Effects of Exogenous ABA on Stomatal Characters and Photosynthetic Characteristics of Rhododendron chrysanthum Pall. Under Low Temperature Stress

Rhododendron chrysanthum Pall.was used as the test materials,after 4days of pretreatment with ABA,and 2days of culture under normal temperature and low temperature stress,the chlorophyll fluorescence content and stomata size were measured respectively.The effects of PSⅡphotosynthetic characteristics and stomatal traits of Rhododendron chrysanthum Pall.on exogenous ABA under low temperature stress were studied,in order to provide a reference basis for exploring the mechanism of cold resistance.The results showed that the normal growth of Rhododendron chrysanthum Pall.seedlings were significantly inhibited by low temperature stress,the maximum photochemical efficiency （Fv/Fm）,photochemical quenching coefficient （qP）,nonphotochemical quenching （NPQ）and potential activity （Fv/Fo）of PSⅡdecreased significantly（P＜0.05）.Under low temperature stress,exogenous ABA could significantly alleviate the effects on photosynthetic capacity of Rhododendron chrysanthum Pall.leaves,optimize the gas exchange process,significantly affect the stomatal length,width and length-width ratio（P＜0.05）and increased the activity of PSⅡreaction center,increased the utilization rate of light energy,promoted the accumulation of materials,and improved the tolerance of Rhododendron chrysanthum Pall.to low temperature stress.