8种城市绿化攀缘植物的光合作用和水分关系特性

Photosynthesis and Water Relations in Eight Urban Landscape Climbing Plants

摘要:

研究了华南地区有较好开发利用前景的8种城市绿化攀缘植物禾雀花(Mucuna birdwoodianauna)、炮仗花(Pyrostegia venusta)、鸡蛋果(Passiflora edulis)、使君子(Quisqualis indica)、蒜香藤(Pseudocalymma alliaceum)、小花青藤(Illigera paviflora)、龙吐珠(Clerodendron thomsonae)和砾叶粉藤(Cissus rhombifolia)盆栽植株叶片的光合速率-光强响应曲线，叶片部分形态特征和水分关系参数。结果表明，8种植物的Pmax(最大光合速率)、LSP(光合作用光饱和光强)、LCP(光合作用光补偿点)均较低，但在光合有效辐射(PAR)强度达1 700 μmol m-2s-1下未出现光抑制现象，显示其光合机构具有应对低光及高光强的可塑性。光强的提高会改变ILUE(瞬时光能利用效率)、Gs(气孔导度)、Tr(蒸腾速率) 和Ci(细胞间隙CO2浓度)值，高光强下（PAR>500 μmol m-2s-1）的Pn(净光合速率)与Gs呈正相关。低Gs和Ci是强光下限制Pn的主要因子。LT(叶片厚度)与水分关系参数（RWC相对含水量，IWUE瞬时水分利用效率，AWLR平均失水速率和RR 复水率）之间没有明显的相关性。不同植物的Pmax, ILUE, LA, LT, IWUE和光合色素（Chl 叶绿素, Car类胡萝卜素）含量等皆有显著的差别。禾雀花、炮仗花和鸡蛋果的光合作用和水分关系特性优于其余种类，而蒜香藤和小花青藤的这些参数的水平最低。

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.