In this article:
We determined water requirement for evapotranspiration (ET), and crop factor (Kc), ie the ratio of crop water use to potential evaporation, for Sultana grapevines (Vitis vinifera L.) grown on own roots or grafted onto Ramsey rootstock during the 1994/95 season at Merbein, Victoria.
The vines were drip irrigated with water from the River Murray, and ET was determined by separately calculating transpiration from sap flux, and soil evaporation with a model. Total ET was similar for both own roots and Ramsey, with an average value of 3165 L per vine (3.84 ML ha or 384 mm).
While the majority of ET was partitioned through transpiration by the grafted vines, soil evaporation accounted for almost 62% of ET in own rooted vines. Transpiration in the two groups of vines was closely associated with the size of the green canopy.
Also, water use efficency can be increased by adopting approaches that match water applications to crop requirements. The effectiveness of the widely used crop factor concept can be improved if parameters of crop vigour such as canopy development are incorporated.
Determination of seasonal water requirement for drip-irrigated sultana grapevines on own roots and Ramsey rootstock in Sunraysia