HORTICULTURE

Detailed explanation-1: -Many different explanations have been proposed for why plant shoots grow “up” and roots grow “down.” (The growth of roots downward, in the direction of the pull of gravity, is called positive gravitropism and the growth of shoots upward, away from the pull of gravity, is called negative gravitropism.

Detailed explanation-2: -Gravitropism, also called geotropism, where geo-means the earth, and tropism refers to turning, is the growth of a plant’s organ or change in the direction of its growth in response to gravity.

Detailed explanation-3: -The roots grown downward in the direction of gravity, which is positive gravitropism, and the shoot grows upward away from gravity, which is negative gravitropism. The reason plants know which way to grow in response to gravity is due to amyloplasts in the plants.

Detailed explanation-4: -Plant parts can grow with or against gravity. This type of tropism is called gravitropism. Roots of a plant grow downward and exhibit positive gravitropism. Stems, on the other hand, exhibit negative gravitropism since they grow upwards and against the force of gravity (see Figure 1).

Detailed explanation-5: -Roots grow downward, or towards the center of Earth, and away from light. These responses to external stimuli are called tropisms. Plants’ growth response to gravity is known as gravitropism; the growth response to light is phototropism. Both tropisms are controlled by plant growth hormones.