干旱区生态环境知识资源中心

Plants belonging to the genus Caragana are selected as preferred legume shrubs for water conservation and sand fixation in the arid and semi-arid areas of the Mongolian plateau. The distributions of three Caragana species (Caragana microphylla, Caragana davazamcii, and Caragana korshinskii) exhibit remarkable regional-level distribution characteristics, whereby they replace each other along a longitudinal water gradient from east (semiarid habitat) to west (arid habitat). We selected these three Caragana species to investigate the cell water relations for this substituted distribution. We found that dehydration and intracellular net solute accumulation were the main regulatory mechanisms used by all three Caragana species to adjust diurnal variation in osmotic potential. The relative contribution of dehydration to osmotic potential changes of C. microphylla, C. davazamcii and C. korshinskii was 76, 56 and 52%, respectively, while that of net solute accumulation was 38, 39 and 34%, respectively. As drought conditions increased, the regulating capacity of cell water gradually increased from C. microphylla to C. davazamcii and C. korshinskii, forming the stable physiological basis for their substituted distribution on the Mongolian plateau.