银杏树干边材液流及水容特性研究

为探明银杏(Ginkgo biloba)枝叶水势、水容特征及其对树干边材液流的调节和影响。利用热扩散式边材液流检测技术、压力室技术等对其树干边材液流、枝叶水势、水容等进行测定。结果表明，春、夏、秋三季银杏树干边材平均液流速率分别为（1.11±0.76）×10^-3、（0.82±0.58）×10^-3、（0.94±0.21）×10^-3 cm·s^-1，三者之间无显著差异。银杏枝条与叶片水势、水容具有相似的“V”型日变化。整个生长季，银杏枝条和叶片平均水势分别为（-1.74±0.24）MPa和（-1.80±0.20）MPa；枝条和叶片水容分别为（0.38±0.02）×10^-3 g·cm^-3·MPa^-1和（5.83±1.9）×10^-3 g·cm^-3·MPa^-1。银杏枝叶水势、水容与树干边材液流速率呈负相关，共同作用和调节其蒸腾耗水，但不同时段其主导因子不同。

Studies on the Characteristics of Xylem Sap Flow and Water Capacitance of Ginkgo biloba

In order to clarify the twig and leaf water potential and capacitance of Ginkgo biloba and its regulating and impacting on sap flow, sap flow velocity (V_sf), twig and leaf water potential (ψ) and water capacitance(C) were measured by using thermal dissipation sap flow velocity probe (TDP) and pressure chamber. The results showed that the average values of daily V_sf were (1.11±0.76)×10^-3, ( 0.82±0.58)×10^-3 and (0.94±0.21)×10^-3 cm·s^-1 in spring, summer and autumn, respectively. But the difference of V_sf in three seasons was not significant. It was a “V” curve for diurnal variation of G. biloba twig and leaf ψ, and C. Through the entire growth season, the average values of twig and leaf ψ were (-1.74±0.24) and (-1.80±0.20) MPa, and the C were (0.38±0.02) and (5.83±1.9)×10^-3 g·cm^-3·MPa^-1, respectively. And the relationships between V_sf and ψ and C were opposite. In conclusion, water transpiration and use of G. biloba was regulated and controlled together by twig and leaf water capacitance, water potential, but in different times the dominant factors were different.