PETIOLE NUTRIENT STANDARDS FOR THOMPSON SEEDLESS VINES ON DOGRIDGE ROOTSTOCK

Petiole nutrient standards available for Thompson Seedless on own root need not be applicable for the same cultivar grafted on rootstock due to variation in the ionic preference of the roots and nutrient interactions. With the aim of determining the critical levels and/or optimum ranges of NO_3-N, N, P, K, Ca and Mg for Thompson Seedless on Dog Ridge rootstock, surveys were conducted in 3–5 year old vineyards of Thompson Seedless in Maharashtra. Regression analysis for the relationship of petiole nutrient contents separately at bud differentiation stage and full bloom with yield revealed that the critical nutrient ranges for N, P, K, Ca and Mg at bud differentiation stage were respectively 1.20–1.53, 0.39–0.47, 0.59–0.60, 0.73–1.03 and 0.88–1.28 percent on dry weight basis. Critical values at full bloom for the same nutrients were, respectively, 1.44–1.80, 0.28–0.36, 1.61–2.95, 0.51–0.81 and 0.58–0.87 percent.