Objectives This study aims to investigate the effects of understorey intercropping of Rhododendron delavayi with Orychophragmus violaceus on the soil bacterial community characteristics of the Baili Rhododendron Nature Reserve. Additionally, it seeks to provide a technical reference for the cultivation mode of intercropping with Orychophragmus violaceus to improve the soil quality in the nature reserve.

Methods The soil chemical property indicators were determined, and the V3‒V4 region fragments of the 16S rDNA gene of bacteria in soils were sequenced using Illumina MiSeq high-throughput sequencing technology to analyze the characteristics of different soil bacterial communities.

Results The Interplanting of Orychophragmus violaceus resulted in an increase in the nutrient content of the understorey soil. The contents of soil organic carbon, total nitrogen, total phosphorus, and total potassium all exhibited an increase following the intercropping process, with a notable elevation observed in soil organic carbon and total nitrogen (P<0.05). Following intercropping with Orychophragmus violaceus, a decrease in the pH value was observed in the rhizosphere soil, indicative of an acidification trend. Following intercropping with Orychophragmus violaceus, an increase in the diversity of the rhizosphere bacterial community was observed. The bacterial communities with the highest proportions in the rhizosphere soil were identified as Proteobacteria, Acidobacteria, and Aspergillus, accounting for 95.44% of the total bacterial community abundance. The metabolic pathways that increased the abundance of soil bacterial communities after intercropping were metabolism, environmental information processing, cellular processes, and genetic information processing.

Conclusions The richness and diversity of soil bacterial communities in the understorey intercropping system of Orychophragmus violaceus increased, and intercropping improved the soil nutrient status. Intercropping measures can be effective for improving soil quality in nature reserves.