Antifungal Activity of Extracts of Scent Leaf (Ocimum gratissimum) and Alligator Pepper (Aframomum melegueta) on the Post Harvest Decay of Carrot in Calabar, Nigeria

Abstract

The bioactive and antifungal effects of ethanol extracts of Aframomum melegueta and Ocimum gratissimum were investigated in vitro on causative agents of post harvest decay of carrots. The phytochemical screening of the two plants were obtained by analysis of their extracts using established procedures. Results showed moderate presence of saponins, tannins, flavonoids, alkaloids, glycosides and polyphenols, in O. gratissimum and high presence of saponnins, glycosides and polyphenols in A. melegueta, indicating high antifungal potency of the plants. The microbial pathogens isolated were Rhizopus stolonifer, Fusarium culmorum, Sclerotinia sclerotiarum and Penicllium expansum. The fungi were cultured with the two plant extracts using potato dextrose agar (PDA), and mycelia growth and inhibition zones of the agar was observed with a corresponding increase in concentration of the plant extracts. At 100% concentration, extract of A melegueta recorded the highest inhibition of mycelia growth in P. expansum (83.33±42%)while that of O. gratissimum was 73.78±3.69%. At 100% concentration, extract of A. melegueta is comparable with Dowicide in the in vitro inhibition of mycelia growth of the fungi. There is evidence of fungicidal attribute in A. melegueta and could be further developed pharmacologically for controlling post harvest rot of carrot caused by several pathogenic fungi.

Key words: Antifungal effect, post harvest, plant extract carrot.