Amino Acids as Biostimulants: Effects on Growth, Chlorophyll Content, and Antioxidant Activity in Ocimum basilicum L

It is necessary to explore possibilities to increase agricultural production in environmentally friendly ways while maintaining the quality standards of plant raw materials. The effect of amino acids on sweet basil ( Ocimum basilicum L.) development may stimulate biomass accumulation and enhance the biosynthesis of secondary metabolites. Investigated varieties “Rosie”, “Red Opal”, “Bordeaux”, “Dark Opal”, “Red Rubin”, “Genovese”, “Cinamon”, “Italiano Classico”, “Marseillais”, and “Thai” were cultivated in a controlled-environment growth chamber and the impact of isoleucine, methionine, glutamine, tryptophan, phenylalanine was studied on biomass accumulation, chlorophyll and phenolic content, and antioxidant activity. Five to six true leaves plants were treated once with an aqueous solution containing 100 mg L −1 of the mentioned amino acids or received no treatment. Our results show that methionine or tryptophan improved the most fresh and dry weight of shoot system of sweet basil plants. Methionine increased chlorophyl a content in 6 of 10 sweet basil varieties, while glutamine had the greatest results in chlorophyl b content. Phenylalanine increased total phenolic content in most treated plants, as well as antioxidant activity. Amino acids may be applied as useful biostimulants in modern agriculture, as they play an important role in ensuring sustainable crop productivity, fostering beneficial plant properties.