Effects Of AMF And Exogenous Salicylic Acid On Cold Resistance Of The Sedum Aizoon L.

Sedum aizoon L.was a perennial succulent plant of the Crassulaceae, was used for medicinal vegetables and landscaping, in recent years, was widely used in the food, gardens and medical fields. Low temperature is one of the important environmental factors in the growth and development of the Sedum aizoon L.in winter, and is one of the key problems to hinder its annual growth. Arbuscular mycorrhizal fungi(AMF) can promote the growth of plants, and enhance its antioxidant defense mechanism. Salicylic acid(SA) is a new type of plant hormones, play a role in the regulation of the plant growing in adversity.In recent years, a large number of studies showed that, AMF have been shown to improve the ability of cold resistance of the Chinese chives, eggplant, beans, Coleus blumei and diospyros lotus; SA is a new type of planthormone on plant stress, has a regulatory role, and has low price advantage.can improve the cold resistance of the tomato, cucumber, strawberry and muskmelon. There is no evidence to show that with AMF and SA can produce an effect on the cold resistance of Sedum aizoonL.. This experiments were carried out to examine the effects on the growth and physiological characteristics of the Sedum aizoon L.with the AMF and SA at the low temperature treatment. The main contents and results in this study are as follows:1. Under low temperature stress, the study found that after ten days at the different low temperature stress at 0℃,5℃,10℃,there were some difference in the degree of injury at low temperature stress.0℃ low temperature stress on the Sedum aizoon L. damage caused significantly greater than 5℃ and 10℃ low temperature stress, at 0℃,the Stems and leaves of the Sedum aizoon L.were soften and wilt.Under low temperature stress, plant height, stem diameter, fresh and dry weight of the Sedum aizoon L. were significantly lower than at room temperature.2. Under low temperature stress,the distinct changes can be distinguished on the relative conductivity, MDA content, SOD, POD, CAT, proline, soluble protein, chlorophyll content and chlorophyll fluorescence in the Sedum aizoon L.. Relative conductivity, MDA content and proline increased with temperature stress decreasing and the stress time increasing.the SOD activity, POD activity, CAT activity and soluble protein showed a downward trend after the first rise, chlorophyll content, Fv/Fm declined.3. According to the prineipal components analysis of all the physiological index of Sedum aizoon L. under different low temperature stress showed that the Relative conductivity, MDA content, proline, chlorophyll a and chlorophyll b, total chlorophyll, Fo and Fv/Fm and the relationship between cold tolerance of Sedum aizoon L. is closer, as an important indicator of the evaluation of Sedum aizoon L. cold resistance, SOD activity, POD activity, CAT activity, soluble protein content can be used as a reference index Sedum aizoon L. on evaluating cold tolerance.4. Low temperature stress inhibited the infection rate of the Sedum aizoonL. Compared with non-AMF treatment, plant height, root length, fresh and dry weigh were significantly elevated in the Sedum aizoon L.. and the growth effect is more obvious under 0℃ low temperature stress, and its total dry weight is increased by 75.38% than non-AMF treatment.Under low temperature stress, the treatments inoculated with AMF could significantly inhibite the increasing of relative electric conductivity and MDA content, alleviate the oxidative damage by membrane lipid peroxidation. AMF was capable of significantly improving antioxidant enzyme activity, such as SOD, POD and CAT, enhance the resistance to oxidation stress, significantly alleviate the damage by low temperature stresses. Thereby, AMF could greatly enhance the high and low temperature tolerance of the Sedum aizoonL..Fv/Fm significantly higher than the non-AMF, control plants were relieved hurt by low temperature stress, enhance support Sedum aizoon L. on low temperature stress tolerance.5. Under low temperature stress, the treatments that the concentration salicylic acid is 0.5mmol/L, 1.0mmol/L,2.0mmol/L can promote the growth of Sedum aizoon L..and the growth effect is more obvious in l.Ommol/L salicylic acid experimental treatment under 5℃ low temperature stress and its total dry weight is increased by 15.89% than contol group.0.5mmol/L,1.0mmol/L,2.0mmol/L concentration of SA processing,salicylic acid treatment can inhibit raising relative conductivity and MDA increasing, improving SOD, POD activity in the leave of Sedum aizoon L.; increasing Soluble protein,Proline, chlorophyll content, can also slow down the Fv/Fm decline under low temperature stress,Slowed photoinhibition damage to plants,Sedum aizoon L. at low temperatures cold indicators have varying degrees of ease.Evaluation results expressed, SA concentration of 1.0mmol/L was the best for 5℃ low temperature stress in Sedum aizoonL.