title: An irreversible red-light-induced growth response in Avena.
abstract: The inhibition of the growth rate of the first internode of Avena by red light occurs in three steps. The first step reduces elongation by ca. 15%. It is produced and saturated by 10(-3) to 10(-1) μW sec cm(-2) at λ=660 nm and is irreversible by far-red irradiation. All wavelengths between 400 and 800 nm produce and saturate this step. The second step, produced by red light quantities between ca. 10 and 10(4) μW sec cm(-2) reduces elongation to ca. 50% of the maximal; it is not produced by far-red light but far-red reverses completely this component of the effect of red light. The third step inhibits mesocotyl elongation to ca. 95% of the maximal. The effect of red light in this step depends on the duration of irradiation rather than on the total quantity of energy, and is not reversed by far-red irradiation. The three inhibition steps in the elongation of the mesocotyl are matched by three growth-promotion steps in the growth of the coleoptile, but the extent of the far-red-irreversible first step outweighs in this case by far the extent of the far-red-reversible second step.
authors: Botanical Laboratory of the State University, Utrecht, The Netherlands.
authors: O H
authors: OH
authors: Blaauw
authors: G
authors: G
authors: Blaauw-Jansen
authors: W J
authors: WJ
authors: van Leeuwen