Physiological Changes of Carallia Brachiata, Ficus Microcarpa and Phoebe Zhennan Seedlings Under Low Temperature Stress

Some physiological indexes of Carallia brachiata, Ficus microcarpa and Phoebe zhennan seedlings were measured under low temperature stress(6°C )for 2, 4 and 6 d and 2 d after release by chilling, respectively. The results show that with increasing stress time chlorophyll content of C. brachiata and F. microcarpa increased followed by a decrease, whereas P. zhennan decreased followed by an increase; soluble sugar content of C. brachiata increased followed by a decrease and then increased again, F. microcarpa decreased followed by an increase, whereas P. zhennan tended to increase; soluble protein content of C. brachiata and P. zhennan tended to increase, whereas F. microcarpa kept at a steady condition. Proline content of the seedlings of three species increased followed by decrease; The SOD activity content of C. brachiata fluctuated slightly and then significantly decreased, F. microcarpa and P. zhennan fluctuated slightly. The MDA content of C. brachiata and P. zhennan increased followed by a decrease, F. microcarpa gradually increased. The two days after low-temperature release, contents of chlorophyll, soluble sugar, soluble protein, proline of seedlings of the three species were higher or similar to control levels; The SOD activity of C. brachiata was lower than the control, and the other species was similar to the control; The MDA content of C. brachiata was lower than the control, P. zhennan was higher than the control, whereas F. microcarpa was similar to the control. The cold-resistance ability of seedlings of the three species was evaluated using principal component analysis, which decreased in order of C. brachiata > P. zhennan > F. microcarpa.