Study On Physiological And Biochemical Changes Of Alfalfa's Root Crown Under Low Temperature And Weak Light

In this experiment,two alfalfa (Medicago sativa) varieties in different fall dormancy(WL414 and Ameristand201)for the experimental materials, were cultivated at low temperature (0℃/5℃and 5℃/10℃)and weak light (50μmol/m-2?s-1 and 100μmol/m-2?s-1) reciprocal as the treatment conditions to study physiological response of the root crown. After 12h, 24h, 36h, 48h and 60h low temperature and weak light treated,used widely physiological and biochemical indicators of crops and pasture resistance identification.we analyzed physiological and biochemical indices such as: free proline, SOD, POD, CAT, soluble protein and MDA. Main results were as follows:1,WL414 and Ameristand201's root crown can perceive the low temperature and weak light stress quickly, and increases SOD and POD activity of antioxidant enzymes to reduce oxidative damage, furthermore, WL414 increased rapidly at 12h, but Ameristand201 increased observably at 24h and 60h.2,with the low temperature and weak light stress increased and sustained long extension, soluble protein and free proline of osmolytes content continues to rise, indicating that at this time crown synthesized in a large number of soluble protein and proline to against low temperature and weak light on the root crown injury.3,WL414 and Ameristand201's CAT activity showed a different degree of decline after low temperature and weak light stress, WL 414 decreased more than Ameristand 201. With the decrease of temperature and light of weakening, MDA content increased, indicating that at this time crown synthesized in a large number of MDA, membrane damage increased.4,The root crown of alfalfa under low temperature and weak light start its own stress response, and make to stress adaptive response.In the same low light condition,0℃/5℃is more significant than 5℃/10℃of the impact of plants, under the same low temperature,weak light 50μmol/m-2?s-1 more significantly compared with weak light 100μmol/m-2?s-1, WL414 and Ameristand 201 have consistent changes, and Ameristand201 indicators of changes excellent than WL414, and Ameristand201 was more tolerant to low temperature and weak light than WL414.