Utilizing Branched-Chain Amino Acids to Promote Increases in Shoot Density of Creeping Bentgrass (Agrostis stolonifera L.).

The Branched-chain amino acids (BCAA) leucine (L), isoleucine (IL), and valine (V) are synthesized in plants and are essential to growth in most organisms. Research has reported that when foliarly applied, these compounds can be absorbed by the plant, and once inside the plant, plant growth regulating activity has been observed. However, plant catabolism of BCAA is not completely understood, and still somewhat a mystery. Since the BCAA compounds contain nitrogen in their chemical structure, they could be potentially used as an organic nitrogen source in plants. The objective of this study was to investigate creeping bentgrass (Agrostis stolonifera L.) responses to foliarly applied BCAA, and how different combinations of BCAA can result in plant growth regulating activity. Creeping bentgrass was established from seed in a greenhouse using a sand-based growing medium. Following germination, samples were treated with either a single, double, or complete combination of BCAA at an equal nitrogen rate of 3.4 kg N ha-1. The complete combination for this study included two ratios (2:1:1, 4:1:1) with leucine being dominant in those ratios. A positive control in the form of urea was also included in the trial for comparisons. At trial end (42-days), plants that received standalone applications of leucine, isoleucine, or valine, as well as plants receiving double combinations of those materials did illustrate the capability of those materials to serve as a nitrogen source, but no plant growth regulating activity occurred. When the complete combination was applied in a 4:1:1 ratio, plant shoot density increased 25% compared to the positive control. When applied in a 2:1:1 ratio, that increase was less pronounced, with shoot density increasing 13.5% compared to the positive control. These results suggest that BCAA could be a suitable organic nitrogen source for use on creeping bentgrass.