Abstract: In order to study the protective mechanism and optimal proportion of gypsum, flyash and polyacrylamide (PAM) on maize growth under saline alkali stress, a pot experiment was conducted to investigate the ionic content, antioxidant enzyme activity, chlorophyll content, and other physiological indicators of maize hybrid Zhengdan 958 seedlings. The results showed that the amendments significantly decreased Na⁺, MDA, proline and soluble sugar contents, and increased Ca²⁺ and K⁺ contents, the activities of antioxidant enzymes (SOD, POD and CAT), chlorophyll a content, fluorescence parameters F₀ and F_m, thereby the total root length, root surface area, root volume, root number, biomass and plant high were also significantly increased. Correlation analysis showed that Na⁺ content was significantly correlated with CAT activity (-0.60), MDA content (0.79) and chlorophyll content (-0.59), and the Na⁺ and MDA contents and CAT activity were significantly correlated with the growth of maize shoot and root. The combination of gypsum and PAM (12 g gypsum + 0.75 g PAM·kg^-1 soil) had the best effects.

Key words: wheat, MCP, phosphorus fertilizer, DAP., application method