What is Coordination in Plants
Coordination in Plants
Coordination is orderly working of different but inter related parts to perform one or more activities very smoothly.
There are 2 modes of control & coordination, chemical & nervous. Plant do not have a nervous system. They possess only chemical controls & coordination.
Plant Hormones:
Auxins
Auxions take part in a number of plants processes. Some are as follow :
- Auxin Promote apical daninance.
- Auxin participates in molecular reaction
- Affects osmotic pressure by increasing solutes
- Affects enzyme action
- Affects nucleic acid activities
- Stimulates respiration
- Promotes root formation
- Helps in inhibition of leaf and fruit abscission
Gibberellins :
- These hormones were first identified in studies of a disease of rice in Japan, the bakanal (foolish seedling) disease caused by Gibberella fujikuroi.
- These are second important growth hormones found in plants. Normally gibberellins causes increased growth, especially in height of stem. So gibberelline are defined as the growth hormones which causes cell elongations.
Cytokinins :
- Cytokinins are defined as compounds having a highly specific hydrophilic group or adenine and one nonspecific lipophilic group.
- Name of some cytokinins are :-
- Kinetin, dihydrozeation, methylthiozeation and riboxylzeatin.
Abscisic Acid (ABA) :
- Acts as growth inhibitor and induces dormancy of buds towards the approach of winter.
- Inhibition of cambium activity – Towards the approach of winter, the activity of combium is inhibited due to the formation of abcisic acid.
- Abscission – Abscisic acid promotes discission of flowers and fruits.
- Senescene – It stimulates senescence of leaves.
- Closure of stomata – The normal causes closure of stomata (by inhibiting K+uptake.
- Inhibition of germination – Abscisic acid inhibits sprouting of cereal grains.
- Resistance – Abscisic acid increases resistance of plant to cold.
- Flowering – ABA delays flowering in long day plants.
- Tubarization in potato – ABA helps in tuber formation in potato.
- Rootning – ABA promotes root initiation in stem cutings of some plants e.g. Ivy, Poinsettia.
Ethylene (CH2 = CH2) :
Functions of ethylene are –
- Transverse growth – Stimulates transverse growth so that stem looks swollen.
- Inhibition of geotropism – Ethylene nullifies geotropism.
- Fruit ripening – Ethylene is a ripening agent, such fruits as apple, banana, mango, citrus etc, Ethylene is used for artificial ripening of these fruits.
- Apical dominance – Ethylene inhibits the growth lateral buds and thus cause apical dominance.
- Root initiation – In low concentration, ethylene stimulates root initiations.
- Abscission – Ethylene acclerates abscission of leaves, flowers and fruits.
- Senescence – Ethylene is associated with the process of senescene (ageing) of leaves and flowers.
- Breaking of dormancy – Ethylene breaks dormancy of storage organs
Uses of Ethylene :
- Ripening of Fruits – Ethylene lamps are used for colour development and ripening of certain flashy fruits (e.g.- apple, banana, mango etc)