Effect of LED Light Source on Steviol Glycosides, Pigments, and Ascorbic Acid Concentration in Leaves of Stevia rebaudiana (Bertoni)

This study concerns the effects of the light source on the steviol glycosides concentration in Stevia rebaudiana (Bertoni) leaves. In addition, the concentration of chlorophylls, carotenoids, vitamin C, and proteins was determined. Plants were illuminated using RGB (red green blue), cold (CWLED) and warm white LEDs (WWLED) and diffused sunlight (S). The highest accumulation of steviol glycosides in the leaves was detected in RGB (8.39% d.w.) and CWLED (8.16% d.w.) exposed plants, whereas the content upon WWLED was almost two-fold lower (3.75% d.w.), however, the ratio of stevioside to rebaudiosite A was more favorable. The plants exposed to RGB and CWLED lighting had the highest content of carotenoids and chlorophylls. RGB and S light also the most profoundly increased vitamin C levels up to 225.7 mg·kg⁻¹ f.w. and 241.3 mg·kg⁻¹ f.w. The obtained results confirm that changing the light spectrum has a significant effect on the amount and composition of steviol glycosides in the leaves.