Soil salinity alters growth, chlorophyll content, and secondary metabolite accumulation in Catharanthus roseus

The effect of salinity on growth, photosynthetic pigment content, and alkaloid secondary metabolite accumulation were studied in an economically important medicinal plant, Catharanthus roseus (L.) G. Don., under pot culture conditions. Plants were treated with different concentrations of NaCl, (e.g. 50 and 100 mM) 30, 45, 60, and 75 days after sowing (DAS). The plants were uprooted randomly 90 DAS to analyse growth, and chlorophyll and alkaloid content. Salinity affected all the morphological parameters and decreased growth performance. At low salinity regimes, a slight decrease was noted in chlorophyll a and b, and total chlorophyll content, but under high salinity conditions a significant reduction in the content of these pigments was observed. The chlorophyll a:chlorophyll b ratio also varied significantly under salinity stress. Alkaloid content increased under saline soil conditions.