Because of its strong adaptability and versatile purposes, nowadays sweet potato has been playing great roles in food security and processing industry in China. Based on the previous experiment that six different types of cultivars in sweet potato had been choosed from 48 varieties or lines of breeding germplasm, and established in the ecological condition of Chongqing, this thesis mainly researched physiological traits such as photosynthetic characteristics, endogenous hormones, distribution of nitrogen an...