What is PGR and explain the many types of plant hormones

PGR are plant growth regulator there are two types of plant hormones one which induced plant growth and one which inhibit plant growth plant growth promoter includes - 1 auxins 2 cytokinin 3 gibralline Plant growth inhibitor includes 1 abscisic acid Ethylene is one of the gaseous plant hormones which can be categorised in either of the categories but majorly its function its inhibition.