The 2012 ASHS Annual Conference

The effectiveness of the light-emitting plasma (LEP) light on the growth and development of leaf lettuce and tomato was investigated. Four cultivars of lettuce (Butterhead, Iceberg A, Little Caesar, and Simpson Elite) were cultured under LEP, high pressure sodium (HPS), and metal halide (MH) lights in a greenhouse and inside a windowless warehouse. When approximate light intensities (350–400 µmol·m^-2·s^-1) were maintained, the biomass yield was similar under the three different lights. However, the architecture of lettuce plants grown under LEP was more desirable than that obtained under other lights. Chlorophyll content as well as tissue solids varied by cultivars. When four tomato cultivars (Cobra, Geranimo, Masada, and Trust) were grown with LEP and HPS inside the warehouse, the plants grown under LEP were shorter and more compact than those grown under PHS, while showing higher biomass yield. The solid content of fruits harvested was slightly higher when plants were grown under LEP lamps compared to HPS lighting. LEP lights consumed about 25% less electricity than HPS lights for the same wattage lamps producing similar light intensity. Both LEP and HPS lamps allowed the production commercial quality tomato fruits when used as sole sources of artificial lighting.