MỘT SỐ ĐẶC ĐIỂM QUANG HỢP CỦA CÂY ĐƯỚC ĐÔI (Rhizophora apiculata Blume) TRONG RỪNG NGẬP MẶN CẦN GIỜ, THÀNH PHỐ HỒ CHÍ MINH

PHOTOSYNTHETIC CHARACTERISTICS OF Rhizophora apiculata Blume IN CAN GIO MANGROVE FOREST, HO CHI MINH CITYThe aim this research work was to assess the intensity of photosynthesis at the leaf level of an adult tree Rhizophora apiculata Blume, natural origin in a Can Gio mangrove forest. The diurnal dynamics of the intensity of photosynthesis and PAR (Photosynthetic Active Radiation) for different parts of the tree crown were investigated. The Michaelis - Menten equation was used to describe the dependence of photosynthesis on PAR. The coefficients equation was used to assess the photosynthetic characteristics of the tree leaf. It was shown that the depression of photosynthesis in the upper part of the crown of a tree might be caused by a violation of the water balance in the leaves. The dependences intensity of photosynthesis on leaf temperature and CO2 concentration were obtained. Furthermore, the optimum temperature for the growth of R. apiculata was ranging from 30.8 to 35.2°C, while an increase in CO2 concentration, the rate of photosynthesis also increased. Based on the obtained dependences, a mathematical model of the intensity of photosynthesis as a function of PAR, leaf temperature and CO2 concentration in air was developed. Overall, the results highlighted that the inhibitory factor affecting photosynthesis process might be an elevated level of photosynthetic radiation from permitted level and deviation of leaf temperature from the values optimal for R. apiculata growth.