Inhibitory effect of parthenium (Parthenium hysterophorus L.) residue on growth of water hyacinth (Eichhornia crassipes Mart Solms.) II. Relative effect of flower, leaf, stem, and root residue.

The relative effect of residue of leaf, flower, stem, and root of parthenium (Parthenium hysterophorus L.) on growth of water hyacinth was studied. The inhibitory activity of the residue as shown by its effect on biomass and healthy leaf number (HLN) of treated plants was in the order: leaf and flower >stem >root. Total phenolic acids in the medium after 72 hr of suspending the plant part residue were maximum in flower followed by leaf, root, and stem, successively. The dry leaf powder (DLP) and dry flower powder (DFP) at and above 0.50% (w/v) and dry stem powder (DSP) at 1.00% (w/v) killed water hyacinth in about one month. Dry root powder (DRP) at the highest dose (1.25% w/v) reduced the growth of the treated plants drastically, but the plants recovered after about one month. The DSP at 0.50% (w/v) and DRP at 0.25-0.75% (w/v) supported growth of treated plants, probably due to lower levels of inhibitors, allowing utilization of constituents of the residue as nutrients. Using wheat seedlings as a reference material, it was observed that in aquaculture at different levels of parthenium plant parts residue, water hyacinth plants were much more sensitive to inhibitory activity. Thus, water hyacinth is suggested as a material for bioassay of inhibitory activity of the parthenium plant residue.