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

Abstract

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 CO_2, 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.