Characteristics of Plant Growth Regulators

Definition of Plant Growth Regulators - This are very small molecules synthesized from the cells of different parts which are associated with the plant cell growth.

Growth in unicellular organism employees the increase in volume or increasing the number of organisms. So it can be said that growth in the unicellular organisms that consists of a single step in higher plants the growth in for three steps or  phase of cell division phase of cell enlargement and phase of cell maturation. Rate of growth is not uniform for a cell organ or an organism if the growth rate of a plant are plotted against time on a paper a sigmoid growth curve or is shaped growth curve is obtained in which we can find lagphase, logphase  or exponential growth phase and senescence phase or declining phase.

Characteristics of plant growth regulators are following-

* Plant growth regulators of very small in size and are simple molecules of diverse compounds. It could be in dole acetic acid (auxin),adenine  derivatives(furfuryl amino purine kinetin), gaseous substances (ethylene) or derivatives of carotenoids or fatty acids (abscisic acid), derrivatives of terpenes ( gibberellins acids).

* Plant growth regulators generally renamed as plant growth hormone or phytohormones.

* Plant growth hormones can be divided into two categories according to their functions in the plant body-

One category plant growth regulators are those which are associated with thecell division, cell differentiation, enlargement of cell , fruiting, flowering, seed formation etc. Examples of this type of plant growth promoters auxin, gibberellin, cytokinins.

* Another category of plant growth regulators are associated with wounding, stress of different biotic and a biotic factors. It plays role in different growth inhibiting activities like –  promotion of dormancy, abscission. Examples - abscisic acid.

* Gaseous plant growth regulator is ethylene which can be enlisted into any group but it inhibits the growth activities. This is responsible for ripening of fruits.

Functions of Plant Growth Regulators:

* All plant growth regulators have different roles in different parts of the plants. Such as we know that oxygen deposited in high concentration against the land and causes the movement of branches and leaves towards the sunlight of plants. So oxygen is associated with photo tropic movement but it may inhibits the growth of root whichgrow against the sunlight under the soil and it’s direction for growth is just opposite to the growth of branches.

* Similar responses can be also promoted by different growth promoting factors. This can be explained by the function of auxins and gibberellins and cytokinin. These are all responsible for the cell elongation and increase the size of the cell so these hormones have same effect on plants.

* Plant growth promoters got active in very low concentration like 10 - 6 mole. They are synthesized in different tissues and cells and they move towards​the other parts of the plant body where they execute their function.

The different group of plant growth regulator have their different functions in different parts of the plant.

Eleventh Grade

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