Physiological responses of three kinds of slope protection shrubs to drought stress

Qitai Highway is located in the arid and semiarid areas of Songnen Plain. Selection of droughttolerant plants applied to slope ecoengineering has great significance in preventing the highway slope from soil erosion, enhancing the stability of the roadbed and ecological restoration of highway surroundings. In this study, twoyearold seedlings of Amorpha fruticosa, Tamarix chinensis and Caragana microphylla were taken as test materials, which were individually treated with five moisture gradients (control, mild stress, moderate stress, severe stress and extremely severe stress). After 21 days, the conductivity、total chlorophyll content, activity of SOD, content of MDA, soluble sugar content and proline content of the seedlings leaves were determined to investigate the droughtresistant abilities of these three kinds of seedlings. The results showed that with the prolonged drought, proline content and membrane permeability of three kinds of seedlings presented a rising trend. Total chlorophyll content and SOD activity of three kinds of seedlings increased in the beginning and then decreased. content of MDA and soluble sugar content in the leaves of A.fruticosa and C.microphylla increased first and then decreased. Content of MDA and soluble sugar content in the leaves of T. chinensis were in an upward trend. Through subordinate function analysis on 6 physical signs, the order of droughtresistant abilities of three kinds of seedlings was: A.fruticosaC.microphyllaT.chinensis, and the difference was not obvious. The results showed that three species were all suitable as Qitai Highway slope protection plant. A.fruticosa was suitable planted in mild drought and very severe drought slope, T.chinensis was suitable planted in moderate stress drought slope and C.microphylla was suitable for planted in severe drought slope.