水分胁迫对云锦杜鹃光合生理和光温响应的影响

以盆栽5年生云锦杜鹃苗木为材料, 研究了不同强度土壤水分胁迫对其叶片某些光合生理特性及其对光温响应的影响。结果表明: 在轻度水分胁迫下净光合速率的下降由气孔限制引起, 而中度和重度胁迫下则由非气孔限制引起。在较高强度的水分胁迫下, 云锦杜鹃光补偿点和气孔阻力升高, 光饱和点、表观量子效率、最大净光合速率、Fv/Fm和蒸腾速率下降, 而暗呼吸速率先升后降, 胞间CO₂浓度先降后升, 高温加重了水分胁迫对光合作用的不利影响。

Effects of Water Stress on Photosynthetic Physiological Characteristics in Leaves of Rhododendron fortunei and Their Response to Light and Tempera ture

The effects of soil water stress on some photosynthetic physiological characteristics in leaves of Rhododendron fortunei and their response to light and temperature were investigated by using 5-year-old pot-cultured seedlings as experimental materials and exposing them to different levels of water stress. Twelve pots of plant seedlings with a similar growth were divided into 4 groups: no stress (control), light stress, moderate stress and heavy stress. Net photosynthesis rate (Pn) declined under water stress conditions. According to the criteria suggested by Farquhar and Sharkey, the depression of photosynthesis may be attributed to stomatal limitation under light water stress conditions, while that may be linked to non-stomatal limitation under moderate and heavy stress conditions. In comparison with the control group, light compensation point (LCP) and stomatal resistance (rs) increased, light saturation point (LSP), apparent quantum yield (AQY), maximal Pn (Pm), Fv/Fm and transpiration rate (Tr) in the other groups declined along the water stress gradients. Besides, the dark respiration rate (Rd) increased under light and moderate stress, but decreased under heavy stress. The intercellular CO2 concentration (Ci) displayed adverse trend compared with that of Rd. High temperature aggravated the stress effect of water on photosynthesis.