Stable soil water shapes the rhizosphere of Solanum lycopersicum L. and improves tomato fruit yield and quality

• The fruit yield and quality of tomatoes were increased by stable soil water. • Soil water stability mediated water use efficiency of tomato. • Stable soil water enhanced soil fertility and promoted microbial metabolism. • Soil water stability altered the structure and composition of microbial community. • Maintaining a stable water pattern is a promising tomato production strategy. Stable soil water can ensure plant yield and water use efficiency, yet its short-term impact on tomato production and soil ecological environment is not well understood. In this study, the effects of stable soil water (SW) under two water levels were examined, with fluctuating soil water (FW) as a control. The assessed parameters included tomato yield and quality, water use, root characteristics, soil properties, and soil microbial community structure. We found that soil water stability was an independent environmental variable that significantly affected the root morphology, yield, and quality of tomatoes, among which most indexes under SW had higher values. Compared with FW, the fruit yield of tomato under SW increased by 28.2 %, and the contents of vitamin C, lycopene, soluble sugars, and titratable acid in fruit increased by 12.1, 18.0, 20.4, and 20.9 %, respectively. When the soil water remained stable as opposed to fluctuating, the available nutrients content and soil enzyme activity in the tomato rhizosphere increased by 6.0–35.0 % and 5.3–17.5 %, respectively. The bacterial and fungal communities in tomato rhizosphere underwent considerable structural and compositional changes in response to soil water stability. Compared to FW, SW tended to increase the relative abundance of Cyanobacteria while decreasing the relative abundance of Proteobacteria, Bacteroidota, and Mortierellomycota. This study revealed the relationship between tomato production and soil water from the perspective of soil water stability, filled the gap in soil water stability and tomato rhizosphere soil, and provided useful insights for the development of management strategies to improve the productivity of vegetable crops.