Study On The Characters Of The Principal Shrubs Under Water Stress Based On The System Of SPAC In Kubuqi Desert

In order to provide proof for tree species selection in the course of vegetation recovering,based on the ovservation of water movement in the system of Soil-Plant-Atmosphere Continuum,the paper experimentize a series of studies of Acriplex canescens(Purgh.)Butt, Caragana microphylla, Hedysarum mongolicum Turcz,in Kubuqi desert.The problems are discussed as follows:· The climate character of the research area· The rule of soil water movement in testing woodland· The change of water potential grads in the system of Soil-Plant-Atmosphere Continuum· The transpiration of testing plants· The physiological response of potted plants under different soil water content· The mechanism of potted plants forbearing drought Major conclusions are summarized as follows:· Soil water have clear seasonal change in the vegetal seasons of 2006.It can be changed into three periods such as stability period in May,consuming period from June to July and convalescence from Auguest to September.· According as the change of leaf water potential in earing morning ,water recoverer of Hedysarum mongolicum Turcz is the best, and it shows some water wane in Acriplex canescens(Purgh.)Butt and Caragana microphylla. There has relationship between the degree of water wane and water recover.·The change of leaf water potential is the result of the rate of transpiration and water supply of roots ,some meteorologic factors can effect leaf water potential through effect transpiration.· Main energy is consumed in the link of leaf and atmosphere in the system of SPAC ,and secondly in the link of soil and root, and energy is consumed in the link of stem and leaf similarly.The difference of water potential takes a trendline of falling follow increasing, the highest difference of leaf water potential and atmosphere water potential is in June and the lowest is in August. the highest difference of soil water potential and root water potential is in July and the lowest is in September.· The result of daily course of transpiration in July shows Acriplex canescens(Purgh.)Butt has normal transpiration ,reflecting it has better water condition,and water supply is not ample'of Caragana microphylla and Hedysarum mongolicum Turcz,thereinto plant water of Hedysarum mongolicum is worse.· Tt has little difference in the daily change of Transpriation and Photosynthesis of potted plants under different soil water content.Tr takes a trendline of falling follow increasing with the development of drough ,at the same time Pn of Acriplex canescens(Purgh.)Butt increase continually,whereas Hedysarum mongolicum Turcz falls continually,and Caragana microphylla and Tamarix ramosissma Ledeb. takes a trendline of falling follow increasing. The light response of potted plants lower continually with the development of water drough .· The result of soil water content when plant withered is 0.578% of Acriplex canescens(Purgh.)Butt, 0.711% of Caragana microphylla, 0.687% of Hedysarum mongolicum Turcz, 2.11% of Nitraria tangutorum Bobror, 1.09% of Tamarix ramosissma Ledeb, 1.22% of Caryopteris mongolica Bunge.The efficiency of water using of potted plants are all above 90%.The capability of plants resisting drough is sized up according soil water depleted index as following: Acriplex canescens(Purgh.)Butt > Caragana microphylla > Hedysarum mongolicum Turcz > Caryopteris mongolica Bunge>Nitraria tangutorum Bobror>Tamarix ramosissma Ledeb.· Mechanism of potted plants resisting drough based on the relatationship between leaf water potential and soil water content is summed up as Caragana microphylla, Hedysarum mongolicum Turcz and Caryopteris mongolica Bunge belong to the plant that have high water potential to delaying dehydration, Acriplex canescens(Purgh.)Butt and Nitraria tangutorum Bobror belong to the plant that have sub-high water potential to delaying dehydration, Tamarix ramosissma Ledeb belongs to the plant that has sub-low water potential to resisting dehydration.