Soil acidification reduces flavonoids and key metabolites in sugarcane roots and rhizosphere leading to yield decline

Soil acidification has negative effects on sugarcane growth, leading to yield reduction. However, little is known about its effects on metabolite composition and functional pathways in sugarcane roots and soil. This study used untargeted metabolomics techniques to analyze metabolite changes in sugarcane roots, rhizosphere soil and bulk soil from highly acidified sugarcane fields in Laibin, Guangxi. Our results showed that the progression of soil acidification not only intensifies soil compaction, resulting in elevated soil bulk density and decreased porosity, but also significantly impacts soil nutrient content adversely. Specifically, soil acidification leads to a decrease in available potassium content by 144% and 123%, respectively, while the concentrations of organic matter and available nitrogen in the rhizosphere soil decrease by 33.09% and 22.45%, respectively. At the metabolic level, we observed a significant decrease in the overall classification of flavonoids in sugarcane roots and rhizosphere soil in acidified fields. Specifically, metabolites such as cellotetraose and levan decreased in sugarcane roots, rhizosphere and bulk soil, while gluconic acid and S-lactoylglutathione were reduced in both sugarcane roots and rhizosphere soil. In addition, catechin and chrysin were significantly reduced in sugarcane roots from acidified fields. Preliminary correlation analysis indicated a significant positive correlation between substances such as S-lactoylglutathione and levan and agronomic traits including sugarcane yield. This study provides a theoretical basis for understanding the mechanisms by which soil acidification affects sugarcane and provides guidance for sustainable sugarcane production. • Homeostatic imbalance in sugarcane growth due to soil acidification. • Acidification is accompanied by soil chemical nutrient loss and physical structure destruction. • Acidification reduces key compound concentrations in sugarcane roots and rhizosphere soil.