Fig. 1

The features of DL properties and the contents of chemical components between two rhubarb subspecies. a OPLS-DA score plots of the DL properties obtained from all batches of two rhubarb subspecies; b Rhubarb samples grown over (solid lines) or under (dash lines) 3000 m were marked on the OPLS-DA score plots, the orange horizontal line indicates the separation between Rheum palmatum L. samples grown over or under 3000 m; c Histograms comparing the DL properties between two rhubarb subspecies. Mean ± SD, ns no significant difference; d Histograms comparing the bioactive components between two rhubarb subspecies. Mean ± SEM, ns no significant difference