Allelopathic Effect of Aqueous Extracts of Parthenium ( Parthenium Hysterophorus L.) Parts on Seed Germination and Seedling Growth of Maize ( Zea Mays L.)

Twice repeated experiment was carried out under laboratory conditions to investigate the allelopathic effects of aqueous extracts of Parthenium hysterophorus L. shoot (stem + branch) and leaf, at 0, 5, 10 and 15 g L-1 (w/v) concentrations on maize (Zea mays L.) seed germination, seedling growth (shoot and root length) and biomass production. The treatments were laid out in completely randomized design with the factorial arrangement in four replications. Result indicated that the highest germination percentage (98.75%) was recorded from control whereas the lowest (43.75 %) was from stem extract at15 g L-1 concentration level. Similar trend was also observed by leaf extract. Root and shoot length of maize crop was reduced by 91.4 % and 70.8% by 85.6 and 35.8% leaf extracts and stem extracts respectively hence the roots were more sensitive to allelopathic effect than shoot. Extract of both leaf and stem at 15 g L-1 strongly reduced fresh and dry biomass of the maize seedling. The highest (100,100 %) tolerance index was recorded from control whereas, the lowest (8.62, 14.74%) was recorded from leaf and stem extract at 15 g L-1 concentration level respectively. Leaf aqueous extract showed more phytotoxic effect (91.37 %) than stem extracts (85.25) at 15 g L-1 whereas was the minimum recorded in control (0.0%). 15 g L-1 minimum value of vigor index (200, 539.2) and higher inhibition potentials (62.5 and 55.78%) were recorded from leaf and stem respectively. therefore allelopathic effect by the parthenium extracts is concentration-dependent manner. Leaf extract had shown highest inhibition potential followed by the stem.