LEDs Control Growth and Flowering in Greenhouse Grown Zinnia Marylandia.

Using Zinnia marylandica as a model organism and LED lighting with independently controlled red, blue, and white light we evaluate four different light treatments in the greenhouse. In each condition natural light was supplemented with 250 µmol m-2s-1 of light. White light was provided at a constant level of 20 µmol m-2s-1 blue light was provided at 0, 20, 40 and 60 µmol m-2s-1, and red light was added to bring light to the final level of 250 µmol m-2s-1. Two additional treatments were evaluated: no supplemental lighting (NSL), and a 400 watt HPS. Results show that addition of increasing levels of blue light yielded a shorter plant, with a similar numbers of flower structures when compared to control plants grown under HPS. Results demonstrate that in the greenhouse environment supplemental light regimes can be created to control plant growth at different stages.