Intercropping of tobacco and maize promoted growth by enhancing nutrient uptake mediated by rhizosphere interaction

Rational intercropping promotes crop growth, and maize is widely interplant in the field during the tobacco-curing period in Southwest China. However, the effects of rhizosphere interactions between the two crops and their mechanisms of nutrient uptake and utilization are not clearly understood. This study aimed to analyse the effects of sufficient rhizosphere interaction between tobacco and maize vegetative stage on nutrient absorption and utilization, and crop growth via a pot experiment. It integrated microbiomics with widely targeted metabolomics to explore the effects of soil microbial communities and rhizosphere metabolites using high-throughput sequencing and LC-MS/MS platforms. The results showed that crop intercropping significantly increased the biomass of tobacco plants, nitrogen (N) and phosphorus (P) accumulation, and the accumulation of N in the aboveground parts (leaves and stems) and potassium (K) in both the aboveground and underground parts (roots) of maize, compared with monoculture. Additionally, intercropping with tobacco enhanced the contents of alkali-hydrolyzable N, available P, and available K, and the activities of sucrose, catalase, urease, and acid phosphatase in maize rhizosphere soil, as well as enhanced the pH value, available K content, and the activities of sucrose, catalase, and nitrate reductase in tobacco rhizosphere soil. Significant differences were observed in the composition and distribution of dominant microbial communities in crop rhizosphere soil between different planting patterns. In the intercropping system, the relative abundance of Arthrobacter, Subgroup_7, and Dactylellina in maize rhizosphere soil, as well as that of Gemmatimonas, Sphingobium, and Myrmecridium in tobacco rhizosphere soil were significantly increased. Moreover, the intercropping has also elevated the number of bacterial and fungal ASVs in the rhizosphere soil of both crops. The metabolites of choline alfoscerate and acetyl-L-carnitine showed translocation between the rhizospheres of tobacco and maize in the intercropping system. Differential metabolites in tobacco rhizosphere soil were significantly enriched in the diterpenoid biosynthesis pathway, whereas those in maize rhizosphere soil were enriched in pathways related to starch and sucrose metabolism, linoleic acid metabolism, ABC transporters, flavonoid biosynthesis, and galactose metabolism. These findings suggested that the rhizosphere interaction between tobacco and maize vegetative stage enhanced soil N, P, and K nutrient availability through alterations microbial community and metabolite composition, thereby promoting crop growth.