Quantitative or qualitative flowering depends upon low temperature . This phenomenon is called

Options

A. Photoperiodism
B. Vernalisation
C. Dormancy
D. Abscission

Answer

**Step-by-Step Solution:**

1. **Understanding the Context**: The question states that the flowering of certain plants depends on low temperatures, which indicates a specific physiological response to environmental conditions.

2. **Identifying the Phenomenon**: The phenomenon where flowering is induced by low temperatures is known as **vernalization**. This term refers to the process where exposure to a prolonged period of cold temperatures promotes flowering in certain plants.

3. **Mechanism of Vernalization**:
- Some plants require a specific chilling treatment to trigger flowering. This chilling treatment must occur before the plant is exposed to the appropriate photoperiod (light conditions).
- The chilling treatment typically involves temperatures between 0 to 5 degrees Celsius.

4. **Biological Sites of Action**: The sites where vernalization occurs include:
- Shoot Apex
- Root Apex
- Leaf Apex
- Embryo Apex
These areas contain highly dividing cells that are crucial for the flowering process.

5. **Requirements for Effective Vernalization**:
- The temperature must remain low during the vernalization period.
- After the chilling treatment, the plant should not be exposed to high temperatures immediately, as this can negate the effects of vernalization.
- Adequate nutrients, water, and conditions for aerobic respiration are also important for the plant’s health during this process.

6. **Outcome of Vernalization**: Once the plant undergoes vernalization, it produces a substance known as **vernaline**, which signals the plant to initiate flowering. This process not only induces flowering but also helps in reducing the juvenile or vegetative stage of the plant and increases its resistance to cold and diseases.

**Final Answer**: The phenomenon where quantitative or qualitative flowering depends upon low temperature is called **vernalization**.

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