Facile synthesis of potassium doped FeS2 nanofertilizers to enhance seed germination and plant growth in S22 tomato seeds

Nanofertilizers (NFs) provide a sustainable and effective alternative to commercial fertilizers at the nanoscale and they have been praised for their agricultural efficiency. NFs are designed to enhance plant growth and soil health while reducing the environmental footprint of commercial fertilizers. This study focuses on the synthesis and characterization of Potassium-doped Iron disulfide nanoparticles (K-doped FeS₂ or KFS NPs). KFS is essential for plant metabolism and stress tolerance, with FeS₂ known for its role in improving soil micronutrient availability and sulfur content. A simple green synthesis approach was used to produce KFS NPs with Arachis hypogaea peel as a fuel. The structural and morphological properties of the NFs were confirmed using advanced techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), as well as elemental analysis, EDAX and Fourier transform infrared spectroscopy (FT-IR). XRD patterns are strongly aligned with the standard JCPDS No. 71–53 of FeS_2, signifying that they belong to the cubic pyrite phase with all the sides of the crystal being equal to 5.4281 Å, associated with the Pa-3 space group. TEM analysis shows the cubic structures of KFS NPs and demonstrates significant germination at a dosage of 20 mg/2 mL. KFS NPs were more effective than commercial fertilizers in enhancing plant growth, chlorophyll and carotenoid levels. Plants treated with NFs have a higher chlorophyll content of 22.41 mg/g than plants treated with commercial fertilizer (11.07 mg/g) and control (4.3 mg/g). KFS-treated (foliar spray) tomatoes have a higher carotenoid content (14.87 mg/g) compared to Control (3.55 mg/g) and commercial fertilizer (6.55 mg/g). The concentration of ascorbic acid was highest in the test sample of (67.7 mg/mL) of KFS-treated tomato and protein content was found to be highest in KFS-NPs-treated tomatoes (2139.956 µg/mL). Findings suggest that KFS NFs hold the multifunctional role in agriculture. It provides an eco-friendly approach to address global challenges such as nutrient inefficiency, soil degradation and environmental pollution.