Evaluation of the Influence of Culture Media and Neem Cake Extract on the Growth Rate of Three Soil Borne Fungi (Trichoderma harzianum, Trichoderma viride and Sclerotium rolfsii)

Aims: To evaluate the performance and efficacy of three fungi on pure Sabouraud dextrose agar (SDA), Potato dextrose agar (PDA), malt extract agar (MEA); SDA, PDA and MEA modified in combination with different neem cake concentrations.

Study Design: The experiment was laid out in a completely randomized design.

Place and Duration of Study: Department of Botany, University of Calabar, between July 2021 and September, 2021.

Methodology: Fungal pathogens were isolated from soil samples and infected fruits of water melon. Different culture media were used to grow the pathogens. Chloramphenicol (250mg) was added to each medium, autoclaved at 1210C for 15 minutes, and kept at room temperature of 21 ± 10C. After inoculation, colonies were sub cultured to obtain pure culture. Media modification was achieved by adding 10g, 20g, 30g and 40g of extract. Cork borer (5mm) of fungi stock culture were transferred to Petri dishes. Linear growth of fungi was recorded after 16 hours. Average linear growth rate was measured at 12 hours interval for five days.

Results: Spore concentration of Sclerotium rolfsii was significantly higher in pure media than in modified media. Among modified media, concentrations were significantly higher in both PDA and MEA at 1.60x106 spores/ml. Trichoderma viride on pure SDA produced the highest spore concentration at 4.80x106 spores/ml followed by pure PDA at 4.10x106 spores/ml, whereas on the modified media, MEA had the highest spore concentration at 1.80x106 spores/ml. Pure Potato Dextroes Agar (PDA) of Trichoderma harzianum produced the highest spores at 6.10x106 spores/ml while MEA and SDA had close range of spore production at 4.90x106 and 4.30x106 spores/ml respectively. Modified MEA had the highest spore concentration at 1.30x106 spores/ml followed by SDA which had 1.1x106 spores/ml.

Conclusion: The mycelia growth rate reveals that both pure and modified MEA supported the growth of all the fungi better than PDA and SDA.