ADAPTATION OF Caragana intermedia TO ENVIRONMENTAL CHANGES WHILE GROWING: PHOTOSYNTHESIS AND WATER POTENTIAL

Plant photosynthesis is one of the most important physiological processes for plant survival and growth. Studies on the photosynthesis characteristics of sand-fixing vegetation of different ages in alpine sandy land provide a scientific basis and theoretical support for vegetation restoration and forest management in the region. In this study, the photosynthesis and water potential of Caragana intermedia plantations 5-, 7-, 10-, 12-, 18- and 32-year-old were measured, and meteorological data was obtained simultaneously. Results showed that utilization efficiency of light energy first decreased and then increased as plants grew; while in the case of CO2, utilization efficiency first increased and then decreased. The highest correlation coefficient between photosynthetic rate (Pn) and physiological or ecological factors were stomatal conductance (Gs) and CO2, respectively. Water potential of C. intermedia decreased then increased on a daily basis; but in old-aged individuals was significantly lower than that of the young-aged, showing a negative correlation with photosynthetically active radiation (PAR). Plants water consumption and water absorption capacity increase to resist external environment, in a physiological adaptation response to the increment of light.