A composition for regulating plant growth, the active ingredient of which is an ester of oxaloacetic acid or a salt thereof, or derivatives thereof, wherein the ester of oxaloacetic acid has the given formula, where R1 and R2 are independently selected from a series of C1-C18 alkyl groups, and wherein the content of the active ingredient corresponds to a concentration of from 10-11 M to 10-3 M. The active ingredients and compositions for regulating plant growth allow for treating plants in order to stimulate the growth thereof and achieve such advantages as increased yields, improved plant quality, improved nutrient absorption and enhanced stress resistance, while allowing such advantages to be achieved using a relatively small amount of an active ingredient(s) which is/are biodegradable and environmentally friendly.
