Objective:To study the effects of exogenous H2O2 on seed germination and growth of Bras-sica napus.Methods:'16VHNTS309'was treated with different concentrations of H2O2(0.0％,0.1％,0.6％,1.3％and 2.1％),and the contents of reacive oxygen species(ROS)and the activities of catalase(CAT),superoxide dismutase(SOD)and peroxidase(POD)in the plants were determined.Results:The results showed that different concentrations of exogenous H2O2 had significant effects on seed ger-mination and growth of B.napus(P<0.05).The seed germination rate and root length of B.napus seedlings increased at first and then decreased with the increase of H2O2 concentration,and reached the highest at 0.6％H2O2 treatment with 95.33％.The longest root length was 3.20 cm when treated with 0.1％H2O2.In order to further verify the effect of H2O2 on the growth and development of B.napus,the seedlings were sprayed with H2O2 after 4 days of normal growth.It was found that the longest root length reached 6.99 cm when treated with 0.1％H2O2,while high concentration of H2O2 resulted in shorter roots and more root hairs.The results also showed that with the increase of H2O2 concentration,the endogenous H2O2 and O2-increased.The antioxidant enzyme(CAT,SOD and POD)activities de-creased with the increase of H2O2 concentration.Conclusion:Low concentration of exogenous H2O2 promoted seed germination and root growth of B.napus,while high concentration of H2O2 reduced the activities of antioxidant enzymes(CAT,SOD and POD)and increased intracellular ROS content in plants,which in turn inhibited seed germination and root growth of B.napus.
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