In the present study an attempt has been made to evaluate the allelopathic effect of parthenium leaf, stem and flower extracts on biochemical parameters of bean seedlings. The aqueous leaf, stem and flower extract of parthenium showed both stimulatory and inhibitory effects on chlorophyll, carbohydrate, protein and phenol content. The chl. a, b, total chlorophyll and carotenoid content were found to be decreased significantly as the concentrations of the extract increased when compared to control. The total carbohydrate content in both root shoot axis and cotyledon increased as the concentration of the extract increased when compared to control. Total protein content in root shoot axis decreased as the concentration of the extract increased when compared to control on the other hand in cotyledon it was found to be increased as the concentration of the extracts increased. The total phenol content in both root shoot axis and cotyledon decreased significantly as the concentration of the extract increased when compared to control. The results of present study clearly showed that both stimulatory and inhibitory effect of parthenium aqueous leaf, stem and flower extract may be due to the presence of allelochemicals like terpenoids, tannins, phenolic acids so on.
