Do macro-nutrient balanced compositions in a subspace of the ionome of Opuntia ficus-indica (L.) Miller maximize fruiting?

Abstract

The current state of knowledge on Opuntia ficus-indica nutrient requirements has important limitations. Macro-nutrient mean concentrations proposed as standards do not consider balances between (or among) elements, and the available compositional nutrient diagnosis norms are not supported by orthogonal references easy to estimate. We hypothesize that O. ficus-indica plants pose macro-nutrient requirements in terms of balanced compositions for producing fruits. The isometric log-ratios allowed us to test that O. ficus-indica variety ‘Rojo Pelón’ plants maximize fruit yield under the basis of true-negative (T-N) or macro-nutrient-balanced compositions in their 1-year-old cladodes. These T-N compositions can be estimated in a straightforward manner using two optimal delimiters, that is, the Mahalanobis distance across the involved isometric log-ratios linked with the highest value of Class Sum of Squares, and a target yield previously defined. When used as a target, these balanced compositions allowed us to identify that true-positive compositions were characterized by P deficiencies and N luxurious consumptions. Novel techniques to perform suitable recommendations based on correct diagnosis interpretation should be developed to address objectively the needed change to enhance the nutrient status of true-positive imbalanced compositions.