水分胁迫与复水对地枫皮生理生态特性的影响.

In order to understand the eco-physiological adaptability to water stress of karst plant, the experiments were carried out with 4-year-old Illicicum difengpi K. I. B. et K. I. M plants, which was a karst endemic medicinal plant. We investigated the photosynthetic variables, chlorophyll fluorescence variables and photosynthetic pigment content of I. difengpi under water stress and rewatering conditions. The results showed that withholding water for 10 d, the net photosynthetic rate (Pn), intercellular CO2 concentration (Ci), stomatal limitation value (Ls) and stomatal conductance (Gs) of I. difengpi leaves decreased significantly under water stress, and stomatal limitation was the main reason for the decrease of Pn. Withholding water for 15 d, under water stress, the diurnal variation of Pn showed a gradual downward trend and the Pn values were close to zero after 9:30 am, which suggested that the depression of photosynthesis might be due to non-stomatal limitation. While the diurnal variation of Pn was dual-peaked in the leaves of control, and stomatal limitation was still the main reason for the decrease of Pn. The decrease of chlorophyll content and the increased of Chl (a/b) under water stress conditions, which reduced the binding proteins (LHC Ⅱ) content, the captured light energy, and the risk of photosynthetic apparatus damage. Under water stress condition, the initial fluorescence (Fo) increased significantly, the maximum fluorescence (Fm), potential activity of photo-system Ⅱ(Fv/Fo) and maximal photochemical efficiency of photo-system Ⅱ(Fv/Fm) decreased significantly, which indicating that water stress could cause a certain degree of damage or fracture to its PS Ⅱ reaction center, therefore, the potential activity and maximal photochemical efficiency of PS Ⅱ were reduced. After re-watering for 5 d, the above-mentioned physiological and ecological parameters of I. difengpi could recover to the control level, indicated that the physiological repair capability of which is very strong after rehydration. [ABSTRACT FROM AUTHOR]