Study On The Adaptive Mechanism Of Halenia Elliptica In The Different Altitudinal Gradient

The factors such as temperature,water,light,soil fertility and the like will affect the distribution and growth of plants in the altitudinal gradient of Qinghai-Tibetan Plateau,plants growing in this particular habitat for a long time had developed unique morphological characters and physiological mechanisms to adapt to this extreme environment.We have investigated the plant of Halenia elliptica which grows in seven altitudinal gradients(2200-4000m)in the east of Qinghai Tibet Plateau.In order to discuss the morphological changes and the physiological mechanism of this plant in the altitudinal gradient to adapt to the environmental hazard factors such as low temperature,strong ultraviolet radiation,strong wind and so on,their morphological characters and physiological and biochemical characteristics such as the plant height,leaf traits,leaf photosynthetic pigment content,osmotic solute,antioxidantative defense system were analyzed.Our results showed:(1)With the increase of altitude,the plant height of Halenia elliptica tended to be dwarfed,in addition,the leaf mass,leaf area and specific leaf area of leaves were significantly negatively correlated with the elevation.(2)The content of malondialdehyde(MDA)in the membrane lipid peroxidation increased with altitude.(3)The contents of chlorophyll a and chlorophyll b in leaves decreased significantly with increasing altitude.(4)With the increase of elevation gradient,the soluble sugar and proline in the leaves were accumulated,while the content of soluble protein showed a single peak curve of the changes in the form.(5)With the increase of altitude,superoxide dismutase(SOD)gradually increased and the peroxidase(POD)reduced gradually.The study has shown,With the increase of altitude,the plant of Halenia elliptica can drawf its height,reduce the specific leaf area to ensure the survival of plants.Meanwhile,The physiological characteristics of the plant have positive response to the ecological factors' stress such as temperature and intensity of illumination,which can be adapted to the alpine environment through the changes of photosynthetic pigments,osmotic solute and antioxidantive defense system.