Tomato cultivation frequently suffers yield losses due to pest and disease pressures, and in recent years, global warming and the increasing occurrence of extreme weather events have further exacerbated production instability. This project aims to establish a systematic evaluation framework to screen functional microbial resources capable of promoting tomato root development and enhancing broad-spectrum disease resistance, thereby accelerating the identification of strains with potential applications in tomato growth promotion and disease management. In parallel, selected promising microbial strains were validated under field conditions to assess their effects on tomato seedling growth and disease resistance, with the ultimate goal of providing diversified microbial inputs and biological control strategies for tomato cultivation.

To evaluate the growth-promoting potential of isolated strains, a standardized plug-tray assay was established in this study, and root architectural traits—including the number of root tips, branching points, root length, branching frequency, and root surface area—were quantified using the RhizoVision Explorer software (Fig. 1). Preliminary results indicated that the candidate strain F exhibited the most pronounced effects on plant height, root tip number, branching point number, and root length.

In tomato bacterial wilt control trials, post-inoculation application of microbial strains showed no significant curative effects (Fig. 2). However, pre-inoculation treatment significantly reduced disease incidence and wilting rates, indicating that functional microbes are more suitable as preventive disease management agents. Among the tested treatments, the commercial microbial product PMB01 provided the highest level of protection, followed by strains A, C, and LA7016, whereas strain F exhibited comparatively lower protective efficacy.

To evaluate the impact of soil microbial inoculants on tomato growth in field trials (Fig. 3), fruit production was assessed. Strains A and F significantly increased the number of fruits per plant. Additionally, while strain F and the commercial Bacillus amyloliquefaciens formulation did not reach statistical significance, they exhibited higher total fruit weights, suggesting their potential to promote yield accumulation. Overall, the results of this study demonstrate that several candidate microbial strains effectively promote tomato root development and plant vigor, and exhibit preventive protective effects in disease management. Future studies will focus on optimizing application conditions, dosage, and field implementation strategies to further enhance their practicality and feasibility for large-scale agricultural application.

▲Figure 1. Effects of soil-isolated microbial strain treatments on tomato root growth performance.		▲Figure 2. Effects of soil isolate strain F on the biological control of tomato bacterial wilt in inoculation assays
▲Figure3. Impact of soil microbial inoculants on the growth of tomatoes in field trials