为了解水杨酸（ SA）提高西洋杜鹃幼苗抗寒性的生理机制，以抗寒性不同的2个西洋杜鹃品种（粉红、普红）为材料，研究叶面预先喷施不同浓度的SA（0，0．3，0．5，1．0，1．5，2．0 mmol/L）对低温胁迫下西洋杜鹃幼苗气体交换参数、光化学效率的影响。结果表明SA预处理能够：1）缓解因低温胁迫导致的净光合速率（ Pn ）、气孔导度（Gs）、粉红品种胞间CO2浓度（Ci）、蒸腾速率（Tr）、PSII最大光化学效率（Fv/Fm）、PSII实际光化学量子产量（Yield）、光化学猝灭系数（QP）的下降；2）缓解低温导致的非光化学猝灭系数（NPQ），普红品种胞间CO2浓度（ Ci ）的上升；3）喷施0．5 mmol/L的SA能显著提高粉红品种的抗寒性，喷施1．5 mmol/L的SA能显著提高普红品种的抗寒性。%In order to understand the physiological mechanism of salicylic acid ( SA) -enhancement of cold tolerance in Rhododendron hybridum seedlings,the seedlings of Fenhong and Puhong were foliar-sprayed with Salicylic acid of different concentrations (0 mmol/L,0.3 mmol/L,0.5mmol/L,1.0 mmol/L,1.5 mmol/L and 2.0mmol/L) to investigate the effects of its pretreatment on leaf gas exchange parameters and photochemi-cal efficiency .The results showed that SA pretreatment effectively alleviated the decrease in net photosynthetic rate (Pn),stomatal conductance (Gs),intercellular CO2 concentration (Ci) of Fenhong,maximal photochemi-cal yield (Fv/Fm),the actual photochemical ef-ficiency of system Ⅱ( Yield) and photochemical quenching coefficient ( QP ).Salicylic acid pretreatment also significantly reduced the increase of non -photochemical quenching coefficient(NPQ) and intercellular CO2 concentration (Ci) of Puhong.Spraying 0.5 mmol/L and 1.5 mmol/L of SA could significantly increase the cold-resistance of Fenhong and Puhong seedlings .
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