Effects of NaCl and isosmotic PEG on free proline and soluble sugar content in maize leaf.

The changes of free proline and soluble sugar in maize leaves caused by isosmotic NaCl and PEG were explored after 24,48,72 hours of different osmotic potential treatments(-0.5,-0.6,-0.7,-0.8MPa).The results indicated that not only under the anisotonic conditions but also under the isotonic conditions,the contents of free proline and soluble sugar in leaves of two maize varieties were different.Salt-resistant maize(Denghai 11) had higher contents of free ploline and soluble sugar in leaves under PEG stress than under NaCl stress.On the contrary,salt-sensitive maize(Suyu 16) contained higher free proline and soluble sugar under NaCl stress than under PEG stress.Therefore, the effects of decreased osmotic potential caused by NaCl stress on physiological metabolization was definitely different from that caused by PEG stress.The responses of plants to osmotic stress was not only depend on the degree of osmotic potential,but also depend on salinity or drought,as well as the plant genotypes.