在群体水培条件下，以国内外不同年代育成的籼稻代表品种（2001年为88个、2002年为122个）为材料，测定叶面积系数、库容量、干物重以及氮素含量等，采用组内最小平方和的动态聚类方法将供试品种的氮素籽粒生产效率从低到高依次分为A、B、C、D、E、F等6种类型，研究各类型籼稻品种有关源库指标的差异以及影响氮素籽粒生产效率的主要源库指标。结果表明，A、B、C、D、E、F类籼稻品种的平均氮素籽粒生产效率2001年分别为20.51、31.04、35.64、39.46、43.55和50.92 g g-1，2002年分别为24.33、31.61、35.83、39.06、43.51和50.00 g g-1；高氮素籽粒生产效率类型籼稻品种源、库的基本特点为抽穗期的叶面积系数较小、灌浆结实期叶面积下降速度慢、净同化率高、库容量大，抽穗期的单位叶面积、单位干物重和单位氮素所承担（形成）的库容量大。多元逐步回归分析表明，单位氮素库容量、单位干物质库容量、单位库容量形成的产量、抽穗期叶面积系数以及抽穗期至成熟期叶面积系数减少量对氮素籽粒生产效率有显著影响（R2=0.749～0.805）。通径分析表明，抽穗期的单位氮素库容量和单位干物质库容量以及单位库容量形成的产量对籼稻品种氮素籽粒生产效率的影响力明显大于抽穗期叶面积系数和抽穗期至成熟期叶面积系数减少量。
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, characteristics of source and sink, and structure of root system in rice varieties with higher nitrogen use efficiency has been reported. In this study, 88 and 122 conventional indica rice cultivars were solution-cultured in 2001 and 2002, respectively. Leaf area index (LAI), sink potential, dry matter weight and nitrogen content of different organs 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 the difference of indexes of source and sink and find out the key one from them in conventional indica rice with different types of NUEg. Results showed that the difference of NUEg in conventional indica rice cultivars used in this study was very large, 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 24.33, 31.61, 35.83, 39.06, 43.51, 50.00 g grain g-1N in 2002, respectively; the basic characteristics of conventional indica rice cultivars with higher NUEg were that LAI at heading stage was small and decrease of LAI during the grain-filling stage was slow, while net assimilation rate was high, sink potential was large, sink potential per unit leaf area , sink potential per unit dry matter weight and sink potential per unit N at heading stage were high. Multiple stepwise regression analysis showed that NUEg was significantly influenced by sink potential per unit N, sink potential per unit dry matter weight, grain yield per unit sink potential, LAI at heading stage and decrease of LAI from heading to mature stage, and the determination coefficient ranged from 0.797–0.854. Path analysis showed that effects of sink potential per unit N, sink potential per unit dry matter weight and grain yield per unit sink potential on NUEg were larger than those of LAI at heading stage and decrease of LAI during the grain-filling stage.
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