Thesis (Ph.D.) - Cairo University - Faculty of Agriculture - Department of Microbiology

Legume trees play important roles in soil conservation and enhancement of soil fertility in agroforestry systems. The present study throw some lights on legume trees rhizobia interactions in the Egyptian environments, this necessitates to isolate rhizobia from root nodules. Tentative identification of isolated rhizobia from legume nodules was carried out. Authentication tests, effect of some stresses beside cross inoculation trial were considered as well. A total of 125 root nodule bacterial isolates was recovered and microscopically examined. All isolates were Gram negative, nonspoeforming rods and motile. The authentication tests confirmed that 92 isolates and 10 reference strains were able to nodulate the host plants (albizzia lebbek, prosopis juliflora, leucaena leucocephala, acacia nilotica, acacia albida, acacia saligna and sesbania sesban). The isolates differed in their colony morphology according to their specific host genotype. Growth and nodulation of trees as affected by rhizobial inoculation and N-fertilization were examined in greenhouse experiments. The isolates AL13, P10, AS8 and S18, isolated from albizzia lebbek, prosopis juliflora, acacia saligna and sesbania sesban in respective order, were the most infective isolates, forming 86, 123, 198 and 134 nodules pot 1, respectively. Cross inoculation of L. leucocephala with rhizobia isolated from acacia, appeared to be less infective microsymbiont for leucaena than those specific for albizzia, sesbania and prosopis

Issued also as CD