银杏树干茎流变化及其对抑制蒸腾措施的响应

Change of Trunk Sap Flow of Ginkgo biloba and Its Response to Inhibiting Transpiration

利用GREENSPAN茎流测定系统监测银杏树干茎流动态变化。结果表明:树干不同高度、不同深度和不同方位的茎流速率存在差异。上位的茎流速率高于中位和下位,但通过上中下位截面的累积茎流通量差异不显著;在不同深度上的茎流速率存在差别,10mm位点的茎流速率最大,20mm位点最小;不同方位的茎流速率是树干南侧最大,西侧次之,北侧最小。使用HOBO气象站同步测定各种气象因子,分析树干茎流日变化、日际变化及其与气象因子的关系,逐步回归分析表明:太阳有效辐射、气温和风速是影响茎流的主要气象因子。通过干预处理研究不同的抑制蒸腾措施对树干茎流的影响,结果表明喷抗蒸腾剂、摘叶和遮荫处理能有效地降低蒸腾耗水,但摘叶和遮荫处理的效果较为明显。

In this article, GREENSPAN sap flow system was used to monitor the dynamics of trunk sap flow of Ginkgo biloba. The results indicated that sap flow velocity was significantly different at different heights, depths and directions of the trunk. Sap flow velocity of upper position at the trunk was more than that of the middle and lower position. But cumulative flux was not significantly different at upper, middle and lower section. Sap flow velocity at 10 mm was the most and that at 20 mm was the least, but sap flow volocity at 5 mm and 15 mm was similar and took the second place among four depths. It also showed that sap flow velocity of the south was the most and that of the west was the second place among the different directions. And an Automatic Weather Station of HOBO was synchronously applied to measure meteorological parameters, which were used to analyze the relationship with changes of trunk sap flow velocity. The results indicated that change of sap flow velocity was a single-peak curve in fine day and multi-peak curve in cloudy and rainy day. In addition, Stepwise regression analyses revealed that PAR, temperature and wind speed were the main environmental factors affecting sap flow velocity. The efficient means to reduce water transpiration of the trees were tried to find through investigating the effect of techniques for inhibiting transpiration including pruning-leaf, overshadowing, spraying of antitranspirants. And the results indicated that spraying of antitranspirants, pruning- leaf and overshadowing could significantly reduce transpiration but the effect of pruning-leaf and overshadowing was far better than that of spraying of antitranspirants.