Effects of drought stress on growth, physiology and secondary metabolites of Two Adonis species in Northeast China

Adonis amurensis Regel et Radde and Adonis pseudoamurensis W. T. Wang are important plant species of Adonis due to their medical and ornamental benefits, and they are widely distributed in Northeast China. The drought resistance mechanism of two Adonis species were measured under natural drought exposure. The seedings of A. amurensis and A. pseudoamurensis were planted in plastic pots which have been filled with soil mixture, and subjected to drought stress by withholding water for 30 days. The changes in growth, physiology and secondary metabolites were monitored. The results showed that the two Adonis species showed stronger resistance in the early stages of drought, mainly expressed as the increase of osmotic substances such as proline (Pro) and sugar (SS) content, enzyme activity (superoxide dismutase (SOD) and ascorbate peroxidase (APX)), secondary metabolites such as flavonoids (FC), total phenols (TPC) and hormone concentrations (abscisic acid (ABA)) and the decrease of relative leaf water content (RLWC). The higher RLWC, FC, TPC, Pro, soluble protein (SP) and ABA content and lower H2O2 content indicates the stronger non-enzymatic antioxidant system and drought resistance of A. amurensis. However, the synthesis of SP and SS, GA, activities of CAT and POD of two plant species were inhibited in the late stages of drought stress. In general, this two Adonis species response to drought stress rely primarily on enhancing osmotic regulators, antioxidant enzymes and secondary metabolite levels.