Influences of Exogenous Nitric Oxide on Seed Germination and Seedling Physiological Characteristics of Fruit Cucumber under Pb~(2+) Stress

The mechanisms of Cucumis sativus L. seedlings responding to Pb stress were studied in order to provide a theoretical basis for lead-resistant. The effects on the germination of cucumber seeds and the contents of soluble protein and MDA,the activities of POD,CAT and SOD and chlorophyll relative contents of cucumber seedlings of the different concentration of exogenous NO( 50,100,300,500 μmol / L) were studied under 200 mg / L Pb( NO3)2. The results showed that the germination of fruit cucumber seeds was inhibited significantly,the contents of soluble protein and MDA increased,while the activities of POD,CAT and chlorophyll relative contents decreased obviously under 200 mg / L Pb( NO3)2. The germination percentage,germination potential and germination indexes of fruit cucumber seeds were stimulated greatly with adding sodium nitroprusside( SNP,nitric oxide donor),which decreased the contents of MDA at the same time,while raised the activities of POD,CAT and the contents of relative chlorophyll and soluble protein. It could obviously promote the germination of fruit cucumber seeds under Pb2 +stress with adding exogenous nitric oxide,enhance the osmotic adjustment capacity of cell,increase the activity of protective enzyme and significantly alleviate oxidative damage to seeding leaves,the effect was the best when SNP was at 100 μmol / L especially.