Effects of bacterial inoculants and irrigation regimes on yield, mycorrhizal colonisation, and photosynthetic efficiency in strawberry cultivars

Strawberries (Fragaria × ananassa) are a globally significant fruit crop with high nutritional and economic value. However, their shallow roots and high water demands make them vulnerable to water stress. The effects of microbial inoculants and irrigation regimes on the yield, root colonisation by arbuscular mycorrhizal fungi (AMF), and photosynthetic efficiency of strawberry cultivars Rumba and Honeoye were investigated. Field and pot experiments were conducted, where plants were subjected to 100% and 50% water supply conditions. The application of Inoculum 1 (C09EX – Pseudomonas sp., Ps150AB Pseudomonas sp.) and Inoculum 2 (JAFGU – Lysobacter sp.) were applied to evaluate their potential to enhance plant growth and resilience under these conditions.A full irrigation regime (100% water supply) significantly increased fruit yield per plant in both cultivars compared to a reduced irrigation regime (50% water supply). Both inoculants positively affected yield, with Inoculum 1 showing the best results under full irrigation and Inoculum 2 under reduced irrigation. Mycorrhizal colonisation of roots was significantly improved by both inoculants, with the highest colonisation levels observed in plants treated with Inoculum 2. Photosynthetic efficiency parameters, such as the maximum quantum yield of PSII (FV/FM) and quantum efficiency of photochemical reaction in PSII (ΦPSII), declined under reduced irrigation, particularly in Honeoye, but microbial inocula mitigated these effects and enhanced performance under both regimes.These findings suggest that microbial inoculants can alleviate the adverse effects of water stress on strawberry plants, enhancing yield and physiological performance. Future research should explore the underlying mechanisms of these interactions and evaluate the long-term benefits of microbial inocula in different environmental conditions.