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Thursday, October 8, 2009

Five Hormones Determine Your Plants Success or Failure.

Five plant hormones have been identified as being responsible for the development of the plant throughout its life. Each of them has complicated functions. The relationship between their activities changes with the plants stage of development. Put simply, they are:

a) Auxins which develop in leaf buds and leaves.
b) Gibberellins which develop in shoot buds and seeds.
c) Cytokinins which develop in root tips.
d) Abscisic Acid which develops in mature leaves.
e) Ethylene which develops as a gas in any plant cell.


These hormones are responsible for stimulating elongation in the plant cells. They tend to concentrate in the root and shoot tips and also on the underside of horizontal branches and stems. They cause the branch or stem to curve upwards to the vertical position.

The Gibberellins affect the rate of cell growth of the plant between the nodes. They are also responsible for slowing the growth in high light situations. They are involved in flowering, breaking the dormant cycle of the plant and in seed growth signalling.

The division of the plants cells is controlled by Cytokinins. They stimulate the starting of leaf and shoot growth. In concentration they stop rooting, so care is needed around clones and seedlings.

Abscisic Acid
This hormone is part of the plants ageing process. It controls seed development as well as closing the stomata during periods of water stress.

Ethylene (C2H2)
This gas is produced within most of the plants cells as it ages and in concentration causes the fruits to ripen, flowers and leaves to age and leaves and fruits to fall.

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