DRIS and Sufficient Range Approaches in Nutritional Diagnosis of “Valencia” Sweet Orange on Three Rootstocks

Abstract

Among several methods of diagnosis for nutritional status, two are more important: the Sufficiency range approach (SRA) and the diagnosis and recommendation integrated system (DRIS). This research compared DRIS with SRA, the diagnostic method currently used by the citrus industry in São Paulo State, Brazil. The study was conducted in irrigated, commercial groves of “Valencia” sweet orange more than six years old and with yield above 40 t ha− 1 in Mogi Guaçú, São Paulo State. Data pertaining to yield, tree spacing, rootstock, and foliar concentrations of nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sulfur (S), iron (Fe), manganese (Mn), copper (Cu), zinc (Zn), and boron (B) in non-fruiting terminals for each plot were processed for the years 1994 through 1998. DRIS indices were calculated by the Jones method of the intermediate functions. Index of nutritional balance (INB) was calculated by the average of the sum (disregarding the sign) of all nutritional index values and the dry matter index. Results indicated that, for the conditions of this experiment: (1) DRIS, when compared with the SRA, complements nutritional diagnosis because it establishes an order of deficiency or excess for each nutrient and detects deficiencies or excesses not considered by SRA; (2) There was agreement between the two methods for nutritional diagnosis of K; (3) Cu, Mn, and Fe concentrations were determined as deficient by DRIS, but were classified as adequate or excessive by SRA.