WATER USE BY A KIWIFRUIT VINE: CALIBRATION, MEASUREMENTS AND A MODEL

The Heat Pulse Velocity technique (HPV) is a method for determining sap flow velocity through plant stems and, subsequently, plant water use. The 'T_max' HPV method measures the time taken for a maximum temperature rise to be recorded by a single sensor downstream from a pulsed heater. This method was used to measure rates of sap movement in stem sections of Actinidia chinensis 'Hort16A' vines. Water passing through these sections was collected and compared with the estimates obtained from the 'T_max' method. Sap flows were also measured, in a whole kiwifruit vine, using the 'T_max' technique and were in good agreement with calculated transpiration rates. Transpiration rates reached a maximum of about 60 L d^-1 for kiwifruit vines in mid summer.