1. What kind of chemical are diuron and paraquat?

 

Paraquat is a toxic chemical that is used as an herbicide, primarily for weed and grass control

Diuron (1,1-dimethyl, 3-(3',4'-dichlorophenyl) urea) is a broad-spectrum residual herbicide that is used in agriculture for pre-emergent and post-emergent control of broadleaved and grass weeds.

Herbicides are plant killers where it acts by interrupting photosynthetic electron flow. The precise sites of action of many of these agents have been found to lie either at the reducing side of photosystem I which can be seen in Paraquat, or in the quinone acceptor complex in the electron transport chain between the two photosystems which is seen in Diuron. The chemical stuctures are shown below :

The mechanism of diuron blocks the electron flow at the quinone acceptors of photosystem II via competing for the binding site of plastoquinone that is usually occupied by QB. While paraquat, accept electrons from the early acceptors of photosystem I and then form superoxide O2- by reacting with oxygen. Superoxide is destructive where it damages the components. A diagram is shown below:

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