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Describe the roles of hormones in growth and development in plants.

      

The question requires to explain hormones that promotes growth of plants.

  

Answers


Josephine
1. Auxin-it is synthesized in shoot and root apexes where it helps in elongation of cells.
2. Cytokinin- synthesized in the root cells and transported to the leaves where action occurs.
3. Gibberellin- promotes stem elongation between the nodes of the stem.
4. Abscisic acid- alerts the rest of the plant that it it water stress.
5. Ethylene- helps in ripening and rooting in plant.
OR
Indole acetic acid/IAA/Auxins; promote cell division and cell elongation; promote tropic response; promote formation of
abscission layers/bring about leaf- fall; promote fruit formation without fertilization i.e parthenocarpy ;promote cell
differentiation (of vascular tissue);causes apical dominance/inhibit growth development of lateral buds; promote growth of
adventitious roots(on stems);IAA + cytokin; induce formation of callus tissue during healing of wounds);
Gibberellins; promote cell division/cell elongation in dwarf varieties.; parthenocapy/initiating formation of IAA/setting of
fruits after fertilization.; promote formation of side branches( of stems) and dormancy in buds);inhibits growth of adventitious
roots; activates (hydrolytic) enzymes during germination/promote germination of seeds hence break seed dormancy; affect
leaf expansion and shapes/retard leaf abscission;
Cytokinins; break dormancy (in some species);promote flowering in some species;’ promote cell division (in presence of
IAA);stabilizes proteins and chlorophyll; promote root formation; low concentration encourages leaf senescence/high
concentration protein increased cell enlargement; promote flowering in some species);
Ethylene/Ethyne; stimulate lateral bud development; ripening of bananas/fruits; induces thickening of stem/inhibits stem
elongation; promotes germination of certain seeds; causes abscission of leaves/fruit/leaf fall;
Abscisic Acid(ABA);High concentration of ABA causes stomata closure (by interfering with uptake of potassium
ions);inhibits germination/growth of embryo/causes seed dormancy; causes abscission of leaves/fruits/leaf fall; inhibits
elongation growth, inhibits sprouting of bud/induce dormancy in buds;
Florigens ;promote flowering;
0715062617 answered the question on January 17, 2018 at 17:41


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