Discuss the types of Cold Injury

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1. Chilling injury: Plants which are adapted to hot climate, if exposed to low temperature for sometime are found to be killed or severely injured. Some effects of chilling are development of chlorotic condition (Yellowing)
Example: Chlorotic bands in the leaves of sugarcane, sorghum and maize in winter months when the night temperature is below 20oC.
In temperate climate two types of injuries occur because of low temperature. They are delayed growth and sterility.
Example: In Japan, rice yield decreases due to insufficient grain maturation caused by low temperature during the ripening period. Flowering is delayed by low temperatures at a certain stage before heading.
A Rice yield decrease due to sterility of spikelet’s caused by low temperature at the booting stage or at anthesis.
The observed injuries may be stoppage of anther development, Pollen un-ripeness, Partial or no dehiscence, Pollen grains remaining in anther loculi, Little or no shedding of pollen grains on stigma and Failure of germination of pollen on stigma.

2. Freezing Injury: Plant parts or entire plant may be killed or damaged beyond repair as a result of actual freezing of tissues.
Ice crystals are formed first in the intercellular spaces and then within the cells. Ice, within the cells, causes more injury by mechanical damage on the structure of the protoplasm and plasma membrane.
Freezing of water in intercellular spaces results in withdrawal of water from the cell sap due to dehydration and causes death of cells. Eg., Frost damage in potato, tea, etc.,.

3. Suffocation: In temperate regions, usually during the winter season, the ice or snow forms a thick cover on the soil surface. As a result the entry of O2 is prevented and plants suffer for lack of O2.
Ice coming in contact with the roots prevents the diffusion of CO2 outside the root zone. This prevents the respiratory activities of roots leading to accumulation of harmful substances.

4. Heaving: This is a kind of injury caused by lifting up of the plants along with soil from its normal position. This type of injury is common in temperate regions. The presence of ice crystals increases the volume of soil. This causes mechanical lifting of the soil.

francis1897 answered the question on January 11, 2023 at 08:24

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Discuss the types of Cold Injury

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