Water use of yellow-fleshed kiwifruit during an annual cycle

Irrigation is particularly important in Italian kiwifruit orchards because of high summer evapotranspiration demand and very low rainfall totals. To date, very little research has been done to define the water needs of kiwifruit (Actinidia chinensis var. chinensis 'Zesy002' commonly known as Gold3) vines. In this project, we are studying the water balance of a kiwifruit orchard during an annual cycle in Italy using a measurement and modelling approach. Field experiments were carried out in an orchard of 6-year-old vines planted in 5.0-m wide rows at a trunk spacing of 2.0 m. Trunk sap flow (T) was measured using the heat-pulse method and soil moisture was measured using time domain reflectometry (TDR). T peaked at 5.5 L h-1during the middle of the day. Corresponding values of the daily sap flow peaked at almost 60 L d-1, on average. The equivalent rate of vine transpiration, ETC, equalled 6.0 mm d-1. Mid-summer values of the reference evapotranspiration, ETO, were up to 8 mm d-1during June and July and they dropped back to about 2 mm d-1during late autumn (October). Results from this study are contributing to the development of guidelines for growers on irrigation best practice that will help overcome reduced productivity resulting from poor orchard irrigation practices.