Impact of Fe-EDTA, EDTA, and Zn Applications on Fe and Zn Levels and Biomass Production in Bread Wheat

Micronutrient deficiencies, particularly of iron (Fe) and zinc (Zn), are a persistent constraint to crop productivity and nutritional quality in calcareous soils with high pH. This study investigated the effects of EDTA (ethylene dinitrilo tetraacetic acid disodium salt dihydrate), Fe-EDTA in combination with different Zn fertilization rates on dry matter yield and tissue Fe and Zn status of bread wheat (Triticum aestivum L., cv. BDME-10). A greenhouse experiment was conducted in a randomized complete block design with four replications. Treatments included Fe-EDTA applied at 0, 2, and 10 mg Fe kg-1, unchelated EDTA at 0, 13, and 65 mg kg-1, together with Zn sulfate at 0, 0.05, and 5 mg Zn kg-1. Both Fe and Zn fertilization enhanced biomass production and Fe and Zn concentrations. The greatest yield improvement, corresponding to a 43% increase compared with control, was obtained with 10 mg Fe kg-1 as Fe-EDTA in combination with 5 mg Zn kg-1. Zinc application also markedly increased Zn uptake, with Zn uptake rising from 1.61 µg plant-1 in the control plants to 37.26 µg plant-1 at the highest Zn dose. However, this increase in Zn dosage led to reductions in Fe concentration and uptake of up to 48%. In Fe-EDTA treatments, Fe uptake reached 76.94 µg plant-1 at moderate Zn supply but decreased to 56.62 µg plant-1 under excess Zn. EDTA, however, also increased both Fe and Zn uptake, yet its effectiveness remained consistently lower than that of Fe-EDTA under comparable conditions. These results demonstrate that Fe-EDTA is a more efficient, supporting higher Fe acquisition and Zn accumulation while reducing the severity of Zn–Fe antagonism. A balanced combination of Fe-EDTA and Zn supply therefore represents a promising approach to improve both yield and Fe and Zn content of wheat in calcareous soils.