| Summary: | This study was conducted to investigate the antagonistic potential of endophytic and rhizospheric bacterial isolates obtained from <i>Citrullus colocynthis</i> in suppressing <i>Fusarium solani</i> and <i>Pythium aphanidermatum</i> and promoting the growth of cucumber. Molecular identification of bacterial strains associated with <i>C. colocynthis</i> confirmed that these strains belong to the <i>Achromobacter</i>, <i>Pantoea</i>, <i>Pseudomonas</i>, <i>Rhizobium</i>, <i>Sphingobacterium</i>, <i>Bacillus</i>, <i>Sinorhizobium</i>, <i>Staphylococcus</i>, <i>Cupriavidus</i>, and <i>Exiguobacterium</i> genera. A dual culture assay showed that nine of the bacterial strains exhibited antifungal activity, four of which were effective against both pathogens. Strains B27 (<i>Pantoea dispersa</i>) and B28 (<i>Exiguobacterium indicum</i>) caused the highest percentage of inhibition towards <i>F. solani</i> (48.5% and 48.1%, respectively). <i>P. aphanidermatum</i> growth was impeded by the B21 (<i>Bacillus cereus</i>, 44.7%) and B28 (<i>Exiguobacterium indicum</i>, 51.1%) strains. Scanning electron microscopy showed that the strains caused abnormality in phytopathogens’ mycelia. All of the selected bacterial strains showed good IAA production (>500 ppm). A paper towel experiment demonstrated that these strains improved the seed germination, root/shoot growth, and vigor index of cucumber seedlings. Our findings suggest that the bacterial strains from <i>C. colocynthis</i> are suppressive to <i>F. solani</i> and <i>P. aphanidermatum</i> and can promote cucumber growth. This appears to be the first study to report the efficacy of these bacterial strains from <i>C. colocynthis</i> against <i>F. solani</i> and <i>P. aphanidermatum</i>.
|
|---|