Ecological adaptation and physiological response ofArtemisia halodendronseedling to sand burial

Abstract

There is a great deal of literatures on the effects of sand burial upon the survival and growth of desert plants, but the physiological and ecological adaption of desert plants to sand burial have as yet rarely been studied. Artemisia halodendron is widely distributed in the semiarid deserts of China and is a dominant species in semi鄄moving dune vegetation.In order to understand the ecological and physiological adaptation of prammophytes to sand burial,,changes of survival rate, plant height, biomass, osmotic regulation substances, protective enzymes and membrane permeability of A. halodendron in different sand burial depths were studies during 2010-2011 in the Horqin Sand Land of Inner Mongolia. The experiment included ten burial treatments: buried to 0% ( CK, no burial) , 25% ( A) , 50% ( B) , 75% ( C) , 100% ( D) , 125% ( E) , 150% ( F ) , 175% ( G ) and 200% ( H ) and 225% ( I ) of seedling height. The results showed that 1 ) A.halodendron had a stronger ability to withstand sand burial stress, with some plants still surviving even if buried to a depth reaching 200% of the seedling heights. Although seedling growth was inhibited significantly once the depth of sand burial reached 50% of seedling height, seedling survive did not decrease significantly until the burial depth exceeded 100% of seedling height; 2 ) MDA content was significantly lower in the partial sand burial treatments compared to CK, but http: / / www.ecologica.cn membrane permeability did not increase significantly. After being subjected to complete sand burial, MDA content was still lower in most the treatments compared to CK, while membrane permeability increased significantly. Sand burial did not produce water stress in the seedlings, a major mechanism causing decreased MDA content is that the darkness, hypoxia and low temperature inhibit production of oxygen free radicals and membrane lipid peroxidation; 3) Compared with CK, SOD activity was significantly lower in all sand burial treatments except for treatments D and H, POD activity was higher in all sand burial treatments except treatment D, and CAT activity showed no significant changes with any of the sand burial treatments except for being elevated in treatments C and D. In general, POD activity increased when the activities of SOD and CAT decreased, and SOD and CAT activities increased when POD activity decreased. MDA content had a positive correlation with SOD and POD and a negative correlation with CAT. These results suggested that although there was a complementary interplay among the three enzymes, POD played a central role and SOD and CAT played supporting roles in scavenging active oxygen and minimizing cell membrane damage; 4) When subjected to partial burial with sand, proline content showed no significant changes and the soluble sugar content decreased significantly compared to CK. After sand burial exceeded the seedling height, proline content increased significantly; although soluble sugar content increased, the difference from CK did not reach a significant level. The res...