Interpretative indices for leaf analysis in vineyards of the Portuguese region of Bairrada

Leaf analysis is an important tool for evaluating the nutritional status of vineyard. During four years, in the Portuguese region of Bairrada, 52 vineyards were observed and leaf samples were collected at full bloom. The study included the most representative regional grape-vine varieties (M. Gomes, Bical, Cerceal and Baga) and the main objective was the establishment of interpretative indices for foliar diagnostics. In each vineyard an experimental plot with 40 plants was installed in order to collect soil and leaf samples as well as to estimate the plant yield. Interpretative indices for N, P, K, Ca, Mg and B are presented, both for blades and petioles, taking into account the differences that were found between varieties. Significant simple correlations were found between N, P, K, Ca, Mg and B petiole and blade concentrations, suggesting the undifferentiated use of both foliar tissues for vineyard nutritional status diagnosis.