Effects of cadmium stress on the germination,growth of seedling and physiological and biochemical characters of wheat

The wheat of Xihan 1 is employed to study changes of seed germination,seedling growth and physiological properties in response to Cd(NO3)2 stress.Low concentrations of Cd2+ promote seed germination while high concentrations inhibite.The length,fresh and dry weight and relative water content of root and shoot decreases remarkably under each Cd2+concentration in comparison with the control;meanwhile,high concentrations of Cd2+ inhibite the growth of root cell elongation and induce lipid peroxidation.Chlorophyll a content decreases with the increase of Cd2+concentration,but total chlorophyll reduces significantly only at 0.6 mmol·L-1 of Cd2+.Analysis of antioxidant enzymes shows significant elevations in the activities of CAT,POD and APX in the leaves of Xihan 1 wheat exposed to Cd2+ stress.In addition,H2O2 content of wheat leaves reduces observably at 0.2 mmol·L-1 of Cd2+,but MDA content in leaves does not show remarkable change under Cd2+ stress.In conclusion,Cd2+ stress inhibites the growth of wheat seedlings,cell elongation inhibition and strong oxidative damage in root tip may be associated with Cd-inhibitory effect on root growth in wheat seedlings.Additionally,increased activities of antioxidant enzymes in wheat leaves may be involved in scavenging H2O2 generation in response to Cd2+ treatment.