Question

What is plant hormones give four different types of plant hormones and state their functions briefly?

Answer 1

Plant hormones or growth regulators are those which affect certain parts of the plant where they are synthesised. They bring about regulation by maintaining the growth stimulation and inhibition timely.

- The ones that induce growth and metabolism are auxins, cytokinins, gibberellins.

- Ethylene causes both growth stimulation and inhibition in the plant body.

- Abscisic acid is a growth inhibitor.

Auxin: These are indole compounds, IAA, IBA etc. It brings about growth in the apical portions such as, shoot apical meristem or root tip. Applied in rooting in stem cutting. Getting rid of dicotyledonous weeds. It is used as herbicides, eg: 2,4D. Controls xylem differentiation. It prevents leaf and fruit drop in early stages but promotes the same when senescence occurs. It was first isolated from human urine.

Cytokinins: They bring about increase in growth of leaves and chloroplasts. They can be used to overcome apical dominance due to auxin. They participate in the cytokinesis stage of cell division. Kinetin is naturally discovered (N6furfurylaninopurine) whereas most are artificially synthesised.

Gibberellins: These are terpenoid substances. They are used for increasing the market period of fruits. They are used in brewing industries for speeding up malting process. They break dormancy in seeds and buds. GA1, GA2, GA3 etc are found where GA3 is the first to be discovered.

Ethylene: It is responsible for respiratory climacteric i.e., increase in the respiration during fruit ripening. It brings about horizontal growth in seedlings and an apical hook formation. Its gaseous form Ethephon is usually sprayed.

Answer 2

HOLA MATE :)

#Plants can sense the presence of stimuli like light, heat, water, touch, pressure, chemicals, gravity, etc..

#the hormones present in the plants called phyto hormones control responses towards the stimuli...

#phyto hormones coordinate the activities of the plant usually by controlling one or the other aspect of the growth of the plant. they are sometimes growth substances.

#plant hormones are usually growth effectors or inhibitors..

#some growth effectors are auxins and gibberellins while inhibitors are like abscisic acid or indole acetic acid ..

1. AUXINS : cell elongation and differentiation of roots and shoots
2. CYTOKININS : promote cell division, promotion of sprouting of lateral buds, delaying the ageing in leaves, opening of stomata
3. GIBBERELLINS : germination of seeds and sprouting of buds, elongation of stems, stimulation of flowering, development of fruits, breaking the dormancy in seeds and buds
4. ABSCISIC ACID : closing of stomata, seed dormancy, promoting ageing of leaves.
5. ETHYLENE : ripening of fruits

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