Effects of Saline-alkali Stress on the Physiological Characteristics of Alfalfa Seedlings

The effects of saline-alkali stress on the physiological characteristics of alfalfa(Medicago sativa 'Zhongmu No.1') seedlings were studied.Alfalfa seedlings were stressed with the different concentrations of NaCl,Na_2SO_4(0,50,100,150,200,250 mmol ? L~(-1)),NaHCO_3 and Na_2CO_3(0,30,60,90, 120,150 mmol ? L~(-1)) under greenhouse conditions.Survival rate,plant height,proline(Pro),malondialdehyde(MDA) and soluble sugar contents of tested seedlings were determined.Results indicated that seedling survival rates had not significant differences between different NaCl and Na_2SO_4 concentrations compared with control and the survival rates decreased with the increase of alkali salt concentration.The plant height of alfalfa decreased with stress increase,whereas proline,MDA and soluble sugar contents increased.The change ranges of tested indices under alkali salt stress were higher than that under neutral salt stress.The effects of saline-alkali stress on alfalfa were ordered as Na_2CO_3 NaHCO_3 NaCl Na_2SO_4.