Drought-resistance Mechanism of Four Kinds of Wild Vitis Seedlings in Karst Regions of Guizhou Province

Drought resistance and its physiological mechanisms of wild Vitis in Karst regions were studied under drought stress by taking four two-year old wild Vitis seedlings as experimental materials.The results show that the drought resistance of these four wild Vitis seedlings were different,the 'Xiaoqikong-3'(Vitis flexuosa Thunb.)had the highest resistance,while the drought resistance of 'Tianhetan-2'(Vitis quinquangularis Rehd.)was the least.During whole drought stress periods,the time of first drought hazard symptom of 'Xiaoqikong-3' was 12 days later than that of 'Tianhetan-2'.The index of drought hazard of 'Xiaoqikong-3' was smaller than those of the others.The relative water content of leaves and the soluble protein of which has high drought resistance were higher than those has lower drought resistance.While the water saturation deficit,the cytolemma osmosis and the contents of malondialdehyde(MDA) were adverse and the difference between the drought-resistant resources and drought-sensitive resources and they were more and more obvious as the drought stress prolonged.The path coefficient analysis showed a significant negative correlation between the relative water content and the index of drought hazard,but a significant positive correlation between the water saturation deficit,the cytolemma osmosis,contents of MDA and the index of drought hazard.The MDA content was the major factor to drought damage.Thus the drought-resistant wild Vitis seedlings had stable membrane,its water dissipation was less,cell electrolyte leakage rate was lower;osmotica soluble protein decreased;accordingly,their physiological and metabolic activity was normal.