Spirulina biomass loaded with iron nanoparticles: A novel biofertilizer for the growth and enrichment of iron content in rice plants

The current investigation was focused to develop a nano-iron-based phycofertilizer to enhance crop quality in an environment-friendly manner. Biosynthesis of nano-iron occurred when Spirulina biomass was exposed to a 0.05M FeCl₃ solution for 48h at pH 5.5 in the dark, resulting in the synthesis of spindle-shaped nano-iron both inside and outside the cells. The particles' sizes were 24.77 ± 5.264 nm as observed in transmission electron microscopy. Further characterizations were carried out using energy dispersive X-ray spectroscopy (EDX), and dynamic light scattering (DLS). The performance of various fertilizers, including those derived from phycosynthesized nano iron (INP), dried Spirulina biomass (SB), and nano-iron loaded Spirulina biomass i.e., nano-phycho-fertilizer (NPF) was compared against conventional NPK fertilizer. The results from field applications indicated significant improvements in rice, with NPF outshining the rest. Notably, NPF demonstrated a remarkable 37.6% increase in shoot length, a 47% boost in crop productivity, and a 15% rise in grain weight of rice compared to NPK. Both unpolished and polished grains of NPF-treated plants contained higher iron contents (44% and 28%) than the NPK-treated plants. Furthermore, the cost-effectiveness analysis underscored the superiority of NPF over conventional fertilizer, representing it as a highly effective and eco-friendly nano-iron-based phycofertilizer.