Studies on diurnal variation of photosynthesis of Phyllostachys edulis cv. pachyloen and their relationships to environmental factors in spring.

The diurnal variation of photosynthesis of Phyllostachys edulis cv.pachyloen was studied by LI-6400,as well as those of photosynthetic photon flux density(PPED),CO2 concentration in air(Ca),relative humidity(RH) and air temperature(Tair) were measured,and the relationships between the diurnal of Pn,Tr and climatic factors were analyzed by correlation coefficient path coefficient and decision coefficient analysis.The results were as follows:in the typical spring sunny days under natural conditions,the curve of net photosynthetic rate(Pn) had one peaks,and the peak value was 9.06 μmol·m-2·s-1,which occurred at 11:00 o'clock in the morning.The curve of diurnal variation of transpiration rate was also one-peaked,but the peak value appeared at 13:00,which was 4.95 mmol·m-2·s-1 or so.For the characteristics of photosynthesis and transpiration,PPED was the primary determining factor,and RH,Ca,and Tair affected Pn,Tr indirectly by acting on PPED.