2.2. Bioassays and experimental design Three important agricultural crops: cereal crop rice (Oryza sativa L.), oil crop mustard (Brassica campestris L.) and vegetable crop Amaranthus viridis L. were selected as bioassay species. Seeds from all the three species were surface sterilized by washing with 0.45% sodium hypochlorite for 10mins. Then the seeds were washed thoroughly with distilled water repeatedly to remove trace amount of hypochlorite. Each bioassay experiment was performed by placing 25 surface sterilized seeds in sterile petridish (11 cm in diameter) lined with whatman filter paper.The seeds were then treated with 10ml of the 1%, 2% and 4% test solution and with water as control. The treatments were laid out in a completely randomized design with factorial arrangement in four replications. The petridishes were incubated at room temperature (28±3˚C) for 3 days.