Study on the Relationship of Nitrogen Application Dose with Nitrate Content and Leaf SPAD Value in Chinese Cabbage

The relationship of nitrogen application dose with nitrate content and leaf SPAD value in Chinese cabbage were studied.The results showed that there were positive correlations between nitrogen application dose,nitrate content,and leaf SPAD value in different life phase of Chinese cabbage when the nitrogen application dose was 0～240 kg/hm2.Moreover,the positive relationship between leaf SPAD value and nitrogen application dose determined on the left,right,and top region of the latest fully expansion leaf was most obvious.