Plant Stimulus and Response

1.3  Plant Stimulus and Response

 

Definition

Plants respond to touch, water, light, and gravity which are divided into two, namely the tropism response and the nastic response.

Types of tropism and reactions:

Type of tropism

Example

Phototropism

Growth of plant parts towards the light

The growth of sunflower shoots in the direction of sunlight

Geotropism

Growth of plant parts towards gravity

Root growth of red chili tree according to the direction of gravity

Hydrotropism

Growth of plant parts towards the water

Growth of pandan tree roots in the direction of water

Tigmotropism

The movement of plant growth against touch or when in contact with an object

Cucumbers have suckers that twist an object that touches them

Nastic response:

  • Plants respond to touch, light, and heat

  • The direction of the response does not depend on the direction of the stimulus

  • For example, the leaves of a semalu tree (Mimosa pudica) are covered when touched

The importance of each response:

Response

Importance

Phototropism

Helps shoots get sunlight for photosynthesis

Geotropism

Helps the roots penetrate the soil to obtain water and the roots can grip the soil firmly

Hydrotropism

Helps plant roots absorb water and mineral salts from the soil

Tigmotropism

Helps plants reach the highest position to get sunlight and maintain an upright position

Nastic movement

Protects leaves from injury

Plant Stimulus and Response

1.3  Plant Stimulus and Response

 

Definition

Plants respond to touch, water, light, and gravity which are divided into two, namely the tropism response and the nastic response.

Types of tropism and reactions:

Type of tropism

Example

Phototropism

Growth of plant parts towards the light

The growth of sunflower shoots in the direction of sunlight

Geotropism

Growth of plant parts towards gravity

Root growth of red chili tree according to the direction of gravity

Hydrotropism

Growth of plant parts towards the water

Growth of pandan tree roots in the direction of water

Tigmotropism

The movement of plant growth against touch or when in contact with an object

Cucumbers have suckers that twist an object that touches them

Nastic response:

  • Plants respond to touch, light, and heat

  • The direction of the response does not depend on the direction of the stimulus

  • For example, the leaves of a semalu tree (Mimosa pudica) are covered when touched

The importance of each response:

Response

Importance

Phototropism

Helps shoots get sunlight for photosynthesis

Geotropism

Helps the roots penetrate the soil to obtain water and the roots can grip the soil firmly

Hydrotropism

Helps plant roots absorb water and mineral salts from the soil

Tigmotropism

Helps plants reach the highest position to get sunlight and maintain an upright position

Nastic movement

Protects leaves from injury