Question

In the fall, the leaves of deciduous trees change color, fall off and die. This shedding of leaves is Mated by which of the following plant hormones?

• A. auxin
• B. gibberellin
• C. abscisic acid
• D. cytokinin
• E. ethylene

Answer 1

The correct option is C abscisic acid

A. Auxin plays role in cell elongation, apical dominance, root initiation, prevention of abscission, induction of parthenocarpy and also used as herbicide.

B. Gibberellin plays role in stem elongation, seed germination, breaking dormancy, elongation of internodes and inducing parthenocarpy.

C. Abscisic acid or ABA is known as stress hormone and induces stomatal closure, provides defence against salt and cold stress, induces dormancy, causes geotropism in roots and abscission of leaves, flowers and fruits.

D. Cytokinin plays role in promoting cell division and organ formation, delay in senescence, promoting lateral bud development in dicots, cell expansion in cotyledons leaves, promoting chloroplast development and chlorophyll synthesis.

E. Ethylene is a gaseous hormone and causes ripening of fruit.

So, the correct answer is 'Abscisic acid'.