What is geotropism in plants?

Geotropism is the growth response of a plant in relation to gravity; roots show positive geotropism, while shoots show negative geotropism.

Geotropism, also known as gravitropism, is a key aspect of a plant's growth and development. It is the process by which plants orientate their growth in response to gravity. This is a vital survival mechanism, allowing plants to grow in the correct direction for optimal access to resources.

The roots of a plant exhibit positive geotropism, meaning they grow downwards, towards the pull of gravity. This allows them to anchor the plant in the ground and absorb water and nutrients from the soil. On the other hand, the shoots of a plant show negative geotropism, growing upwards, away from the pull of gravity. This enables them to reach sunlight for photosynthesis, the process by which plants convert light energy into chemical energy to fuel their growth.

The mechanism behind geotropism involves plant hormones called auxins. When a plant is tilted, gravity causes these auxins to accumulate on the lower side of the plant. In the roots, this high concentration of auxins inhibits growth, causing the roots to bend and grow downwards. In the shoots, however, the auxins promote growth, causing the shoots to bend and grow upwards.

In summary, geotropism is a fundamental biological process that guides the directional growth of plants in response to gravity. It involves the differential growth of plant parts, regulated by the distribution of auxins, which ensures that roots grow down into the soil and shoots grow up towards the light.