INHIBITORY POTENTIAL OF SORGHUM LEAF AND ROOT EXTRACTS AGAINST FUSARIUM OXYSPORUM F.SP LYCOPERSICI

Abstract

A study was conducted to determine the efficacies of aqueous and methanolic extracts of sorghum leaf and root on mycelia inhibition of Fusarium oxysporum f.sp lycopersici (FOL).  Sorghum leaves and root parts were collected at harvest, air dried at 28±2^oC for 21 days and blended into powder. Aqueous extract was prepared by adding 100 ml of sterile distilled water to 10 g of ground tissue while methanolic extract was obtained with 90% methanol in a Soxhlet extractor to obtain stock. Preliminary phytochemical analysis of the extracts was carried out following a standard procedure. Fungitoxicity was determined by adding 15 ml Potato dextrose agar (PDA) to 1 ml extract in 9 cm Petri dish while PDA without extract served as control. Each plate was inoculated with 3mm of a 7-day-old fungal culture and incubated at room temperature (28±2^oC) for 7 days. Data collected were subjected to statistical analysis. Phytochemical screening revealed the presence of saponins and cardiac glycosides in both extracts. Leaf and root methanolic extracts significantly (P≤0.05) reduced radial mycelial growth of FOL compared to the aqueous extract. Mycelia growth inhibited by methanolic leaf and root extracts at 10 mg/ml ranged between (53 – 57 %) and significantly higher than inhibition by aqueous extract (29 – 40 %). Summarily, both leaf and root methanolic extracts at 10 mg/ml had the highest mycelial growth inhibition of 57.28 and 53.06 %, respectively. It is concluded that sorghum leaf and root extracts possess fungicidal potentials that could be explored in the management of tomato Fusarium wilt.