EFFECTS OF BICHROMATIC AND TRICHROMATIC LED SPECTRA ON GROWTH AND NUTRITIONAL QUALITY OF TWO REGIONAL LEAFY VEGETABLES

Abstract

The primary objective of this thesis was to explore the effects of red-blue (RB) and red-green-blue (RGB) light-emitting diode (LED) spectra on the physiological and nutritional quality of Choy Sum (Brassica rapa var. parachinensis) and Kai Lan (Brassica oleracea var. alboglabra). The first study investigated the effect of RB LEDs (70 – 75% red) against white LEDs at three different growth stages. Significant interactions were found between growth stage and LED spectrum for most antioxidant capacity assays and photosynthetic pigments tested, indicating plant metabolism will respond to LED spectrum variably at different growth stages. The second study examined three RGB spectra on plant growth and nutritional quality. High proportions of red light depressed antioxidant capacity, while high proportions of blue or green light promoted antioxidant capacity or ascorbic acid content. Overall, the studies affirm the importance of red light in biomass accumulation, and blue and green light in promoting nutritional quality.