Microbial Inoculant–integrated Hydroponic System for Sustainable Production of Fenugreek (Trigonella foenum-graecum)

Hydroponics is an advanced soilless cultivation technique that facilitates efficient and sustainable crop production, particularly for leafy vegetables such as fenugreek. However, conventional hydroponic systems rely predominantly on synthetic nutrient solutions, which raise concerns regarding environmental sustainability. The present study aimed to develop and evaluate a biofertilizer-based nutrient solution as a sustainable alternative to synthetic inputs for hydroponic cultivation of fenugreek using the floating raft method with cocopeat as the substrate. A total of six treatments were evaluated, comprising a standard Hoagland nutrient solution, individual biofertilizers—Methylobacterium extorquens, arbuscular mycorrhizal fungi (AMF), Spirulina sp., Azospirillum brasilense—and a microbial consortium. Growth, yield, physiological, and biochemical parameters were assessed. Among the treatments, the Spirulina.–based nutrient solution demonstrated superior performance across multiple parameters, recording the highest root length (21 cm), leaf area (4.78 cm²), total phenolic content (4.44 mg GAE g⁻¹), and TSS (10 °Brix). These results highlight the potential of targeted microbial bio inputs to enhance plant growth, physiological performance, and nutritional quality in hydroponic systems. These results demonstrate the potential of biofertilizer-based hydroponics as a sustainable alternative to sole reliance on synthetic nutrient solutions. Overall, the integration of selected biofertilizers offers a promising strategy to improve hydroponic productivity while reducing dependence on chemical fertilisers, thereby promoting more sustainable and environmentally friendly cultivation practices.