Comparative Study on Leaf Anatomy and Photosynthetic Characteristics of 3 Tropical Tea-oil Camellia

The study was conducted to compare and analyse the anatomical structure and photosynthetic physiological parameters of the leaves of Camellia hainanica, C. osmantha and C. vietnamensis by physiological measurements and cytological methods. The results showed that leaves were the thickest, with well-developed spongy tissue, the largest stomata and the highest stomatal density, and its chlorophyll content was significantly higher than the other 2. The net photosynthetic rate(P_n) of the three tea-oil Camellia was C. hainanica > C. vietnamensis > C. osmantha. According to the fitting results of the photosynthetic response curve, C. hainanica has a high light saturation point(LSP), a low light compensation point(LCP), and a dark respiration rate(R_d), showing strong tropical adaptation. C. vietnamensis has tighter leaves with high utilisation of bright light. The leaves of C. osmantha were the thinnest, with PSⅡ primary light conversion efficiency(F_v/F_m), actual photochemical efficiency(Φ_PSⅡ), transpiration rate(T_r) and stomatal conductance(G_S) significantly lower than those of the other 2, which were less adapted to the tropics.