INDUCED SOME MECHANISMS OF RESISTANCE BY AM FUNGUS G.mosseae AND Bacillus subtilis BACTERIUM AND Trichoderma harizanum FUNGUS AGAINST R. solani THE CAUSAL AGENT OF CUCUMBER DAMPING-OFF DISEASE

Abstract

The xperiment was conducted in pots to detect some mechanisms of induced resistance by mycorrhizal fungus G.mosseae, the bacteriumB. subtilis and the fungus T. harizanum against R. solani the causal agent of cucumber damping - off. The results of pathogencity of two isolates of R. solani showed high virulence for two isolates on cucumber plant .asmanifested by significant decrease in the percentage of germination as well as a significant increase in the rate of preemergance and postemergance seedling infection. The experiment of greenhouse showed the ability of the tested biotic inducer agents to increase the enzymatic activity of phenylalaninamonialyase and peroxidase enzyme in the absence and presence of pathogen. theT. harizanum treatment was excel in increased the speed of response in plant against pathogen through increase the activity of each enzymes in 5 days of agriculture . as well as the treatment of combination between T. harizanum and G. mosseae are excel of all interaction treatments in the increase the speed of plant response . The results also showed the stability of enzymatic activity for both enzymes which caused a significant reduced in the percentage of seedling death and the severity of disease and the separately treatment of B. subtilis excel of all separated treatments in the percentage of seedling death and severity of disease which are (13.33% and 12.5%) respectively compared with control treatment (R.solani only) which recorded (100% and 100%) respectively .