Influence of deficit irrigation on nutrient indices in wine grape ( Vitis vinifera L.)

Abstract

Deficit irrigation is widely used in wine grape production (Vitis vinifera L.) to meet wine quality goals yet its influence on tissue nutrient indices has not been well studied. The objective of this research was to determine whether response to water deficit compromised the prescriptive usefulness of tissue nutrient analyses. Tissue macro and micronutrient composition at bloom and veraison were evaluated over multiple seasons in nine wine grape cultivars grown under well-watered or deficit-irrigated conditions. Deficit-irrigated vines sampled at veraison had 2 to 12-fold higher petiole nitrate-nitrogen concentration, 6% lower blade nitrogen concentration and 13% lower blade copper concentration compared to well-watered vines. Water deficit influenced blade potassium concentration at veraison differently according to cultivar and was lower (cv. Malbec, Petite syrah, Viognier, Lemberger and Sangiovese), higher (cv. Merlot, Cabernet franc and Cabernet Sauvignon) or similar (cv. Grenache) to well-watered vines. Results from this study indicate that nutrient analysis of petiole or blade tissue sampled at veraison has limited diagnostic and prescriptive usefulness when vines are grown under a water deficit.