abstract: In crops, Zinc deficiency is an important problem, causing decreased crop production and food quality. Cereals have significant role in satisfying daily calorie intake, but they very low in Zn contents in grain specially when grown on Zn-deficit alkali soils of Iran. Amendment in seed zinc content through agronomic biofortification is one of the most important agronomic strategies to overcome Zn deficiency in human. This study was conducted to evaluate the effects of Zn application on yield, yield components, seed zinc and protein content as randomized complete block design based factorial with three replications. Three spring wheat cultivars (Darya, Tadjan and N-80-19) with five fertilizer levels including; 0 (control), 25 kg ha^-1 (soil application of zinc sulfate in planting time), 0.5% zinc sulfate (spraying in booting stage), 0.5% zinc sulfate (spraying in booting and milk stages) and 0.5% zinc sulfate (spraying in milky and dough stages), were used. The results showed that there were significant difference among cultivars in seed number per spike, max seed number per spikelet, biomass, seed protein and Zn content, thousand kernels weight and yield. Zinc application showed significant effect on spike number per m^-2, maximum seed number per spikelet, biomass, seed protein and Zn content, and yield. Interaction effect of zinc on cultivar was only significant on seed protein and Zn content (P≤0.01). Zinc sulfate application at the planting time had the most significant effect on number of spikes number per m2. Zinc foliar application had no significant impact and there was no difference between those treatments and control. Number of seed per spike was the highest in Darya with zinc application at planting time. Darya showed highest seed number per spikelet with significant difference with N-80-19 and Tadjan. Only Zn application at boot stage had no effect on maximum seed number per spikelet and soil application and dual application of Zn increased significantly maximum seed number per spikelet. The highest 1000 kernel weight was belonged to Tadjan and N-80-19 cultivars, but, there was no significant difference with diverse zinc applications. This may be explained by the highest number of seeds with “Darya” spikes and with reverse relationships between 1000 kernel weight and seed number per spikes. Zinc application had no considerable effect on 1000 kernel weight. Zinc application significantly influenced total yield of plants. Highest seed yield was recorded with zinc sulfate application at the planting time and with Darya and Tadjan cultivars. Considering, soil based application of Zn surely affects the quality and protein content of grains. Interaction effects of variety and zinc application were significant (P≤0.01) on grain protein content. Zinc application during milky and dough stages led to the highest Zn accumulation with Darya. Furthermore, the highest protein accumulation was traced at Tadjan with the soil application of zinc sulfate.  Further experiments at diverse environments are needed to explore the different responses of varieties to Zn different types and times of application. According to ours, the highest seed yield and protein content were belonged to soil based application of Zn treatments, however, based on Zn biofortification, foliar spray of Zn treatments during the milky and dough stages had the most promising effects. These results showed that agronomic biofertification method appear to be essential in maintaining adequate Zn transport to the grains specially during reproductive growth stage.