Phytochrome action in Oryza sativa L. VII. Effects of light and aeration on coleoptile growth under submerged conditions

Coleoptile growth of intact rice seedlings under submerged conditionswas not much affected by the continuous irradiation of red light.But, if aerated, growth was strongly inhibited by a low-energybrief irradiation of red light, and this red light-induced effectwas reversed by a brief exposure to far-red light. The responsesto red and far-red light were repeatedly reversible. The amountof photometrically detectable phytochrome in non-aerated coleoptiletissues was found to be as low as one third that in aeratedones. After the conversion of Pr to Pfr by a brief red irradiation,the total (A) of the aerated tissues decreased to about onefifth that of the original level within 6 hr at 24?C, whilethe Pfr in the non-aerated tissues was significantly less decayed. ¹Present address: The Ocean Research Institute, University ofTokyo, Nakano, Tokyo 164, Japan. (Received April 30, 1974; )