What is the primary response of roots to gravity known as?

The primary response of roots to gravity is known as positive geotropism. This phenomenon occurs when roots grow downward, towards the gravitational pull of the Earth. This growth pattern is crucial for the plant as it anchors the roots in the soil, allowing the plant to absorb water and nutrients effectively.

Roots exhibit positive geotropism to ensure they establish a stable and secure environment, which supports the overall growth of the plant. In contrast, shoots of the plant usually exhibit negative geotropism, as they grow away from gravity, reaching upward toward light sources. Phototropism refers to growth in response to light rather than gravity, while hydrotropism relates to the growth response of roots to moisture gradients in the soil. Therefore, the specific growth response of roots downward in relation to gravity is accurately identified as positive geotropism.