Organic farming significantly improves microbial community structure, network complexity, and functional diversity in the Gannan navel orange orchard.

Background: In recent years, improper agricultural management practices have led to the loss of biodiversity and poor fruit quality in orchards. Converting conventional farming to organic farming is an environmentally responsible approach to improving sustainable fruit production. However, questions remain regarding how the microbial community responds to different farming practices in citrus trees. Specifically, this study aims to investigate how organic and conventional farming affect the microbial community structure and functional diversity in the Gannan navel orange orchard using 16S rRNA gene sequencing and Biolog Eco-Plate analysis.

Results: The results showed that the soil bacterial diversity (α-diversity index) under organic farming was higher than that under conventional farming. Actinobacteria, Bacteroidetes, and Firmicutes were more abundant in root and fruit compartments under organic farming, indicating that organic farming promotes the enrichment of copiotrophic bacteria (r-strategists). Furthermore, organic farming resulted in a considerable increase in the relative abundance of Burkholderia and Streptomyces in root tissues. Interestingly, organic farming exhibited a more complex bacterial network. Biolog analysis further revealed higher functional diversity of the soil microbial community under organic farming when compared with that under conventional farming.

Conclusions: These findings provide evidence that organic farming improves the bacterial community structure and promotes microbial functional diversity in the citrus orchards, contributing to the overall health and production of the citrus crop. Synthetic microbial communities of the organic citrus orchards hold great promise for more efficient environment-friendly orchard management towards sustainable agriculture.