Effect Of Long-term Continuous Cropping On The Growth Of Peanut And Resistance Of Different Varieties Peanut To Cercospora Arachidicola Hori And Phoma Arachidicola

Peanut is an important cash crop and oil crop in our country.Due to the long-term pursuit of planting efficiency,continuous cropping has become more and more serious in major peanut production areas in China.In this study,the effects of continuous cropping 2,3,4,5,10 years on the agronomic characters,yield,yield components and disease occurrence of peanut were investigated by field plot experiment,and Thirty-four peanut varieties were selected from several peanut breeding units in China to evaluate the resistance to net spot and brown spot,and different resistant varieties were obtained.From infected peanut network plaque bacteria and plant pathogens were isolated by cercospora leaf spot of bacterium,through laboratory culture,vaccination to healthy peanut plants of different resistance,measure its after an infected catalase?CAT?and peroxidase?POD?and superoxide dismutase?SOD?,phenylalanine ammonia enzyme?PAL?,malondialdehyde?MDA?and superoxide anion?O₂^-?activity or content to explore the physiological mechanism of peanut resistance to net spot and brown spot,and to provide theoretical support for breeding resistant varieties.At the same time,the filtrate of arachidopsis reticulosa culture was extracted by ethyl acetate,and the obtained crude toxin was inoculated on healthy peanut leaves by in vitro acupuncture method.The effects of crude toxin on MDA,O₂^-content and SOD activity of different resistant peanut varieties were analyzed,which laid the foundation for further experiments.The main research results show that:1.Continuous cropping years had significant effects on peanut plant traits,yield and disease occurrence.The longer continuous cropping years were,the lower plant height,lower branch number,shorter branch length,lower yield and more serious disease occurrence of peanut.Continuous cropping has obvious inhibitory effect on the growth and development of peanut,and the longer the continuous cropping period is,the more serious the inhibitory effect will be.In order to improve the yield of peanut in wind-sand land area of liaoning province,reverse cropping rotation should be implemented in the third or fourth year of continuous cropping.2.The resistance of peanut varieties to net and brown spot was significantly different.Among the tested varieties,there were no varieties completely immune to grid and brown spot disease.For grid spot disease,5 varieties with high resistance,12 varieties with disease resistance,10 varieties with moderate resistance,4 varieties with disease resistance and 3 varieties with high resistance were selected.For brown spot disease,3 high resistant varieties,9 medium resistant varieties,11 resistant varieties,8 susceptible varieties and 3 high susceptible varieties were selected.This conclusion with the use of each variety of disease index of field survey for clustering analysis of statistical index of 34 with peanuts,peanut varieties of leaf spot related cluster analysis results,Zhonghua 2 and 5 varieties of stronger resistance to net spot,Ji9801 and six varieties of stronger resistance to leaf spot,can further take advantage in the varieties of hybrid breeding and production.3.The contents of O₂^-and MDA of the tested peanut varieties were first increased and then decreased at 0-144h after inoculation with reticulosa,and the content peak and outbreak time were negatively correlated with the resistance of the varieties.The activity of CAT,POD,SOD and PAL were significantly different when the strains were not inoculated with reticulosa?0h?.After inoculation with reticulosa,the activity of POD and PAL was basically positively correlated with the resistance of the strains,while the activity of SOD was negatively correlated with the resistance of the strains,while the activity of CAT was not correlated with the resistance of the strains.There were significant differences in the responses of different resistant varieties of peanut to reticular plaque bacteria,and the activity of POD and PAL as well as the content of MDA and O₂^-could be used as an index to measure the resistance of peanut to reticular plaque.4.The variation trend of O₂^-content of peanut varieties inoculated with brown spot fungus for0-144h was approximately similar to that of the inoculated net spot fungus.Within the range of 0-24h,MDA content of susceptible varieties decreased,while that of disease-resistant varieties increased.At 144h,MDA content of all varieties was higher than 0h,and the final increment of MDA of disease-resistant varieties was lower than that of relative susceptible varieties.The activity of CAT,POD,SOD and PAL were significantly different when the strains were not inoculated with brown spot bacteria?0h?.The POD and CAT activities of the resistant cultivars were significantly higher than those of the susceptible cultivars after inoculation,and the POD activities of all cultivars were higher than that at 0h.At 144h,PAL activity of fuhua 17 and luhua 11 was lower than 0h,and PAL activity of sigranhong and huayu 20 was higher than0h.At 144h,the activity of SOD was the highest in luhua 11,followed by fuhua 17,huayu 20 and sigranhong.The response of different resistant varieties of peanut to brown spot fungus was significantly different.The activity of POD,CAT and the content of MDA and O₂^-could be used as an index to measure the resistance of peanut to brown spot.5.Use sterile water,methanol,anhydrous ethanol,ethyl acetate four solvents to dissolve 1g toxin,methanol consumption volume is the least,so choose methanol as the toxin solvent.The bioactivity was determined by diluting methanol to different concentrations.The results showed that when the concentration of methanol solvent was 20%,the solvent would not damage the peanut leaves.The crude toxin was diluted to 0.02g/m L with a concentration of 20%methanol,and 20%methanol was used as the control.The bioactivity test results showed that the crude toxin dissolved in 20%methanol had pathogenicity,while 20%methanol had no pathogenicity.Therefore,20%methanol was the optimal solvent.The SOD activity,MDA and O₂^-contents of crude toxin inoculated in peanut leaves were similar to those of inoculated bacteria.