Tree root-mediated soil metabolome in agroforestry enhancing the growth and quality of Panax notoginseng

The ecological cultivation of Panax notoginseng under a forest canopy relies on the coupling of the P. notoginseng growth environment and the forest ecosystem

In this study, six tree species, such as Platycladus orientalis (L.) Franco, were chosen to research the effects of species interactions on the growth, quality, and disease occurrence under intercropping with P. notoginseng, with single P. notoginseng serving as the control.

Intercropping P. notoginseng with PO (Platycladus orientalis, a coniferous tree species) or with SW (Schima wallichii Choisy, a broad-leaved tree species) promoted the accumulation of P. notoginseng biomass, reduced the occurrence of root rot, improved the contents of nitrogen, phosphorus and potassium in P. notoginseng, and increased the saponin concentration. Then, 43 differentially abundant metabolites were screened in the P. notoginseng-tree intercropping system by soil metabolism analysis and compared with those in the monocropped system. Indole-3-carboxaldehyde showed a significant negative relationship with the occurrence of root rot disease and inhibited Fusarium oxysporum. In addition, 2-naphthalenesulfonic acid was significantly positively correlated with biomass and increased the dry weight in the underground part of P. notoginseng in the pot experiments. 

Thus, the coniferous tree species PO and the broad-leaved tree species SW are potentially good neighbours of P. notoginseng, and soil metabolic changes may be important mechanisms for the growth and disease resistance benefits observed in the understorey of P. notoginseng.