2018 ASHS Annual Conference

We investigated the effect of UV-A for coloring red-leaf lettuce (Lactuca sativa L. s. var. crispa) under controlled culture conditions (plant factory). It is well known that anthocyanin which is the main pigment in red-leaf lettuce induces by UV. Red-leaf lettuce varieties do not turn red in plant factory condition, because recent artificial lights (like as white LEDs or fluorescent lights) do not contain UV enough. We tested additional UV-A equipped with white cold cathode fluorescent lamp. We grew plants on hydroponic culture in plant factory condition. The result showed that applying UV-A accelerated coloring of red-leaf lettuce. However, the growth was inhibited under long-term exposure condition to UV-A. This technique might be efficient for growing red-leaf lettuce cultivation in plant factories although we have to find more suitable treatment.