Study On Nitrogen Efficiency Of Different Cotton Genotypes Varieties (G. Hirsutum)

Thirty domestic non-transgenic typical conventional cotton varieties were used as experiment materials in the paper. Cotton seedlings were cultured and managed by a new seedling technology named floating nursery nutrient seedling. These seedlings were treated with two levels of nitrogen, normal nitrogen (N+) or no nitrogen (N-) respectively.Dry weight, nitrogen efficiency and other physiological indexes of different cotton genotypes were compared at seedling stage, and these verities were evalued comprehensively and classified according to principal component analysis and clustering analysis by. Furthermore, field yield and fiber quality traits of different cotton vatieties with various nitrogen efficiency wree copared. The main results are as follows:1. Nitrogen stress can lead to a significant decrease in dry weight, shoot ratio, chlorophyll content, nitrogen content, nitrogen accumulation and chlorophyll saturated ETR values, and a marked increase in shoot ratio of cotton seedlings.2. Principal component analysis showed that nitrogen efficiency of cotton varieties at seedling stage can be evalued by three principal componets. The first principal componet includes relative dry weight of shoot, total relative dry weight, the total nitrogen accumulation. The second one comprises total relative nitrogen accumulation and overground nitrogen content. The third principal componet includes relative overground nitrogen content, underground nitrogen content and relative underground nitrogen content. Cluster analysis showed that Xinluzao20, Jinmian19, Jinmian11as the higher nitrogen use efficiency of cotton varieties, and nitrogen utilization of Simian4, Xiangmian10, Emian14and other varieties is relatively low at seedling stage.3. Cluster analysis of five yield traits from tested cotton genotypes with different nitrogen use efficiency showed that higher comprehensive score were for Chuanjian1, Zhongmiansuo16, Xinluzao20and so on, lower scores for Xiangmian16, Ekangmian9, Zhongmiansuo23, Zhongmiansuo12, Chuanmian56and so on.4. Cluster analysis of five cotton fiber quality traits from various nitrogen efficency genotypes found that comprehensive score were higher for Chuanjian1, Lumian12, Ganmian47, Zhongmiansuo19, Simian3and other varieties score higher, while lower scores were for Jinmian11, Yumian19, Emian18, Jimian25, Zhongmiansuo16and so on.