Abstract:Identification and evaluation of the sensitivity of nitrogen is an important content to breed maize varieties for low nitrogen tolerance and nitrogen used efficiency. In this research, a pre-built, rapid and non-destructive determination of the relative chlorophyll content based on SPAD data was used into the different parts of the leaf at the different growing stages across 189 maize inbred lines, which were widely used into maize breeding programs and corn production in China, under low nitrogen and normal nitrogen treatments. The variance analysis results showed that the chlorophyll contents were significantly difference of genotype and environment in both the low and normal nitrogen treatments. The genetic variance was one of the most important reasons of the difference in nitrogen sensitivity among inbred lines. The chlorophyll content of the three ear leaves, the most important functional leaves in pollination stage, had high significant positive correlation at the 0.01 level with that of ten days after pollination stage. However, the chlorophyll content of the full expanded leaves in pre-tassel stage only had moderate significant positive correlation at the 0.01 level with the chlorophyll contents of other leaves measured in different growing stages. We defined the nitrogen sensitive coefficient as the ratio of the difference between normal nitrogen trait value and low nitrogen trait value versus the normal nitrogen trait value. The sensitive nitrogen average index ranged from 23.86% to 36.00% among 189 inbred lines. Forty inbred lines such as He 344 and Chang 7-2 are highly low-nitrogen resistant materials. While, 40 inbred lines out of them such as CML206 and CA375 are highly sensitive materials. This study has provided a quick and an efficient nitrogen sensitivity way for identifying and evaluating maize germplasm, and provided some basic and important data for maize breeding for nitrogen use efficiency and low nitrogen tolerance.