中文摘要：

运用SPSS统计分析软件,对不同氮素选择压力下的88份稻种资源苗期农艺性状与氮素营养效率进行分析。结果表明,稻种资源苗期氮素营养效率相关性状存在明显的基因型差异,且受氮素选择压力的影响。同一氮肥水平下,不同稻种资源间的单株根体积、地上部干重、吸氮量和根干重变异较大,而倒3叶SPAD值、氮素利用效率和绿叶数的变异较小;不同氮肥水平下,各性状的变异程度不同,单株根体积、根半径和冠根比的变异系数差异较大,而苗高、黄叶数和单株总干重的变异系数差异较小。在不同氮素选择压力下存在表征氮素营养效率的共同性状,与氮素利用效率偏相关显著的共同性状是倒3叶SPAD值,与氮素吸收效率偏相关显著的共同性状是倒3叶SPAD值和单株总干重。水稻苗期氮素利用效率筛选与鉴定的最佳施氮水平为高氮（60mg/kg）,可行指标为倒3叶SPAD值;水稻苗期氮素吸收效率筛选与鉴定的最佳施氮水平为低氮（20 mg/kg）,可行指标为倒3叶SPAD值和单株总干重。

英文摘要：

The analysis of the agronomic characters related to nitrogen nutrition efficiency at seedling stage of 88 accessions of rice germplasm resources was conducted under different nitrogen selection pressure using the statistical analysis software SPSS. The results indicated that the correlated characters of nitrogen nutrition efficiency at seedling stage in rice germplasms had significant genotypic difference and were influenced by the nitrogen selection pressure. Under the same level of nitrogen fertilization,the root volume per plant,shoot dry weight per plant,nitrogen content per plant and root dry weight per plant had a larger variation among different rice germplasms,while the SPAD value of top third leaf,nitrogen use efficiency and number of green leaves per plant had a smaller variation.Under different levels of nitrogen fertilization,each character had a different degree of variation. The root volume per plant,root radius and shoot / root ratio had a larger difference in the coefficient of variation,while the seedling height,number of yellow leaves per plant and total dry weight per plant had a smaller difference in the coefficient of variation. There existed common characters of the representation of nitrogen nutrition efficiency under different nitrogen selection pressure. The common character with a significant partial correlation to the nitrogen use efficiency was the SPAD value of top third leaf,and the common characters with a significant partial correlation to nitrogen absorption efficiency were the SPAD value of top third leaf and the total dry weight per plant. For the screening and identification of nitrogen use efficiency at seedling stage in rice,the best nitrogen application level was high（ 60 mg / kg） and the feasible indication was the SPAD value of top third leaf. For the screening and identification of nitrogen absorption efficiency at seedling stage in rice,the best nitrogen application level was low（ 20 mg / kg） and the feasible indication was the SPAD value of top third leaf and th