不同氮肥水平下中熟籼稻和粳稻产量、氮素吸收利用差异及相互关系

选用生育期相近的中熟中籼(138~143 d)和中熟中粳(136~145 d)，于大田条件下探讨了4种氮肥水平即0、150、225、300 kg hm^-2纯氮对产量的影响及不同生育阶段氮素吸收利用的差异。结果表明，随着氮肥施用量的增加粳稻平均产量呈增加趋势，而籼稻平均产量中氮水平达最高，高氮水平有所降低。各处理下籼稻产量明显高于粳稻，籼稻有较高的穗粒数和千粒重，平均分别比粳稻高22.45%、7.51%。植株氮素阶段吸收量，拔节、抽穗和成熟期籼稻平均分别比粳稻高24.26%、3.14%和6.45%；植株氮素阶段吸收速率，移栽至拔节、拔节至抽穗和抽穗至成熟阶段籼稻平均分别比粳稻高38.07%、16.05%和23.22%。相关分析表明，籽粒产量与氮素阶段吸收量、阶段吸收速率和氮肥利用率呈显著或极显著正相关关系。说明生育期相近的中熟中籼产量高于中熟中粳与籼稻植株较强的氮素吸收特性有关。

Differences and Correlations in Grain Yield, N Uptake and Utilization between Medium-Maturing Indica and Japonica Rice under Different N Fertilizer Lev-els

Nitrogen (N) is a very important nutrition element in improving rice yield. Study on the relationship between N absorption and grain yield is necessary to optimize their productivity and reduce environment pollution risk. In this research, a field experiment with 10 medium-maturing medium indica rice (138–143 d) cultivars and 10 medium-maturing medium japonica rice (136–145 d) cultivars was carried out in 2006 and 2007 on the farm of Yangzhou University, Jiangsu province, China. The effects of different N levels including 0, 150, 225, and 300 kg ha^-1 N on rice grain yield and the N absorption and utilization of plant at different growth stages were analyzed. Results showed that, with the increase of N application, grain yield of japonica rice increased continuously while yield of indica rice get the highest under the N level of 225 kg ha^-1 and then declined under the N level of 300 kg ha^-1. Grain yield of indica rice was higher than that of japonica rice under four N levels, which was resulting from the large number of panicles and 1000-grain weight in indica rice with 22.45% and 7.514% higher than those in japonica rice respectively. N accumulations of indica ricein elongation, heading and maturing stages were 24.26%, 3.14%, and 6.45% higher than those of japonica rice, respectively. And N uptake rates of indica rice from transplanting to elongation, from elongation to heading and from heading to maturing were 38.07%, 16.05%, and 23.22% higher than those of japonica rice respectively. Correlation analysis indicated that there existed significant or highly significant positive correlations between yield and indexes of N uptake and utilization, which also illustrated that the higher yield of indica rice was from the intensive N absorption of its plant.