Effects of osmotic and salt stress on some physiological indexes of wheat seedlings

Salt-sensitive wheat cultivar 'Lumai No.15' (Lu 15) and salt-tolerant wheat cultivar 'Dekang 961' (Dk 961) were used as experimental materials. With the increase in concentration of NaCl and iso-osmotic PEG, MDA content and respiration rate of Lu 15 obviously increased and the increase of which under NaCl stress was more than that under iso-osmotic stress; however, MDA content and respiration rate of Dk 961 increased relatively less under the same stress intension. Salt stress of low concentration obviously promoted SOD activity and photosynthetic rate of leaves of Dk 961. Under salt stress of high concentration, SOD activity and photosynthetic rate of Lu 15 was obviously restricted more than that of Dk 961, and the decrease of SOD activity and photosynthetic rate of Lu 15 was more than that under iso-osmotic stress. Salt-tolerance of wheat cultivars showed negative correlation with MDA content and respiration rate, while positive correlation with SOD activity and photosynthetic rate. The significant increase in MDA content and respiration rate of salt-sensitive cultivar very likely resulted by toxic effects of Na+ under high salinity stress.