Effects of Monochromatic Light Irradiation by LED on the Growth and Anthocyanin Contents in Leaves of Cabbage Seedlings

The effects of monochromatic lights on the growth of seedlings and the biosynthesis of plant pigments in leaves were investigated. Seedlings of cabbages (Brassica oleracea var. capitata L. 'Kinshun' (green leaf), 'Red Rookie' (red leaf)) at the stage of having 2 unfolded true leaves were transferred under four monochromatic lights, such as blue, blue-green, green and red LEDs which have peak wavelengths of 470, 500, 525 and 660 nm respectively, and cultivated for 30 days at 50 mu mol m(-2) s(-1) PPFD. The elongation of main stem and petioles in 'Kinshun' was promoted under blue light. Seedlings of 'Red Rookie' showed different responses from those of 'Kinshun'. Although petiole elongation was promoted under blue light, there were no significant differences in main stem length. Top fresh weight in both cultivars also showed no significant difference among respective light treatments. In 'Red Rookie', red light irradiation caused to increase the anthocyanin content, though there was no difference in chlorophyll contents. On the other hand, in 'Kinshun', anthocyanin contents were the same level regardless of light quality, and chlorophyll contents were higher under blue and blue-green light than under green and red light.