Growth Performance of Guava Trees after the Exogenous Application of Amino Acids Glutamic Acid, Arginine, and Glycine

A 2020-2021 study was performed on five-year-old guava trees to examine the influence of the foliar application of three amino acids, glycine, arginine, and glutamic acid, at a concentration of 500 or 1000 ppm. Additionally, two combinations of the three mentioned amino acids were also applied: 500 glycine + 500 arginine + 500 glutamic acid (combination 1) and 1000 glycine + 1000 arginine + 1000 glutamic acid (combination 2), and compared with a control (untreated trees). The results indicated that the application of the three amino acids, solely or in combination, was effective at increasing the shoot length, shoot diameter, and leaf chlorophyll. Additionally, the applied treatments also improved markedly the fruit set percentage, fruit yield, fruit firmness, fruit content of total soluble solids (TSS %), vitamin C (VC), and total sugars as well as the leaf mineral content (nitrogen, potassium, and phosphorus) compared with untreated trees in 2020 and 2021. Moreover, the results indicated that the combinations were more effective than individual applications and that glycine had a greater influence than arginine or glutamic acid, particularly when it was applied at 1000 ppm.