Abstract: Under water stress,this project studied the correlation between leaf chlorophyll content （CHL.C） and leaf total nitrogen （TN） content,and analyzed Red Edge Area and canopy total nitrogen content using first derivative spectral data in cotton main growing periods.As result that there was a high positively correlation between leaf chlorophyll content （CHL.C） and leaf total nitrogen （TN） content,correlation coefficient （r=0.8723^∗∗,n=39）,the first derivative spectral data deduce Red Edge Area positively correlation with canopy TN content,correlation coefficient （r=0.7394^∗∗,n=40）.Established mathematic regression models were used to estimate TN content in Xin Luzao No.6and Xin Luzao No.8respectively,the results show that RMSE is0.3859and0.4272.The study imply that leaf chlorophyll content can efficiently estimate leaf TN content, and Red Edge Area had lager applied potential capacity to estimate total nitrogen content in cotton canopy.

Key words: cotton, waters tress, hyperspectral, chlorophyll content, TN content Red Edge Area