Question

An example of long day plant

• A. Cotton
• B. Sugarbeet
• C. Chrysanthemum
• D. Tobacco

Hint:

To remember common photoperiodic classifications:
- Short-Day Plants: Soybean, Rice, Chrysanthemum, Strawberry.
- Long-Day Plants: Wheat, Barley, Spinach, Sugarbeet, Radish.
- Day-Neutral Plants: Tomato, Cotton, Sunflower, Maize, Dandelion.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Photoperiodism is the physiological response of plants to the relative lengths of light and dark periods in a 24-hour cycle.
Plants are classified into short-day plants (SDPs), long-day plants (LDPs), and day-neutral plants (DNPs) based on their flowering requirements.
Long-day plants flower only when the day length (light period) exceeds a specific critical photoperiod, or when the dark period is shorter than a critical duration.

Step 2: Detailed Explanation:
Let us analyze the photoperiodic responses of the given plant species:
Cotton (*Gossypium hirsutum*) is a day-neutral plant because its flowering is initiated after a certain vegetative growth stage, regardless of the day length.
Chrysanthemum (*Chrysanthemum* species) is a classic short-day plant that flowers in late autumn when day lengths shorten.
Tobacco (*Nicotiana tabacum*) is generally classified as day-neutral or short-day depending on the specific cultivar (such as the mutant Maryland Mammoth which is a classic SDP).
Sugarbeet (*Beta vulgaris*) is a biennial plant that requires exposure to long days (typically more than $14\text{ hours}$ of light) along with low-temperature vernalization to induce bolting and flowering.
Therefore, Sugarbeet is a classic example of a long-day plant.

Step 3: Final Answer:
An example of a long-day plant is Sugarbeet.
This corresponds to Option (B).