Drought Resistance Research About Four Shrub Species

A drought resistance research for Caragana microphylla Lam, Hedysarum fruticosum Pall vat, Nitraria tangutorum Bobr and Tamarix chinensis Loar is devised in east of Kubuqi Desert in this paper. The main results are as follows: Under the four water gradients, as the soil water content respectively accounts for 25%, 35%, 55% and 75% of the soil-water holding capacity, photosynthesis rate, transpiration rate, light response, diurnal changes of leaf water potential, free praline, soluble sugar content, and malondialdehyde content were measured. The results are as follows:1.Under the four water gradients, photosynthesis rate and diurnal change of transpiration rate for the four species showed different changing rules.2.When the soil water content accounts for 75% of the soil-water holding capacity, light compensation point for the four species is Caragana microphylla Lam＞Tamarix chinensis Loa＞Hedysarum fruticosum var. lignosum＞Nitraria tangutorum Bob. light saturation point is Tamarix chinensis Loar＞Hedysarum fruticosum var.lignosum＞Caragana microphylla Lam＞Nitraria tangutorum Bobr.3.When the soil water content accounts for 25%, 35%, 55% and 75% of the soil-water holding capacity, Diurnal mean value of leaf water potential are Hedysarum fruticosum vat. lignosum＜Nitraria tangutorum Bobr＜Tamarix chinensis Loaf＜Caragana microphylla Lain, Caragana microphylla Lam＜Tamarix chinensis Loar＜Hedysarum fruticosum vat. lignosum＜Nitraria tangutorum Bobr, Tamarix chinensis Loar＜Caragana microphylla Larn＜Hedysarum fruticosurn vat. lignosum＜Nitraria tangutorum Bobr and Caragana microphylla Lam＜Tamarix chinensis Loar＜Nitraria tangutorum Bobr＜Hedysarum fruticosum vat .lignosum, respectively.4.Under the four water gradients, the contents of free praline and soluble sugar for Nitraria tangutorum Bobr significantly more than other species. when the water content is 35%, the contents of free praline and soluble sugar for the four species reached the highest value.5.Superoxide dismutase content for Tamarix chinensis Loaf, Hedysarum fruticosum var. lignosum and Nitraria tangutorum Bobr reached the highest value when the soil water content accounts for 35% of the soil-water holding capacity. But the highest value for Caragana microphylla Lam occurs at 75%.6.Catalase content for the four species reached the highest value when the soil water content accounts for 35% of the soil-water holding capacity. Catalase content of Caragana microphylla Lam significantly higher than other species in all water gradients.7.As Li Lu-jun's method, we made a comprehensive study of drought resistance: drought resistance sort is Tamarix chinensis Loaf＞Nitraria tangutorum Bobr＞Caragana microphylla Lam＞Hedysarum fruticosum Pall vat.8.As Deng Ju-long's grey correlative analysis: Drought indicators associated with the highest degree of the former 4 is free praline, photosynthesis rate, conductance, transpiration rate, it illustrates the impact of several indicators is the most important. So, this can be used as four species identification of the important indicators of drought resistance.