Asian Journal of Research and Review in Agriculture

Three famous medicinal plants; Bitter leaf (Vernonia amygdalina), Basil (Ocimum gratissimum) and Hibiscus (Hibiscus sabdariffa) were evaluated for their allelopatic interaction with parasitic nematode infestation in Makurdi yam field in Benue State, Nigeria where yam is intensively cultivated. The experiment was carried out using a randomized complete block design (RCBD) with four treatments for the three plants intercropped with "Hembakwase" white yam cultivar and the control group (without intercrop). This was repeated three times at a spacing of 1m x 1m occupying an area of ​​12m². Data for tuber count/plant, tuber weight, tuber diameter, final nematode count/plot and root gall index were recorded. Separation of means was done using Duncan's multiple range test (DMRT) at a 5% probability level. The obtained results showed that the Vernonia amygdalina intercrops gave significantly higher number of tubers/plant (4.71), tubers length (34.22), tubers girth (21.22) and yield per plot (5.6) than other treatments, while the untreated control had lower yield (1.5). Significantly higher root gall index (P < 0.05) of Meloidogyne spp. was recorded from the peels of tubers in untreated treatment (4.3), Ocimum gratissimum (3.1), Hibiscus sabdariffa (2.3), and the lowest gall index was scored from yams grown with Vernonia amygdalina (1.3) intercrop, respectively. This further affirms the allelopathic potential of Vernonia amygdalina in suppressing nematode populations. It is recommended to encourage intercropping of bitter leaf in nematode infested fields among farmers as this will help suppress nematode populations and serve as stakes for yams planted.