Effects of Supplemental UV-A Irradiation on Growth and Bitterness of Lettuce and Radish Plants Grown under Artificial Light

Abstract

In order to know the effect of supplemental UV-A irradiation on the growth of lettuce (Lactuca sativa L. cv. Okayama) and radish (Raphanus sativus L, cv. Comet), these plants were grown under artificial irradiation with 3-band fluorescent lamps and additional UV-A lamps. The UV-A irradiation promoted shoot growth of both plants, and reduced the bitter taste intensity of mature lettuce leaves. However, the UV-A effects varied with stage of vegetative development. Moreover, there was no significant effect of the UV-A on the hypocotyl growth of radish plants.