Effect Of Drought Stress On Physiological And Biochemical Characteristics Of Amorpha Fruticosa Seedlings

In recent years, drought stress has become the global focus of attention. Relevant research, such as adaptive mechanisms, drought resistance and so on, has become one of important issues of plant physiological ecology.Amorpha fruticosa is an easy perennial legume breeding deciduous shrub with strong adaptability. It belongs to semixerophyte and has strong drought resistance. The objective of the research was to study the physiological and ecological characteristics and adaption characteristics of Amorpha fruticosa seedlings under drought stress so as to provide theory and reference for its application and dissemination in arid, semi-arid areas.1. Amorpha fruticosa seedlings grew well under light water stress condition. The severe drought stress significantly inhabited the normal growth of Amorpha fruticosa seedlings. It displayed as:drought stress reduced its height and leaf area, the extent of inhibition was related to water stress intensity and duration. The effect of inhibition was enhenced with the increasing degree and stress duration.2.With the development of drought stress, water saturation deficit (WSD), plasma membrane permeability and MDA content increased, while Pn, Tr, and Gs decreased. However, water use efficiency (WUE), SOD activity, K content, soluble sugar and free proline (Pro) increased evidently. Soluble sugar and Pro played an important role in osmotic adjustment. Contents of chlorophyll a (Chla), chlorophyll b (Chlb), total chlorophyll (Chl) and carotenoid (Car) pigment also increased along with the decrease of water content in the soil. At the same time, as the intensity of drought stress increased, the ratio of Cha/Chb had no remarkably change. Physiological injury appeared under the condition of drought stress in Amprpha fruticosa. It carried on the osmotic regulation by the way of accumulating inorganic ions or synthesizing organic solute in the cell vacuole to reduce or avoid injury. Amorpha fruticosa seedlings increased its drought resistance by changing inner physiological characteristics and it had a certain resistance to drought stress.3. Under water stress, the stem water potential and root water potential showed significantly response to different soil water content. Under conditions with sufficient and deficient soil water supply, the difference value of stem water potential was 2.83 MPa while root water potential reached 3.84 MPa. These results indicated that stem water potential and root water potential were closely related to water supply capacity of soil.4. With the increasing degree of drought stress, soil water potential, stem water potential and root water potential all decreased to some extent. The difference value of soil water potential and root water potential reached 2.96 MPa under 35%relative soil water content, it was little higher than other treatments. These results indicated that Amorpha fruticosa seedlings can improve its water absorbing ability by increasing the difference value of soil water potential and root water potential when soil water content was lower.5. Drought stress on physiological and biochemical characteristics of Amorpha fruticosa seedlings had a certain difference. Generally, the greater the intensity of drought stress was, the more distinctly index changed. Tr, WUE, Pro content, soluble sugar content, K content, SOD and POD activity, root water potential and stem water potential were objective reflections of Amorpha fruticosa seedlings adaptive mechanisms to drought habitats and could be used as identification indexs of its drought resistance.In conclusion, dry adaptation characteristics in Amorpha fruticosa seedlings could provide theory and reference for its application and dissemination in arid, semi-arid areas. It was considered by integrated analysis that Amorpha fruticosa is worth widely spreading in desert region of arid or semi-arid areas, sandy bare land, dry and barren land in the mountainous region, dry slope land and so on.