在群体水培条件下，以国内、外不同年代育成的常规籼稻代表品种（2001年为88个、2002年为122个）为材料，测定叶面积系数、干物重（包括根系）、氮素含量、产量及其构成因素等，采用组内最小平方和的动态聚类方法将供试品种按氮素籽粒生产效率(NUEg)从低到高依次分为A、B、C、D、E、F等6类，研究各类品种产量构成的基本特点。结果表明，（1）供试品种间NUEg的差异很大（344%、425%），A、B、C、D、E、F类品种的平均NUEg 2001年分别为20.51、31.04、35.64、39.46、43.55、50.92 g·g-1，2002年分别为24.33、31.61、35.83、39.06、43.51、50.00 g·g-1；（2）随着NUEg水平的提高，籼稻品种的产量水平显著提高，两年结果一致；多元回归分析表明，氮素总吸收量（包括根）和NUEg对产量均有显著影响，改良二者均可提高籼稻品种的产量水平；（3）高NUEg类品种的基本特点为单位面积穗数较多、库容量大、结实率高、抽穗期叶面积系数较小、抽穗期单位叶面积籽粒产量高、经济系数高，而每穗颖花数、千粒重以及生物产量等与籼稻品种的NUEg水平关系不密切。
Improving nitrogen use efficiency in crops is of great importance both in crop production and environmental protection. Genetically improving crop varieties so as to make full use of the potentials in nitrogen uptake and utilization has been considered as one of the most economical and effective ways to enhance nitrogen use efficiency in crops. Nitrogen use efficiency depends on the ability of nitrogen uptake and utilization in rice plant. Many studies have shown that there exist genotypic differences in nitrogen use efficiency for biomass and grain production in rice. Yet, little information in the characteristics of yield components, biomass production and allocation, nitrogen uptake and allocation and structure of root system in rice varieties with higher nitrogen use efficiency has been reported. In this study，eighty eight and one hundred and twenty two conventional indica rice cultivars were solution-cultured in 2001 and 2002, respectively. Leaf area index, dry matter weight (including root system), nitrogen content of rice plant, yield and its components were measured. The tested rice cultivars were clustered into 6 types (i.e. A, B, C, D, E and F，A was lowest, F was highest) based on their nitrogen use efficiency for grain output (NUEg) level by the MinSSw method, to study their characteristics of yield and yield components. Results were as follows: (1) Difference of NUEg in the cultivars used in this study were very large, the ratio of the maximal NUEg to the minimum NUEg in 2001 and 2002 were 344% and 425%, respectively. The average NUEg of A, B, C, D, E and F were 20.51, 31.04, 35.64, 39.46, 43.55 and 50.92 g grain·g-1N in 2001, and were 24.33, 31.61, 35.83, 39.06, 43.51, 50.00 g grain·g-1 N in 2002, respectively. The result of experiments in two years showed the same tendency. (2) As NUEg increased, yield level of conventional indica rice cultivars significantly increased. Polynomial regression analysis showed that yield level was significantly influenced by total nitrogen uptake (including root system) and NUEg which indicated that higher yield level can be reached by improving nitrogen uptake and NUEg of conventional indica rice cultivars. (3) The cultivars with high NUEg were higher in panicle number, sink potential, grain setting percentage, grain yield per unit leaf area and harvest index, but lower in leaf area index. The relationships between spikelet number per panicle, 1000-grain-weight, biomass and NUEg were not significant.
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