Very Short Question and Answers - Plant Hormones

Plant hormones, also called phytohormones, are chemical substances produced in plants that control and regulate growth, development, and responses to stimuli.

Auxins, Gibberellins, Cytokinins, and Abscisic Acid (ABA) are the four major types.

Auxins are mainly responsible for cell elongation in stems.

Auxins accumulate more on the shaded side of a plant shoot, causing that side to grow faster and the shoot to bend towards the light.

Gardeners use synthetic auxins to promote rooting in stem cuttings for plant propagation.

Gibberellins can make dwarf pea and rice plants grow taller by stimulating stem elongation.

Gibberellins help seedless grapes develop by making them larger and causing the fruits to grow further apart.

Gibberellins are crucial because they speed up the germination of barley grains, which is necessary for malt formation.

Cytokinins promote cell division (cytokinesis), delay leaf aging, and encourage shoot growth.

Cytokinins delay the aging (senescence) of leaves, keeping vegetables green and fresh for longer.

ABA causes stomata to close, reducing water loss through transpiration and helping the plant survive drought.

Abscisic acid promotes seed dormancy, preventing seeds from germinating in winter until conditions are favorable.

Cytokinins are found in high amounts in coconut water and used in plant tissue culture.

Auxins are sprayed to prevent premature fruit drop, helping to hold fruits like apples and oranges on trees until harvest.

Gibberellins increase stem internode length, resulting in taller plants and greater yield in sugarcane.

Cytokinins are applied to stimulate the formation of more shoots in plant tissue culture.

Promoting rooting in stem cuttings and promoting uniform fruit setting (such as producing seedless tomatoes).

Abscisic acid promotes leaf abscission, helping trees shed their leaves in autumn.

They help control crop growth, allow mass propagation, improve fruit quality, and aid in harvest and post-harvest handling.

a) Auxins - 4) Phototropism, b) Gibberellins - 3) Stem elongation, c) Cytokinins - 1) Delays ageing, d) Abscisic Acid - 2) Inhibits growth.