Integrating intercropping and straw returning increases wheat grain yield: Insights into soil aggregate stability and root plasticity

Global food security is challenged by population growth and climate change, particularly in arid regions where water scarcity and soil degradation from long-term intensive cultivation limit crop productivity. Thus, exploring agricultural management strategies that improve soil structure and enhance grain yield is crucial for maintaining a stable food supply. A ten‑year field experiment with a split‑plot design was conducted in northwest China. The main plots consisted of wheat monoculture and wheat-maize intercropping. The sub-plots included three agricultural management practices: no tillage with straw mulching (NTSM), conventional tillage with straw incorporation (CTS), and conventional tillage with straw removing (CT). Compared with monoculture, intercropping increased wheat grain yield by 47.8%. NTSM and CTS raised net yield by 15.9% and 7.5% relative to CT, with NTSM outperforming CTS by 7.9%. The yield advantage of intercropping arose from soil aggregate stability, which mediated wheat root morphological and physiological plasticity. In the intercropping system, NTSM increased mean weight diameter and geometric mean diameter by 16.0% and 13.7% over CT. Consequently, NTSM raised root density in the 0–20 cm layer by an average of 24.4%. NTSM also enhanced stress resistance in intercropped wheat root, increasing antioxidant enzyme activity by 22.0% and osmolyte content by 18.6% over CT on average. The root salicylic acid to abscisic acid ratio of intercropped wheat was 11.6% higher under NTSM than under CT during grain filling. Therefore, integration of intercropping and no tillage with straw mulching provides a practical field management solution to improve soil structure and increase crop yield in arid regions