弱光下水杨酸对烤烟光合特性与叶绿素荧光的影 响

目的]探讨外源水杨酸（SA）能否提高烤烟在弱光条件下的生理功能及其作用机制。方法]在弱光条件下，对烤烟叶面进行 SA喷施，测定喷施后烟草植株的生理指标，包括植株鲜重和干重、叶绿素含量、光合参数和叶绿素荧光参数。数据采用 SPSS17.0和 Excel软件进行方差分析和显著性检验。结果]弱光下烤烟叶片的光合速率（Pn）、气孔导度（Gs）和蒸腾速率（Tr）分别降低，而胞间 CO2浓度（Ci）有所升高，说明不同弱光下烤烟 Pn下降的主要原因是非气孔限制；而使用100 mg/L的 SA处理能够缓解弱光对烤烟植株叶片的生长抑制；并能使烤烟叶片的光合速率、PSⅡ最大光化学效率、PSⅡ潜在活性、PSⅡ有效光化学效率以及光化学猝灭系数的升高，使非光化学猝灭系数（NPQ）的下降。结论]弱光下叶面喷施SA对烤烟的光合特性影响显著，在弱光条件下使用 SA有利于烤烟的光合产物的合成分配，提高烟株光能利用率，促进烟株正常生长发育。

Effects of Salicylic Acid on Photosynthesis and Chlorophyll Fluorescence Characteristics of Flue- cured Tobacco Leaf in Subdued Light

Objective] This study aimed to test whether salicylic acid （SA） can im-prove the physiological functions of flue-cured tobacco under subdued light condition, and to determine the mechanism of its action. Method] The tobacco plants under subdued light were foliar-sprayed with 100 mg/L of SA. Then, the physiological in-dices such as plant fresh weight and dry weight, chlorophyl content, photosynthetic parameters and chlorophyl fluorescence parameters were measured. SPSS17.0 and Excellwere adopted for variance analysis and significance test. Result] The leaf photosynthetic rate （Pn）, stomatal conductance （Gs） and transpiration rate （Tr） of tobacco plants in subdued light were al decreased while the intercellular CO2 con-centration （Ci） was increased, suggesting that non-stomatal limitation led to the de-crease of Pn under weak light intensity stress. SA released the inhibition of tobacco plant growth in weak light, as it elevated the leaf photosynthetic rate, the maximum photochemical efficiency of PSⅡ, potential activity of PSⅡ, effective photochemical efficiency of PSⅡ and photochemical quenching coefficient in weak light significant-ly, and reduced the non-photochemical quenching coefficient. Conclusion] SA has significant effects on the photosynthetic characteristics of flue-cured tobacco in weak light, and it can improve the synthesis or distribution of photosynthesis product, and the efficiency of light energy, conducive to plant growth and development.