ABSTRACT:- In plants, many behavioral patterns and functions are controlled by hormones. These are “chemical messengers” influencing many patterns of plant development. Plant hormones – a natural substance (produced by plant) that acts to control plant activities. They include growth promoting and growth retarding substances. Chemical messengers (Plant growth hormones) are produced in one part of a plant and then transported to other parts, where they initiate a response. They are stored in regions where stimulus are and then released for transport through either phloem or mesophyll when the appropriate stimulus occurs. According to Sinha (2004), Growth hormones differ from growth regulators. Plant growth regulators – include plant hormones (natural & synthetic), but also include non-nutrient chemicals not found naturally in plants that when applied to plants, influence their growth and development. Plant Growth Regulators (PGR) known as bio-stimulants or bio-inhibitors modifies physiological processes in plant. These organic compounds act inside plant cells to stimulate or inhibit specific enzyme or enzyme systems to regulate plant metabolism. These growth regulators are naturally produced in plants to control the growth and other physiological functions. They act even in very minute quantities.

Keywords:- Plant growth regulators, chemical messenger, bio stimulants