Which of the following hormones is used in root formation on stem cutting?

Options

A. Kinetin
B. GA
C. ABA
D. IBA

Explanation

To determine which hormone is used in root formation on stem cuttings, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Plant Growth Hormones**:
- Plant growth hormones, also known as phytohormones, are substances that regulate various aspects of plant growth and development. They can be natural or synthetic.

2. **Identify the Role of Auxins**:
- Auxins are a class of plant hormones that play a crucial role in the growth and development of plants. They are particularly important in processes such as cell elongation, apical dominance, and root formation.

3. **Focus on Root Formation**:
- When it comes to root formation, auxins are specifically known to stimulate the development of roots from stem cuttings. This is a common practice in plant propagation.

4. **Identify Specific Auxins**:
- Among the auxins, several types are used for promoting root growth. The most commonly referenced ones include Indole-3-butyric acid (IBA), Naphthaleneacetic acid (NAA), and Indole-3-acetic acid (IAA).

5. **Determine the Correct Answer**:
- The hormone that is most commonly used for root formation on stem cuttings is IBA (Indole-3-butyric acid). It is effective in stimulating root growth and can be found in both natural and synthetic forms.

### Final Answer:
The hormone used in root formation on stem cutting is **Indole-3-butyric acid (IBA)**.

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