Phytochemical and Antifungal Efficacy of Leaf and Stem Bark Extracts of Parkia biglobosa on Fungi Associated with Seed Rot of Green Bean (Phaseolus vulgaries L.) in Akpabuyo, Cross River State, Nigeria

The phytochemical and antifungal efficacy of the ethanolic and methanolic stem bark and leaf extracts of Parkia biglobosa on the fungal pathogens isolated from infected green bean seeds obtained from the field in Akpabuyo, Cross River State, Nigeria were investigated in vitro. The pathogens were Botryodiplodia theobromae and Aspergillus niger. Various concentrations of the extracts ranging from 10g/100ml, 20g/100ml, 30g/100ml, 40g/100ml and 50g/100ml were separately added to PDA media. Results of the in vitro antifungal assay shows that at 40g/100ml and 50g/100ml concentrations, ethanolic stem bark and leaf extracts of P. biglobosa completely inhibited the radial growth of B. theobromae and A. niger after seven days observation period while those of methanolic extracts completely inhibited the redial growth of the fungal pathogens at 50g/100ml concentration. Results, however, shows that the extracts had a significant effect (P<0.05) on the radial growth of the fungal pathogens at all the different concentrations tested as compared with the control. Pathogen growth inhibition was most effective at 30g/100ml, 40g/100ml and 50g/100ml concentrations. The inhibitory action of the extracts increased/decreased with a corresponding increase/decrease in the concentration of the plant extracts. Ethanolic stem bark and leaf extracts of P. biglobosa was found to be more effective in inhibiting the redial growth of the fungal pathogens than those of methanolic extracts, also ethanolic and methanolic stem bark extracts were observed to be more effective in the inhibition of the radial growth of the fungal pathogens than leaf extracts. Phytochemical screening of the extracts revealed the presence of cardiac glycosides, reducing sugars, flavonoids, saponnins and tannins with traces of alkaloids in stem bark extracts while flavonoids, alkaloids, cardiac glycosides, saponnins, tannins and terpenoids were present in leaf extracts.