Why are plant growth regulators used in fruit tree cultivation, and what are their characteristics?

The scientific application of plant growth regulators to manage the growth and development of fruit trees represents a new approach to producing high-value fruit. These regulators are versatile: they can either promote seed germination or prolong dormancy; stimulate shoot elongation or inhibit/delay shoot growth; aid in flower and fruit retention or facilitate flower and fruit thinning; and either accelerate fruit ripening or delay it to extend shelf life and improve storage and transport quality. They yield significant results in areas where traditional agricultural techniques often struggle to provide solutions; consequently, they are highly valued by fruit growers and agricultural scientists alike.

Plant growth regulators encompass substances—such as endogenous plant hormones—produced by plants or microorganisms themselves that significantly promote or inhibit fruit tree growth and development even at very low dosages. They also include synthetic compounds with diverse chemical structures and properties capable of regulating plant growth and development; these synthetic versions are often referred to as exogenous plant hormones. Plant growth regulators frequently exhibit "multiple effects" from a single application, and the results can vary drastically depending on the dosage; improper use can lead to irreparable losses.

Plant growth regulators are not fertilizers and cannot replace the nitrogen, phosphorus, potassium, and various trace elements essential for fruit tree growth and development, though they can improve the efficiency with which these nutrients are utilized.