Allelopathic Effect of Aqueous Extracts of Four Weed Species on Germination of Some Crops

We evaluated the allelopathic potential of extracts from common weed (Phragmites australis (Cav) parthenium (Parthenium hysterophorus L.), Jimson weed (Datura alba L.) and poplar (Populus deltoides W. Bartram ex Marshall) on chickpea (Cicer arietinum L.), rice (Oryza sativa L.) and maize (Zea mays L.) crops. The experiment was laid out in completely randomized design with three replications; distilled water was used as control and was also included for comparison in the experiment. Significant differences were observed for germination percentage, mean germination time (MGT), germination index (GI) and growth retardation in the tested crop species. Chickpea showed the greatest tolerance to the three plant extracts, with a germination of 78% while rice was more susceptible, with only 35% germination. Water extracts of poplar caused more phytotoxicity than extracts from other plants, resulting in low levels of germination compared with the control. The highest mean GI (3.10) was recorded in chickpea followed by those of maize (1.15) and rice (0.47). The presence of poplar on the borders of farmers' fields may be one of the reasons for failure of seed germination of the studied crops because the leaves of polar have the potential to inhibit seed germination of many crops.