Sugarcane-peanut intercropping enhances industrially relevant crop traits mediated by key soil and plant multifunctionality: Meta-analysis and field evidence

Sugarcane-peanut intercropping system has garnered global attention, primarily for its role in promoting sustainable agriculture. Yet, its impacts on industrially relevant traits and underlying mechanisms regulating these outcomes remain largely elusive. To address these critical knowledge gaps, we leveraged a multi-scale approach, integrating data from a synthesis of experiments with long-term field trials. Our long-term field trial demonstrates that this cropping system significantly enhances industrially relevant sugarcane traits while reducing heavy metal levels in bulk and rhizosphere soils. Sugarcane-peanut intercropping also enrich key plant growth- and stress-regulating bacteria, including Anaeromyxobacter and Bradyrhizobium in the rhizosphere soil and root tissue, Rhizomicrobium and Streptomyces in root tissue, and Bacilli in stem tissue. The vast majority of these taxa show significant positive associations with a number of industrially relevant sugarcane traits. Concurrently, this cropping system enriches key growth- and stress-related metabolites such as β-sitosterol, abscisic acid, and gibberellin A7 in the rhizosphere soil and root tissue, while potentially phytotoxic compounds are suppressed. Other key compounds, including flavonoids (95.63%), dominate the entire plant and soil compartments and exhibit significant associations with industrial traits. The meta-analysis identifies soil multifunctionality (40%) as the dominant predictor of variation in industrially relevant sugarcane traits. Taken together, these findings suggest that the benefits of sugarcane-peanut intercropping emerge from the integration of multiple soil-plant processes rather than from any single factor, highlighting the importance of a whole-system perspective when evaluating intercropping outcomes.