Field evidence of the effects of microbial consortia on tomato performance and water-use efficiency under climate-driven abiotic stress

Agricultural productivity is constrained by climate variability and the increasing frequency of extreme events, such as drought, salinity, and heat stress. These events are largely mediated by water availability and soil moisture dynamics. The European sustainability targets framework is driving the need for solutions that boost crop resilience while maximising water and nutrient efficiency in field conditions. In the face of climate variability, there is growing interest in microbial biostimulants, especially microbial consortia, as a means to enhance plant resilience to abiotic stress and optimise water usage. Through a systematic review of the literature, this study provides a synthesis of field-based evidence on the effects of microbial consortia in tomato (Solanum lycopersicum L.) under abiotic stress. Following PRISMA 2020 guidelines, a comprehensive screening of the Scopus database (up to September 2025) identified only 34 inherent records, of which 7 papers (30 treatment combinations) met the pre-defined inclusion criteria. The results show that microbial consortia usually improve how crops in the field perform under abiotic stress conditions. When yield was measured per unit area, it increased in 76.9% of cases, with a mean improvement of +94.1% compared to non-inoculated controls. In the experiments s where yield was quantified also at the plant level, fruit fresh weight increased in 85.7% of treatments (+481.0% on average). Fruit quality traits (Brix or total soluble sugars) improved in 46.2% of cases (+65.6%), suggesting partial mitigation of stress-induced physiological limitations. Resource optimization was demonstrated in specific cases, where consortia allowed for irrigation cuts of up to 50% and phosphorus savings while substantially increasing yields under stress compared to controls; however, these benefits were not ubiquitous, as other studies showed mixed effects under abiotic stress or lacked the precise nutrient data required for a definitive assessment. These findings emphasize the potential of microbial consortia to enhance tomato resilience under fluctuating climates. However, a critical research gap remains: the limited number of field trials and the lack of standardized quantitative data across agronomic, physiological, and input parameters hinder predictable deployment. Despite promising tomato yield gains, future research must prioritise multi-site and multi-year field validations using a standardized core set of metrics to bridge the gap between experimental success and the reliable adoption of consortia in climate-resilient agriculture.