Effects of Light Quality on Seed Germination and Seedling Growth of Cattleya Orchids in vitro.

Abstract

Red, yellow, and blue light significantly enhanced the germination of Cattleya walkeriana var. coerulea 'Hi' x Cattleya walkeriana var. semialba in vitro. Both fresh and dry weights of germinating seedling grown under red, yellow, and blue light were heavier, but those grown under green light were lighter in comparison to those germinating under white light. In subsequent culture, shoot and root growth of seedlings was also enhanced under red and yellow light. Blue light enhanced fresh weight and shoot length, but it did not enhance the dry weight of seedlings. Under green light shoot length and the number of leaves per plant increased, but fresh weight, dry weight, leaf length and width, and root growth of seedlings were smaller. Green light also accelerated shoot and root development from the leaf axis. Dehydrogenase activity in roots, as evaluated by the TTC method, was the highest in blue light and the lowest in red light treatment.