Asian Journal of Soil Science and Plant Nutrition

The present study evaluated the synergistic effects of arbuscular mycorrhizal fungi (AMF) and beneficial rhizospheric microorganisms on the growth, root colonisation, and yield of mustard (Brassica juncea L.), a crop traditionally regarded as a poor or non-mycorrhizal host. A field experiment was conducted during the rabi seasons of 2023–2024 and 2024–2025 at the Research Farm of Nirmal Seeds Pvt. Ltd., Maharashtra, India, using the mustard variety NIMOH-8. The experiment was laid out in a randomised block design (RBD) with seven treatments and three replications. The treatments comprised soil application of a mycorrhizal powder formulation alone or in combination with Trichoderma viride, Trichoderma harzianum, and Pseudomonas fluorescens. Standard agronomic practices were followed throughout the study. Plant growth, yield attributes, and root colonisation were assessed at harvest, and roots were stained using the Phillips and Hayman (1970) technique. The application of bio-inoculants significantly improved growth and yield parameters compared with the untreated control. The highest number of siliquae per plant (541.9), seed yield per plant (14.13 g), and seed yield (23.28 q ha⁻¹) were recorded in T4, which comprised mycorrhizal powder formulation (250 g ha⁻¹) + Trichoderma viride WP (2.5 kg ha⁻¹). Treatment T7 (mycorrhiza + T. viride + Pseudomonas fluorescens) produced comparable results, with 525.7 siliquae per plant and a yield of 23.15 q ha⁻¹. Microscopic examination of stained roots confirmed AMF colonisation in the combined inoculation treatments, characterised by intraradical hyphae, vesicles, external mycelium, and arbuscules; no fungal colonisation was observed in the untreated control. Enhanced root colonisation was associated with improved plant growth and productivity, indicating a positive interaction between AMF and beneficial rhizospheric microorganisms. The study demonstrated that integrating AMF with Trichoderma viride and Pseudomonas fluorescens enhanced mycorrhizal establishment, nutrient acquisition, and mustard productivity. Among the treatments tested, the combination of mycorrhiza and T. viride was the most effective. These findings indicate the potential of microbial consortia as an environmentally compatible strategy for improving mustard yield and crop productivity.