A Study on Photosynthesis and Its Relation to Ecological Factors of Rhododendron Fortunei Seedling

The photosynthetic diurnal variations in leaves of Rhododendron fortunei seedling under natural conditions had been studied. The results were as follows: 1) In clear summer days, the diurnal variations of net photosynthetic rates (Pn) of Rhododendron fortunei were double-peaked curves. The diurnal variations of internal CO2 concentration (Ci) were just opposite to Pn. The increasing of Ci at midday showed that the decreasing of Pn was related to non-stoma restriction factors. 2) By the method of stepwise multi-regression, the most excellent equation of the diurnal variation of Pn was attained as follows: Y=28.3043+0.0028X1-0.2821X2-0.8538 X4 +0.0414 X5. The analysis of partial correlation and path coefficient on Pn and factors showed that the diurnal variation of Pn had closer relations to the primary direct factors including photosynthetic active radiation (PAR) , air CO2 concentration (Ca) , ambient temperature (Ta) and leaf temperature (T1).