Impact of Spraying with Some Micronutrients on Onion (Allium Cepa L.) Yield and Nutrients Uptake with Application of 15N

Micronutrients are essentially as important as macronutrients to improve growth, yield and quality in plants, especially when growing in reclaimed lands. Onion was grown on sandy soil under field conditions and exposed to different rates of Fe, Mn, Cu and Zn either individually or in combination of them in order to follow up its impact on some growth traits, micronutrients uptake and nitrogen derived from mineral-N fertilizer, phosphorus and potassium uptake by whole plant. Two successive field experiments were carried out during winter seasons of 2019-2020 and 2020-2021 under drip irrigation system. Sprayed individual Fe, Mn, Cu, Zn and combination of them were applied in different rates. Experiments were designed in a split-plot design. Micronutrients mixture added at medium concentration induced the highest plant height, number of leaves, fresh and dry weight, blub yield and quality, bulb diameter, total soluble solids, ascorbic acid concentration, macro and micronutrient uptake, nitrogen (as 15 N) derived from fertilizer and fertilizer nitrogen (as 15 N) recovery. Additionally, zinc treatment came to the next after the mixed solution in increasing all tested parameters, followed by individual iron, then manganese, and finally copper.