Agriculture
Stress Management :: Temperature

HIGH TEMPERATURE STRESS

Plant life exists between temperatures of -890C to +580C . However most of the plants are adapted to limited range of temperatures. If the temperature drops below 150C plants experience low temperature stress and if it is above 450C , plants are subjected to high temperature stress.

Increase of 15 – 200C above normal temperature causes deeper modification of growth without being necessarily lethal viz., protein denaturation, enzyme inactivation, reduction in chloroplast’s photosynthetic activity.

Heat stress on growth and development

  • Seedling establishment is hampered
  • Pollen development is affected
  • Grain and fruit development and quality is affected

Cellular Changes during heat stress

When plants are exposed to temperatures higher than 450C it experiences heat stress. The cellular changes due to heat stress are

  • Disruption of cytoskeleton and microtubules.
  • Fragmentation of golgi complex
  • Increase in number of lysosomes
  • Swelling of mitochondria thereby resulting in decreased respiration and oxidative phosphorylation
  • Disruption of normal protein synthesis
  • Disappearance of polysomes
  • Disruption of splicing of mRNA precursors
  • Cessation of pre-RNA processing
  • Decline in transcription by RNA polymerase I
  • Inhibition of chromatin assembly
  • Decline in DNA synthesis
 

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