DRIS Use on Apple Orchard Nutritional Evaluation in Response to Potassium Fertilization

Abstract

Abstract The aim of this work was to use the diagnosis and recommendation integrated system (DRIS) method to evaluate the nutritional status of an apple orchard, cv. Gala/MM106, at Vacaria, State of Rio Grande do Sul, Brazil. Treatments consisted of four levels of annual maintenance potassium fertilization. Data on fruit production and fruit pellicle color were restored from 1995 to 2000, as well as the data on leaf macro and micro-nutrient concentrations. The DRIS indices and nutritional balance index (NBI) for each nutrient were determined using three methods: Beaufils, Jones, and Elwali and Gascho. The results showed that (i) the NBI, calculated from the generated norms, were negatively correlated negative correlated with productivity and fruit coloration, and (ii) the DRIS method, described by Elwali and Gascho and using the F value, was the most suitable for apple tree orchards, because the NBI values obtained with this method best indicated the nutritional status of the plants and provided a more accurate nutritional diagnosis.