Preliminary study on variation characteristics of photosynthetic rate in Radix Pseudostellariae

In order to prove up the variation characteristics of photosynthetic rate in Radix Pseudostellariae. Under the proper condition of sunny day, Li6400 portable photosynthesis system was used to study the diurnal and different growth periods variation in photosynthetic rate (Pn), transpiration rate (Tr), stomatal conductance (Gc) of the top second leaf in R. pseudostellariae. The results showed that the curves of diurnal variation in photosynthetic rate of R. pseudostellariae represented single peak type, and it did not exhibit the midday depression phenomena．The photosynthetic rate and transpiration rate of R. pseudostellariae. were depended on the stomata conductance in great extent, and both were extremely significantly positive correlated（P0.01）with the stomata conductance. The photosynthetic rate and transpiration rate increased slowly, and then decreased rapidly during the withering period along with the growth of R. pseudostellariae