In agricultural and horticultural practices, which of the following...

Auxins are widely used in agricultural and horticultural practices. They help to initiate rooting in stem cuttings, an application widely used for plant propagation. Auxins also induce parthenocarpy, for example, in tomatoes. They are widely used as herbicides (like 2,4-D).

Gibberellins are used to increase the length of grape stalks, elongate and improve the shape of apples, delay senescence, and speed up the malting process.

Cytokinins help produce new leaves, chloroplasts in leaves, lateral shoot growth, and adventitious shoot formation.

Abscisic acid acts as a general plant growth inhibitor and an inhibitor of plant metabolism.

Answer: Auxins