Yield and Anthocyanin Concentration in Hibiscus sabdariffa L. with Foliar Application of Micronutrients
The consumption of nutraceutical foods, such as extracts of roselle (Hibiscus sabdariffa L.) calyces, improve health and prevent several diseases, attributable in part to the activity of their anthocyanins. Exposure of plants to high concentrations of some heavy metals stimulates the synthesis of anthocyanins; therefore, the objective of this study was to determine the effect of foliar application of Zn and Cu at high concentrations on calyx yield, anthocyanin content and physicochemical characteristics in three roselle genotypes. The Criolla Guerrero, Criolla Michoacán and Reina Roja genotypes were sown under rainfed conditions. The foliage of the plants in vegetative stage was sprayed with Zn and Cu solutions separately, making in total four applications of 300 mg∙L-1. Both elements reduced the calyx yield in Criolla Guerrero, did not modify it in Criolla Michoacán and in Reina Roja the Zn increased the yield by 15.9 %, achieving 1,232 kg∙ha-1 In all genotypes, the applications of these elements improved the content of anthocyanins and titratable acidity and decreased the content of ascorbic acid. Criolla Michoacán had the highest increase in anthocyanins, with 187 % Cu and with 175 % Zn; however, this genotype did not exceed the final anthocyanin content in Reina Roja, which with Cu recorded 22.68 mg∙g-1. Therefore, the application of these elements is an alternative to increase the content of anthocyanins, to which some nutraceutical qualities are attributed.