Effects Of Heat And Drought Stress And Re-watering On Physiological Characteristics Of Phyllostachys Edulis Seedlings

With pot culture method in the controlled environment machine,and by setting 4 treatments groups of optimal temperature and normal hydration as control group,optimal temperature and drought,high temperature and normal hydration,high temperature and drought,Phyllostachys edulis seedlings were studied on the changes of physiological-biochemical characteristics and effects of re-watering after drought,to investigate resistance mechanism of Ph.edulis seedlings under different stress or recovery mechanism after re-watering,hoping to provide theoretical reference for experiments of Ph.edulis forest against heat and drought stress.Through the analysis of the various indexes in the experiments,main results and conclusions are as follows:(1)The most increase of activity under high temperature was seen on SOD and CAT,and that under drought was POD.There was a dramatic increase of activity of POD and APX under combined stress,which may be used to remove ROS and relieve lipid peroxidation.Activity of SOD significantly increased under three types of stress.The results indicated that Ph.edulis seedlings had different protective mechanisms under different stress,and SOD was most important protective enzyme when Ph.edulis under heat or drought stress.(2)Contents of soluble sugar,fructose and sucrose were significantly increased under drought stress,suggested fructose and sucrose in Ph.edulis leaves participated in osmotic adjustment positively under drought.There was a significantly increase of starch content and FBP activity under heat and drought stress,suggested that Ph.edulis raising FBP activity to promote the accumulation of photosynthetic.The most increase under combined stress was seen on soluble sugar,fructose and glucose contents and SPS activity,and activity of FBP decreased,carbohydrate accumulation was affected.(3)Chorophyll fluorescence parameters showed 3 types of stress inflicted damage on Ph.edulis,Fm and Fv/Fm achieved maximum under the combined stress,meanwhile F0 and NPQ achieved minimum under the combined stress,indicated primary conversion efficiency and photosynthetic potential decreased,the protection of PSII against over excitation through regulating of photo-protective mechanism under the combined stress of heat and drought.Effects of different types of stress on Ph.edulis are different,high temperature and drought mutually intensified damage that single factoe did.Value of SPAD under drought and the combined stress were respectively declined 7.7%,9.4% and 26.1% compared with CK,indicated 3 types of stress all led to decline of chlorophyll content,and the biggest drop was seen on the combined stress.(4)After 3 days of re-watering,the protective enzyme activity and contents of soluble sugar,MDA and H2O2 in the leaves of the Ph.edulis that under drought stress all declined,returned to control level,and cell osmotic potential returned to normal.But the Ph edulis seedlings under high temperature and drought stress,after 3 days of re-watering,the protective enzyme activity decreased significantly,and the difference was obvious when compared with drought stress and control group,meanwhile soluble sugar content also increased significantly.After drought stress,water recovery 3 days can make each physiological function of Ph edulis recovered better,however,after combined stress,water recovery 3 days,stress injury of Ph edulis seedlings didn't get effective relief.