Irradiation (light) Stress

• The radiant energy from the sun which plant convert into chemical energy by the process of photosynthesis, is one of the most important and variable components of plant environment
• Autotrophic plants are directly influenced by the intensity of light

Effects of light deficit:

• Low light intensities below the compensation point(suitable for photosynthesis) leads plant to lean and become thin but tall, increase in leaf area and in severe case, etiolation occurs

Effect of bright light: (λ =750-800)

• Bright light intensity above the compensation point increases the photosynthetic rate as well as the enzymatic activities than the normal one
• Alteration of light intensity results in disruption of plant metabolic processes which is termed as irradiation stress

Effect of ultra violet radiation: (λ= 100-400nm)

• Plant expands to such radiation after membrane permeability, inhibition of photosynthesis and respiration

Measures to overcome irradiation stress:

• Nursery plants and thatch loving plants should be protected from bright light by placing thatches and roofs over them
• Short day plants shouldn’t be grown in long day condition and vice versa
• Timely training and pruning for better exposure of trees to sun light