Log-transformed nutrient ratio for evaluation nutritional of cultivated cupuaçu trees

The logarithmic transformation of the bivariate relationships in the calculation of integrated system of diagnosis and recommendation indices (DRIS) has been suggested as a way to improve the accuracy of the system, mainly by reducing the inconsistency between the frequency distribution of the forms expression of direct and inverse of the same relationship. Accordingly, the objective of this study was to evaluate the use of log-transformed relationship between different populations of reference. Cupuaçu leaf samples were collected at 153 commercial orchards; trees were part of either monoculture or agroforestry systems and ranged from 5 to 18 years old. For each individual, the nutritional relationship was calculated for the nutrients: N, P, K, Ca, Mg, Fe, Cu, Zn and Mn. Log-transformed and no- transformed nutrient ratio were obtained for the entire population and specific conditions.The results showed that the log-transformed relationship contributes to greater consistency of results between the direct and inverse forms between DRIS norms.

Nutritional diagnosis; benchmarks; Theobroma grandiflorum

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