【目的】探究无患子(Sapindus saponaria )生殖物候期树干液流的时滞特性以及遮蔽花序枝叶修剪对时滞的影响,为无患子的科学培育提供指导。【方法】在福建省建宁县无患子国家林木种质资源库,以5年生‘媛华’品种示范林为试验对象,在其生殖生长季(5—11月)运用热扩散液流探针技术对修剪和不修剪(对照)处理无患子的树干液流速率(Fd)进行实时监测,并同步监测光合有效辐射 (PAR)、空气温度(Ta)、空气相对湿度(RHa)等环境因子,运用错位相关法分析液流速率对主导环境因子间的时滞响应。【结果】无论是否进行修剪处理,PAR和饱和水汽压亏缺(VPD)均是影响该地区无患子树干液流的主导环境因子。典型晴天时,无患子树干液流与主导环境因子均呈现“迟滞回环”的关系,其中与PAR的响应过程呈逆时针方向,与VPD的响应过程呈顺时针方向。对照组和修剪组树干液流在花芽膨大期、开花期、初果期、果实膨大期、果实转色期、果实成熟期等6个生殖物候期分别比PAR滞后10、10、0、10、20、50 min和0、20、10、10、20、50 min;比VPD提前160、120、90、90、130、100 min和190、110、70、90、130、100 min。【结论】不同生殖物候期无患子树干液流与主导环境因子间的时滞存在差异,修剪减小了花芽膨大期Fd-PAR的时滞,增大了开花期和初果期Fd-PAR的时滞,但修剪在各生殖期对Fd-VPD的时滞影响相反。该研究为准确评价环境因子对林木耗水产生的影响提供了科学依据,也有助于构建更准确模拟白天蒸腾过程的模型。

【Objective】This study aims to investigate the time lag characteristics of sap flow during reproductive phenological periods in Sapindus saponaria and the effect of shading inflorescence branching and leaf pruning on the time lag of sap flow.【Method】In the experimental area of the Sapindus saponaria National Forest Germplasm Repository in Jianning County, Fujian Province, five-year-old S. saponaria ‘Yuanhua’ asexual lines were employed as experimental materials. Sap flow was measured using a thermal diffusion probe, and environmental factors including photosynthetically active radiation (PAR), air temperature (Ta), and relative air humidity (RHa) were simultaneously measured during the reproductive growing season.Time lags between sap flow velocity and the dominant environmental factors were analyzed using the mismatch correlation method.【Result】PAR and VPD were the dominant environmental factors affecting sap flow, independent of pruning treatments. On typical sunny days, the relationship between sap flow and these environmental factors showed a “hysteresis loop”, with PAR responsed in a counterclockwise direction and VPD responsed in a clockwise direction. Across six reproductive phenological periods (bud swelling, flowering, early ovary growing, fruit developmet, fruit colour change, fruit ripening), the control (CK) and pruning group sap flow lagged PAR by 10, 10, 0, 10, 20, 50 min and 0, 20, 10, 10, 20, 50 min, respectively; and advanced VPD by 160, 120, 90, 90, 130, 100 min and 190,110, 70, 90, 130, 100 min at six key reproductive phenological periods.【Conclusion】The time lag between sap flow and dominant environmental factors varied across different reproductive phenological periods. Pruning impacted these time lags differently: it reduced the time lag of Fd-PAR during bud swelling and increased it during the flowering and early ovary growing periods, while it had the opposite effect on Fd-VPD. This study provides a scientific foundation for accurately evaluating the influence of environmental factors on the water consumption of forest trees and contributes to the development of more precise models to simulate daytime transpiration processes.