Tropism means movement of the part of the plant either in the direction of the stimuli or away from the stimuli. Stimuli can be light, gravity, water or chemicals. For example, in case of phototropism means movement of part of the plant in the presence of light, in this two type of movement is seen shoots moves or grows in the direction of light whereas in case of roots, it grows in the direction opposite to the light. So, with different stimulus plants show different tropism or directional movement.

It is true that plants shows tropism to stimulus. For example , sunflower get directed towards the sun. The flower changes it's direction accordingTo the sun. One another example is that of roots ,if we place a pot in horizontal direction then the roots will be directed downwards.

Plant Show Tropism in Response to Stimuli

Plants are remarkable organisms capable of responding to external stimuli. Tropism is a type of plant response that involves growth or movement towards or away from a stimulus. These responses allow plants to adapt and optimize their growth in various environmental conditions. Tropisms are vital for plant survival, as they enable plants to obtain the necessary resources for growth and reproduction.

Types of Plant Tropisms:

There are several types of tropisms that plants exhibit, including:

1. Phototropism: Phototropism is the growth or movement of a plant towards or away from light. This response is crucial for plants to maximize their exposure to sunlight, which is essential for photosynthesis. The cells on the shaded side of the plant elongate, causing the plant to bend towards the light source.

2. Gravitropism: Gravitropism, also known as geotropism, is the growth or movement of a plant in response to gravity. It allows plants to orient their growth in relation to the Earth's gravitational pull. Roots exhibit positive gravitropism, growing downwards into the soil, while shoots display negative gravitropism, growing upwards towards the light.

3. Thigmotropism: Thigmotropism is the growth or movement of a plant in response to touch or mechanical stimuli. This tropism allows plants to respond to physical contact, such as climbing or wrapping around a support structure. Examples include vines entwining around a trellis or tendrils curling around a support.

4. Hydrotropism: Hydrotropism is the growth or movement of a plant in response to water. It enables plants to direct their roots towards sources of moisture. Plant roots exhibit positive hydrotropism, growing towards areas with higher water content.

Mechanisms of Tropism:

Tropisms are primarily controlled by plant hormones, specifically auxins. Auxins are plant growth hormones that regulate cell elongation and growth. They are produced in the apical meristems and transported throughout the plant in a polar manner.

The Role of Auxins:

In phototropism, auxins accumulate on the shaded side of the plant, promoting cell elongation and bending towards the light source. In gravitropism, auxins accumulate on the lower side of the horizontal root or shoot, inhibiting cell elongation and causing downward or upward growth, respectively.

Conclusion:

Plant show tropism is a fascinating phenomenon that allows plants to respond and adapt to their surroundings. By exhibiting phototropism, gravitropism, thigmotropism, and hydrotropism, plants can optimize their growth and survival strategies. These tropisms are controlled by plant hormones, particularly auxins, which regulate cell elongation and growth. Understanding tropisms is vital for understanding plant behavior and how plants interact with their environment.