Plant Growth Regulators: Backgrounds and Uses in Plant Production

Plant growth regulators are widely used in modern agriculture, horticulture and viticulture. "True" plant growth regulators interfere directly with the plant's hormonal status. They are represented by plant hormones or their synthetic analogs, by inhibitors of hormone biosynthesis or translocation and by hormone receptor blockers. "Atypical" plant growth regulators act by displaying a local and/or transient phytotoxic effect. Approximately 40 active ingredients are in use, applied either as a single component or as combinations. Many plant developmental processes can be actively regulated in cultivated plants, for example, acceleration or delay of seed germination, dormancy breaking in woody perennials, stimulation or reduction of shoot elongation, induction of flowering and fruiting, reduction or increase of fruit set, acceleration or delay of senescence processes including fruit ripening and defoliation. The achieved benefits range from facilitating crop management to increasing and securing yield and quality of the harvested produce and improving its storage and shelf life. Systematic use of plant growth regulators started in the 1930s. Current global annual sales are in the range of US$ 1.2 billion.