Effect And Its Physiological Mechanisms Of Exogenous Salicylic Acid On The Anti-bacterial Fruit Blotch Of Cucumber The Research Of Inductive

Bacterial fruit blotch,BFB, caused by Acidovorax citrulli is an important seed-borne bacteria disease to cucumis melo, watermelon and other cucurbitaceae crops Since the 80 s of the 20 th century, BFB was worldwide spread, resulting in cucurbit crops production, especially the West melon fruit production and seed production suffered huge losses. BFB has become a serious threat to the safety of the crop industry in the world because of its resistance to pathogens, the limitations of chemical fungicides and the lack of resistance to diseases. Current research on the BFB world just started, to disease-causing bacteria and molecular biology-based knowledge is limited. The exogenous agent of non pollution resistance at home and abroad is salicylic acid, and exogenous salicylic acid has become the most concerned research object in the research of plant diseases and insect pests. The inducing factor of this experiment is exogenous salicylic acid, and the induced effect of cucumber seedling induced by exogenous salicylic acid is induced, and the physiological mechanism of cucumber seedling is further analyzed. The induction mechanism of exogenous.The test was conducted to screen the concentration of salicylic acid which was inducing the bacterial fruit blotch resistance through cucumber. Changchun Mici cucumber varieties as materials, training room potted seedlings respectively induction treatment by 3,5,7,9,11 mmol/L SA concentration after sowing 6 days, inoculating scratch or no injuries Acidovorax bacteria after 3days’ induction of cucumber packet, cotyledon lesion severity, chlorophyll content and photosynthetic rate are taken as indexes to choose the effective induce resistance concentration, and then take the the change of the relative water content of plant tissue, chlorophyll content and photosynthetic rate as indexes to choose the best induce resistance concentration. 5 mmol/L SA and 7 mmol/L SA induction treatment have a significant effect to restrain the growth of the bacteria bacterial fruit spot, slow down the relative water content of cucumber seedling tissues caused by germs and decrease of chlorophyll content;7mmol/L SA induction treatment significantly increased the photosynthetic rate of cucumber(P<0.01), and may slow the rate of infection of a reduction in photosynthetic cotyledons. Comprehensive display the indicators show that 7 mmol/L SA treatment may induce cucumber seedlings Acidovorax bacteria produce a certain degree of resistance.salicylic acid(SA) on the anti oxidative enzymes and pathogenesis of cucumber against bacterial leaf blight. Doing scratch inoculated Acidovorax bacteria after induction of 7 mmol/L SA on cucumber cotyledons, taking samples and texting SOD,POD,CAT,PAL,PPO,O2-! and H2O2 after 0 d,2 d,4 d and 6 d inoculation. The result shows that 7 mmol/L SA can significantly improve the net photosynthetic rate of a normal cucumber,CAT activity and POD activity; can induce infected the activity of SOD,POD,CAT, PAL and PPO of cucumber cotyledon increased in the early stage(2 d) of infection process, SA induction induced in vivo induction of active oxygen scavenger inhibits active oxygen content, SOD activity can improve the catalytic O2-! disproportionation reaction and produce toxic oxygen molecules and H2O2, while improving the CAT activity and can further catalyze the decomposition of H2O2, reduce the accumulation of H2O2, with the progression of the disease exacerbate all types of activity showed varying degrees of decline, indicating that SA-induced cucumber all kinds of enzymes anti-bacterial fruit spot pathogen effect the existence of timeliness.