Responses of free running leaf movements to light,in particular to red and far red light during sunrise and sunset

Summary Daily leaf movements were compared with the intensities and proportions of red and far red light during sunrise and sunset. A linear relationship exists between the inverse of the 1/3 power of the minimum leaf movement against the elapsed time for its occurrence since either sunrise or sunset. A minimum of the ratio of the intensities of red to far red light at 6 min after sunrise and 16 min before sunset are suggested to be related to minimal levels of far red phytochrome and of ATP activity.