Antifungal potential of Hyptis sauveolens extract against African yam bean seed (Sphenostilis stenocarpa (Hoechst ex. A Rich) harms pathogens
Akalazu J N
Imo State University, Nigeria
: J Plant Physiol Pathol
Abstract
Seeds are known to harbor pathogens which cause yield losses, reduce the nutritional composition and contaminate food. Farmers and agricultural workers are exposed to different species of fungal spores especially aflatoxin-producing strains. Hyptis sauveolens is reported to contain essential oil which has antibacterial, antifungal properties and as mosquito repellent. The aim of this study is to ascertain the effect of crude ethanol extract of H. sauveolens on mycelia growth inhibition of seedborne fungi of African yam bean seed. About 80 g of powdered plant material was soaked in 800 ml of absolute ethanol for 4 days and then filtered. The pasty crude extract was dissolved in 50% concentration of dimethyl sulphoxide (DMSO) in the ratio of 1:10 (1g of crude extract dissolved 10 ml of DMSO) to get a concentration of 100 mg/ml which act as the stock. Then serial dilutions were made from the stock to obtain concentrations of 60 mg/ml and 20 mg. About 2 ml of the extract were aseptically dispensed into sterile petri dishes and 18 ml of molten tetracycline-modified Potato Dextrose Agar (PDA) was poured into each petri dishes containing plant extract. About 5 mm of the mycelia disc were placed inside the petri dishes containing the plant extract and (PDA). The petri dishes without plant extract served as control. The experiment was in 3 replications. The result showed that seed-borne fungi associated with African yam bean seed are Aspergillus niger, Aspergillus flavus and Fusarium spp. However, percentage frequency of occurrence of the isolated pathogens showed that Aspergillus niger was the most frequently occurred fungi, followed by A. flavus while Fusarium spp. occurred least. In addition crude ethanol extract of H. sauveolens at different concentrations inhibited the mycelia growth of the fungi. The percentage inhibition of the mycelia growth of the fungal isolates by H. sauveolens ranged from 33-80.6%, 37-93.6%, 54.6-88.71% for A. flavus, A. niger and Fusarium spp. respectively. Hyptis sauveolens leaf extract is effective in controlling the growth of these fungi therefore it could be applied to stored seeds, grains and tubers in form of powder.
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