Question

plant hormones and their function​

Answer 1

Plant hormones are known as phytohormonesin botanical terms. They are chemicals just like animal hormones that help in the growth, development, and functioning of plants. Like animals, plants too are living organisms that function as a unit. They carry out vital biochemical reactions that are required to survive. These biochemical reactions require hormones also known as 'plant growth substances'. These hormones help in the formation of leaves, flowers, stems, fruit, etc. They also help in determining the sex of the flowers, the color of the fruits, and leaves. They help in formation of tissues, respiration, energy production, and even plant longevity and death. Just as hormones are necessary for an animal body to function without any glitches, they too help the green living beings to survive normally. In this article, we shall cover some information related to these secretions and their functions.

What Are the Functions of Plant Hormones?

These hormones help in regulation of the plant body by responding to the various signals from the plant and environment. The hormones are regulated in different tissues during the different development stages. There are five major hormones which are auxin, cytokinin, gibberellin, abscisic acid, and ethylene. Each hormone differs in its effects. The auxins, gibberellins, and cytokinins act as growth stimulators, whereas, abscisic acid and ethylene act as growth inhibitors. Plant hormones are simple in their structure as compared to those of animals or humans. There are no specific or specialized glands that produce these hormones. In fact, they are synthesized anywhere in the plant and act on any part as their target. Besides the hormones, there are many plant growth factors that affect the function and growth of plants.

List of Plant Hormones

Auxin

This hormone is present in the seed embryo, young leaves, and apical buds' meristem.

Functions of Auxins

Stimulation of cell elongation, cell division in cambium, differentiation of phloem and xylem, root initiation on stem cuttings, lateral root development in tissue culture

Delaying leaf senescence

Suppression of lateral bud growth when supplied from apical buds

Inhibition or promotion of fruit and leaf abscission through ethylene stimulation

Fruit setting and growth induced through auxin in some plants

Auxin can delay fruit ripening

In Bromeliads, the auxin hormone promotes flowering

Stimulation of flower parts, femaleness of dioecious flowers, and production of high concentration of ethylene in flowering plants

Cytokinin

They are synthesized in roots and then transported to other parts of the plant.

Functions of Cytokinins

Stimulation of cell division, growth of lateral buds, and apical dominance

Stimulation of shoot initiation and bud formation in tissue culture

Leaf cell enlargement that stimulates leaf expansion

Enhancement of stomatal opening in some plant species

Etioplasts converted into chloroplasts through stimulation of chlorophyll synthesis.

Ethylene

Ethylene is present in the tissues of ripening fruits, nodes of stems, senescent leaves, and flowers.

Functions of Ethylene

Leads to release of dormancy state

Stimulates shoot and root growth along with differentiation

Leaf and fruit abscission

Flower induction in Bromeliad

Stimulation of femaleness of dioecious flowers

Flower opening is stimulated

Flower and leaf senescence stimulation

Stimulation of Fruit ripening

Abscisic Acid

Abscisic acid is found mostly near leaves, stems, and unripe fruit.

Functions of Abscisic Acid

Stimulation of closing of stomata

Inhibition of shoot growth

Inducing seeds for synthesizing storage of proteins

Gibberellin

Gibberellins are present in the meristems of apical buds and roots, young leaves, and embryo.

Functions of Gibberellins

Stimulates stem elongation

Leads to development of seedless fruits

Delays senescence in leaves and citrus fruits

Ends seed dormancy in plants that require light for induction of germination

Answer 2

Functions of plant hormones:

${ \red{ \bf{ Auxins: }}}$

${ \green{ \bf{ Site\: of \: Synthesis:}}}$

Synthesized primarily in shoot apical meristems and young leaves.

${ \green{ \bf{ Functions: }}}$

Promote cell elongation.

Suppress the growth of lateral buds.

Delay fall of leaves.

Induce formation of parthenocarpic fruits.

${ \red{ \bf{Gibberellins: }}}$

${ \green{ \bf{ Site\: of \: Synthesis:}}}$

Synthesized primarily in the meristems of apical buds and roots.

${ \green{ \bf{ Functions: }}}$

Help in stem-elongation.

Break dormancy of seeds and buds.

Delay senescence.

Induce parthenocarpy.

${ \red{ \bf{ Cytokinins: }}}$

${ \green{ \bf{ Site\: of \: Synthesis:}}}$

Synthesized primarily in roots and transported to other organs.

${ \green{ \bf{ Functions: }}}$

Stimulate cell-division and cell enlargement.

Prevent ageing of plant parts.

Inhibit apical dominance.

${ \red{ \bf{ Ethylene:}}}$

${ \green{ \bf{ Site\: of \: Synthesis:}}}$

Synthesized in senescent leaves and flowers, germinating seeds and ripening fruits.

${ \green{ \bf{Functions: }}}$

Induces fruit ripening.

Promotes senescence.

${ \red{ \bf{ Abscisic \: acid: }}}$

${ \green{ \bf{ Site\: of \: Synthesis:}}}$

Synthesized in green fruits and seeds at the beginning of the wintering period.

${ \green{ \bf{ Functions: }}}$

Induces dormancy of buds and seeds.

Inhibits seed-germination and development.

Stimulates closing of stomata.