To increase sugar production in sugarcanes, they are sprayed with

Options

A. I A A
B. cytokinin
C. gibberellin
D. ethylene

Explanation

To solve the question of what substance is sprayed on sugarcanes to increase sugar production, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Context**: The question pertains to increasing sugar production in sugarcanes, which are a significant crop for sugar extraction.

2. **Understand Plant Hormones**: The options given are indole acetic acid, cytokinins, gibberellins, and ethylene. Each of these hormones has different roles in plant growth and development.

3. **Analyze Gibberellins**: Gibberellins are known to promote stem elongation and increase the overall height of plants, including sugarcanes. This elongation can lead to a higher yield of sugarcane.

4. **Evaluate Other Hormones**:
- **Indole Acetic Acid (IAA)**: Primarily involved in cell elongation and root growth.
- **Cytokinins**: Promote cell division and can influence shoot and root growth but do not directly increase sugar content.
- **Ethylene**: Involved in fruit ripening and senescence but does not significantly affect sugar production in sugarcanes.

5. **Conclusion**: Since gibberellins are specifically known to increase the length of sugarcanes, which in turn can lead to increased sugar production due to higher biomass, the correct answer is gibberellins.

### Final Answer:
To increase sugar production in sugarcanes, they are sprayed with **gibberellins**.

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