Effect of Rootstocks on grapevine mineral nutrition in the Central Coast

This study is comparing the differences in vine mineral nutrient status as influenced by rootstock in Central Coast wine grapes. Six rootstocks trials have been sampled to date 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. All of the sites have been sampled at bloom while two of the sites (York Mountain and Santa Ynez) have also been sampled at veraison. Analyses include total N, N03-N, P, K, Ca, Mg, Na, CI, B and Zn. Generally, the results are demonstrating the strong influence that rootstocks can have on scion mineral nutrition. The information should be helpful in anticipating potential nutritional problems, guiding fertilizer recommendations, and selecting rootstocks partly on the basis of nutritional adaptability to the site. The information is preliminary, as additional years of sampling, including fruit analysis, will be needed to determine multi-season responses. However, some preliminary responses are worth noting, especially when they are showing some consistency among sites. They include: 5C = lower N, CI, and Zn; 110R = lower CI and K; 3309 = lower P and Ca; 1202 = higher P and N; 039-16 and 043-43 = higher N, Na, and CI; Freedom = higher N and K but lower Zn; Harmony = lower N, P, and Ca; St. George = lower CI but higher N and Mg; 5BB = lower K; 5A = lower N and K; Ramsey = higher N, P and Mg; and Schwarzmann = mostly minor differences. Many of the noteworthy differences showed some consistency among the irrigated sites. This included the relatively poor performance of Harmony (often noted in Coastal sites), the high nutritional status of Freedom and Ramsey, and the potentially high sensitivity of 039-16 to Na and CI problems. Generally, St. George performed well on the dryland site. Additional information and recommendations should be forthcoming as the study progresses.