Metabolites of Penicillium citrinum as potent herbicides against Parthenium weed.
This study was undertaken to assess the herbicidal activity of metabolites of Penicillium citrinum against parthenium weed (Parthenium hysterophorus L.). Two growth media viz. malt extract (ME) broth and potato dextrose (PD) broth were used for preparation of fungal metabolites by growing the fungus in these media for 15 days. The metabolites were evaluated in laboratory bioassays using their original (100%) and diluted (50%) concentrations, and compared with a negative control as well as with original and diluted growth media. In general, both the growth media had insignificant effect on germination and various growth parameters except root length where original ME broth significantly increased this parameter. Both the concentrations of the metabolites prepared in different growth media significantly (P ≤ 0.05) suppressed germination and various shoot/root growth parameters over control. Metabolites prepared in PD broth exhibited more activity than the metabolites prepared in ME broth. There was up to 31%, 77%, 92% and 77% decrease in germination, shoot and root lengths, and seedlings dry weight due to metabolites in ME broth, while these parameters were decreased by 57%, 89%, 94% and 93% due to application of metabolites in PD broth, respectively.