76.Hormone antagonist to gibberellins is: A. IAA B. ABA C. Zeatin D. Ethylene
Option B. Gibberellin or Gibberellic Acid (GA) is produced in embryos, roots, and young leaves and it enhances growth. Abscisic acid is a naturally occurring growth inhibitor found in wide variety of plants, synthesised in leaves. Gibberellin delays senescence in plants. Abscisic acid promotes the senescence of leaf, i.e., fall of leaves happens due to abscisic acid. Gibberellin breaks dormancy of seeds and as opposed to Abscisic acid, which induces dormancy of buds and seeds. Hence, due to their opposite effect on plant growth, Gibberellins and Abscisic acid can be said to be an antagonist to each other. So, the correct answer is 'ABA'
