Study On The Physiological Response Of Six Clones Of Zelkova Serrata To Water Stress

In order to study the physiological response mechanismIn of different clones under different water stress,6 clones of tow-year cuttings of Zelkova serrata were experimented with natural drought and soil flooding stress in pot.Based on the analysis of the change in the growth and physiological indexes of photosynthesis and adversity of seedlings during the stress period and after rewater and drainage,the principal component analysis wase ued to evaluate the drought resistance and submergence tolerance of each clone.In order to provide theoretical basis for the selection of superior clones of afforestation in mountain region and greening construction of plain and river.The results showed that:1.With the increasment of stress time,the damage degree in leaves of each clone became more serious.However,the influence of flooding on leaf morphology was significantly less than that of drought.Water stress can inhibit plant height and ground diameter growth,but promote root growth.Thus,the ratio of root shoot to shoot and total biomass were increased.The growth of above ground part of Z.118 which showed symptoms of water stress is the worst.2.Compared with flooding,the relative water content of leaves showed higher sensitivity to drought stress.Water deficit caused certain damage to water holding capacity of leaves.The leaf relative water content of Z.118 under drought stress had the largest decline.3.Water stress significantly inhibited the chlorophyll content of seedlings.The trend of chlorophyll a/b showed the following three conditions: declining,first rising and then falling,and then falling and rising.The carotenoid content showed a trend of rising first and then decreasing.With the extension of water stress,net photosynthesis rate,stomatal conductance and transpiration rate of different clones had a downward trend,but water use efficiency ever had a substantial rise during the stress time.4.The activity of SOD showed a trend of rising first and then decreasing.The trend of POD activity of different clones showed different trends.Compared with the enzyme activity,The change of MDA content whcin showed a decline trend under drought stress had a small fluctuation.At the end of drought stress.5.The content of soluble sugar had a decline after drought stress,except Z.305.During theflooding time,the soluble sugar content decreased and then increased.The soluble protein content of Z.118 significantly decreased after drought stress,while Z.305 was improved by 1.07 times.The soluble protein content of Z.118?202 and 305 increased significantly after water stress,while the other clones had a downward trend.6.After 14 days of rewatering and drainage,clones with strong adaptability to drought and flooding showed strong self regulation and recovery ability.7.Through the the principal component analysis of 6 clones of Zelkova serrata with 17 indexes,the result showed that the order of drought resistance and submergence tolerance of 6 clones were:Z.107>305>201>114>202>118;Z.305>107>114>202>201>118.