Biocontrol of Fusarium oxysporum f. sp. lycopersici by plant growth promoting bacteria on Tomato plant .


This study was carried out to study the efficiencyof six strains of plant growth promoting bacteria(Bacillus subtilis, Bacillus pumilus, Pseudomonas fluorescence, Azotobacter chroococcum1, Azotobacterchroococcum2and Bacillus sp.)as biocontrol agents against the pathogenic fungus Fusarium oxysporum the causal pathogen of wilt disease of tomato plants under greenhouse conditions .The results of antagonistic activity of the six bacterial strains against F.oxysporum showed that the tested strains varied in their abilities in reducing growth rate of the pathogen and increasing the percentage of pathogen inhibition as compared to control treatment.B.subtilis was the superior in reducing the radial growth rate of pathogen20.33mm as compared to control treatment34.66 mm .The results revealed that most the tested bacterial strains significantly increased the percentage of seeds germination and the 1stgermination .B. subtilis , P. fluorescence and B. pumilus were the best in increasing seeds germination which recorded(97.33,95.33 and 93.66)% respectively as compared to control treatment ( 77.40 % ) .The greenhouse experiment revealed that the plants treated with B.subtilis recorded maximum ( shoot length , root length , branch no./ plant ,fresh and dry weight of plant ,branch no. / plant , fruit no/plant and plant productivity ) . All these parameters were increased by 317.6 cm , 29.4 cm , 5.1 branch / plant ,(1456.6 , 298.6) g / plant ,(5.1) branch / plant ,11.63 fruit / plant , 1361.6 g / plant respectively,also the results showed B.subtilis significantly decreased disease incidence and severity of tomato plants infected by F. oxysporum which recorded( 20.6 %,0.14 ) respectively as compared to both positive ( without pathogen)and negative( with pathogen) control treatment( 6.90 % , 0.05) , ( 82.70 % , 0.69 ) respectively .