Study On Induced Resistance Of Tobacco Extract To Cucumber Downy Mildew And Its Physiological Basis

By using 40%ethanol 60%acetone and distilled water as the inducers the first true leaf width of cucumber seedlings was 5 cm and two induction treatments were carried out after three days.The results showed that:1.Nutritional growth index:The ratio of plant height stem diameter and maximum leaf area to 60%acetone increased 10.7 cm0.55mm39.19cm2;17.73 cm0.77mm62.99cm2.compared with distilled water respectivelyThe plant height stem diameter and maximum leaf area of ethanol treatment group were higher than 40%ethanol control 48.2cm 1mm larger than 105.94 cm2;higher than distilled water control 44.82cm 1.03 mm larger than 121.52 cm2..2.Natural pathogen-inspired disease test:The plant rate leaf rate and disease index were 13.33%2.61%1.74%lower than 60%acetone control and 46.66%26.9%9.44 lower than distilled water control.The plant rate leaf rate and disease index were 13.33%2.61%1.74%lower than 60%acetone control and 46.66%26.9%9.44 lower than distilled water control.3.Physiological changes:The activity of superoxide dismutase(SOD)peroxidase(POD)and catalase(CAT)in the leaves of cucumber plants increased first and then decreased in the acetone treatment group and ethanol treatment group.Ethanol treatment group PPO activity peak on the third day after induction stem B the treatment was significantly higher than that of control and other treatments;the MDA content was lower than the initial value but showed an upward trend and the content MDA stem treatment was lower than that of control.4.Direct disease control test:direct spraying has an effect on cucumber downy mildew disease the disease development is slow acetone treatment group C stem is 4.76 lower than 60%acetone control disease index 11.43 lower than distilled water to disease index control effect is 28.575%ethanol treatment group B stem is 14.29 lower than 40%ethanol control disease index 11.43 lower than distilled water control disease index control effect is 28.575%.5.Cucumber yield measurement:The number of melons yield yield per mu average number of melons per plant and average weight of cucumber were increased by 174.31g,475.9Kg,0.77 and 30.44g respectively.The average weight of cucumber plants treated with C increased by 38.94g.compared with that of controlThe number of melons yield yield per mu average number of melons per plant average weight per plant and average weight per plant were 4611.26 g,1241.67Kg,3.84,682.02 g,8.75g.higher than those of control.Combined with the above indexes the growth and development of the acetone treatment group was the best and the condition of cucumber downy mildew was the lowest.In the ethanol group cucumber growth development and disease control were better after the treatment of ethyl stem induction.