Relational analysis of leaf characteristics and photosynthetic capacities of plants

Southeast-facing matured leaves of five plants Viburnum odoratissimum (VO), Ginkgo biloba (GB), Oxalis triangularis cv Purpurea (OTP), Ficus elastica cv. Decora Burgundyi (FEDB) and Morus alba (MA) were used to determine the characteristics and photosynthetic capacities of plant leaves in sunny days. The Li-Cor 6400 Portable Photosynthesis Measuring System, Modulated Chlorophyll Fluorescence System (IMAGING-PAM M-Series), Dual-PAM-100 Measuring System and conventional methods were used to analyze the relationships among leaf characteristics and photosynthetic capacities. The results showed significant differences (P < 0.05 or P < 0.01) in leaf characteristics and photosynthetic capacities among different plants. Differences in specific leaf dry weight 35~215 g (DW)·m^-2 among plants were higher than those in specific leaf fresh weight 0.28~1.04 kg (FW)·m^-2. Leaf chloroplast pigment contents chlorophyll a (Chla), chlorophyll b (Chlb), total chlorophyll (Chl) and carotenoid (Xc) of MA and VO were the highest, followed by GB and FEDB and those of OTP were the lowest. While anthocyanin (Ant) content of OTP was maximum for 0.122 mg·g^-1(FW) and 0.488 mg·g^-1(DW), those of the others plants were low and similar. While OTP leaf Chla/Chlb (6.27), MA leaf Chl/Xc (9.97), MA leaf Chl/Ant (43.81) and VO leaf Xc/Ant (7.17) were the highest, OTP leaf Chl/Ant (0.49) and Xc/Ant (2.46) were the lowest. The orders of stomata conduction, transpiration rate, intercellular CO₂ concentration and net photosynthetic rate (Pn) of the plants were MA > GB > OTP > VO > FEDB. MA and VO leaf practical quantum PSII Y(II) was the highest and that of GB was low. Although MA, OTP and FEDB PSI were high, MA and FEDB PSI photo-protection was weak and that of OTP strong. Correlation analysis indicated that the effects of Ant and Xc on Pn were insignificant. Also stomata characteristics and chlorophyll content positively regulated P>/i>n. Y(II) mainly depended on chloroplast pigment content (especially Chla) and the relationship between Y(I) and Chl/Xc was positive. Leaf stomata opening and chlorophyll content negatively regulated PSII and PSI photo-protection. It, however, positively regulated PSII photo-damage. The effect of Xc was the exact reverse of that of Chl.