Silicon interaction with nitrogen-fixing bacteria alters biomass partitioning and pod–seed yield traits in peanut (Arachis hypogaea L.)

Improving biomass and yield in legumes remains a major agronomic challenge, and the interaction between silicon fertilization and microbial inoculation in regulating these responses is not well understood. This study evaluated the combined effects of silicon (Si) application and microbial inoculation with Azospirillum and Bradyrhizobium on growth and yield components of peanut. A factorial Completely Randomized Design was used with three microbial treatments (none, Azospirillum, Bradyrhizobium) and two silicon levels (0 and + Si). Significant Microbe × Silicon interactions were observed for total biomass, harvest index, pod traits, and seed yield whereas root structural traits did not show significant treatment responses. Under non-silicon conditions, Azospirillum produced the highest seed yield mainly through increased seed number. In contrast, silicon increased biomass accumulation under Bradyrhizobium but reduced yield when combined with Azospirillum. Correlation and multivariate analyses identified seed number and harvest index as key variables associated with yield variation. Overall, the results demonstrate that peanut responses to silicon differed depending on the microbial inoculant applied, highlighting the importance of considering microbial inoculation when evaluating silicon management strategies for improving growth and yield in legume production systems.