The productivity of agroecosystem and loss of biodiversity are caused by phytotoxic activities of an invasive exotic weed Parthenium hysterophorus. The present study was conducted to assess the relative phytotoxicity of 15, 25, 50, 75 and 100% aqueous extracts of stem and root of Parthenium on the rate of seed germination and seedling growth of Phaseolus mungo a pulse crop, in laboratory condition. The rate of seed germination in P.mungo in stem and root aqueous extracts of Parthenium decreased from 1 to 2% and 9 to 100%, respectively. The inhibition in root length in stem extract varied from 4.23% to 73.41% and in root extract from 7.62% to 100%. The inhibition in shoot length in stem extract varied from 9.45% to 18.15% and in root extract from 9.45% to 100% compared to control condition. The Seed Vigour Index (SVI) value decreased from 14.59 to 28.14% in stem extract and 8.78% to 100% in root extract. The root extract of Parthenium was more phytotoxic than the stem extract in Phaseolus mungo. The phytotoxic impacts of plant parts (stem and root), treatments (15%, 25%, 50%, 75% and 100% concentrations) and interactions between plant parts and treatments were highly significantly different at p < 0.000. Thus the present study indicated that the aqueous extract of root of Parthenium was recorded more phytotoxic than stem extract on Phaseolus mungo.
