Abstract:The increased UV-B radiation and nitrogen deposition have become two important environmental factors affecting plant growth. Here, a medical plant Catharanthus roseus was subjected to altered UV-B and nitrogen level to study their influence in a sole or combined way on growth and vinblastine production. Our results showed that the UV-B exerted an obviously adverse effect on plant growth and biomass accumulation. The UV-B stress also led to physiological damages, for instance, the elevated MDA content. The increased supply with nitrogen nutrition could largely alleviate the inhibitory effects and damage symptom induced by UV-B stress. The UV-B absorbing compounds were enhanced remarkably by the supplementary UV-B radiation, and it was increased further when the nitrogen nutrition were supplied. The vinblastine content was increased markedly in the supplementary UV-B radiation, and which were increased further when the nitrogen supply increased. It was concluded that an increased nitrogen supply could not only alleviate the inhibitory effect of UV stress on plant growth, but enhance vinblastine accumulation in plants. We proposed that enrichment of nitrogen nutrition provide more N source for alkaloid synthesis induced by UV-B radiation, eventually resulting in increased alkaloid content.