Increased water supply promotes photosynthesis, C/N ratio, and plantamajoside accumulation in the medicinal plant Plantago depressa Willd

Abstract

Anthropogenic activities are changing global precipitation regimes and result in many middle latitude arid and semiarid regions experiencing less precipitation and more extreme weather events. However, little is known about the response of active ingredient accumulation in the medicinal herb Plantago depressa Willd. Therefore, we carried out a greenhouse experiment in order to study effect of control (CK, normal water supply equal to 309 mm per four months), -30 (-WS) and +30% (+WS) of the control water supply on the photosynthesis (P N), C/N ratio, and plantamajoside accumulation in P. depressa. Our results showed that compared with the–WS and CK treatments, the +WS treatment significantly enhanced biomass, the C/N ratio, plantamajoside concentration, yield in shoots and roots, and P N, but declined the N concentration in shoots and roots. The plantamajoside concentration was positively correlated with P N, the soluble sugar content, and the C/N ratio, but negatively correlated with the N concentration. Our results suggested that, under experimental conditions, +WS increased the C/N ratio and promoted the plantamajoside accumulation of P. depressa.