The responses of root exudates and microbiome in the rhizosphere of main plant and aromatic intercrops to soil Cr stress.

Soil chromium (Cr) stress has a well-recognized negative impact on plant growth, and intercropping is a commonly used method to mitigate heavy metal toxicity to main plants. However, the responses of root exudates-microbial and their interactions among soil zones to soil Cr stress are always in need of clarification in intercropping system. In this study, three intercropping patterns (CT, Malus only; TM, Malus × Mentha and TA, Malus × Ageratum) with different soil Cr addition levels (NCR, LCR, HCR) were applied, and the rhizosphere ecological traits in the main plant (FRS) and intercrop (ARS) were investigated. The results indicate that intercropping with either Mentha or Ageratum has a positive effect on main plants response to soil Cr stress, and intercropping with Ageratum showing a more significant effect. Importantly, we found that the rhizosphere of main plant tends to alleviate stress by accumulating organic acids and amino acids, while aromatic plants exhibit a broader accumulation of metabolites. Additionally, we identified five core differential microbial genera. Our findings provide novel insights into intercrop Cr detoxification in the main plant.