Allelopathic management of some noxious weeds by the aqueous extracts of Parthenium hysterophorus and Carthamus oxyacantha.
Weed occurrence in cultivated fields may cause significant losses of agricultural crops as a result of competition and allelopathic stress. In this study, 100 g l-1 aqueous extracts of leaves and roots of two wild plants Parthenium hysterophorus and Carthamus oxyacantha were evaluated for their effect on germination, seedling growth and biomass of commonly occurring weeds in wheat fields (Chenopodium album, Lepidium didymium, Phalaris canariensis and Rumex dentatus). Negative allelopathic effect of P. hysterophorus and C. oxyacantha were observed on test weeds, however, 100 g l-1 leaf and root extracts of P. hysterophorus had a more drastic effect on the weeds than C. oxyacantha. The sensitivity of subject weeds to allelopathic stress were recorded in the order Lepidium didymium > Rumex dentatus > Chenopodium album > Phalaris canariensis. The study suggests that P. hysterophorus possesses phytotoxic activities and may serve as a potential candidate in natural weed management strategies.