Reference Levels for Leaf Nutrient Diagnosis of cv. Tempranillo Grapevine in the Rioja Appellation

Plant nutritional diagnosis requires specific reference levels for each variety to effectively reflect the nutritional status of the crop. A vine nutritional survey was undertaken in the Rioja A.O.C., northeastern Spain. The survey method was used to establish the preliminary reference levels for the nutritional diagnosis of leaf blade and petiole tissues of Vitis vinifera L., cv. Tempranillo on Richter-110 rootstock. These references were generated from data obtained during the course of 11 years (2000-10) from 166 vineyards trained on Gobelet and Vertical Shoot Position (VSP), pruned in Guyot or Double Cordon Royat, systems. The database obtained included information from different altitudes, soil types, cultural practices, and climatic conditions within the Rioja appellation. The majority of the vineyards had no irrigation and soil was tilled mechanically. Nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), manganese (Mn), zinc (Zn), copper (Cu), and boron (B) were analyzed in leaf blade and petiole dry tissues sampled at both flowering and veraison. Vineyards with phytosanitary damages, flowering problems, and data with extreme nutrient values were discarded. Data were statistically analyzed to obtain the normal average values considering the ( +/- 0.25 sigma) of the central data as optimal levels and the tails values ( +/- 0.84 sigma) of the population as excessive or deficient levels. The statistical procedure included the Kolmogorov-Smirnov nonparametric test for normality, data transformations for normality, and the calculation of percentiles when those transformations to normal distributions become unlikely (P20, P40, P60, and P80). Finally, reference levels for leaf blade and petiole at both flowering and veraison are proposed for the nutrition diagnosis of the cv. Tempranillo grapevine in the Rioja A.O.C.