无患子液流时滞特性及对遮蔽花序枝叶修剪的响应OA北大核心CSTPCD

[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.