为探讨星花玉兰〔Yulania stellata (Maxim.) N. H. Xia〕及其相关品种‘菊花’（‘Chrysanthemiflora’）和‘贝蒂’（‘Betty’）在梅雨期间叶片的光合响应机制，对淹水胁迫1、3、7和14 d星花玉兰、‘菊花’和‘贝蒂’3年生嫁接苗叶片的净光合速率、气孔导度、胞间CO₂浓度和蒸腾速率进行比较。结果表明：淹水组星花玉兰、‘菊花’和‘贝蒂’叶片的净光合速率、气孔导度和蒸腾速率均低于对照组（正常浇水），并随淹水时间延长逐渐下降，而胞间CO2浓度则高于对照组，并随淹水时间延长逐渐升高。与对照组相比，淹水胁迫14 d 星花玉兰、‘菊花’和‘贝蒂’叶片的净光合速率、气孔导度和蒸腾速率分别下降了94.6%～100.9%、84.7%～95.6%和80.6%～86.2%，而胞间CO₂浓度升高了74.1%～135.0%。总体来看，淹水胁迫对星花玉兰、‘菊花’和‘贝蒂’的叶片光合特性均有一定的影响，其中，‘贝蒂’受到的影响最小。

To explore the photosynthetic response mechanism of leaves of Yulania stellata (Maxim.) N. H. Xia and its related cultivars ‘Chrysanthemiflora’ and ‘Betty’ during plum rain period, the net photosynthetic rate, stomatal conductance, intercellular CO₂ concentration, and transpiration rate of leaves of three-year-old grafted seedlings of Y. stellata, ‘Chrysanthemiflora’， and ‘Betty’ after waterlogging stress for 1, 3, 7, and 14 d were compared. The results show that the net photosynthetic rate, stomatal conductance, and transpiration rate of leaves of Y. stellata, ‘Chrysanthemiflora’, and ‘Betty’ in waterlogging group are all lower than those of the control group (normal watering), and gradually decrease with the elongation of waterlogging time, while the intercellular CO₂ concentration is higher than that of the control group, and gradually increases with the elongation of waterlogging time. Compared with the control, the net photosynthetic rate, stomatal conductance, and transpiration rate of leaves of Y.stellata, ‘Chrysanthemiflora’， and ‘Betty’ after waterlogging stress for 14 d decrease by 94.6%-100.9%, 84.7%-95.6%, and 80.6%-86.2%, respectively, while the intercellular CO₂ concentration increases by 74.1%-135.0%. In general, waterlogging stress has some influences on leaf photosynthetic characteristics of Y. stellata, ‘Chrysanthemiflora’, and ‘Betty’, in which, ‘Betty’ is the least affected.