**Effect of Auxins in Different Parts of Plant**

Auxins are a group of plant hormones that play a crucial role in the growth and development of plants. They are primarily produced in the apical meristem (growing tip) of the plant and are transported to various parts of the plant to regulate various physiological processes. Here, we will discuss the effects of auxins in different parts of the plant.

**1. Apical Dominance:**
- Auxins promote apical dominance, which means that the growth of the main shoot is favored over lateral shoots or branches.
- The apical meristem produces high concentrations of auxins, which inhibit the growth of lateral buds.
- This results in the upward growth of the main shoot, while lateral shoots remain dormant.

**2. Stem Elongation:**
- Auxins stimulate cell elongation in the stem, resulting in increased stem length.
- They promote the synthesis of proteins required for cell expansion and stimulate the uptake of water by cells, leading to an increase in cell turgor pressure.
- This elongation growth is known as phototropism, where the plant bends towards a light source.

**3. Root Growth:**
- Auxins play a crucial role in promoting root growth.
- They inhibit cell elongation in the root, resulting in the formation of a dense root system with increased surface area for water and nutrient absorption.
- Auxins also stimulate the development of lateral roots, which further enhance the root system's efficiency.

**4. Fruit Development:**
- Auxins are involved in fruit development and ripening.
- They promote cell division and enlargement in the developing fruit, leading to fruit growth.
- Additionally, auxins regulate the production of enzymes responsible for fruit ripening, such as cellulases and pectinases.

**5. Leaf Abscission:**
- Auxins control leaf abscission, which is the natural shedding of leaves.
- They inhibit the abscission process by preventing the formation of a separation layer between the leaf and stem.
- However, when auxin levels decrease, such as during autumn, the abscission layer forms, and the leaves fall off.

**6. Tropisms:**
- Auxins are responsible for various tropic responses in plants, such as phototropism (response to light), geotropism (response to gravity), and thigmotropism (response to touch).
- In phototropism, auxins accumulate on the shaded side of the stem, causing elongation and bending towards the light source.
- In geotropism, auxins accumulate on the lower side of the root, inhibiting cell elongation and causing downward growth.

In summary, auxins have diverse effects in different parts of the plant. They promote apical dominance, stem elongation, root growth, fruit development, and regulate leaf abscission. Additionally, auxins are responsible for various tropic responses in plants. Understanding the effects of auxins is crucial for manipulating plant growth and development in horticulture and agriculture practices.