Effect Of Graphene Oxide On The Growth And Development And Drought Tolerance Of Brassica Napus L.

Rapeseed is the largest oil crop in China,with a perennial planting area of about 100 million mu,providing about 55% of domestic vegetable edible oil,which is of great significance for ensuring the safety of China’s edible vegetable oil supply.With global warming,seasonal drought is becoming increasingly serious,which has a significant impact on rapeseed production.Nanomaterials refer to materials in which at least one dimension in the three-dimensional space is in the nanoscale range(1 to 100 nm)or composed of them as basic units.nanoparticles have been found to combine with sulfhydryl and carboxyl groups to change the activity of proteins and regulate plant growth and development.Graphene oxide is a new type of nano material.Due to its many excellent properties and no obvious toxicity,it is widely used in the fields of pharmaceutical carriers,biosensors,environmental protection,and plant growth regulation.This experiment took Brassica napus L.as the research object,conducted indoor pot culture,hydroponic culture experiments,and field experiments,systematically studied the effects of graphene oxide on the growth and development,yield,and drought resistance of Brassica napus L.,providing theoretical basis and technical support for using graphene oxide to regulate the growth and development of Brassica napus L.,improve yield,and enhance drought resistance.The main research results are as follows:(1)The suitable concentration of graphene oxide promotes the germination of rapeseed seeds.The seeds of different rapeseed varieties were soaked with graphite oxide,and the germination potential of Zhongshuang 9 and Zhongshuang 11 treated with 100 mg/L graphite oxide was the highest,significantly higher than that of the control.The germination potential of Huayouza 50,Yangguang 2009 and Huayouza 62 treated with50 mg/L graphite oxide was significantly higher than that of the control.The treatment of 5～100 mg/L graphite oxide significantly increased the seed germination potential of Zhongshuang 9,Zhongshuang 11,Yangguang 2009 and Huayouza 62,indicating that the appropriate concentration of graphite oxide could promote the seed germination of Brassica napus L..(2)Soaking seeds with appropriate concentration of graphene oxide can improve the yield of Brassica napus L..Different varieties of Brassica napus L.were treated with graphite oxide seed soaking.Compared with the control group,the results showed that 10,25 and 50 mg/L graphite oxide treatment significantly increased the yield of Zhongshuang 9,25 mg/L graphite oxide treatment significantly increased the yield of Zhongshuang 11 and Yangguang 2009,and 10 mg/L and 25 mg/L graphite oxide treatment significantly increased the yield of Huayouza 50.(3)The seed soaking concentration and time of graphene oxide affect the growth promotion effect and rapeseed quality of Brassica napus L..The seeds of Huayouza 50 were treated with graphite oxide for different soaking time(12,24 h and 48 h)and different concentrations(0,15 mg/L and 25 mg/L).The results showed that plant height and root length increased significantly after 18 weeks of graphite oxide treatment;When the seed soaking concentration of graphite oxide was 15 mg/L,the leaf length,underground fresh weight and dry weight of plants in the12 h seed soaking treatment group were significantly increased,while those in the 24 h seed soaking treatment group were significantly increased;When the soaking concentration was 25 mg/L,with the increase of soaking time,the underground fresh and dry weight of rapeseed showed an increasing trend,both significantly increasing.After soaking for 24 hours,the above ground dry weight significantly increased,while after soaking for 48 hours,the leaf length,leaf width,above ground fresh weight,and above ground dry weight significantly increased.Graphite oxide treatment can increase the yield of huayouza 50.The oil content of rapeseed was significantly increased and the protein content was significantly reduced in the 15 mg/L graphite oxide seed soaking groups for 12 h and 24 h;In the 15 mg/L graphite oxide treated group,the thousand seed weight and protein content of rapeseed increased significantly,while the oil content decreased significantly;25 mg/L graphite oxide seed soaking for 12 h and 24 h significantly increased the oil content and significantly reduced the protein content;25 mg/L graphite oxide seed soaking for 12 h and 48 h significantly increased the 1000 seed weight of rapeseed;The effective pod number,seeds per pod and protein content of rapeseed in the 25 mg/L graphite oxide soaking group for 48 h increased significantly.(4)Soaking seeds with graphene oxide can improve drought resistance of Brassica napus L..In the 15 mg/L graphite oxide seed soaking treatment group,on the 10 th day of drought stress,the transcription level of GA synthesis gene GA3 was up-regulated,the transcription level of IAA signal transduction related genes ARF2,IAA2 and ABA synthesis related genes NCED,AAO,NCED3,ZEP was down regulated,the content of IAA and ABA was significantly reduced,the plant height,fresh weight,water content,POD activity,SOD activity,proline and soluble protein content and intercellular carbon dioxide concentration were significantly increased,and the reducibility of tetrazole was enhanced,Significantly improve the drought resistance of Brassica napus L..In the 25 mg/L graphite oxide seed soaking treatment group,on the 10 th day of drought stress,the transcription level of GA synthesis gene GA3 was up-regulated,the transcription level of ABA synthesis related gene ZEP was down regulated,and the transcription levels of IAA2,ABA synthesis related genes NCED,AAO and NCED3 were up-regulated,significantly increasing the content of IAA and ABA.The plant height,fresh weight,dry weight,water content,CAT activity,and APX activity were significantly increased,while the net photosynthetic rate and tetrazole reducing ability were significantly reduced.The intercellular carbon dioxide concentration was significantly increased,but the phenotype did not show any significant changes.Graphite oxide seed soaking treatment affected the transcription level of ABA,IAA synthesis and signal transduction related genes in Brassica napus L.under drought stress,affected the activities of POD,SOD and other protective enzymes,hormone,proline and soluble protein content,plant root activity,and improved the drought tolerance of Brassica napus L..(5)Spraying graphene oxide at seedling stage can improve drought resistance of Brassica napus L..Under drought stress,after spraying graphite oxide,the seedlings were rewatered3 days later,and after rewatering,25 mg/L graphite oxide treatment significantly improved the survival rate of seedlings.Under drought stress,after treatment with 15mg/L graphite oxide for 12 h,the transcription level of ARF2,the signal related gene of IAA,NCED,ZEP and AAO,the transcription level of ABA synthesis related gene,and the content of GA and IAA increased,and the content of ABA decreased.Significantly reduce SOD activity,malondialdehyde content,and significantly increase APX activity.25 mg/L graphite oxide treatment,GA signal related genes RGA,GA synthesis related genes GA3,IAA signal related genes IAA2,ABA synthesis related genes NCED transcriptional levels were up regulated,IAA signal related genes ARF2,ABA synthesis related genes ZEP,AAO transcriptional levels were down regulated,GA,IAA content significantly increased,proline content and soluble protein content significantly increased,malondialdehyde content significantly decreased.Graphite oxide spraying at seedling stage affected the transcription level of GA,IAA synthesis and signal transduction related genes in Brassica napus L.under drought stress,affected the content of hormone,malondialdehyde,proline and soluble protein,and improved the drought tolerance of Brassica napus L..