Abstract: Taking two herbaceous peony (Paeonia lactiflora Pall.) cultivars, Lan Fushi (L) and Da Fugui (D), as test materials, a pot experiment was conducted to investigate the growth and physiological changes of herbaceous peony under five NaCl concentration treatments (0, 100, 200, 300, 400 mmol/L). The results showed that the salt tolerance of Lan Fushi (L) was stronger than that of Da Fugui (D). With the increase of NaCl concentration, the phenotypic score, leaf relative electrical conductivity, soluble protein content, soluble sugar content, malondialdehyde (MDA) content and peroxidase (POD) activity of both cultivars increased significantly, while the leaf thickness, net photosynthetic rate (Pn) and maximum photochemical quantum yield (Fv/Fm) decreased significantly. Correlation analysis indicated that the salt-tolerance phenotypic score was significantly negatively correlated with plant height (P<0.05), and extremely significantly negatively correlated with leaf thickness, SPAD value, Pn, Fv/Fm and leaf relative water content (P<0.01). Meanwhile, it was extremely significantly positively correlated with leaf relative electrical conductivity, soluble protein content, soluble sugar content, catalase (CAT) activity, POD activity and MDA content (P<0.01), but had no significant correlation with superoxide dismutase (SOD) activity (P>0.05). Furthermore, stepwise regression analysis was used to establish the optimal linear regression equation: Salt-tolerance phenotypic score = 4.198-3.747 × Fv/Fm, and Fv/Fm was identified as an evaluation index for salt tolerance of herbaceous peony.

Key words: herbaceous peony(Paeonia lactiflora Pall.), salt stress, physiological response mechanism, salt tolerance evaluation, maximum photochemical quantum yield (Fv/Fm)