Diseño de mezclas para optimizar las proporciones de K+, Ca2+ y Mg2+ en solución nutritiva para tomate hidropónico

Abstract

The methodology for mixture design can be used to optimize the proportions of ions in nutrient solution, thereby maximizing crop yield; however, it is rarely used. The aim of this work was to apply a mixture design to evaluate nutrient solutions with different proportions of K+, Ca2+ and Mg2+ on the average weight, number and yield of fruits, and to determine the optimal combination that maximizes the fruit yield of tomato (Solanum lycopersicum cv. Legionario) grown in a closed hydroponic system. The simplex-lattice experimental design {3,2} was used, with 10 nutrient solutions and a total concentration of 40 meq∙L-1 of ions in each solution. The maximum values of fruit number and yield (27 and 135.8 t∙ha-1, respectively) were obtained with proportions of 0.375 K+, 0.400 Ca2+ and 0.225 Mg2+ in the nutrient solution, equivalent to 7.5, 8 and 4.5 meq∙L-1, respectively. The polynomial regression model estimated to predict yield as a function of K+, Ca2+ and Mg2+ mixtures is of the fourth degree (special quartic), with a coefficient of determination (R2) equal to 0.81, which explains 81 % of the variability of the yield data. The maximum estimated yield was 142 t∙ha-1, with partial desirability of 0.964, which would be obtained with 0.358 K+, 0.421 Ca2+ and 0.220 Mg2+, equivalent to 7.28, 8.26 and 4.46 meq∙L-1, respectively, in the nutrient solution.