How you can increase the size of orange fruit?

1. Genetic selection: Use varieties known for producing larger fruit.

2. Soil conditions: Ensure the trees have well-draining, loamy soil rich in organic matter.

3. Water management: Provide consistent, even irrigation during fruit development.

4. Fertilizer application: Use a balanced fertilizer with micronutrients, like zinc and boron, that contribute to fruit size.

5. Pest and disease control: Protect the trees from pests and diseases to avoid yield loss, including proper management of citrus tristeza virus through rootstock selection.

6. Pruning: Pruning can enhance fruit size by increasing the tree's ability to direct resources to developing fruit.

7. Temperature and sunlight: Adequate levels of sunlight facilitate photosynthesis, and ideal temperatures help in fruit expansion.

8. Gibberellic acid application: Use of plant growth regulators like gibberellic acid may enhance fruit size, however, this practice may vary under local regulations and market requirements.

9. Irrigation methods: Using efficient irrigation techniques like drip irrigation helps ensure plants receive water evenly in dry conditions.

Remember that environmental conditions and local regulations can influence the feasibility of applying these practices. Consultation with local agricultural experts is recommended to understand what best suits specific orange-growing areas.