Effect of Rootstocks on Grapevine Mineral Nutrition in the Central Coast Region

This study has compared the differences in vine mineral nutrient status as influenced by rootstock in Central Coast wine grapes. Six rootstock trials have been sampled to include Chenin blanc and Chardonnay in Soledad, Chardonnay at York Mountain (Paso Robles), and Cabernet Sauvignon at Santa Ynez, Soledad, and San Lucas. All are irrigated sites, except York Mountain, and compare 7 to 10 rootstocks, depending on location. The rootstocks included at the various sites included Ramsey, Freedom, Harmony, St. George, 5A, 5BB, 5C, 11 OR, 3309, 1202, AXR#1, 99R, Schwarzmann, 039-16, 043-43, and trials, depending on site and year planted. All of the sites have been petiole sampled at bloom while two of the sites (York Mountain and Santa Ynez) have also been sampled at veraison. Petiole analyses include total N, N03-N, P, K, Ca, Mg, Na, CI, B and Zn. Fruit samples were also taken at harvest in the York Mountain Chardonnay and Santa Ynez Cabernet Sauvignon for N and K analyses. Generally, the results have demonstrated a strong influence of rootstocks on scion mineral nutrition. The information should be helpful in anticipating potential nutritional problems, guiding fertilizer recommendations, and selecting rootstocks adapted to the nutritional characteristics of the site. Certain nutrient-rootstock relationships were notable as being more extreme and/or consistent among all of the six trials as follows: Nitrogen: high – 039-16, St. George, Ramsey, 3309 low – Harmony, 5A, 5C, 5BB Phosphorus: high – 1202, 110R, AXR#1, Ramsey low – 3309, Harmony, Freedom Potassium: high – Freedom, Harmony, St. George low-AXR#l,5BB, 110R Calcium: high – 5BB, 5A, 5C low – Harmony, 3309, Ramsey