What is tropism in plants?

Tropism in plants refers to the growth response of plants to external stimuli such as light, gravity, and touch. There are different types of tropisms, including phototropism (response to light), gravitropism (response to gravity), and thigmotropism (response to touch).

• Phototropism: Plants exhibit phototropism by bending towards a source of light. This response allows plants to optimize their exposure to sunlight for photosynthesis. The hormone auxin plays a crucial role in regulating phototropism by promoting cell elongation on the shaded side of the plant, causing it to bend towards the light source.

• Gravitropism: Also known as gravitropism or geotropism, this tropism refers to the growth response of plants to the force of gravity. Roots exhibit positive gravitropism, growing downward into the soil, while shoots exhibit negative gravitropism, growing upward away from the soil. The differential distribution of auxin in response to gravity is responsible for these growth patterns.

• Thigmotropism: Thigmotropism is the growth response of a plant to touch or mechanical stimuli. For example, climbing plants such as vines exhibit thigmotropism by growing towards a support structure and wrapping around it. This enables the plant to climb and better access sunlight.

Tropisms are important for plants to adapt to their environment and maximize their chances of survival and reproduction. By responding to external stimuli, plants can optimize their growth patterns and resource acquisition.