EFFECT OF BLUE LIGHT ON PHOTONASTIC REACTION OF RICE LEAVES

Effect of blue light on the epinastic reaction of rice plant leaves (Oryza saliva L.) was studied. The inclination angle of intact leaves, when the plants were grown either in the light or in the dark, was greatly increased by blue light irradiation but not much increased by green, yellow, orange, red or white light. The effect of blue light on the epinastic reaction was, however, obscure in excised leaves, especially when they were placed on the horizontal. The photonastic reaction required a prolonged irradiation of high intensity. The photosensitive site localized at the leaf-nodal part. Response spectra for the photonastic reaction were characterized by 2 distinct peaks at 420-440 mμ and 460-480 mμ and a fairly strong response in the near ultra-violet region. © 1969 Oxford University Press.