Allelopathic effect of Parthenium hysterophorus L. on seed germination and seedling growth of two crops wheat (Triticum aestivum) and barley (Hordeum vulgare) was studied at the concentrations level of 0%, 1%, 5% and 10% leaf, stem, flower and root extracts of Parthenium hysterophorus. Seed germination of wheat and barley was completely inhibited at 10% of all extract of Parthenium hysterophorus especially on flower extract. The seed germination, plumule, radicle length production were reduced with increasing concentration of aqueous solution. As per this study, increasing concentration of extract of Parthenium hysterophorus has adverse effect on germination, radicle length, and plumule length. Root and shoot length of seedlings decreased significantly (p<0.05) with increasing concentration of parthenium. Maximum root (7.00 cm) for wheat and (5.5 cm) for barley and shoot length (6.00 cm) for both wheat and barley were obtained for control (0%) in which the value reduced to 0 cm for both of them at a higher parthenium concentration 10%, respectively. Qualitative analysis of aqueous parthenium hysterophorus leaf, root, stem and flower extract was studied for the presence of carbohydrate, alkaloid, steroid, sterols, glycosides, tannin, phenolic, compounds, flavonoid, oil, carbohydrate, protein, amino acid and were determined by testing with chemical laboratory in the presence of reagent
