Cyanobacteria are one of important groups of prokaryotes due to their effects on growth and development of plants and its role in biological control of phytopathogenic fungi such as : Fusarium oxysporum and Rhizoctonia solani on flax by producing various biologically active substances . In the present study , fourteen cyanobacterial strains were isolated from rice rhizosphere in kafr Elsheikh (k) ( North Delta Region ) and El-Dakahliya (D) ( East Delta Region ) . Only five cyanobacterial strains showed antagonistic effects against the both pathogenic fungi and were indentified as Nostoc muscorum k , Anabaena oryzae D , Anabaena oryzae k , Nostoc pruniforme D and Oscillatoria brevis D. The strains were analysed for phosphate solubilization , production of IAA , ammonia , HCN , production of some enzymes , and effect of their filterates on seed germination of flax seeds . Flax seeds treated with cyanobacterial filtrates germinated faster and produced higher seedlings compared with the nontreated ones .

Twelve bacterial isolates were recovered from the rhizosphere of cotton, flax, and tomato seedlings of the most predominat commerical cultivars in Egypt. Bacterial isolates determined for their activities against three phytopathogenic fungi: Fusarium oxysporum, Rhizoctonia solani and Sclerotium rolfsii.When the six most antagonistic isolates were classified by standard tests, it was found that 4 strains (57 %) were belonging to Bacillus spp., 2 strains (40 %) were belonging to pseudomonas spp. In vitro,Bacillus subtilus (2strains),Bacillus sp. (2strains) , Pseudomonas flurorescens and Pseudomonas sp. were effective antagonists. Ammonia,chitinase, amylase and cellulase in bacterial culture by Bacillus sp., were produced and also, the production of siderosphore,ammonia, lipase and chitinase by Pseudomonas spp.may contribute to the antagonistic activities of the bacterial isolates.

No abstract

he germplasm evaluated in this test was a part of the Screening Program for Fusarium Wilt Resistance. This program is conducted annually in the greenhouses of Cotton and Fiber Crops Diseases Research Dept, PPRI. The present test included 200 families of ten experimental genotypes and 745 families of seven commercial cultivars. The experimental genotypes were supplied by Cotton Breeding Dept, and the commercial cultivars were provided by Cotton Maintenance Dept, Cotton Research Institute. Healthy survival rate of plants of the families was used as a criterion to evaluate the reactions when the genotypes were grown in autoclaved highly infested soil with a mixture of race3 of Fusarium oxysporum f.sp.vasinfectum isolates. The experimental genotypes, except G5 and G8, showed distinguished range of resistance to Fusarium wilt as expressed by healthy survival ranging from 97.28 to 100%., thus, classified as very highly resistant (VHR). Within this narrow range, no significant differences in resistance could be observed; significant differences, were however, observed between G5 or G8 and any of the other VHR genotypes as well. The difference between G5 and G8 was also significant. The experimental genotypes were classified into three distinct groups based on the dissimilarity distance (DDs) generated from cluster analysis of their symptom profiles. The first group included G1,G3,G2,G7,G6,G4,G9, and G10.The second group included G8.The third group, which was unrelated to the previously mentioned two groups, included G5). Within the first group, genotypes were identical in their symptom profiles. Most of the families of the tested commercial cultivars were classified as VHR. The percentages of families in this reaction class ranged from 86.92 (families of Giza 45) to 100% (families of each of Giza 86 and Giza 88). The commercial cultivars were classified into two distinct unrelated groups based on the DDs generated from cluster analysis of the profiles of their reaction classes. Giza 45 was included in one group and the remaining cultivars. were included in the other group.