Physiological Response To Drought Stress And Drought Resistance Estimation Of Five Desert Shrub Seedling In Hexi Region

This paper discusses the characteristics of physiological adaptation of five typical desert shrubs: Caragana microphylla Laxm., Caragana roborovskyi Kom. , Ammopiptanthus mongolicus (Maxim.) Cheng f., Hedysarum scoparium Fisch.et Mey. and Zygophyllumxanthoxylom Maxim.),which simulated the soil under drought stress in terms of the potted plants with water-break, meanwhile, the subordinate function value method is applied to evaluate drought resistance of these five shrubs synthetically, hoping to provide theoretical basis for exploration of drought resistance of desert plants, and government of desertification. There are main experimental results as follows:(1) It is because of drought stress that causes decrease of relative water content of tissue of seedlings leaves, but increases water saturation deficit. The shrubs leaves with strong drought resistance those are relatively of small amplitudes, and strong with maintenances of normal water works.(2) Chlorophyll content of five shrubs is changing differently in the course of drought stress. At the end of drought stress, chlorophyll content of Caragana roborovskyi Kom. decreases obviously more than Zygophyllumxanthoxylom Maxim., of which Caragana microphylla Lam. increases remarkably more than Ammopiptanthus mongolicus (Maxim.) Cheng f. as well as Hedysarum scoparium Fisch.et Mey..(3) It is manifested that Osmotic adjustment substance of these five desert shrubs under the situation of drought stress stimulates accumulation of proline and soluble sugar of the leaves. The proline content of Caragana roborovskyi Kom. is notably higher than those of Caragana microphylla Lam., Ammopiptanthus mongolicus (Maxim.) Cheng f., Hedysarum scoparium Fisch.et Mey. and Zygophyllumxanthoxylom Maxim.. The soluble sugar content of Hedysarum scoparium Fisch.et Mey. is universally higher than those of Caragana microphylla Lam., Ammopiptanthus mongolicus (Maxim.) Cheng f., Caragana roborovskyi Kom. and Zygophyllumxanthoxylum Maxim..(4) The content of MDA increases with aggravation of drought stress, and in the same situation, MDA content of Hedysarum scoparium Fisch.et Mey. is sharply higher than other species. Three protective enzyme activities, SOD,POD,CAT, are all increasing under drought stress, however, the changes among species are different.(5) It is analyzed by principal component of physiological and biochemical indexes of shrubs seedlings that relative water content of leaves, proline, soluble sugar and antioxidant enzyme activities have relatively close relationships with drought resistance of these five shrubs.(6) The five desert shrubs drought resistances are evaluated by the subordinate function value method of fuzzy mathematics, and it is got to know that Caragana roborovskyi Kom.> Caragana microphylla Lam.> Ammopiptanthus mongolicus (Maxim.) Cheng f.> Hedysarum scoparium Fisch. et Mey.> Zygophyllumxanthoxylom Maxim..