Effects of arbuscular mycorrhizal fungi on growth and physiological characteristics of Sedum aizoon under low temperature stress

We used Sedum aizoon to determine the growth index, relative conductivity, malondialdehyde (MDA) content, antioxidant enzyme activity, proline content, soluble protein content, chlorophyll content, and chlorophyll fluorescence parameters following low temperature stress (0, 5, 10, and 25 ℃) for 2, 4, 6, 8, and 10 d after inoculation with arbuscular mycorrhizal fungi (AMF). The results showed that mycorrhizal colonization abilities and mycorrhizal dependency were significantly (P<0.05) inhibited by low temperature. Low temperature stress significantly inhibited the growth of S. aizoon, and the plant height, stem diameter, and root length growth were significantly greater than in the normal control. The growth effect was greater under 0 ℃ temperature stress, and total dry weight was 75.38% greater than that of the non-AMF treatment. Under low temperature stress, relative conductivity, MDA content, and proline increased as temperature decreased and the stress time increased. Superoxide dismutase(SOD) activity, peroxidase(POD) activity, catalase(CAT) activity, and soluble protein showed a decreasing trend after an initial increase. Furthermore, chlorophyll content and Fv/Fm declined. Compared with the non-AMF treatment, AMF inoculation significantly inhibited the increase in relative electric conductivity and MDA content, significantly improved antioxidant enzyme activity, such as SOD, POD, and CAT, and induced greater soluble protein and proline content. It also indicated that Fv/Fm in AMF plants was significantly higher than that in the non-AMF plants. Therefore, AMF could greatly enhance the low temperature tolerance of S. aizoon and reduce damage from low temperature stress.