Types of Stress-Environmental soil and

Physiological surface

By

Arooba Tariq

M.Sc(Hons) PBG

Stress:

‘Stress’ in plants can be defined as any external

factor that negatively influences plant growth,

productivity, reproductive capacity or survival.

It divided into two main categories:

Abiotic or environmental stress factors.

Biotic or biological stress factors.

Biotic or biological stressBiotic stress would include such living

disturbances as fungi or harmful insects, e.g.,

Animal stress, insect stress, fungi stress, etc.

Fungi by rotting of heart wood, animals by

breaking and grazing, insects by

eating skeleton or leaves, etc.

Animal Stress by grazing

Insect stress by eating leaves

Fungi stress by rotting

A biotic or environmental stressA biotic stress is defined as the negative

impact of non-living factors on the

living organisms in a specific environment.

A biotic stress factors or stressors are naturally

occurring factors such as intense sunlight or

wind that may cause harm to the plants and

animals in the area affected.

Stresses can be studied classifying into the following different kinds:Drought stress.Water stress.Salt stress.Heat stress.Wind stress.Nutrient stress.

Drought stress:It occurs when the available water in the soil is

reduced and atmospheric conditions cause

continuous loss of water by transpiration

or evaporation. Drought stress is seen

in almost all plants but its extent varies from

species to species and even within species

Drought stress

Water stress:Water stress may result in the arrest

of photosynthesis, disturbance of metabolism

and finally the death of plant. Water stress

inhibits cell enlargement more than cell

division. It reduces plant growth by affecting

various physiological and biochemical

processes. 

Water stress

Salt stress:It includes wild plants that thrive in the

saline environments along the sea shore and

saline deserts. These plants, called halophytes,

have distinct physiological and anatomical

adaptations to counter the hazards of

water deficit. Salinity can affect any process in

the plant's life cycle.

Salt stress

Heat stress:Heat stress often is defined as where

temperatures are hot enough for sufficient time

that they cause irreversible damage to plant

function or development. In addition, high

temperatures can increase the rate of

reproductive development, which shortens

the time for photosynthesis to contribute to

fruit or seed production.

Heat stress

Wind stress: Wind stress is visual stress incurred by wind

causes damage to seedlings, breaking branches

and even uprooting the whole plants.

Wind stress

Nutrient stress:Nutrient stress is one of the major stressor

causing dying back in plants. It causes due to

the shortage of nutrients in soil such as

nitrogen, phosphorus, iron, etc.

Nutrient stress

Difference between biotic and abiotic stress:

Abiotic damage often occurs on many plant species.

Drought stress will likely cause damage on several

types of plants in a yard or garden. In contrast,

Biotic disease problems are more limited to a certain

species. The fungi that cause tomato leaf blight do

not cause damage on sweet corn.

Abiotic damage does not spread from plant to plant

over time. Biotic diseases can spread throughout one

plant and also may spread to neighboring plants of the

same species. Wind-blown rain is a common way for

disease agents to spread from plant to plant.

Biotic diseases sometimes show physical

evidence (signs) of the pathogen.

Abiotic diseases do not show the presence of

disease signs.