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The response spectrum for green light induced-acceleration of heading in wheat cv. Norin 61 was investigated using narrow-bandwidth (10 nm) green light within the range of 520–550 nm. Heading was observed from approximately 30 days after emergence. The earliest heading was observed at 540 nm, which suggests the presence of a green light photoreceptor different from hitherto known photoreceptors.

The developmental rate of wheat was investigated under continuous light of eight different qualities (in eight plots) obtained by combining three out of four different kinds of fluorescent lamps (white, blue, purplish red and ultraviolet-A) at a constant temperature of 20°C. A Japanese spring wheat var. Norin 61 and a winter wheat var. Shun-yo were used.The number of days from seeding to heading varied extensively with the variety and the light quality. The first heading wasobserved in the plot under three white fluorescent lamps (W + W + W) at 37 and 81 days after seeding in Norin 61 and Shun-yo, respectively. The developmental rate in both cultivars was significantly correlated with the ratio of energy in 500–550 nm range (green light) and 600–700 nm range (red light) to that in the whole spectral range (250–1,000 nm). These results suggest that green and red lights play important roles in the regulation of the developmental rateindependent of photoperiodism and vernalization.