The effects of irrigation regimes combining different rates, frequencies and emitter densities were studied to find optimum regimes that lead to high fruit quality and water use efficiency while reducing excess stress and crop losses due to winter injury. Experiments were conducted with Merlot and Pinot gris on coarse textured (sandy soils). High frequency irrigation reduced vine stress while improving water use efficiency, and fruit quality by enhancing skin tannins and reducing berry pH while maintaining crop yields. Reducing the irrigation rate to a moderate deficit also increased water use efficiency but reduced crop yields, fruit soluble solids (brix), juice TA and skin tannins, and increased juice pH. The only benefit of the reduced irrigation treatment was a slight enhancement of berry anthocyanins. Reducing emitter density to give longer, deeper penetrating irrigations increased crop yields and water use efficiency but had no other effects. Sensory analysis of wines made from Pinot gris showed that more frequent irrigation enhanced wine body and fruit flavour.
Dr. Pat Bowen, Agriculture and Agri-Food Canada, Summerland Research and Development Centre.