Agricultural Engineering

Effects of seed priming with iron (Fe) aminochelates on soil Fe chemical fractions and sunflower Fe nutrition

Document Type : Applicable

Authors

Mina Alipour Babadi 1
Mojtaba Norouzi Masir 2
Abdolamir Moezzi 3
Afrasyab Rahnama Ghahfarokhi 4
Mehdi Taghavi Zahedkolaei 5

1 Ph.D. Graduate, Department of Soil Science, Faculty of Agriculture, Shahid Chamran University of Ahvaz, Ahvaz, Iran

2 Associate Prof., Dept. of Soil Science and Engineering, Faculty of Agriculture, Shahid Chamran University of Ahvaz, Ahvaz, Iran

3 Professor, Department of Soil Science, Faculty of Agriculture, Shahid Chamran University of Ahvaz, Ahvaz, Iran

4 Professor, Department of Plant Production and Genetics, Faculty of Agriculture, Shahid Chamran University of Ahvaz, Ahvaz, Iran

5 Associate Professor, Department of Chemistry, Faculty of Science, Shahid Chamran University of Ahvaz, Ahvaz, Iran

https://doi.org/10.22055/agen.2026.51384.1796
Abstract
Introduction: Iron (Fe) deficiency remains a major constraint in calcareous soils, where high pH and carbonate-rich conditions restrict Fe mobility and convert it rapidly into poorly soluble forms. These limitations reduce Fe availability to plants and highlight the need for strategies capable of modulating Fe transformation pathways within the soil solid phase. Aminochelate-based Fe sources, particularly Fe–amino acid complexes, have gained attention due to their greater resistance to precipitation and their potential to alter Fe fractionation dynamics. Unlike conventional Fe fertilizers such as FeSO₄, which are prone to oxidation and fixation shortly after application, Fe aminochelates may contribute to a more persistent and plant-accessible Fe pool. Considering these characteristics, the present study aimed to determine how seed priming with Fe-glycine [Fe(Gly)₂] and Fe-methionine [Fe(Met)₂] aminochelates influences the distribution of Fe chemical fractions in calcareous soil and to assess how these changes translate into Fe concentration and Fe uptake in sunflower (Helianthus annuus L. cv. Oscar).

Materials and Methods: A field experiment was conducted using a randomized complete block design (RCBD) with three replications. Treatments consisted of seed priming with [Fe(Gly)₂] and [Fe(Met)₂] (2%), FeSO₄ (2%), and a non-primed control. At harvest, soil samples were analyzed for pH, DTPA-extractable Fe, and Fe fractionation using a modified Tessier sequential extraction procedure. Fractions quantified included exchangeable (EXC-Fe), organically bound (ORG-Fe), carbonate-bound (CAR-Fe), Fe/Mn oxide-bound (OX-Fe), and residual (RES-Fe). Fe concentration in seeds and leaves, as well as seed Fe uptake, were also measured.

Results and Discussion: Seed priming with Fe aminochelates markedly influenced soil chemical behavior and plant Fe nutrition. Both [Fe(Gly)₂] and [Fe(Met)₂] lowered soil pH relative to the control and FeSO₄, contributing to improved Fe solubility. DTPA-extractable Fe increased by 29.2% under [Fe(Gly)₂] and 36.1% under [Fe(Met)₂] compared with the control. Similarly, seed Fe concentration increased by 10.4% and 12.6%, and seed Fe uptake by 60.7% and 71.5%, respectively. The overall distribution pattern of Fe fractions followed RES-Fe > OX-Fe > CAR-Fe > ORG-Fe > EXC-Fe. Aminochelate treatments, especially [Fe(Met)₂], altered this pattern by shifting Fe towards more labile forms, specifically EXC-Fe and ORG-Fe, while reducing the contribution of CAR-Fe. Strong correlations were observed between DTPA-extractable Fe and both EXC-Fe (r = 0.86**) and ORG-Fe (r = 0.84**). These two fractions also showed positive associations with seed Fe uptake (r = 0.84** for EXC-Fe; r = 0.80** for ORG-Fe), indicating their decisive role in mediating Fe acquisition by the plant. The pronounced response observed with [Fe(Met)₂] suggests a higher chelation strength and a greater capacity for stabilizing Fe in readily accessible pools, thereby supporting continued Fe mobilization in the soil–plant system.

Conclusion: Overall, the findings demonstrate that seed priming with Fe aminochelates, most notably [Fe(Met)₂], substantially enhances Fe bioavailability in calcareous soils by redirecting Fe from less soluble reservoirs toward more exchangeable and organically bound fractions. This shift results in improved Fe uptake and superior Fe nutritional status in sunflower. Consequently, Fe aminochelates represent an effective and sustainable alternative to conventional FeSO₄ for managing Fe deficiency in high-pH soils and for improving micronutrient efficiency in calcareous agroecosystems.

Keywords

Keywords: Carbonate-bound iron
Calcareous soil
Exchangeable iron
Seed priming
Subjects

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Agricultural Engineering
Volume 48, Issue 4
December
Autumn 2026
Pages 567-547

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