Efficacy of aqueous extracts of different plant parts and biocontrol agents was tested against the growth of three post-harvest fungal pathogens of banana (Macrophomina phaseolina R-4242, Fusarium oxysporum sp. QJC- 1403 and Nigrospora oryzae NRRL 54030).The plant extracts when applied as pre- and post-inoculation treatments were effective in controlling the growth of the three pathogenic fungi. Extracts of medicinal plants like Azadirachta indica, Eucalyptus globulus and Ocimum sanctum were effective in inhibiting the growth of N.oryzae, while the extracts of Allium cepa and Allium sativum effectively inhibited the pathogenic activity of all three pathogens under investigation. Out of the different bioagents tried, Penicillium citrinum and Streptomyces spp. could effectively control the growth of the three fruit-rot fungi under in vivo conditions
Banana fruits infected with Macrophomina phaseolina R-4242, Fusarium oxysporum sp.QJC-1403 and Nigrospora oryzae NRRL-54030 had deteriorated within eight days of incubation at room temperature (27±2oC). Extracts from the infected fruits exhibited cellulase activity, however uninfected fruits lacked cellulase activity. The cellobiohydrolase (C1) activity could be traced on 2nd day of inoculation in all the four varieties of banana which continued to increase till the end of the observation period. However, the C1 activity showed decreasing trend by the end of 8th day in Cavendish and Curry varieties infected with N. oryzae and F. oxysporum respectively. Endoglucanase (CX) activity was also witnessed in the diseased tissues of all the four varieties of banana which, however, varied with the pathogens inoculated. CX activity decreased after 6th day of infection in all the varieties of banana under investigation. The occurrence of cellulase in banana fruits infected with the three fruit-rot fungi and its absence in uninfected fruits suggest the role of this enzyme in pathogenicity of the fungi understudy. Cellulolytic components of the fruits are degraded; the fruits are deteriorated and are lost to the postharvest pathogens.
The production of cellulase (C1 and CX) by the three pathogenic fungi isolated from banana on seven different media was investigated. All the three pathogens were able to produce cellulase in one or the other media tried. Medium G supported good growth and maximum enzyme production by the three fruit-rot fungi. Supplementation of medium A with carboxymethyl cellulose (medium C) as the substrate did not make much difference in the degree of cellulase production, suggesting the constitutive nature of the enzyme produced by the fungi understudy