Assessment of allelopathic properties of Parthenium hysterophorus residues

A study was conducted to explore the allelopathic properties of unburnt (UR) and burnt (BR) residues of Parthenium hysterophorus towards the growth of two winter crops-radish and chickpea. The extracts prepared from both UR and BR were toxic to the seedling length and dry weight of the test crops, those from BR in particular. The difference was attributed to the highly alkaline nature of the extracts prepared from BR. Growth studies conducted in soil amended with UR and BR extracts and residues also revealed phytotoxic effects towards test crops, UR being more active than BR unlike crude extracts. These effects were attributed to the presence of phenolics rather than to any significant change in pH or conductivity.