Abstract:The photosynthetic rate-light response curves, some morphological features of leaves and water relation parameters in leaves of eight common landscape climbing plants in South China: Mucuna birdwoodiana, Pyrostegia venusta, Passiflora edulis, Quisqualis indica, Clerodendron thomsonae, Pseudocalymma alliaceum, Illigera paviflora, and Cissus rhombifolia were investigated using one-year-old plant. The lower levels of maximum net photosynthetic rate (Pmax), light saturation point (LSP) and light compensation point (LCP), accompanied with no apparent photoinhibition under high light condition in all tested species revealed that their photosynthetic machinery had obvious plasticity in response to low and high light intensity. The instantaneous light use efficiency (ILUE), stomatal conductance (Gs), transpiration rate (Tr) and intercellular CO2 concentration (Ci) varied with increasing light intensity. A positive correlation between Pn and Gs, and a negative correlation between ILUE and light intensity were observed in the range of light intensity from 500 μmol m-2s-1 to 1 700 μmol m-2s-1. Therefore, Gs and Ci are likely to be the main factors restricting net photosynthesis. However, no significant relationship was observed among leaf thickness (LT) and water relation parameters (average water loss rate, rehydration rate, instantaneous water use efficiency). The values of Pmax, ILUE, IWUE, LT, leaf area and photosynthetic pigments (chlorophyll, carotenoid) contents differed pronouncedly among eight species. Three species, Mucuna birdwoodiana, Pyrostegia venusta and Passiflora edulis displayed an advantage in photosynthesis and water relations, whereas Illigera paviflora and Pseudocalymma alliaceum showed the lowest levels of these parameters.
