LED light quality intensifies leaf pigmentation in ornamental pot plants

Light stimulates the production of anthocyanins in leaves. Assimilation light is needed in the production of red colored foliage plants during the dark winter period in order to obtain a commercially attractive product. In this study we tested whether this can be achieved by growing those plants for a limited period at the end of the production cycle in a growth chamber under specific LED (Light Emitting Diodes) light spectra. The experiment was conducted on three species: Hypoestes phyllostachya ‘decor pink’ and ‘decor red’ or polka dot plant, Guzmania lingulata ‘Theresa’ with yellow and red bracts and Cryptanthus carnosus ‘Tricolor’, also known as earth star. Different combinations of blue, red and far red light were applied and control treatments were given with and without HPS (High Pressure Sodium) lamps in the greenhouse. In all three species a minimal amount of blue light is compulsory. When only red LEDs are used in Hypoestes, leaves become curly and plants are not sufficiently compact. Without the addition of blue light the Guzmania bracts turn entirely yellow and Cryptanthus leaves are much more pale. In all cases, the use of LED was an improvement for the anthocyanin content when compared to plants that were grown without supplementary light. We demonstrated that for all three species a
limited growing period under specific light spectra at the end of the production cycle can be a good way to produce attractive colored foliage plants when natural light is limited.