Which of the following effects of auxins on plants is the basis for their commercial application?

Options

A. Callus formation
B. Curvature of stem
C. Induction of root formation in stem cuttings
D. Induction of shoot formation

Answer

To answer the question regarding the effects of auxins on plants that serve as the basis for their commercial application, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Auxins**: Auxins are a type of plant hormone that play a crucial role in the growth and development of plants. They are involved in various processes such as cell elongation, root formation, and the regulation of plant responses to light and gravity.

2. **Commercial Applications of Auxins**: Auxins have several commercial applications, particularly in agriculture and horticulture. One of the most significant uses is in promoting root formation in plant cuttings.

3. **Root Formation in Stem Cuttings**: When stem cuttings are taken from a plant, auxins can be applied to encourage the development of roots. This process is essential for vegetative propagation, where new plants are produced from parts of existing ones.

4. **Synthetic Auxins**: In commercial practices, synthetic auxins such as NAA (Naphthalene Acetic Acid) are often used to enhance root formation in cuttings. These synthetic hormones mimic the natural auxins and are effective in promoting rooting.

5. **Identifying the Correct Option**: Given the context of the question, the correct answer would be the effect of auxins that specifically relates to the induction of root formation in stem cuttings, as this is widely utilized in commercial applications for propagating plants.

### Final Answer:
The effect of auxins on plants that serves as the basis for their commercial application is the **induction of root formation in stem cuttings**.

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