水分状况与大白菜光合作用关系的研究

水分状况与大白菜光合作用关系密切,正常水分条件下叶片的光合速率远大于水分胁迫条件下的,其差异随光强和CO_2浓度的增加而增加。水分胁迫使大白菜光合作用的光饱和点和CO_2的饱和点降低,补偿点升高。轻度的水分胁迫对光合作用的影响表现为气孔限制,而严重的水分胁迫则表现为非气孔限制,这是因其叶肉细胞光合活性下降所致。大白菜光合速率随叶片相对含水量(RLWC)的减少而下降,当RLWC低于86％时,光合速率出现大幅度下降。短期内空气相对湿度变化对光合速率影响不大。

Effect of Water Conditions on Photosynthesis in Chinese Cabbage

Effects of water conditions on photosynthesis of leaves on Chinese cabbage C Brassica campestris ssp. pekinensis (Lour) Olsson] were studied under pot cultivation in 1990~ 1991, the results were as follows: There was a close relationship between photosynthesis and water conditions. Photosynthetic rate under normal water condition was higher than that under water stress, the photosynthetic rate increased with the increase of light intensity and CO_2 concentration. The compensation points of light and CO_2 rose and their saturation points dropped under water stress. The results indicated that Chinese cabbage expressed stomatal limitation to photosynthesis under mild water stress, and nonstomatal limitation under severe water stress. The photosynthetic rate of Chinese cabbage declined with the decrease of the relative leaf water content (RLWC) . The variation of air humidity in a short duration had little effect on the rate of photosynthesis in Chinese cabbage.