الفهرس 
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Abstract
Current study was done in Lab. and greenhouse of Maize and Sugar Crops Diseases Research Department, Plant Pathology Research Institute, A.R.C., Giza.
Findings obtained throughout current study can be summarized as follows:
1. Total numbers of 110 rhizobacterial fluorescent pseudomonad isolates were recovered from the rhizosphere of maize and sugar beet.
2. Twenty four out of these isolates were found to have the potency to antagonize two major root-infecting pathogens of maize in vitro. These pathogens are: Cephalosporium maydis and Fusarium verticillioides. In pot experiment, four bacterial isolates were shown to be effective in reducing infection with each of the target pathogens.
3. Biochemical tests classified tentatively these efficient organisms as species of fluorescent pseudomonads.
4. Based on the genotypic identifications, they could be identified as Pseudomonas putida (Pau9), P .putida (Pau11), P. putida (Psf3) and P. aeruginosa (Psf9).
5. Extracellular enzymes produced by these efficient strains were assayed and found that cellulase and chitinase as the most important enzymes that can affect the pathogenesis were actively produced by most of these strains. Cellulase, however was found to be produced only by P. aeruginosa Psf9. Whereas, Chitinase was detected in growing media of the tested strains, except P. putida Pau11.
6. Study the antibiosis revealed that phenazine was the only antibiotic produced by P. aeruginosa Psf9. Specific primers of the other antibiotics negatively shown the probability of production of any other antibiotics by these strains. HCN as the volatile antibiotic was found to be produced by P. putida Psf3 and P. aeruginosa Psf9. It was found that siderophores were actively produced by all bacterial strains under study.
7. IAA was found to be produced by three of these bacterial strains. These are P. putida Psf3, P. putida Pau11 and P. aeruginosa Psf9 excrete phytohormones. But, P. putida Pau9 was unable to excrete this phytohormones.
8. Availability of each of P and K by Pseudomonas strains under study was assayed and found that all of them have the ability to solubilize both of potassium and phosphorus in growing media.
9. Analytical identification of the secondary metabolites produced by the four Pseudomonas strains was done by GC-MS and found that several compounds were produced by each of these bacterial strains.
10. Coating maize seed with the mixture of the four strains and seeding in potted-soil infested singly with one of the two target pathogens, or in combination revealed that fresh and dry weights of resulting plants were significantly increased compared with the control. Treatment caused significant increase in root lengths, but insignificant increase in shoot lengths. This is correct in soil infested with C. maydis. Whereas, in soil infested with F. verticillioides, treatment caused significant results in all of the growth parameters of plants. Combining the two pathogens in soil showed that insignificant effect of coating seed with the mixture of bacteria on any of shoot or root lengths. Whereas, significant results were found in shoot and root weights compared to the non-treated control.
11. Biochemical study on the foliage of the resulting potted-plants revealed that coating maize seed with the bacterial mixture caused substantial increase in total chlorophyll, whether in soil infested singly or by the combination of the two pathogens, generally.
12. Activity of peroxidase was shown to be increased in leaves of maize plants in soil infested with ¬F. verticillioides singly or in combination with C. maydis. Yet, no effect of the bacterial application on the activity of this enzyme was found in soil infested singly with C. maydis.
13. The majority of detected compounds belonged to phenolics. But, some other compounds were found to be specifically produced by one or more bacterial strains