Abstract: Aims Dendrobium huoshanense is a national category I Protected Endangered Wild Plant of the Orchidaceae family and the genus Dendrobium. It is also a traditional Chinese medicinal resource plant that can be used both as medicine and food. Currently, facility cultivation and underforest cultivation have become the primary methods for the cultivation of D. huoshanense. However, the correlation characteristics between the aboveground biomass, quality of D. huoshanense and the microbial community in the substrate/soil under these two cultivation modes remain unclear. This limitation hinders the understanding of the aboveground-belowground processes and mechanisms of D. huoshanense. Methods In light of this, a field experiment and sampling were conducted at the D. huoshanense cultivation base in the Dabie Mountains, Anhui, with the aim to investigate the regulatory relationship between nutrients and plant-microbe interactions in the facility and underforest cultivation modes of D. huoshanense. Important findings Underforest cultivation of D. huoshanense significantly altered the microbial community in the soil, whereas facility cultivation did not change the microbial community in the substrate. Significant differences in microbial biomass, community structure, and diversity were observed between the facility and underforest cultivation modes. Specifically, compared to the underforest soil, the substrate showed higher microbial biomass carbon (MBC) and nitrogen (MBN) contents, as well as a higher abundance of phylum Glomeromycota fungi and bacterial diversity. The fresh weight of D. huoshanense in the substrate was significantly higher than that in the underforest soil. Structural equation modeling (SEM) results indicated the regulatory relationships between nutrients-microbes in the substrate/soil and the fresh weight of D. huoshanense in the two cultivation modes. In detail, the eutrophic conditions in the facility cultivation shaped a higher bacterial diversity, which promoted the aboveground biomass of the plants. In contrast, under the oligotrophic conditions of the underforest, an increase in pathogen abundance reduced the aboveground biomass, while potentially prompting an increase in the resistance of secondary metabolites (such as flavonoids) in D. huoshanense. This study clarifies the associations between plant biomass and microbial communities in the facility and underforest cultivation modes of D. huoshanense, providing a scientific basis for the development of functional microbial inoculants to promote plant growth and quality regulation in the artificial cultivation process of D. huoshanense, as well as the conservation of rare and endangered plant resources.

Key words: Dendrobium huoshanense, Cultivation modes, Soil microorganism, Biomass, Quality, Nutrient