Modulation of Soil Iron Fractions and Productivity of Wheat Under Iron Nano-Particles and Bulk Salt in Alkaline Calcareous Soil

Abstract

ABSTRACT Agronomic bio-fortification of wheat with iron (Fe) can improve Fe content in plant tissues and alleviate its deficiency in the food chain. Field investigation was conducted over two consecutive growing seasons to evaluate Fe sources, levels, and application methods for modulating Fe fractionation in soil and wheat productivity. Experimental plan comprising two soil addition levels (5 and 10 kg ha−1), two foliar levels (0.25% and 0.5% Fe solution) and four combinations of soil addition and foliar spray, with a common control. Iron oxide nanoparticles (Fe-NPs) and iron sulfate heptahydrate (Fe-BS) were used as Fe sources. Fe-NPs demonstrated a greater efficacy than Fe-BS. Application methods were ranked as soil addition+foliar spray > soil addition > foliar spray in improving wheat productivity. Among the treatments evaluated, Fe-NPs at 10 kg ha−1 through soil addition combined with 0.5% foliar spray (S-Fe-10+F-Fe-0.5) produced highest improvements in wheat growth, yield, physiology, and grain quality. The S-Fe-10+F-Fe-0.5 treatment maximally increased chlorophyll by 41.0 and 47.36%, photosynthetic rate 31.22 and 22.5%, grain yield 25.24 and 23.46%, and grain protein 18.26 and 24.0% during 2021–22 and 2022–23, respectively, compared with the control. Soil Fe was fractionated into six fractions, which altered markedly with Fe fertilization. DTPA extractable Fe was most effectively modulated and maximally improved by 387 and 369% with Fe-NPs at 10 kg ha−1 during 2021–22 and 2022–23, respectively, compared with the control. Fe-NPs at S-Fe-10+F-Fe-0.5 proved most efficient in improving grain Fe concentration and grain yield, and could be recommended for better wheat productivity under alkaline calcareous conditions.