Salicylic acid (SA) and propolis (PR) are known to regulate the physiological process and to have a relevant role in bioactive compounds content. Our experiment was designed to evaluate the effect of SA and PR application on the growth, yield, and quality parameters of tomato grown for the fresh market in field conditions in Egypt. We studied the effect of twelve treatments where SA (0.50, 1.00, 1.50, 2.00, and 2.50 mM) and PR (1, 2, 10, 20, and 100 mg propolis mL−1) were applied at increasing doses as a sole agent or combined each other (1.50 mM + 10 mg mL−1 for SA and PR, respectively). An untreated control was also considered. Tomato plants treated with SA (0.50, 1.00, and 1.50 mM) showed a significant effect in all traits especially SA1 (0.50 mM) in growth parameters and SA2 (1.00 mM) in pigment and antioxidant content. Propolis foliar application was more effective than SA as it revealed that raising the concentration of aqueous extract enhanced the growth parameters and pigment in tomato. The best result was obtained by the 10 mg mL−1 treatment. The effect of propolis on antioxidant enzymes varied as the 10 mg mL−1 treatment was effective on peroxidases and superoxide dismutase, while 100 mg mL−1 was more effective on catalase. Salicylic acid and propolis have a positive effect on both preserving tomato plants and on nutrient supply, so the mixed intermediate concentration (1.50 mM + 10 mg mL−1) is considered very effective and results in an improvement of all plant traits.

Propolis is an organic substance that considered a biostimulant agent and plays a vital role in increasing bioactive compounds content in plants. The study investigated the properties of two different kinds of propolis i.e., Egyptian and Chinese propolis. The physical and chemical analyses results of the Egyptian propolis showed that it contain 253.703 mgGAE/g total phenolic compound, 76.766 mgQE/g total flavonoid compound and 5.417 g/100g total alkaloid. Also, the effect of five concentrations of aqueous extract of the Egyptian propolis was studied as a foliar spray on tomato plants, which were (1, 2, 10, 20, 100 mg propolis ml-1). Tomato plants treated with propolis (100 mg/ml) showed a significant effect in antioxidant content and other bioactive compounds compared to control plants.