Explain the physiological effects of ABA.

Explanation

• It helps in reducing transpiration rate by closing stomata. It inhibits Kuptake by guard cells and promotes the leakage of malic acid. It results in closure of stomata.
• It spoils chlorophylls, proteins and nucleic acids of leaves making them yellow.
• Inhibition of cell division and cell elongation.
• ABA is a powerful growth inhibitor. It causes 50% inhibition of growth in Oat coleoptile.
• It induces bud and seed dormancy.
• It promotes the abscission of leaves, flowers and fruits by forming abscission layers.
• ABA plays an important role in plants during water stress and during drought conditions. It results in loss of turgor and closure of stomata .
• It has anti-auxin and anti-gibberellin property.
• Abscisic acid promotes senescence in leaves by causing loss of chlorophyll pigment decreasing the rate of photosynthesis and changing the rate of proteins and nucleic acid synthesis.