Introduction: Sesame (Sesamum indicum L.), an ancient drought-tolerant oilseed crop, thrives in arid regions where other crops fail, offering one of the highest oil contents among oilseeds. In Iran’s calcareous soils of arid/semi-arid zones, widespread zinc (Zn) and iron (Fe) deficiencies limit crop productivity. Micronutrients critically influence plant growth, yield, and human nutrition, with foliar application emerging as a key strategy for biofortification. Weed competition further exacerbates yield losses, particularly during sesame’s slow establishment phase, where weed-crop leaf area ratios at canopy closure significantly impact productivity. Despite the agroeconomic potential of sesame in the understudied tropical Somar region (southwest Kermanshah province), no prior research exists on integrated weed and nutrient management for this crop. This study addresses this gap by evaluating Zn and Fe sulfate’s foliar effects on sesame yield and oil quality under weed competition, aiming to optimize sustainable practices for this high-value crop.Sesame’s resilience to drought and high oil content (45–55%) make it a vital crop for marginal arid lands. However, calcareous soils in Iran’s arid zones, including Somar, exhibit severe Zn and Fe deficiencies, limiting sesame’s productivity. Micronutrients like Zn and Fe are essential cofactors in enzymatic processes, chlorophyll synthesis, and stress tolerance, directly influencing yield and seed quality. Foliar supplementation bypasses soil nutrient fixation, enhancing uptake efficiency. Concurrently, weed interference during sesame’s early growth stages reduces light and resource capture, with weed leaf area dominance at canopy closure being a critical yield-limiting factor. Seed purity standards (99.99%) for edible oil further necessitate rigorous weed management. The Somar region, with its tropical climate and untapped agricultural potential, lacks evidence-based strategies for sesame cultivation. This study bridges this gap by investigating synergistic weed control and micronutrient applications to boost yield and oil quality, supporting socioeconomic development in resource-rich but underutilized regions.
Materials and Methods: A split-factorial experiment was conducted in 2023 in Somar, employing a randomized complete block design with three replications. The main factor comprised weed management: control (mechanical/chemical) and no control. Sub-factors included Fe sulfate (0, 150, 300 ppm) and Zn sulfate (0, 300, 500 ppm) applied as foliar sprays at 6- and 15-leaf stages. Soil analysis confirmed baseline Zn (0.8 mg kg⁻¹) and Fe (4.2 mg kg⁻¹) deficiencies. Weed biomass, seed yield, oil content, and nutrient uptake were measured. Data were analyzed using ANOVA, and means compared via LSD (p ≤ 0.05).
Results and Discussion: Weed competition reduced sesame yield by 29% compared to the controlled treatment. The highest seed yield (1068.8 kg ha⁻¹) occurred under weed-free conditions with 300 ppm Fe and 300 ppm Zn, highlighting micronutrients’ role in mitigating abiotic stress. Fe and Zn sulfate significantly increased oil content: 500 ppm Zn yielded 51.9% oil, while 300 ppm Fe achieved 52.2%, surpassing lower doses (p < 0.01). Weed interference reduced oil quality by 12–15%, likely due to resource diversion and reduced photosynthetic efficiency. The synergistic Fe-Zn application enhanced nutrient partitioning to seeds, improving both yield and oil synthesis. These results align with studies linking micronutrients to ROS scavenging and lipid biosynthesis in oilseeds.
Conclusion: Integrated weed management and foliar Zn/Fe supplementation significantly enhance sesame productivity and oil quality in calcareous soils. The optimal combination—300 ppm Fe + 300 ppm Zn under weed-free conditions—increased yield by 29% and oil content by 18–20%, demonstrating the socioeconomic viability of sesame in Somar. This strategy addresses soil constraints and weed pressure, offering a model for semi-arid regions. Future research should explore genotype-specific responses and long-term soil health impacts.