Plant Hormone        Site of Synthesis                     Function
1.     Auxin Synthesized primarily in shoot apical meristem and young leaves ·        Promote cell elongation

·        Suppress the growth of lateral buds

·        Delay fall of leaves

·        Induce formation of parthenocarpic fruits

 

 

 

2.     Gibberellins Synthesized primarily in the meristems of apical buds and roots ·        Helps in stem- elongation

·        Break dormancy of seeds and buds

·        Delay senescence

·        Induce parthenocarpy

 

 

 

3.     Cytokinins Synthesized primarily in roots and transported to other organs ·        Stimulate cell- division and cell                                   enlargement

·        Prevent ageing of plant parts

·        Inhibit apical dominance

 

 

4.     Ethylene Synthesized in senescent leaves and flowers, germinating seeds and ripening fruits ·        Induces fruit ripening

·        Promotes senescence

 

 

5.     Abscisic acid Synthesized in green fruits and seeds at the beginning of the wintering period ·        Induces dormancy of buds and seeds

·        Inhibits seed- germination and                               development

·        Stimulates closing of stomata

 

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PLANT HORMONES AND THEIR FUNCTION