Effects Of Seed Soaking With Hydrogen Peroxide On Seed Germination And Seedling Growth In Rape Under Chilling Stress

Rape is one of the most important oil seed crops in China,the sown area and yield are the largest in the world.The middle and lower reaches of the Yangtze River is the largest rape producing area in China,rice is the former crops in this area,the trend of late harvest will lead to late-sowing of rape.In addition,the spread of direct-sowing rape will directly lead to the postponement of sowing time.But late direct-sowing rape is susceptible to the effects of low temperature during germination,and low temperature will lead to the lower germination rate and the emergence rate of seedlings,which cause irregular shooting and the weak seedlings and eventually led to a fall in production.The study took Nannongyou 4 and Zhongshuang 11 of two different cold resistance rapeseed varieties as experimental materials to analysis the effects of H2O2 soaking on the low temperature germination and seedling growth,to further clarify the effects of low temperature on the inhibition mechanism of different rape varieties and the promote effect of H2O2 soaking on seed germination and seedling growth,which could provide technical support for the late direct-sowing rapeseed germination and the cold resistance mechanism of seedling stage.The results were showed as followed:1.0.05%H2O2 soaking could significantly alleviate the inhibitory effect of low temperature on seed germination,enhance SOD,POD and CAT activities and increase the AsA and GSH content during seed germination of two rape varieties,which increased ROS scavenging ability,reduced the content of H2O2 and relieved the degree of membrane lipid peroxidation.Meanwhile,0.05%H2O2 soaking could induce the gene expression of Cu/Zn-SOD and BnICEl under low temperature.These indicates that H2O2 could improve antioxidant enzymes activities and non-enzymatic antioxidants contents to quickly remove excess H2O2,inhibit the MDA content and effectively promote the expression of cold resistant gene during low temperature stress,thus enhance low temperature tolerance of seeds,which could promote rape seed germination under low temperature2.Low temperature could inhibit the activity of related enzymes in the process of seed germination,hinder the process of maternal decomposition and reduce the directly available material and energy sources during seed germination.0.05%H2O2 could effectively improve the amylase,endopeptidase and lipase activities of rape seeds under low temperature,accelerate the decomposition process of major storage materials(starch,crude protein and crude fat),which improved the cold resistance of seed germination and promoted rape seed germination under low temperature.3.Low temperature stress not only affected the antioxidant enzyme activities and non-enzymatic antioxidants contents of rape seedling,also influenced the rapeseed growth of leaf stage and three leaf stage,chlorophyll content and leaf photosynthetic ability.0.05%H2O2 could improve the POD and CAT activities,the content of non-enzymatic antioxidants AsA and GSH,further decrease H2O2 content of seedling.These caused increases in the cotyledon of radicle and plumule length,the seedling height,root length,fresh and dry weight,chlorophyll content,and promoted rape leaf photosynthetic capacity to a certain extent raise under low temperature.The results indicates that exogenous H2O2 could significantly alleviate the effect of low temperature stress caused by injury to plants from the plant physiological level,effectively reduce the inhibitory effect of low temperature stress on rape seedling growth,and improve the resistance ability of rapeseed seedling under low temperature.