Effects of Atonik Growth Regulator and Chemical Fertilization on Vegetative Growth and Chemical Composition of Lemon (Citrus limon L.) Seedlings

Background: An important indication of agricultural development is foliar (non-root) nutrition. Research and experiments have shown that it is possible to provide plants with different nutrients by spraying them with solutions of these elements. Aim: The purpose of this study is to ascertain the impact of chemical fertilizer and tonic acid spraying, as well as the interaction between the two, on the chemical content and vegetative growth characteristics of lemon seedlings. Methods: the study was conducted during 2023-2024 season to study a tonic acid and chemical fertilizer effect on lemon seedling vegetative growth and chemical contents (nitrogen, potassium, chlorophyl and phosphorus). A factorial experiment was arranged using three levels of Atonic (0, 5, and 10 mg/ L⁻¹) and three levels of fertilizer (0, 0.7, and 1.4 g plant⁻¹). Results: The results showed that chemical fertilization significantly improved vegetative growth, particularly plant height, while Atonic had a moderate effect on growth traits. Both treatments significantly enhanced chlorophyll and nutrient contents (N, P, and K). The interaction between Atonic and fertilization further improved plant performance, with the highest values recorded under combined treatments. Conclusion: The study showed that combined effect of application of tonic acid and chemical fertilizer enhance significantly the vegetative growth and chemical contents of lemon seedling.