Abstract:Grain weight per plant and its response index to nitrogen was used as index of tolerance to low nitrogen in this study.Tolerance to low N-fertilized level for rice germplasm and coefficient correlation among grain weight per plant and its response index to nitrogen and main agronomic traits were analyzed.The results showed that the tolerance to low N-fertilized level was larger difference among rice materials under different N-fertilized levels,and the order of difference for most of agronomic traits were N-unfertilized >low N-fertilized >general N-fertilized.The difference of grain weight per plant,straw weight per plant and panicles per plant among different N-fertilized levels were larger than that of other agronomic traits.Grain weight per plant was positively correlated with straw weight per plant,response index to nitrogen for grain weight per plant was positively associated with grain weight per plant,straw weight per plant and ratio of grain to straw under all of different N-fertilized level.The correlation between grain weight per plant and plant height,panicles per plant ,spiklets per panicle,straw weight per plant,and between response index to nitrogen and panicles per plant,straw weight per plant,grain weight per plant and ratio of grain to straw under N-unfertilized level were higher than that of low or general N-fertilized level.Hwabongbyeo,Zhongzuo9059,Upland rice 9,Upland rice 502 and IRAT359 with higher tolerance to low N-fertilized level,which were nonsensitive to nitrogen.