Effect of iron and zinc foliar application timing on barley (Hordeum Vulgare L.) yield components and grain quality in southeastern Tigray Ethiopia

Abstract

Soil fertility decline and micronutrient deficiencies, particularly zinc (Zn) and iron (Fe), are major constraints to barley production in northern Ethiopia. This study evaluated the effects of foliar-applied Zn and Fe and their application timing on barley yield, yield components, and grain nutritional quality. A field experiment was conducted during the 2017 main cropping season at two sites (Dejen and Kedamay-Weyane) in southeastern Tigray, Ethiopia. The experiment was arranged in a split-plot design with three replications. Four micronutrient treatments (control, 16 kg Zn ha−1, 16 kg Fe ha−1, and 8 kg Zn + 8 kg Fe ha−1) were assigned to the main plots, while three foliar application timings (stem elongation, stem elongation + booting, and stem elongation + booting + early milking) were assigned to the subplots. Foliar application of Zn and Fe significantly improved plant growth, yield components, and grain quality. The combined application of Zn and Fe (8 kg Zn + 8 kg Fe ha−1) produced the highest grain yield and biomass at Dejen. Grain Zn, Fe, and protein contents were significantly enhanced when micronutrients were applied at multiple growth stages, particularly when extended to the early milking stage. Repeated applications increased grain Zn concentration to 52.5 mg kg−1 and Fe concentration to 149.5 mg kg−1. Foliar application of Zn and Fe, particularly when applied at multiple growth stages, significantly improves barley grain nutritional quality and productivity. Integrating micronutrient fertilization with appropriate application timing can contribute to agronomic bio-fortification and improved food security in micronutrient-deficient regions.