Synergistic Interaction Between Endophytic Bacillus pumilus and Indigenous Arbuscular Mycorrhizal Fungi Complex Improves Photosynthetic Activity, Growth, and Yield of Pisum sativum.

Abstract

The demand for sustainable agriculture has prompted the exploration of alternative methods to boost crop growth and yield. Microbial biostimulants offer effective solutions to enhance plant performance and reduce reliance on chemical fertilizers. This study investigated the effects of Bacillus pumelo (B. pumilus), applied individually and in combination with a mycorrhizal fungi complex, on the growth, yield, and photosynthetic activity of pea (Pisum sativum). Pea seeds were grown in sterilized soil under four treatment conditions, including a non-inoculated control, inoculation with 2.5 mL of B. pumilus culture per seedling, inoculation with an indigenous mycorrhizal fungal complex, and a combined treatment of B. pumilus and the mycorrhizal complex. The biostimulant treatments significantly influenced all measured photosynthetic and growth parameters. The results showed that B. pumilus substantially promoted pea growth, leading to notable improvements in biomass, plant height, and photosynthetic efficiency. When combined with the mycorrhizal fungi complex, these growth-promoting effects were significantly amplified, resulting in a ~69.7% increase in shoot fresh weight, a ~72.7% rise in root dry weight, and a ~73.6% boost in flower production. Additionally, the chlorophyll content increased by ~180% and photosynthetic yield (Fv/Fm) improved by ~18.5%. The combined treatment also produced the highest SPAD index value, reflecting a ~57% increase. The synergistic interaction between B. pumilus and mycorrhizal fungi enhances photosynthetic efficiency and overall plant performance. The study highlights the potential of using these microbial inoculants as biostimulants to improve pea cultivation in agroecosystems, offering a sustainable alternative to chemical fertilizers.