The factors affecting net photosynthetic rate in endangered plant Erythropsis kwangsiensis in Guangxi

The diurnal variation and the factors affecting net photosynthetic rate(Pn) in Erythropsis Kwangsiensis were measured using LI-6400 portable photosynthetic analyzer in sunny days during October 2009,and the data were analyzed statistically for correlation,stepwise regression and path analysis.The results showed two different peaks in the curve of diurnal variations in Pn,and a similar trend was observed with transpiration rate(Tr).The midday depression in photosynthesis was significant,and it was principally caused by decrease in stomatal conductance(Gs).The main physiological factor which affected diurnal variation in Pn was found to be Tr,and the main ecological factors were the light intensity(PAR) and relative humidity(RH).The light transmittance increase,proper management of irrigation during the cultivation may help in adjusting Tr,increasing Pn,and promoting the growth of seedlings.