What are plant hormones?
These are organic compounds which is synthesized by cells and tissues of plants called plant hormones/ phytohormones. They actively promote, or inhibit some factors and developmental processes of plants. five major groups of plants hormones are present:-
1. Auxin:- it stimulates cell elongation in stems by the protein expansin, which has low pH, 4.5. The amount of xylem and phloem ratio are regulated by auxin.
2. Gibbererllin:- It promotes the internodal elongation of plants. It also helps in seed germination by activating vegetative growth of embryo in plants.
3.Cytokinin:- It involves the cell division in which formation, maintainance and growth of root apical meristem and shoot apical meristem by cytokinin's both positive regulators in shoot apical meristem and negative regulators in root apical merisrtem. Also helps in chloroplast maturation.
4. Abscisic acid:- It is also known as stress hormone which acts in the stress condition of a plant (eg. closing of stomata in extremely drought conditon). It also promotes the root and shoot growth with seed dormancy and germination, also includes wilting of leaves.
5. Ethylene:- It is a gaseous hormone, present in almost every plant because it is responsible for may factors like flowering, fruit ripening, rooting and also for senescence (depends on its concentration).
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