樟科幼树水分生理特征的种间差异和相关性分析

Interspecific Comparisons and Correlation Analysis of Water Physiological Characteristics of Tree Saplings of Lauraceae

摘要:

为了阐明樟科（Lauraceae）幼树的水分生理特征，比较了同质园中自然生长的5年生刨花楠（Machilus pauhoi）、香樟（Cinnamomum camphora）和闽楠（Phoebe bournei）幼树在生长季节叶片的水分生理特征和地径（D）、株高（H）的差异。结果表明，香樟的相对含水量（RWC）、叶片水势（Ψ）、枝条木质部比导率（K_s）都显著高于闽楠和刨花楠（P<0.05），而枝条木质部导水损失率（PLC）则显著低于闽楠和刨花楠（P<0.05），说明香樟具有更高的保水能力、水分传输效率，并对水分缺失具有更高的抵抗力。3物种幼树均会因枝条空穴化的加强而降低枝条水分的运输效率。刨花楠幼树通过提高水分利用效率以应对导水效率的降低，香樟幼树叶片具有较高的含水量，气孔保持膨胀，可实现较高的蒸腾速率，闽楠幼树通过提高水分运输的效率和安全性以维持叶片相对含水量。

Abstract:

In order to understand the water use ability of Lauraceae species, the water physiological characteristics and ground diameter (D), tree height (H) of three five-year-old saplings, including Machilus pauhoi, Cinnamomum camphora and Phoebe bournei grown in common garden were compared in growth season. The results showed that the water content (RWC), water potential (Ψ) and branch specific conductivity (K_s) in C. camphora were significantly higher than those of M. pauhoi and P. bournei, while the loss rate of hydraulic conductivity (PLC) were significantly lower (P<0.05). It indicated that C. camphora had high water retention capacity, water use efficiency and water loss resistance among the three species. Therefore, three saplings reduced efficiency of water transportation due to strengthening of cavitation. Machilus pauhoi saplings increased water use efficiency to cope with reduction of water transfer efficiency. The leaves of C. camphora saplings had high water content, which kept stomata inflate to achieve high transpiration rate. Phoebe bournei saplings could maintain relative water content of leaves by increasing efficiency and safety of water transport.