Development of a Drip Irrigation Schedule for Average-Canopy Vineyards in the San Joaquin Valley

A drip irrigation schedule (ETvine) was developed for vineyards of average canopy size in California9s San Joaquin Valley. ETvine is based on the National Weather Service9s historical evapotranspiration values for the reference crop alfalfa (ETp) utilizing the Jensen-Haise energy balance equation. The ETvine was evaluated by two consecutive years of field testing. Shoot growth and yield were reduced with daily drip irrigations at ½ ETvine, whereas [unknown] ETvine delayed fruit maturity and reduced shoot growth. Leaf water potential (ψ L ) became less negative with increasing amounts of water applied. Soil water matrix potential (ψ M ) was reduced as well as stored soil water with less than schedule amounts. Results verified ETvine to be an effective drip irrigation guide for average-canopy vineyards (55% of the ground area shaded with the sun directly overhead).