Plant Growth Regulators: Meaning of Plant Growth Regulators: Phytohormones
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Meaning of Plant Growth Regulators
Those chemical substances, which govern all the factors of development and growth within plants.
Phytohormones and plant growth hormones are the other names for Plant Growth Regulators.
Plants need light, water, oxygen, and nutrition to grow and develop.
Phytohormones
These chemical messengers coordinate cellular activities.
They control and modify the physiological processes such as the growth, development, and movement of plants.
Characteristics of Plant Growth Regulators
Ripening of fruits.
Seed dormancy.
Formation of leaves flowers and stems.
Elongation and differentiation of cells.
They can accelerate as well as retard the rate of growth in plants.
Types of Plant Hormones
Auxin
Gibberellins (GAs)
Cytokinins
Abscisic acid (ABA)
Ethylene
Types of Plant Growth Regulators

Types of Plant Growth Regulators
Plant Growth Regulators
Auxins
Charles Darwin discovered phytohormone as the first Auxin.
Auxins play an important role in producing fruit without prior fertilization.
They are also used by gardeners to keep lawns free from weeds.
They are produced by the apex of root and shoot.
They are also used in the process of plant propagation.
Gibberellins
They are plant hormones that regulate various developmental processes.
This includes stem elongation, germination, dormancy, flowering, flower development, and leaf and fruit senescence.
They are one of the longest-known classes of plant hormone.
They are involved in leaf expansion.
They are acidic in nature.
They are used in the brewing industry to accelerate the malting process.
Cytokinins
They are a class of plant growth substances (phytohormones).
They promote cell division, or cytokinesis, in plant roots and shoots.
They are involved primarily in cell growth and differentiation.
They promote nutrient mobilization.
They keep flowers fresh for a longer duration.
Plant Growth Inhibitors
Abscisic Acid
It is a plant hormone.
It functions in many plant developmental processes, including seed and bud dormancy.
It is also involved in control of organ size and stomatal closure.
It further inhibits plant metabolism and seed germination.
It is also used a spraying agent on trees.
Ethylene
It is a hydrocarbon which has the formula or .
In pure state, it is a colorless flammable gas with a faint “sweet and musky” odour.
It is used as both plant growth promoters and plant growth regulators.
It enhances respiration rate during ripening of fruits.