Studies On Drought Resistance Of Sedum Aizoon L. And Sedum Spectabilis Boreau

The key point of the research is to carry out the studies of drought resistance of Sedum aizoon L. and S. spectabilis Boreau which have market potential and high application value. Water supply was controlled in potted materials, to study the effects of leaf anatomical structure, growth and physiological feature of materials in different soil water stress. The purposes of the studies are to investigate the eco-physiological feature and the adaptability of Sedum in drought adversity and provide evidences to exploit and promote their applications.The main findings are summarized as follows:1. Observing leaves of Sedum aizoon L. and S. spectabilis Boreau,the structure of fleshy xerophyte were observed. They have thin cuticle and no trichomes on the surfaces, and ambiguous differentiation between spongy and palisade tissue in mesophyll. There have well-developed aquiferous tissues in the mature leaves. Some vesicle shape cell on the epidermis which can reserve and holding much water. Developed cell aperture in tissue which communicated with the stomatic chamber. They have developed vascular bundle, and more idioblast around them which can drank and reserved much water below the epidermid cell. Also they have abundant chloroplasts.The density of the mature stomata of materials Were decreased with intensify of drought, but more immature stomata discovered and the density of immature stomata were increasing with the water stress going on, thus the tatal density of stomata were increasing; the thickness of midrib of them were decreased and the thickness of leaves were increased at first and then decreased.2. As the water stress was intensified, the increment of height, leaf number, total leaf area and biomass of two species showed declining trend; and the growth of Sedum aizoon L. was more retarded than S.spectabilis Boreau. The biomass distribution was significantly affected by stress of drought, the root/shoot first increased, then decreased. Moreover, drought decreased the water contents of two species and the extent of decrease of S. spectabilis Boreau less than Sedum. aizoon L. obviously.3. As the water stress was intensified, osmotic substance increased, such as PRO contents of materials were increased and PRO content or S. spectabilis Boreau was more than that ofSedum. aizoon L..The contents of soluble protein of them were increased.4. The MDA contents were increased of them under the water stress, which Sedum. aizoon L. was higher than S. spectabilis Boreau, it showed that cell membrane systems of Sedum. aizoon L. were harmed more severely.The date indicated that the contents of chlorophyll decreased with the water stress going on, drought accelerated decompose of their chlorophyll.Protective enzyme activities such as SOD, CAT of materials showed the variation tendency of falling after rising,and the variation tendency of SOD, CAT of them were semblable.According to the experimental results, the drought resistance expressed in Sedum. aizoon L. and S. spectabilis Boreau are consistent under the studies of the leaf anatomical structure, growth and physiological characteristics and hence they interrelated.