水杨酸对干旱下烤烟幼苗膜质和叶绿素荧光特性的影响

以烤烟品种龙江911为材料,研究了叶面喷施水杨酸（SA）对干旱胁迫下烤烟幼苗叶绿素含量、叶绿素荧光特性和细胞膜伤害程度的影响。结果表明,干旱胁迫下烤烟幼苗叶片的膜系统受到了伤害,光合作用的原初反应和光能在两个光系统之间的分配发生了改变。叶面喷施0.5 mmol·L-1和1.0 mmol·L-1SA减轻了干旱引起的细胞膜丙二醛的增加,有效地保护了烤烟幼苗叶片的膜系统。同时,0.5 mmol·L-1和1.0 mmol·L-1SA减轻了干旱胁迫下叶绿素的分解,有效缓解干旱对类囊体膜和PSⅡ反应中心的伤害,增强了烤烟幼苗对干旱胁迫的适应能力,其最适宜的浓度为0.5～1.0 mmol·L-1。2.0 mmol·L-1SA对烤烟幼苗有一定的毒害作用。

Effects of Exogenous Salicylic Acid on Cell Membrane and Chlorophyll Fluorescence Characteristics in Leaves of Tobacco Seedlings under Drought Stress

Taking tobacco "Longjiang 911" grown in pots as test material,we studied effects of salicylic acid spraying on chlorophyll content,chlorophyll fluorescence characteristic and cell membrane injury in leaves of the tobacco under drought stress.Results showed that the membrane system of tobacco leaves was damaged and the primary reaction of photosynthesis and distribution of absorbed light energy changed under drought stress.Spraying 0.5 mmol·L-1 or 1.0 mmol·L-1 salicylic acid on leaves of the tobacco has reduced the content of MDA in leaves of tobacco,and could effectively protect the membrane system under drought stress.Meanwhile,0.5 mmol·L-1 or 1.0 mmol·L-1 salicylic acid spraying could decrease the decomposition of chlorophyll to alleviate the damage to thylakoid membranes and PSⅡ reaction center under drought stress,and improve greatly its drought-resistance.In experiment,0.5~1.0 mmol·L-1 was the optimal concentration of salicylic acid spraying on leaves of tobacco under drought stress,but 2.0 mmol·L-1 salicylic acid spraying would be toxic to the tobacco seedlings.