Study On Adaptive Mechanisms Of Alfalfa(Medicago Sativa) In Drought Stress At Seedling Stage

Seventeen morphology indexes and growth indexes that can reflect plant drought resistance truly were chosen to comprehensively evaluate the drought resistance of 10 alfalfa germplasm resources both at home and abroad, on the basis of the results, three alfalfa germplasm resources were selected as strong drought-resistance medium drought-resistance and weak drought-resistance experiment materials to study the adaptive mechanisms of alfalfa under drought stress in order to accumulate data to investigate drought resistance mechanisms of alfalfa. The main results of research are as followings:1 .With principal components analysis and subordinate function analysis seventeen morphology indexes and growth indexes could be divided into 4 groups: biomass factor; plant morphological factor, root factor; stress index factor, the drought resistance's order of alfalfa from better to worse is Longdong, BL-02-388, Aohan, BL-02-312, BL-02-344, Gongnong No 1, Zhongmu No 1, BL-02-353, XinjingDaye, BL-02-329. Strong drought -resistance (Longdong) medium drought-resistance (GongnongNo1) and weak drought -resistance (BL-02-329) were chosen for the study of drought resistance mechanisms.2.O₂^·-generation and clearing mechanism in the leaves of Longdong GongnongNol and BL-02-329 were studied and the results show: under drought stress, O₂^·- generation rate MDA content and damage of cell membrane increased. Campared with weak drought-resistance alfalfal there were low O₂^·- generation rate less accumulation of MDA content and lighter damage of cell membrane in the leaves of strong drought-resistance alfalfa when stressed by drought, and strong drought-resistance alfalfa can recovery faster after rewatering.at the same time SOD POD activity enhanced and antioxidation substance increased.There are higher endogenous coordination of antioxidation enzyme system and nonenzyme system in strong drought-resistance alfalfa.3.The results of study on water metabolism and osmotic adjustment substance in the leaves of three alfalfa show :the water potential water relative content water saturated deficit and bound water content increased under drought stress. There were higher decrease extent of...