RECOVERY OF GROWTH OF SOYBEAN HYPOCOTYLS UNDER CONTINUOUS RED-LIGHT

Red light accelerated the elongation of the hooks of dark-grown soybean seedlings (Glycine max L.) but suppressed the elongation of the elongation zone of the hypocotyls. The lag time prior to the acceleration of hook elongation by red light was longer by about 19 h than that associated with the suppression of elongation of the elongation zone. Twenty-seven h after the onset of red light, the enhanced elongation of the hook part balanced the reduced elongation of the elongation zone, and the plant resumed stem elongation at the maximum rate in spite of continued red irradiation. Subsequently, the growth rate of soybean seedlings exposed continuously to red light was equal to that of non-irradiated seedlings of the same age.