Abstract: A pot experiment was conducted to study the effects of arbuscular mycorrhizal (AM) fungus Glomus etunicatum on the growth, relative chlorophyll content, chlorophyll fluorescence, and photosynthesis of maize (Zea mays L.)plants under low temperature (15 ℃ and 5 ℃) stress. Low temperature decreased the AM root colonization. The shoot and root dry mass and the relative chlorophyll content of AM maize plants were higher than those of non-AM maize plants. AM maize plants had higher maximal fluorescence (F_m), variable fluorescence (F_v),maximum photochemical efficiency (F_v/F_m), and potential photochemical efficiency (F_v/F_o),and lower primary fluorescence (F_o), compared with non-AM maize plants, and the differences were significant under 5 ℃ condition. The photosynthetic rate (P_n) and transpiration rate (T_r) of maize inoculated with G. etunicatum increased markedly. Under low temperature stress, the stomatal conductance(G_s) of AM maize plants was significantly higher than that of non-AM maize plants, while the intercellular CO₂ concentration (C_i) of AM maize plants was notably lower than that of nonAM maize plants. It wassuggested that AM fungi could alleviate the low temperature damage on maize plants via improving their leaf chlorophyll content, photosynthesis, and chlorophyll fluorescence, and enhance the low temperature tolerance of maize plants, resulting in the promotion of host plant growth and the increase of host plant biomass.

Key words: arbuscular mycorrhiza, chlorophyll fluorescence, low temperature stress, maize, photosynthesis, saline-alkali soil, community structure, clone library, diversity, dominant populations.