Effects of Different Formulations of Exogenous Nutrient Bag Waste on Soil Properties and Physiological Activities and Root Transcriptomic Responses of Oat

This study used typical chestnut soil from Huangyuan County, Qinghai Province as the experimental soil, and selected three oat varieties, “Baiyan 7”, “Qingyan 2”, and “Qinghai 444”, for mixed sowing. A blank control (CK) and five treatments with different ratios of exogenous nutrient bag waste (PF-R-1 to PF-R-5) were established. Through soil physicochemical analysis, microbial biomass determination, RNA sequencing (RNA-Seq), and weighted gene co-expression network analysis (WGCNA), the effects of exogenous nutrient bag waste with different ratios soil nutrient availability, microbial activity and root gene expression in oats were systematically evaluated. The results showed that most treatments enhanced soil organic matter, nitrogen content, and microbial activity. Transcriptomic analysis revealed that the comparison between PF-R-3 and PF-R-2 treatments exhibited the highest total number of differentially expressed genes (DEGs), with enrichment in pathways related to ribosomal protein translation, oxidative phosphorylation energy metabolism, and DNA damage repair. These enrichment patterns suggest potential changes in energy metabolism and protein synthesis, although direct functional validation was not performed. Moreover, DEGs uniquely identified in PF-R-3 were significantly enriched in nitrogen metabolism and secondary metabolite biosynthesis pathways; WGCNA identified the coral2 module as the core regulatory module, with its genes predominantly enriched in functions related to transmembrane transport and plant hormone signal transduction, which were highly consistent with efficient root nutrient acquisition and the maintenance of metabolic homeostasis. Fluorescence staining confirmed the successful colonization of oat root tissues by Morchella mycelium. Taken together, based on the integration of soil nutrient supply stability, root gene expression regulation, and fungal colonization evidence, the PF-R-3 treatment (wheat + corncob + oat) emerged as a promising candidate among the tested formulations under the experimental conditions. However, further field trials incorporating yield and quality data are needed before a definitive recommendation can be made. This study provides a theoretical basis and technical support for the resource utilization of exogenous nutrient bag waste and the green cultivation of oat in alpine regions.