The use of plant growth regulators (PGR's) in horticulture is well established by growers of horticultural commodities,and much university research has explained the biochemical pathways which are the targets of the applied chemical. They all interfere with the synthesis of the Gibberellins, a primary growth hormone made in apical meristems.Thus deprived of the stimulus for growth the effects are a great reduction in new growth at the apical meristems of the plant. They are metabolized slowly,and have lasting effects. The plants' physiology changes when new growth ceases. There is more starch available for root tissues enhancement. Read more.