Nature of Light - Floral Induction

Red light promotes flowering in short day plants. If the dark regime of a short day plant is interrupted by red light, flowering is inhibited, indicating the importance of the uninterrupted dark period. If a brief exposure to far-red light follows the exposure to red light it can over the inhibitory effect of red light. All these observations suggest the involvement of a pigment. Chlorophyll can be ruled out as chlorophyll never shows any such far-red light reversal effects.