟3个生育阶段的氮和磷吸收速率都呈二次曲线关系(r=0.892^**，r=0.736^**，r=0.512^**)。(5)相关分析表明，产量与拔节期、抽穗期和成熟期的吸氮量和吸磷量以及播种至拔节期和拔节至成熟期的吸氮速率和吸磷速率呈极显著正相关关系。增施氮肥有利于水稻氮和磷吸收利用的提高，但氮肥过高时氮和磷吸收利用不再增加，甚至有所降低。

Characteristics and Correlation Analysis of N and P Uptake and Utilization of Early Maturing Late Japonica under Different N Fertilizer Levels

A field experiment was carried out with 50 early-maturing late japonica rice varieties adopted in the region of Yangtze River under seven nitrogen application levels (0, 150.0, 187.5, 225.0, 262.5, 300.0, and 337.5 kg ha^-1) to investigate N and P accumulation, N and P uptake rate, N and P use efficiency and correlations between them. The main results were as follows. (1) In the range of 0–337.5 kg ha^-1, N concentration and accumulation amount were significantly increased with the increase of N fertilizer under three growth stages. P concentration and accumulation amount were significantly improved with the increase of N fertilizer at elongation and heading of rice, but P accumulation was significantly deceased at maturing when N fertilizer was too high. (2) N and P uptake rates were significantly increased with the increase of N fertilizer during sowing to elongation. During elongation to heading, N and P uptake rates were increased at first and then decreased with the increase of N fertilizer. There were no regular patterns of N and P uptake rate under different N fertilizer levels, and the maximum of N and P uptake rate was at 225.0 kg ha^-1 N fertilizer during heading to maturing of rice. (3) N and P use efficiencies of grain yield production (NUEg and PUEg) were significantly decreased with the increase of N fertilizer (except PUEg at 0 kg ha^-1). There was a parabola regular pattern of N and P harvest index in the range of 0–337.5 kg ha^-1 N fertilizer, and the maximum was at 262.5 kg ha^-1 N fertilizer. (4)The relationship of nitrogen and phosphorus uptake and utilization was significantly synergic during the rice growth stage. Rice yield was significantly correlated with N/P accumulation and N/P uptake rate before heading. Increasing N fertilizer may help to increase nitrogen and phosphorus uptake and utilization. But it may not increase or even decrease when N fertilizer is too high.