Forage Grass Disease In The Main Field Of Sichuan Artificial Pasture And Study On Pathogenic Mechanism Of Large Spot And Brown Spot In Forage Maize

Pasture disease is one of the main reasons for the slow development of animal husbandry.Forage grass disease directly leads to the deterioration of pasture quality,reduced yield,and causes huge economic losses.At present,the most important disease in grassland is fungal diseases.The research of the predecessors mainly focused on a small number of artificial pastures such as Gansu and Inner Mongolia,such as loquat and sand dynasty.However,the investigation and research on fungal diseases in artificial grassland in Sichuan is limited.Therefore,this paper conducts a systematic survey on the fungal diseases of turfgrass in Sichuan,Chengdu,Pingchuan,South Sichuan,and northern Sichuan.The pathogenic mechanism of the fluid is studied.From 2016 to 2018,disease investigations were conducted on pastures in the main push areas of Sichuan pastures,diseased plants were collected,symptoms were observed,and pathogens were identified.A variety of diseases were isolated and cultured using routine isolation and identification methods.Seven rusts,one smut,one powdery mildew,and downy mildew were identified based on the morphology of the spores,the types of host plants combined,and disease symptoms.2 species,2 species of large spot,1 spot of leaf blight,5species of leaf blight,2 species of sheath blight,2 species of brown spot,1species of macular disease,1 species of black stem,1 species of verticillium wilt,2 root rots,1 black spot,1 purple spot,3 spot,1 red spot,1 sick bar,1black rot,1 mildew,Sclerotinia 1 species,1 species of soft rot,1 species of red spot disease,and 3 species of viral disease.It involves 4 families of grassland plants.In this paper,preliminary studies were conducted on the biological activity,protein and soluble sugar content,pathogenicity,and their changes in feed defense enzyme activity in forage corn.The test results are as follows:?1?Bioassay and component analysis of crude corn leaf spot and crude extracts of brown spot pathogens in forage maize showed that crude extracts of toxins have inhibitory effects on seed germination and radicle elongation in forage maize;and The inhibition of seed germination and radicle elongation in forage maize aggravated with the increase of crude extract concentration.Coomassie brilliant blue method and anthrone colorimetry method were used to determine the protein content of the crude extracts of the corn leaf spot and brown spot pathogen toxin was 892.283?g·m L^-1and 233.587?g·m L^-1,respectively,and the soluble sugar content was 333.333?g·m L^-11 and 297.778?g·m L^-1.The pathogenicity of crude corn leaf spot and crude extracts of brown spot pathogens in forage maize showed that the relative electrical conductivity of the radicles of forage maize was affected by the length of treatment time with forage corn leaf spot and crude extract of brown spot pathogen toxin.The effect is significant.Under the condition of the same toxin crude extract concentration,the conductivity of the treated group first decreased and then increased with the prolonged treatment time,while there was a slight increase in the control group.Under the same treatment time,compared with the control,the relative conductivities of the extracts were increased after treatment with crude extracts of different concentrations,but the increase range of each concentration was different.With the prolongation of the action time of crude extracts,there were differences in malondialdehyde?MDA?content and amplitude of changes at different times.The content of malondialdehyde?MDA?in the treatment group first decreased and then increased,while the change in the control group was small.After treatment of different concentrations of toxin crude extract for 2days,the content of malondialdehyde?MDA?in the radicle was significantly increased.With the decrease of crude extract concentration of toxin,the content of malondialdehyde?MDA?in the radicle decreased,and the rate of increase of content decreased.The difference between treatments was significant.The concentration of chlorophyll a and b and the total chlorophyll content in fodder maize leaves were significantly decreased.There was a significant difference in the index values between the treated and control groups.The reduction rate of total chlorophyll content was 23.70%and 49.78%,respectively.The greatest reduction in toxin treatment was chlorophyll a,with a reduction rate of 25.40%.After treatment with brown toxin crude toxin,the largest decrease was chlorophyll b with a reduction rate of 64.89%.It can be seen that the infection of the crude extracts of the toxins caused by the pathogens of broad patch and brown spot reduces the absorption of light energy by plant leaves.?3?The defensive enzymatic activities in the radicles of forage maize showed that the crude extracts of two kinds of pathogenic toxins from the same concentration of 25%corn were treated with crude extracts of two toxins after1.5d,2d,3d,4d and 5d.As the time went by,the activity of peroxidase?POD?,superoxide dismutase?SOD?,polyphenol oxidase?PPO?and phenylalanine ammonia lyase?PAL?in the radicle decreased to varying degrees.The enzyme activity of crude toxin extract showed a trend of rising first and then decreasing,and the catalase?CAT?activity showed a trend of decreasing first and then increasing;with 50%,25%,12.5%,6.25%,3.125%.After two days of treatment with two different concentrations of the two crude extracts of pathogenic toxins,peroxidase?POD?,superoxide dismutase?SOD?,polyphenol oxidase?PPO?activity,phenylalanine in the radicle The activity of lyase?PAL?and the activity of catalase?CAT?decreased to varying degrees.With the decrease of crude extract concentration of toxin,the enzyme activity mainly showed an upward trend,and there were different significant relationships between the results of different concentrations of treatment.