紫花苜蓿对碱胁迫的生长与生理响应OA

To explore the growth and physiological response patterns of alfalfa(Medicago sativa L.)under different alkali concentration stresses,hydroponic experiments were conducted in the western Songnen Plain of Northeast China.Alfalfa was taken as the research object for alkali stress analysis.Different concentrations of Na2CO3(0,5,10,and 15 mmol/L)were applied to simulate alkali stress,and the changes in the growth and physiological characteristics of alfalfa seedlings were investigated after 48 hours.The results showed that with the increase of alkali stress concentration,the damage degree to plants intensified.Specifically,under the treatment of 15 mmol/L Na2CO3,the aboveground parts of alfalfa showed lodging.Compared with the control group(0 mmol/L),the aboveground biomass in the 10 mmol/L and 15 mmol/L treatments significantly decreased by 24.62％and 42.88％,respectively,and the chlorophyll content also decreased synchronously.In addition,alkali stress caused leaf plasma membrane damage and malondialdehyde(MDA)accumulation,and the MDA accumulation reached the peak under the 15 mmol/L treatment.The activities of superoxide dismutase and peroxidase in roots showed a trend of first increasing and then decreasing.The highest activities of SOD and POD were discovered under the 10 mmol/L treatment,which were 64.04％and 74.85％higher than those of the control,respectively.The contents of proline and Na+in the aboveground parts were the highest under the 15 mmol/L treatment,meanwhile,the ratios of K+to Na+and Ca2+to Na+were the lowest.In conclusion,the 15 mmol/L alkali stress significantly inhibited the growth of alfalfa(P＜0.05),induced membrane lipid peroxidation and reduced antioxidant enzyme activities,and the accumulation of proline reached its peak.The alkali tolerance threshold of alfalfa is approximately 10 mmol/L,and alfalfa's physiological functions are severely damaged beyond this concentration.