Paraquat is a quarternary nitrogen herbicide
widely used for broadleaf weed control. It is a fastacting,
non-selective compound, which destroys
tissues of green plants on contact and by translocation
within the plant. Paraquat exerts its herbicidal
activity by interfering with the intracellular
electron transfer systems in plants, thereby inhibiting
reduction of NADP to NADPH during
photosynthesis (Pasi, 1978). This disruption leads
to the formation of superoxide anion, singlet
oxygen, as well as hydroxyl and peroxyl radicals
(Autor, 1977; Pasi, 1978). These reactive oxygen
species (ROS) interact with the unsaturated lipids
of membranes resulting in the destruction of plant
organelles, inevitably leading to cell death