Comparison and Cluster Analysis of Photosynthetic Characters and Water Use Efficiency in Tea (Camellia sinensis) Cultivars

Photosynthetic parameters in leaves of 52 tea cultivars were determined under field conditions. Significant differences (P < 0.01) among cultivars were observed in net photosynthesis rate (Pn), transpiration rate (Tr), stomatal conductance (Gs), intercellular CO2 concentration (Ci), and water use efficiency (WUE). Based on these parameters, the first 3 principal components were chosen for further analyses. Their cumulative contribution of variance was more than 96.98%. Parameters Pn, Tr, and Gs were the main factors in the first principal component, and WUE and Ci were the main factors in the second and the third principal components, respectively. Fifty-two cultivars were classified into 5 clusters based on Pn, Tr, Gs, and WUE. Cluster I consisted of 15 cultivars characterized with high Pn, medium Tr, high Gs, and high WUE. Therefore, this group was favorable for improving tea cultivars. Five discrimination models with good distinguishability were set up based on Pn, Tr, Gs and WUE.