Plant Growth Factor

any one of several natural and synthetic compounds that intensify growth processes in plants. Natural plant growth factors include phytohormones (auxins, gibberellins, and cytokinins) and certain vitamins. Some growth factors, particularly those from the auxin group (heteroauxin and its analogues, indolylbutyric acid and a-naphthylacetic acid), can be produced synthetically.

Balanced growth of plants involves two-way regulation by means of natural growth substances that stimulate and inhibit the growth process. The use of synthetic plant growth factors partially deactivates the endogenous growth inhibitors and activates the phytohormones; as a result, there is temporary intensification of growth and organogenetic processes.

Plant growth factors are used in horticulture in the form of aqueous solutions, pastes, emulsions, dusts, aerosols, and vapors. They accelerate the rooting of cuttings of many cultivated plants (cherry, plum, rose). The substances are also used to accelerate flowering and, hence, fruit formation (eggplant, tomato, fig, and mandarin) and to increase the size of fruits and berries (grapes). In addition, plant growth factors are used to prevent preharvest falling of apples and pears, to bring seeds, tubers, and bulbs out of dormancy, and to accelerate ripening of picked fruits.