Effects of Low Temperature Stress and Release on Photosynthetic Indexes of Greening Seedlings of Three Tree Species

摘要

Photosynthetic characteristics of seedlings of Carallia brachiata, Ficus microcarpa and Phoebe zhennan were studied at 6°C low temperature stress using Artificial Climate Box. After continuous treatments of 0 d, 2 d, 4 d, 6 d and a recovery of 2 d in nature, the photosynthetic indexes of the seedlings were determined, and their cold-resistance ability was evaluated using principal component analysis. The results showed that with increasing low temperature stress time, the net photosynthetic rate, the stomatal conductance and the transpiration rate of the seedlings of three tree species decreased; the intercellular carbon dioxide concentration of C. brachiate increased followed by a decrease, whereas that of F. microcarpa and P. zhennan continuously increased; the stomatal limit of C. brachiata and P. zhennan continuously decreased, whereas F. microcarpa decreased followed by an increase. Two days after low-temperature release, the net photosynthetic rate, the transpiration rate and the stomatal limit of the seedlings of three tree species increased, whereas their intercellular carbon dioxide concentration decreased. The stomatal conductance of C. brachiata decreased, whereas that of F. microcarpa and P. zhennan increased. The comprehensive cold-resistance ability of photosynthetic indexes of the seedlings of three tree species was evaluated with principal component analysis, which decreased in the order of C. brachiata>P. zhennan>F. microcarpa.