Exploring the impact of intercropping on the rhizosphere microbial communities of cultivated lettuce

The influence of microbial diversity on plant growth and health is well described as microorganisms contribute to enhanced nutrient uptake and increased resilience against various stressors. Integrating this perspective into agricultural practices has the potential to result in improved crop productivity and resistance. Intercropping, the simultaneous cultivation of multiple crops in the same field, has been explored as an alternative to monoculture, revealing benefits such as heightened microbial diversity and improved plant growth in various cropping combinations. In this study, we aimed to assess the effect of intercropping on the microbial composition of the rhizosphere of Lactuca sativa var. capitate L. Rhizosphere samples were collected at three time points during the growing season from fields with different cultivation methods, including monoculture with and without mulching, and intercropping with narrow or wide. High-throughput sequencing of the 16S rRNA gene fragment and ITS region was done to analyze the taxonomic structure of bacterial and fungal communities, respectively. The relative abundance of both bacterial and fungal communities was primarily influenced by the sampling time point, followed by the cultivation method. Moreover, the Shannon diversity index revealed significantly higher diversity in both intercropping treatments at the first time point compared to the monoculture. PERMANOVA analysis indicated that both sampling time and cultivation system contributed similarly to the observed variance. Non-metric multidimensional scaling (NMDS) plots revealed distinct clustering of samples based on cultivation systems, illustrating a shift in bacterial and fungal communities due to different treatments. In summary, while intercropping had a pronounced effect on microbial diversity early in the cultivation season, mulching also exhibited an increase in diversity over time, although determining distinct communities compared to intercropping.