Photosynthetic response of greening seedling of four tree species to low temperature stress

Photosynthetic indexes of Cassia bakeriana, Syzygium hainanense, Ilex rotunda and Phoebe sheareri seedlings were determined under simulated low temperature stress using artificial climate chambers. The results showed that with increasing low temperature time, the net of photosynthetic rate (P_n), stomatal conductance (G_s) transpiration rate (T_r) and stomatal limitation (L_s) of seedlings of the four tree species decreased; intercellular CO₂ concentration (C_i) of C. bakeriana fluctuated and then increased, S. hainanense continuously increased, I. rotunda and P. sheareri decreased followed by an increase. Two days after low-temperature release, P_n, T_r, G_s and L_s of seedlings of the four species increased. C_i of C. bakeriana, S. hainanense, and P. sheareri increased, whereas I. rotunda decreased. The photosynthetic indexes of seedlings of the four tree species was evaluated using principal component analysis, indicating that cold-resistance ability decreased in the order of C. bakeriana>P. sheareri>I. rotunda>S. hainanense