Types of Responses

 
5.1 Types of Responses
 
 
  Tropism
Definition A response of plant in which the direction of response is determined by the external stimulus 
Reason of action  Is controlled by phtohormones
Time of action Slow and not apparent
Direction

Positive tropism: growth towards direction of stimulus

Negative tropism: growth away from stimulus

Examples

Geotropism: plant response to gravity

Phototropism: plant response to light

chemotropism: plant response to chemical

Hydrotropism: plant respose to water

Thigmotropism:plant response to touch

 
 
  Nastic
Definition A response of plant toward a stimulus but the direction of response is determined by itself,not the stimulus direction
Reason of action Is controlled by changes of turgal pressure and some nastic responses are intended for survival
Time of action Rapid and apparent
Examples

Photonasty: plant response to light

Seismonasty: plant response to mechanical stimulus

Thermonasty: plant response to changes in temperature

Thigmonasty: plant response to vibration

Nyctinasty: a circadian rhythm that responds towards the onset of darkness

 

Types of Responses

 
5.1 Types of Responses
 
 
  Tropism
Definition A response of plant in which the direction of response is determined by the external stimulus 
Reason of action  Is controlled by phtohormones
Time of action Slow and not apparent
Direction

Positive tropism: growth towards direction of stimulus

Negative tropism: growth away from stimulus

Examples

Geotropism: plant response to gravity

Phototropism: plant response to light

chemotropism: plant response to chemical

Hydrotropism: plant respose to water

Thigmotropism:plant response to touch

 
 
  Nastic
Definition A response of plant toward a stimulus but the direction of response is determined by itself,not the stimulus direction
Reason of action Is controlled by changes of turgal pressure and some nastic responses are intended for survival
Time of action Rapid and apparent
Examples

Photonasty: plant response to light

Seismonasty: plant response to mechanical stimulus

Thermonasty: plant response to changes in temperature

Thigmonasty: plant response to vibration

Nyctinasty: a circadian rhythm that responds towards the onset of darkness