Inhibition of Germination and Growth Behavior of Some Cowpea Varieties Using Neem (Azadiracta Indica) Leaf Water Extracts

The experiment was conducted to observe the inhibitory effects of the leaf extract derived from neem (Azadiracta indica) on germination and growth behavior of some cowpea varieties (receptor). Experiments were set on sterilized petridishes with a photoperiod of 24 hours at room temperature of 27-30oC. The effects of the different concentrations of aqueous extracts were compared with distilled water (control). The aqueous extracts of leaf caused significant inhibitory effects on germination, root and shoot elongation and development of lateral roots of treated plants. Bioassays indicated that the inhibitory effect was proportional to the concentrations of the extract, as concentration increased the extent of inhibition also increased. The study also revealed that inhibitory effect was much pronounced in root and lateral root development rather than germination and shoot growth.Keywords: Neem, Allelopathic effect, Leaf extract, Germination, Growth behavior