Studies on the photosynthetic characteristics of Xiangli pear trees

In order to offord a thory for planting of pear in the dry area,the characteristics of photosynthesis in leaves of Xiangli pear trees was studied.The results showed that the diurnal variation of net photosynthetic rate(Pn) of peripheral leaves and inner leaves were in double-peak curves with feature of decreasing at noon.The peak of peripheral leaves was recorded at 13:00 and 16:00;The peak of inner leaves was recorded at 13:00 and 15:00.The net photosynthetic rate Pn of peripheral leaves was higher than the Pn of inner leaves.The yearly changes of Pn were double-peak curves,peaks occurring at 6 month and 8 month.The light compensation point and light saturation point of peripheral leaves were 1 550 μmol/(m~2·s) and 51.1 μmol/(m~2·s).The change of the stomata conductance(Cs) of the tree was single curve,the highest value was recorded at 11:00.The highest value of transpiration rate was recorded at 11:00.