Comparative study of osmoticum accumulation in wheat under osmotic and ionic stress

Salt-tolerant wheat cultivar ‘Dekang 961’ (Dk 961) and salt-sensitive wheat cultivar ‘Lumai No.15’ (Lu 15) were used as experimental materials. Na+ ionic and osmotic stress could lead to accumulation of free proline and soluble sugar in wheat cultivars with different salt-tolerance. However, the accumulation of free proline and soluble sugar under ionic stress was much more than that under osmotic stress. These results indicated that ionic effect played an important role in increasing the osmoticum content of wheat. Free proline and soluble sugar content of salt-tolerant cultivar ‘Dk 961’ increased less and had a low variation rate. Salt-tolerance of wheat cultivars was negatively correlated with the accumulative quantity of osmoticum. Abundant accumulation of osmoticum in salt-sensitive cultivar ‘Lu 15’ might be caused by metabolism disorder under salt stress of high concentration and should be a representation of salt damage.   Key words: Wheat, osmotic stress, ionic stress, free proline, soluble sugar.