Abstract: The effects of wheat rotation on the species and abundance of soil metabolites in continuous cropping greenhouse of watermelon (Citrullus lanatus) were investigated by wide-targeted liquid chromatography-mass spectrometry. The results indicated that there were significant differences in both the composition and abundance of metabolites between the winter fallow soil (CK) and the wheat-rotated soil (WT). A total of 1 405 metabolites were detected in the two soil groups, which were mainly concentrated in lipid and lipid-like molecules, organic acids and their derivatives, organic heterocyclic compounds, benzene derivatives, etc. A total of 228 differential metabolites were identified, including 41 up-regulated metabolites and 187 down-regulated metabolites. Compared with the CK, the abundance of compounds associated with anti-pathogenic microorganism in the WT group was significantly higher, such as roridin L, reticulinylium, and smilagenin. Conversely, the abundance of compounds linked to continuous cropping obstacles, such as indoxyl sulfate, bisphenol, behenic acid, and 9,10-epoxy stearic acid, was markedly reduced. KEGG enrichment analysis revealed that the pathway of cutin, suberin, and wax biosynthesis was significantly enriched. It could be seen that wheat rotation could improve the types and abundance of metabolites in watermelon continuous cropping greenhouse soil.

Key words: watermelon (Citrullus lanatus), continuous cropping obstacle, wheat rotation, soil metabolites