Intervention of rhamnolipid improves the rhizosphere microenvironment of cotton in desert saline lands

Rhamnolipids have been extensively studied for the remediation of soils contaminated with petroleum hydrocarbons. However, the literature on the effects of rhamnolipids on the soil microenvironment is scarce. In this study, we adopted a drip irrigation technique to apply a rhamnolipid solution to soil planted with cotton in a saline desert area. The results showed that the addition of rhamnolipids increased soil organic matter by 5.0–31.6 % and reduced soil electrical conductivity by 0.3–42.4 %. Additionally, it improved soil nutrient conditions, reshaped the composition and function of the microbial community in the rhizosphere soil, and ultimately promoted cotton growth by 3.3 – 9.0 %. Simultaneously, the addition of rhamnolipids enriched the diversity of the bacterial community. Although it reduced the diversity of fungal communities, it optimized the community structure of fungi. It is worth noting that higher concentrations of rhamnolipids may have toxic effects on soil fungi, the mechanism of which is unknown. These findings shed new light on understanding the effects of rhamnolipids on rhizosphere soil microorganisms and provide a new direction for sustainable agricultural production.