Nutritional diagnosis in banana in the state of Sao Paulo (Brazil): Dris norms and critical levels

Preliminary DRIS norms and leaf nutrient critical levels (NCL) for Cavendish bananas growing in plantations of Sao Paulo State (Brazil) are presented. DRIS norms and NCL were established from a data bank of leaf nutrient concentration (N, P, K, Ca, Mg, B, Cu, Fe, Mn and Zn) and yield of banana with 188 samples. Data bank comprises information from plants of Grand Naine and Giant Cavendish growing in irrigated and non-irrigated areas, with different sources and rates of fertilizers during five crop cycles. Despite of the great diversity of cropping conditions, the regression between nutrient balance index and fruit yield was significant (R-2=0.60; p<0.0001). The NCLs were derived using multiple linear regressions relating to the foliar nutrient concentration with DRIS indices of all nutrients. These values were similar to those presented in the literature, except the NCL for K which the value for local conditions was lower.