Effects of Waterlogging Stress on Leaf Gas Exchange Parameters of Four Kinds of Garden Greening Seedlings

Effects of waterlogging stress on leaf gas exchange of Michelia chapensis, Schima wallichii, Rhodoleia championii and Cinnamomum camphora were investigated so as to understand the physiological mechanism of waterlogging resistance of these four kind seedlings and provide a reference for the selection of waterlogging resistant species in southern China. The results showed that net photosynthetic rate (Pn) of the four kind seedlings tended to decrease with increasing waterlogging time. Pn of M. chapensis, S. wallichii, R. championiiand C. camphora reached their minimum with values of 1.87, 0.43, -0.26 and 0.62 μmol·m^-2·s^-1, respectively, in 35 days under waterlogging stress, and their stomatal conductance (G_s) tended to decrease with values of 0.032, 0.005, 0.008 and 0.006 mol·m^-2·s^-1, respectively, in 35 days under waterlogging stress; intercellular mole fraction of CO₂(x_CO2) of M. chapensis，S. wallichii and C. camphora decreased followed by an increase, whereas x_CO2 of R. championii continuously increased; with increasing waterlogging time, transpiration rate (Tr) of M. chapensis, S. wallichii, R. championii and C. camphora tended to decrease with values of 0.04, 0.13, 0.02, 0.10 mmol·m^-2·s^-1, respectively, in 35 days under waterlogging stress. The waterlogging resistance of the four kind seedlings was evaluated using principal component analysis, and the order of waterlogging resistance was M. chapensis > S. wallichii > C. camphora > R. championii.