Agricultural and food processing wastes, such as corn steep liquor (CSL) and myo-inositol (MI), are promising biostimulants for enhancing crop resilience under abiotic stress. While our previous work established the effectiveness of CSL-MI co-application in mitigating salt stress in Brassica rapa, critical knowledge gaps persist regarding their combined mechanisms in regulating root system architecture and nutrient acquisition efficiency. Here, we investigate the comparative efficiency of CSL and MI in promoting growth and nutrient acquisition in Chinese cabbage under saline conditions (2.25g·kg⁻¹ NaCl stress). Plant biomass, root architecture, photosynthetic pigment content, and total nitrogen and total phosphorus concentrations were measured. We found that co-application of CSL and MI increased the shoot fresh weight by 124.48% and the root fresh weight by 169.49% and plant total nitrogen content increased by 39.49% and plant total phosphorus content increased by 56.87% as compared to the salt treatment alone. The results emphasize the potential of agricultural waste-derived biostimulants for sustainable crop production under salt stress, with Chinese cabbage exhibiting similar responsiveness to combined CSL-MI application compared to other cabbage under similar stress.

Cadmium (Cd) contamination of soil threatens agricultural productivity and food safety. In this study, a dual-component remediation strategy combining lanthanum-cysteine chelate (CLa) and corn steep liquor (CSL) was developed to alleviate Cd toxicity in Chinese cabbage (Brassica rapa subsp. pekinensis). CLa enhanced photosynthetic efficiency, antioxidant enzyme activity, and root viability, while reducing Cd translocation to shoots. In contrast, CSL acted primarily through organic nutrient supplementation, stimulating chlorophyll synthesis and promoting the growth of beneficial rhizosphere microbes. Notably, the combined treatment (CLCS) exhibited a synergistic effect, significantly enhancing biomass production, nutrient uptake, photosynthetic performance, and oxidative stress tolerance, while reducing Cd accumulation in plant tissues. Furthermore, CLCS optimized the soil microenvironment and microbiota composition, reinforcing plant resilience under Cd stress. This study offers a promising and cost-effective approach for mitigation of heavy metal stress and crop productivity improvement by coordinated plant–microbe–soil interactions.