Allelopathic effects of Populus nigra and Persicaria hydropiper aqueous leaf extracts were studied on the germination, radicle and plumule length of Pennisetum glaucum  and Zea mays. Both of the plant leaf extracts were tested on each targeted   species. Three concentrations of extract (5g, 10g and 15g) were used and each concentration was further based on three soaking duration (24, 48 and 72 hours). The extracts were applied to five replicates each having ten seeds of test specie and water was used as control. The allelopathic effect was mostly concentration dependent followed by soaking duration. As the concentration of extract is increased there is a significant decrease in the germination and growth parameters observed. After the concentration the inhibitory activity of soaking duration existed in which the extract soaked for 72 hours was more potent in allelopathic effect as compared to the extract of 48 hours and 24 hours. The extracts from P.hydropiper was more phytotoxic than P.nigra leaf extract. From this study it was concluded that P. nigra and P.hydropiper could be useful for weed management in the variety of agricultural settings to develop sustainable agriculture options and control the unwanted weeds by natural remedies.

Keywords: Allelopathic effects, P.hydropiper, P. nigra, Germination, P. glaucum, Zea mays, Sustainable agriculture.