Insights into the tripartite interaction: effects of Arbuscular mycorrhizae and Rhizobium on root morphology, soil enzymes, and biochemical properties in pea cultivation in alluvial soils of Punjab, India

Arbuscular Mycorrhizal Fungi (AMF) and Rhizobium (RHZ) are key bio-inoculants in sustainable agriculture, known for their symbiotic relationships with plants. However, their effects on soil functions under different proportions of inorganic fertilizers are not well understood. This study, conducted during the Rabi seasons from 2019 to 2021 in alluvial soils of Punjab, India, investigates the impact of AMF and RHZ inoculation on root morphology and rhizospheric soil chemical properties in field pea (Pisum sativum L.). The findings indicate that dual inoculation with AMF and RHZ (RHZ + AMF + N50%+P50%+K100%) significantly enhances root growth and improves soil chemical properties. Despite an initial increase in pH that negatively affected micronutrient availability at 60 days after sowing (DAS), a stabilizing trend at 90 DAS was observed, leading to better availability of Fe, Cu, Mn, and Zn, along with higher Cation Exchange Capacity and macronutrient availability. This dual inoculation strategy is found to maximize profitability in terms of root morphology and soil chemical properties. Notably, lower root Cation Exchange Capacity compared to soil Cation Exchange Capacity may be due to factors like soil structure and root interactions. Principal Component Analysis (PCA) of soil parameters effectively distinguishes between treatments, showing that RHZ and AMF respond differently to various NPK proportions. For instance, treatments T3 (RHZ + N50% + P100% + K100%), T4 (RHZ + N75% + P100% + K100%), and T6 (AMF + N100% + P75% + K100%) are grouped together, while treatments T5 (AMF + N100% + P50% + K100%) and T7 (RHZ + AMF + N50% + P50% + K100%) cluster separately. This suggests that dual inoculation, especially as seen in Treatment T7, is recommended for sustained soil health and enhanced productivity.