Study On Induced Resistance Of B Vitamins And Ascorbic Acid To Cucumber Downy Mildew

In this experiment,B vitamins（B₁,B₂,B₆）and ascorbic acid（V_C）were used as inducers.When the cucumber seedlings were fully flattened and the first true leaf width was 5 cm,two induction treatments were performed.Distilled water was used as a control and induced.After treatment,cucumber vegetative growth index,disease condition,defense enzyme activity and yield were measured to study the effect of cucumber-induced resistance to downy mildew,and the best inducing substances and concentrations were selected.The results show:1.Nutrition growth index:the plant height of cucumber plants after 2.0%V_C induction was increased by 22.60cm in the same period,and the stem diameter increased 1.22mm,and the maximum leaf area increased by 104.38m².2.the test of natural pathogen induced disease:the plant disease rate of cucumber plants after 2.0%B₂ induction treatment decreased by 3.4%,the disease leaf rate decreased by 4.66%,the disease index decreased by 22.58%,and the induced resistance was 42%.3.The disease test of pathogen induced by artificial inoculation:the condition of 2.0%B₂ induced cucumber plants decreased by 9.7%,the rate of disease leaves decreased by 35.33%,the disease index decreased by 30.26%,and the effect of inducible resistance reached 52%.4.the activity of defense enzyme:the activity of polyphenol oxidase（PPO）and peroxidase（POD）in the leaves of cucumber plants increased first and then decreased,and reached the peak at third days and second days after the induction treatment.After 2.0%B₂ induction treatment,the（PPO）was higher than that of the plant by 0.029mg^-11 and 2.0V_C induced.The（POD）increased 0.0024mg^-11 compared with the control plant,and the activity of superoxide dismutase（SOD）in the leaves of cucumber plants increased gradually,and the plant after 2.0%B₂ induced treatment increased 132ug.g^-11 compared with the control plant.5.yield:After 2.0%V_C treatment,the plant yield was significantly higher in the control plants,the number of population in the plot increased by 52 compared withthe control,the yield in the plot increased by 10.12 kg,the yield per mu was 6750.04kg,and the average per plant weight increased by 129.70 g.The number of melons increased by 0.7;the average single melon weight increased by 22.70 g over that of the control plants.6.Direct prevention and control test:the disease of cucumber leaves was sprayed with 2.0%B₂,the disease developed slowly,compared with the control condition index of 19.3%,and the direct control effect of 2.0%B₂ reached 33%.Above all,we screened the Cucumber after 2.0%B₂ induction,the lowestcondition of downy mildew,and the best cucumber growth after 2.0%V_C treatment.