Any substance or mixture of substances intended, through physiological action, for accelerating or retarding the rate of growth or maturation or for otherwise altering the behavior of ornamental or crop plants or the produce thereof, but not including substances intended as plant nutrients, trace elements, nutritional chemicals, plant inoculants, or soil amendments.
The use of plant growth regulators in morden agricultural production began in the 1930s. The first discovery and use of plant growth regulators was with acetylene and ethylene, which enhanced flower production in pineapple. Subsequently, use of plant growth regulators has grown exponentially to become a major component of agricultural commodity production.
Certain herbicides and insecticides that are not true plant growth regulators cause some plant-growth-regulating effects. For example, the widely used insecticide carbaryl is used to thin apple fruit from trees and to aid in encouraging annual bearing.
Active ingredient | Registered crops and functions |
---|---|
Ancymidol | Ornamental plants – growth inhibitor |
Butralin | Tobacco – shoot inhibitor |
Alcohols | Tobacco – shoot inhibitor |
Chlormequat chloride | Ornamental flowers – shoot inhibitor |
Cytokinin | Ornamental plants, vegetables, fruits including citrus – hasten maturity, enhance fruit color, growth enhancer, enhance tuber color, improve tuber quality |
Daminozide | Ornamental plants – growth inhibitor |
Ethephon | Turfgrass – reduces mowing frequency Various fruits, vegetables, and nuts – hastens ripening and maturity, enhance fruit color and floral stimulant Cucurbits – increases flowering Ground covers – inhibits flowering Ornamental trees – inhibits fruiting Tobacco and cotton – hastens maturity Cereal grains and grasses grown for seed – reduces lodging |
Flurprimidol | Ornamental woody plants and ground covers – reduces pruning Turfgrass – reduces mowing frequentcy |
Gibberellic acid | Small fruits, cucurbits – increase fruit set Citrus – promote rind/peel integrity, prevent fruit drop Rice, cotton – growth enhancer |
Gibberellin mixtures | Cut flowers – plant preservative Tree fruit – increase fruit size, hasten maturity, shoot stimulant Evergreen trees – floral stimulant, stimulate germination |
Indole-3-butyric acid (IBA) | Ornamental plants and trees – root stimulant |
Maleic hydrazide, potassium salt | Tobacco – shoot inhibitor Stored bulbs – sprout inhibitor |
Mefluidide | Ground covers, shrubs, ornamental trees – reduces pruning Turfgrass – reduces mowing frequency |
Mepiquat chloride | Cotton - growth inhibitor, enhance uniform fruit maturity |
Mepiquat pentaborate | Cotton – growth inhibitor, enhance uniform fruit maturity |
Naphthalene-acetic acid (NAA) | Ornamental plants – stimulates rooting, increase vegetative growth |
1-Naphthaleneacetamide (NAD) | Woody ornamental cuttings – rooting stimulant |
n-Decanol | Tobacco – shoot inhibitor |
Paclobutrazol | Ornamental flowers – promotes uniform flowering Ornamental plants – reduces internodal length Ornamental trees – growth inhibitor Turfgrass – increased plant thickness, growth inhibitor |
Prohexadione calcium | Peanut, Tree fruit, turfgrass grown for seed – growth inhibitor, reduce vegetative growth |
Trinexapac-ethyl | Turfgrass – reduces mowing frequency |
Uniconazole | Ornamental plants – growth inhibitor |