Abstract

This study was conducted to evaluate the response of Lemon (Citrus limon L.) saplings to the exogenous application of seaweed extract and Salicylic Acid (SA), both independently and in combination, focusing on vegetative growth parameters and foliar chemical composition. The experiment was carried out at the nursery of the College of Agriculture, University of Samarra, during the 2024–2025 growing season (October to May). A Randomized Complete Block Design (RCBD) was employed in a factorial arrangement with two factors at three levels each.The results demonstrated that the synergistic treatment (Seaweed Extract + Salicylic Acid) significantly outperformed other treatments, yielding the highest values for vegetative development and nutrient accumulation. Specifically, plant height, stem diameter, leaf count per sapling, and leaf area reached 40.72 cm, 3.30 mm, 65.41 leaves, and 28.80 cm², respectively. Furthermore, the findings indicated a marked increase in the foliar concentration of macronutrients. These results highlight the potential of using integrated bio-stimulants to enhance the growth vigor and the endogenous levels of Nitrogen (N), Phosphorus (P), Potassium (K), and carbohydrates in lemon nursery stock. This study underscores the critical role of natural extracts and phytohormones in optimizing the performance of citrus saplings under nursery conditions.