Influence of nutritional stress on content and production of stevioside during Stevia rebaudiana development

Abstract

This paper presents the results of two experiments about stevioside in Stevia rebaudiana (Bert.) Bertoni. In the first one the effects of the deficiencies of N, P, K, Ca, Mg, S, B and Zn as well as the B and Zn toxicity on the stevioside concentration in nutrient solution grown plants were evaluated. In the second trial the objetive was to estimate the content of the stevioside produced during the first cycle of growth under field conditions. Only severe Ca deficiency caused reduction in the glycoside concentration. The content of stevioside under field conditions reached a maximum value 30 days after transplanting (dat), namely 8.2% which dropped to 6.0% at 90 dat. The highest production rate of the glycoside, taking into account either the preexisting total dry weight or leaf area, took place before transplanting and between 15 and 30 dat. During the interval of 30 to 45 dat, a period of vigorous growth of the inflorescences, there was a decrease in the stevioside production rate.