A growth regulator is simply any chemical used to alter the growth of a plant or a part of the plant. Growth regulators can stimulate accelerated growth by promoting the formation of auxins, decrease fruit production by affecting the formation of cytokinins, and ripen fruit by increasing ethylene.
Plants treated with growth regulators produce an equal amount of energy as untreated trees, but allocate that energy differently. Over a three-year period, treated trees grow at a rate 40-70% less than the growth rate of untreated trees. The less energy plants are spending on vegetative growth, the more they have to allocate to other resources such as defense compounds, fibrous root growth, carbohydrate storage, and reproductive structures like flowers.