Leaf Blade versus Petiole Analysis for Nutritional Diagnosis of Vitis vinifera L. cv. Tempranillo

The temporal stability and the analysis reproducibility of nutrient concentration of leaf blades and petioles of Vitis vinifera L. cv. Tempranillo were evaluated at a vineyard representing the soil and climate conditions within the AOC Rioja region of Spain. Leaf blade and petiole were sampled throughout the growing season and analyzed for N, P, K, Ca, Mg, Fe, Mn, Zn, Cu, and B concentrations. For reproducibility of the analyses, leaf blade had a lower percent coefficient of variation (%CV) of total N, and K than petiole, while petiole had a lower %CV than leaf blade for B. Phosphorus and Mg had similar %CV in blade and petiole at flowering, while blade had lower %CV at veraison for both nutrients. Calcium, Mn, and Fe had similar %CV in both tissues throughout the growing season. Seasonal changes of nutrient concentration in leaves confirmed the need for specific reference values for both leaf blades and petioles in each phenological stage. In general, nutrient concentration trends throughout the growing season showed short periods without differences between consecutive samplings near the 100% capfall phenological stage, while no statistical differences were found between samples obtained at any time throughout veraison. Results suggest that blade could be a more appropriate tissue for total N and K evaluation, whereas petiole is more appropriate for B evaluation. Calcium, Mn, and Fe will have a similar accuracy in both tissues at any phenological stage. While P and Mg had similar reproducibility in blade and petiole at flowering, blade seems be a better tissue for P and Mg nutritional diagnosis at veraison.