Effect of Various Abiotic Stresses on Growth and Physiological Characteristics of Alfalfa(Medicago sativa L.)WL712 Seedlings
Alfalfa(Medicago sativa L.)WL712,originally from the United States,has been intro-duced and cultivated in Southern China due to its high yield and premium quality.However,it exhibits lim-ited tolerance to specific abiotic stresses.The objective of this study was to investigate the growth and physiological characteristics of this variety under various stresses,including high temperature,low tempera-ture,drought,waterlogging,and salt stress.The overall physiological stress resistance was evaluated by measuring growth and eight physiological indices,including chlorophyll content,soluble sugar content,soluble protein content,Relative electrical conductivity(REC),malondialdehyde(MDA)content,and the activities of three antioxidant enzymes(superoxide dismutase,SOD;catalase,CAT;peroxidase,POD).The results showed that the growth of alfalfa was significantly inhibited by all five stresses(P<0.05).Among them,high temperature,low temperature,and waterlogging stress exerted a more pro-nounced inhibitory effect on the growth of WL712 compared to the other two kind of stresses.The height,root length,and biomass of alfalfa were substantially decreased,while the contents of osmoregulation sub-stances(soluble sugar and soluble protein)were relatively limited.Under low temperature and waterlog-ging stress,the chlorophyll content significantly decreased,and the three antioxidant enzymes(POD,SOD,and CAT)in leaves and roots,responsible for eliminating reactive oxygen species,were relatively low.In summary,WL712 exhibits limited resistance to heat,cold,and waterlogging,particularly being vulnerable to low temperatures and waterlogging.Therefore,it is advisable to avoid planting WL712 in damp and rainy areas or regions with extreme temperatures in the southern region.Appropriate manage-ment practices are necessary to ensure optimal yield and quality.
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