EFFECTS OF RED AND FAR-RED ILLUMINATION ON THE ELONGATION OF FERN PROTONEMATA AND RHIZOIDS

Abstract
The elongation of fern protonemata is controlled by red and far-red light in an atypical fashion. Red light promotes the elongation of young plants but inhibits the elongation of older plants. Far-red light promotes elongation regardless of filament age, and the maximum promotion by far-red is greater than the promotion which red light causes in young filaments. The elongation of rhizoids is under typical red, far-red control. Red light promotes elongation, and a period of far-red illumination following red light treatment negates the promotive effects of red light.