Effects of rhizobium and phosphate-solubilizing bio-fertilizers on growth and yield of fenugreek

Abstract

Fenugreek (Trigonella foenum-graecum L.) is a multipurpose legume cultivated for its leaves and seeds. Its growth depends on adequate nitrogen and phosphorus nutrition, yet the availability of these nutrients is shaped by biological as well as chemical processes in soil. Compatible rhizobia form root nodules that can supply nitrogen through biological nitrogen fixation. Phosphate-solubilizing bacteria (PSB) can mobilize some forms of phosphorus that would otherwise be poorly available to roots. Their combined application is therefore of interest: phosphorus is needed for root development and the energy-intensive process of nitrogen fixation, while improved nitrogen nutrition can support foliage, flowering, and seed formation. This article critically reviews the proposed mechanisms and the available evidence concerning fenugreek growth and yield. Fenugreek-specific experiments have reported improved germination, biomass, nutrient uptake, or stress responses following treatment with selected beneficial bacteria. Research across other legumes provides support for studying interactions between rhizobia and phosphorus-mobilizing microorganisms. Nevertheless, responses depend on bacterial strain, host compatibility, soil properties, nutrient status, moisture, and inoculant quality. Early growth responses must not be treated as proof of increased seed yield, and results from other legumes cannot establish a fertilizer recommendation for fenugreek. The article proposes a field research framework that compares single and combined inoculation, evaluates both leaf and seed harvests, and measures soil and plant responses across seasons. Rhizobial and PSB inoculants offer a promising component of integrated fenugreek nutrition, provided that recommendations are based on reproducible local evidence rather than assumed benefits.