Influence of green synthesised iron and zinc nano-particles in enhancing yield and nutrient content of rabi sorghum (Sorghum bicolor L. Moench) through seed priming and foliar application

A field study conducted in MARS, Dharwad, Karnataka, during the rabi season of 2023-24 aimed to assess the efficacy of green-synthesized iron (Fe) and zinc (Zn) nanoparticles (NPs) compared to conventional fertilizers. The standard concentrations for seed priming (SP) and foliar spray (FS), determined in lab and controlled conditions were applied in the field. The standardized SP and FS concentration for Fe, Zn and (Fe + Zn) under lab and controlled conditions were (200, 500 and 400 ppm) and (400, 500 and 400 ppm), respectively. Foliar spraying occurred at the panicle initiation and flowering stages. The experiment was laid out in RCBD with three replications comprising fourteen treatments viz., T1-SP with Fe NPs @ 200 ppm, T2-SP with Zn NPs @ 500 ppm, T3-SP with (Fe + Zn) NPs @ 400 ppm, T4-FS of Fe NPs @ 400 ppm, T5-FS of Zn NPs @ 500 ppm, T6-FS of (Fe + Zn) NPs @ 400 ppm, T7-SP with Fe NPs @ 200 ppm + FS of Fe NPs @ 400 ppm, T8-SP with Zn NPs @ 500 ppm + FS of Zn NPs @ 500 ppm, T9-SP with (Fe + Zn) NPs @ 400 ppm + FS of (Fe + Zn) NPs @ 400 ppm, T10-FS of FeSO4 @ 0.5%, T11-FS of ZnSO4 @ 0.5%, T12-FS of (FeSO4 + ZnSO4 @ 0.5%), T13- RPP (RDF + 15 kg ZnSO4 ha-1 and seed treatment with Azospirillum @ 500 g ha-1) and T14- Control (RDF-50:25 kg N and P2O5 ha-1). RDF was applied to all the treatments. Results revealed that, SP with (Fe + Zn) NPs @ 400 ppm + FS with (Fe + Zn) NPs @ 400 ppm (T9) recorded significantly higher grain yield, stover yield, grain and stover Fe content (44.75 q ha-1, 7.73 t ha-1, 39.95 and 43.42 mg kg-1) grain and stover Zn content (29.06 and 29.54 mg kg-1) compared to control (T14)(36.17 q ha-1, 6.26 t ha-1, 34.36 and 36.18 mg kg-1, 25.41 and 25.76 mg kg-1, respectively).