Evaluation of the effect of a hormonal combination with amino acids on growth parameters and yield in rosemary plants

A factorial experiment was carried out using Randomized Complete Block Design layout (RCBD) at the experimental research station, College of Agriculture Engineering Science – University of Baghdad- Al-Jadriyah, in an open greenhouse during the spring season 2023–2044. The aim was to determine the influence of a hormone combination with amino acids on some growth parameters, yield and chemical composition as well as antioxidant activity of rosemary plant (Rosmarinus officinalis L.), local variety. The experiment included two factors, each with three levels, and three replicates, where plants were sprayed with the growth regulators benzyl adenine (BA) and kinetin (Kin) at a rate of 50 mg L-1, In addition to glutamic acid and aspartic acid amino acids at equal concentrations, in three successive sprays throughout growth stages. Statistical analysis revealed significant differences for most of the traits studied. The kinetin application showed significant amelioration in some vegetative growth parameters; such as leaf area, leaf width, dry weight of the vegetative total, leaf content of total chlorophyll, in addition to the fresh and dry leaf yield of the plant per unit area. On the other hand, benzyl adenine significantly enhanced the number of branches and leaf thickness, as well as total fresh weight and dry weights of vegetative parts, percentage of total vegetative mass and dry leaf yield. Among amino acids, glutamic acid was the most superior with respect to plant height, leaf thickness, dry vegetative biomass and its percentage as well as fresh and dry leaf yield. Conversely, aspartic acid increased the number of branch and leaf width and thickness, blade fresh weight, and chlorophyll content. Most visible effects on growth traits, yield, chemical composition and antioxidant status including the improvement in synthetic production of volatile oil compounds are the result of the combined activity of growth regulators with amino acids. These results support the use of this mixture to enhance growth and quality of rosemary plants