Given below are the five experiments (A-E) showing effects of duration of the light and dark periods on flowering of the short-day plants (SDP) and long-day plants (LDP).

Which one of the following options represents the combination of all correct flowing responses?

Correct option is B

(b) A, B, and E

Sol. Let's break it down:

• Experiment A: This experiment shows that the SDP flowers with a long period of darkness and a short light period, which is correct for short-day plants (SDP). SDP needs a longer dark period to flower.

• Experiment B: This experiment shows that the SDP remains vegetative when exposed to a short period of darkness and a long period of light. This is correct as SDP requires a long dark period for flowering, and this shorter darkness does not trigger flowering.

• Experiment E: This experiment shows the LDP flowering with a long light period and short darkness, which is correct for long-day plants (LDP), as they need long light periods to flower.

Why Option A, B, and E are correct:

• Experiment A correctly shows the flowering response of SDP, as SDP requires long dark periods and short light periods to flower.

• Experiment B shows the correct vegetative response for SDP, as short dark periods do not induce flowering in SDP.

• Experiment E shows the correct flowering response for LDP, as they need long light periods and short dark periods to flower.

Information Booster:

• Short-Day Plants (SDP): These plants flower when the dark period exceeds a critical duration (usually more than 12 hours), and they remain vegetative if the dark period is too short. Experiment A and Experiment B correctly show how SDP behaves under different light and dark conditions.

• Long-Day Plants (LDP): These plants require long light periods (usually more than 12 hours) and short dark periods for flowering. Experiment E correctly shows that LDP flowers under long light exposure.

Additional Information:

• Experiment C: The response shown for SDP in Experiment C (flowering under short darkness) is incorrect, as SDP requires long darkness for flowering. Hence, this does not match the correct flowering response for SDP.

• Experiment D: In this experiment, SDP flowers with a long light period, which is not correct. SDP requires a long dark period, not long light exposure, for flowering. Therefore, this response is incorrect for SDP.