Varietal differences in soil physicochemical properties and rhizosphere microbial communities of sugar beet under waterlogging stress

Sugar beet, a strategic sugar crop in China, plays a crucial role in ensuring national sugar security. Waterlogging significantly reduces soil oxygen content, adversely affecting nutrient use efficiency and crop yield. It is well established that waterlogging stress strongly inhibits plant growth. However, the response mechanisms of sugar beet seedlings to flooded soil conditions remain inadequately understood. We studied a waterlogging-tolerant sugar beet variety and a sensitive variety. The results showed that waterlogging stress significantly altered the rhizosphere soil environment. Compared to the sensitive variety, the tolerant variety under waterlogging exhibited increased available potassium in the rhizosphere. In contrast, no difference was observed between the two cultivars under CK conditions. Notably, waterlogging stress significantly affected the rhizosphere pH in both varieties. At the fungal community level, the relative abundance of Ascomycota was significantly higher in the tolerant variety than in the sensitive one, suggesting this microbial group may be linked to waterlogging tolerance in sugar beet. Mantel tests revealed significant correlations between soil physicochemical properties and microbial community structure, indicating that sugar beet cultivars can shape the microbial community by regulating the rhizosphere environment. Flooding stress altered the rhizosphere microbial community structure, enriched beneficial microorganisms, and potentially alleviated stress.