Four Species Of Drought Resistance

The four species of Michelia including Micheliaplatyetala,Micheliatsoi,Micheliafoveola2 taMicheliamaudiae were important afforest and ecological landscape trees in south of china.The effect of drought stress on different varieties two-year-old seedlings of the four Michelia trees were used as materials in this experiment,and water supply was controlled in potted Michelia, to measure leaf anatomic index and study the changes of physiological and biochemical characters and their relationship and to choose the one which had the strongest resistance. The test indices including leaf thickness, cutin layer thickness, stockade tissue thickness, sponge tissue thickness, ratio of stockade tissue thickness to sponge tissue thickness, tightness of leaf tissue structure, sedimentation of leaf tissue structure and stoma density, water saturated deficit, chlorophyll content and relative electric conductivity, MDA content, SOD activity, POD activity, CAT activity, PRO content, soluble carbohydrate content, soluble protein content, net photosynthetic rate, transpiration rate, diumal variation of photosynthetic rate and diumal variation of transpiration rate.The results showed that the differences of leaf thickness,cutin layer thickness, stockade tissue thickness , sponge tissue thickness, ratio of stockade tissue thickness to sponge tissue thickness, tightness of leaf tissue structure, sedimentation of leaf tissue structure and stoma density are significent while differences Of the sizes of upper epidermis and lower epidermis were not remarkable.With drought stress going on, osmotic substance increased such as soluble carbohydrate content, Pro content and the content of soluble protein increased, but root activity reduced. The above-mentioned indexes change range differed greatly with different varieties and the change laws of indexes are unanimous. The cell membrane systems of Michelia were harmed and the osmotic capability boosted up under the water stress, relative electric conductive and MDA content increased. Protective enzyme activaties of different Michelia varieties showed the variation tendency of falling after rising, such as SOD,POD,CAT,while the changing laws of three kinds of enzymes were different to some extent. Every test result was analysed, indicating that every variety drought-resistance has greater difference. The date indicated that the content of chlorophyll, net photosynthetic rate and transpiration of every variety of the Michelia tree...