The current study was carried out to investigate the efficiencies of foliar supplementations of Zinc and/or chitosan on the growth and physiology of tomato (Lycopersicon esculentum L.) and clarify the involved mechanisms. Seedlings were sprayed with three concentrations (0, 50, and 100 mgL-1) of chitosan and/or three levels of Zinc sulfate (0, 50 and 100 mgL-1). The application of Zn and/or chitosan led to increases in shoot fresh mass, about 31%, over control. In comparison with the control, enhancement (approximately 28.5%) in shoot dry mass resulted from the single application of chitosan or zinc while this percentage reached to about 45% for seedlings simultaneously treated with the chitosan and Zn supplements. About 29% improvements in the plant height resulted from the chitosan and/or zinc. Higher amounts of chlorophyll contents were recorded in the chitosan and/or zinc-treated plants, among which the highest levels were found in the combined treatments. Simultaneous applications of chitosan and zinc were the most effective treatments to induce PAL (phenylalanine ammonia lyase) activity (about 64%) when compared to the control. Chitosan and/or zinc treatments, especially the latter, significantly promoted the activity of (SOD) superoxide dismutase enzyme (about two folds), over the control. Also, increases in proline contents was provoked by applying the treatments. Foliar supplementations of these compounds as an eco-friendly solution may have considerable potential to act as exogenous elicitors and trigger various physiological traits, thereby improving plant growth and resistance under abiotic stress conditions. Manuscript profile