Control of Postharvest Rot of Two Species of Kolanut (Cola Nitida and Cola Acuminata) Using Guiera Senegalensis Leaf Extract in Jimeta Market, Yola Adamawa State

Abstract

Kolanut fruits are widely cultivated in West Africa, where they are used as stimulants to counteract fatigue, suppress thirst and hunger, rich in caffeine, the kola nut offers significant health benefits. Kolanut production in Nigeria faces significant challenges, with fungal rot diseases caused by different fungi, being a major concern to both traders and farmers of the crop. The study aimed to assess the anti-fungal potential of Guiera senegalensis Leaf extracts against some identified pathogens of Kola-nut rot. The fungal pathogens were successfully isolated from the diseased sample and were identified using standard techniques, leaves of Guiera senegalensis were collected from the university village and were prepared by dispensing 10g of extracts in 100ml of sterile distilled water. Three concentrations of 20%, 40%., 60 % were prepared using serial dilution techniques. The efficacy of plant extract against fungal pathogens were evaluated using poison food techniques. Data were analyzed using ANOVA and means were separated using LSD. From the results, four fungal pathogens identified include: Aspergillus parasiticus, Rhizopus stolonifer, Fusarium oxysporium and Aspergillus flavus. Only one crude plant extract from leaf of Guiera senegalensis was evaluated for its antifungal activity using In vitro and In vivo assessment. The antifungal assays demonstrated that the extract inhibited the growth of all tested fungi, with higher concentrations (60 %) producing the greatest inhibitory effect. Rhizopus stolonifer (33%) and Aspergillus parasiticus (43.28%) were the most sensitive to the extract, while Fusarium oxysporium(50.7%) and Aspergillus flavus(50.3%) showed less sensitive at lower concentrations. Phytochemical analysis revealed the presence of alkaloids, flavonoids, phenols, saponin, tannins and terpenoids. Quantitative analysis showed variations in metabolite concentrations (Tannins has the highest in concentration in both aqueous and ethanol with 2.920 & 2.810 respectively while alkaloid has the lowest in concentration with 0.069 & 0.075 in both aqueous and ethanol respectively). Overall, this study underscores the potential of Guiera senegalensis extracts as natural antifungal agents against postharvest rot in Kola nut. Additionally, it provides insights into the phytochemical changes associated with postharvest rot infection in Kola-nuts. Such findings could contribute to the development of effective strategies for managing postharvest rot and improving Kola-nut production in Nigeria.