Abstract: Methods for retarding plant growth are described. The methods include treating a plant with 2-aminobutyric acid or a salt thereof, 3-aminobutyric acid or a salt thereof, or a mixture thereof. The compounds may be combined with an additional active agent. The additional active agent may include, for example, a fertilizer, pesticide or an herbicide.

Abstract: The specification describes combinations of fertilizer with certain organic compounds to increase fertilizer efficiency, plant productivity, growth, and nutrient accumulation. These beneficial effects are accomplished using combinations of a fertilizer and an amino acid selected from .gamma.-aminobutyric acid, glutamic acid, and a mixture of .gamma.-aminobutyric acid and glutamic acid. A source of proteinaceous amino acids and a carbon skeleton may also be used with the fertilizer and the amino acid. The specification describes compositions and methods employing such combinations to take advantage of their beneficial effects.