Effect of Soil-Applied L-tryptophan on the Amount of Biomass and Nitrogen and Sulfur Utilization by Maize.

As natural plant growth stimulators, amino acids are widely used to improve crop yield and quality. There are numerous studies documenting the influence of amino acids on plants, which is not always positive. This study was conducted to determine the effect of soil-applied L-tryptophan (L-TRP) on the accumulation and utilization of nitrogen and sulfur by maize. The study was carried out under the conditions of a pot experiment. The experimental design included three treatments: soil without fertilization (control), soil with mineral fertilization (NPKS), and soil with mineral fertilization and L-tryptophan addition (NPKS + L-TRP). The application of tryptophan to the soil, supported by mineral fertilization, caused a significant increase in maize biomass. Although no significant differences in nitrogen and sulfur contents in maize biomass were found between treatments without and with the addition of L-tryptophan, significantly higher intakes of both elements were observed in the NPKS + L-TRP treatment. The application of L-tryptophan increased the biosynthesis of Chlorophyll a. Utilization of nitrogen and sulfur by maize in the NPKS + L-TRP treatment was more than 27% and 17% higher, respectively, compared to the NPKS treatment. Maintaining the recommended contents of individual nutrients in the rhizosphere is not a guarantee of optimal quantitative and qualitative intake of nutrients. Problems with maintaining optimal relationships between individual nutrients may be compounded by soil properties. [ABSTRACT FROM AUTHOR]