If the dark period is interrupted by a flash of red light of 660 nm, then the short day plants do not flower. But if it is followed by ____, these plants will flower.

Step-by-step solution

Short-day plants require a continuous critical dark period for flowering. The photoreceptor responsible for measuring the dark period is phytochrome, which exists in two interconvertible forms: P_r (absorbs red light at 660 nm ) and P_ fr (absorbs far-red light at 730 nm ). During the dark period, P_ fr slowly converts back to P_r . If the dark period is interrupted by a flash of red light ( 660 nm ), P_r is rapidly converted to P_ fr , which inhibits flowering in short-day plants. This inhibitory effect of red lig