Effect of Blue and Red Lights on Leaf Inclination of Wheat Plant

Abstract

The effect of monochromatic light and the interaction of blue and red lights on leaf blade inclination in wheat plants) Triticum aestivum L., cv. Shirasagi-Komugi) were studied.1) Blue light caused inclination of the blades of the first leaves. When 7-day-old seedlings grown in darkness were exposed to blue, green, yellow, red, far-red and white lights, and to darkness for 72 hours, the angles of the leaf blade were 113°, 13°, 13°, 14°, 30°, 30° and 12°.2) The spectral regions effective for inclination were the wavelengths between 380 and 510 nm, with a marked response at 430-480 nm.3) Blue light of 2000 erg/cm2/sec was fully effective, the maximum inclination response was obtained 72 hours after the start of irradiation. Photosensitivity to blue light showed a maximum response 2-3 days after the laminar joint appeared from the top of the coleoptile.4) Red or yellow lights applied simultaneously with blue light counteracted inclination. The counteracting spectral regions appeared at wavelengths between 560 and 690 nm with a marked response at 630-640 nm.5) The counteracting effect of red light on blue light differed with the mixed ratio of red light to blue light (R/B ratio) . The blade angle of leaves in wheat plants exposed to blue light (2000 erg/cm2/sec) for 72 hours was about 100°, whereas the angle for the R/B ratio of 1/10 was about 40°, 30° for the 1/4 ratio, 25° for the 1/2 ratio, and 20° for the 1/1 ratio.