An effect of light on the production of ethylene and the growth of the plumular portion of etiolated pea seedlings.

The production of ethylene by etiolated pea epicotyls (Pisum sativum L., cv. Alaska) is confined to the plumule and plumular hook portion of the epicotyl, and occurs at a rate of about 6 mul.kg(-1).hr(-1). Such a rate is sufficient to give physiologically active concentrations of ethylene within the tissue. Exposure of etiolated seedlings to a single dose of red light caused a transient decrease in ethylene production and a corresponding increase in plumular expansion. Far-red irradiation following the red light treatment decreased the red effect to the level achieved by the far-red alone, suggesting that the ethylene production mechanism is controlled by phytochrome and thus that the ethylene intervenes as a regulator in the phytochrome control of plumular expansion.