Comparison of photosynthetic characteristics among 14 Toona sinensis provenances

Toona sinensis is a China endemic timber species of high quality and fast growth.This study was aimed at investigating differences in photosynthetic characteristics among different T.sinensis provenances, and providing a theoretical basis for selection of superior provenances.

Five photosynthetic indices of one-year-old seedlings of T.sinensis provenances collected from 14 counties in 11 provinces were measured with Li-6400 and analyzed.

There were highly significant differences among different provenances in five photosynthetic indices including net photosynthetic rate (Pn), stomatal conductance (Gs), intercellular CO₂ concentration (Ci), transpiration rate (Tr) and water use efficiency (WUE).The variation coefficient of Gs was the highest (27.52%), and that of Ci was the lowest (4.24%).The repeatability of Pn was the highest (96.08%), and that of WUE was the lowest (78.52%).Pn was highly significantly positively correlated with Gs, Tr and seedling height (P < 0.01), and significantly positively correlated with ground diameter (P < 0.05).Gs was highly significantly positively correlated with Ci, Tr and seedling height (P < 0.01).Ci was significantly positively correlated with Tr (P < 0.05).Tr was highly significantly positively correlated with seedling height (P < 0.01) and significantly positively correlated with ground diameter (P < 0.05).Provenances collected from Xing'an and Napo of Guangxi Province, and Peng'an of Sichuan Province had relatively high Pn compared to those from other counties, and provenances from Xing'an of Guangxi Province and Lechang of Guangdong Province had relatively high WUE.

Two principal components were obtained from five tested indices using the principal component analysis.Fourteen T.sinensis provenances can be divided into three groups including the group with the lowest Tr, the group with relatively high Pn and WUE, and the group with relatively strong photosynthesis and low WUE.