Photosynthetic Characteristics of Manglietia yuyuanensis in Different-Aged Compound Mixed Forest Community at Mausoleum of Dr. Sun Yat-Sen

摘要

The photosynthetic physiological indices of Manglietia yuyuanensis Law in different-aged mixed forest community at the Mausoleum of Dr. Sun Yat-sen were studied using Li-6400 Portable Photosynthesis System. Meanwhile, the diurnal variations of photosynthesis were observed. The results are as follows: light saturation point (LSP), light compensation point (LCP), dark respiration rate (Rd), maximum photosynthetic rate (Pmax) and apparent quantum yield (AQY) were 1,600 umol m"2·s"', 8 umol m-2·s1, 0.1462 umol·m·s-1, 6.154 umol rn-2·s-1 and 0.0192, respectively. The Pn of leaves increased with the increase of CO2 concentrations to a certain extent. CO2 compensation point (CCP) and the carboxylation efficiency (CE) were 68 umol'mol"1 and 0.0122, respectively. The diurnal variation of the net photosynthetic rate (Pn) in sunny day displayed a smooth one-peak curve and showed no phenomena of "midday depression". The peak of curve appeared at 12:00, attaining 6.13 umol·m·2s-1. The diurnal variation of Pn was in agreement with those of photosynthetic active radiation (PAR), stomatal conductance (Gs) and transpiration rate (Tr), of which, Pn had very significant positive correlation with PAR ,vapor press difference (Vpd) and Tr. the results show that the tree species of M. yuyuanensis in different-aged mixed forest community at the Mausoleum of Dr. Sun Yat-sen can adapt to the weak light environment in forest.