Applications of a PGR should be made under ideal turf conditions. They should never be applied when the turf is under high stress or periods of stress are anticipated. PGRs should only be applied to healthy turf with a good fertility program in place. Many times turf that has had PGR applications also has higher quality ratings. PGR's affect the composition and development of the turf system.
Gibberellic acid is the plant hormone that is responsible for plant tallness.
Gibberellins are terpenoids consisting of 20 carbons, which is made from four isoprenoid units. GA1 is the active hormone involved with cell elongation. All GA s are formed from a long pathway beginning at photosynthesis. Carbohydrates from photosynthesis fuel glycolysis that produces phosphoenol pyruvic acid and acetyl CoA. Mevalonic acid is formed from acetyl CoA. Mevalonic acid is the starting compound for all terpenoid biosynthesis. The isoprene units are added together, resulting in geranylgeranyl pyrophosphate that is a compound containing twenty carbon atoms.