When intermediate light is given red → far red → red
When light period is interrupted by a flash of far light
When light period is interrupted by a flash red → far light
All of the above
Correct answer: (a)
Solution: Short day plants flower, when the length of daylight falls below a certain critical level. A short day plant requires a minimal length of uninterrupted darkness in each 24 hour period before floral development can begin. It has been determined experimentally that a short day plant does not flower if a dark period is interrupted by a brief exposure to a red light (660-665 nm wavelength. The inhibitory effect of the red light can be overcome by the subsequent exposure to the far red light (730-735 nm wavelength. However, if the light period is interrupted with red light, the flowering is not inhibited.