Abstract
This paper analyzes the transpiration and vapor conductance of a whole tree of Zelkova serrate in summer using its weight measurement results, taking into account the effects of the water stress of the tree. Measurement data of transpiration for water supply condition and no water supply condition are used for the analysis, and the effects of the water stress on the transpiration and vapor conductance are analyzed. The vapor conductance increased and was saturated as PPFD increased under the water supply condition. The photic saturation point was from 700 to 800 [μmol／(m2s)]. The peak of vapor conductance appeared in morning and that of transpiration appeared in afternoon under clear sky conditions. The transpiration rate increased by 1.7 times as saturation deficit increased by three times under the photic saturation condition. The peak value of transpiration and vapor conductance decreased as the soil water content decreased. The relashionship between vapor conductance and soil water content was hysteretic when the soil water content was varied by the water-supply stop test. Decrease in vapor conductance appeared two days after the water-supply stop, and recovery in vapor conductance appeared three days after the water-supply resumption.
