Step 1: Herbicide Classifications.
Herbicides are categorized by their action and target specificity. They can be:
- Selective: Targeting specific weeds while sparing crops.
- Non-selective: Affecting all plant life they contact.
Furthermore, their mode of action can be contact (localized effect) or systemic (translocated within the plant).
Step 2: Understanding Paraquat.
Paraquat is identified as a non-selective, contact herbicide.
Its mechanism involves immediate destruction of plant cell membranes upon contact with green tissue.
As it is not systemic, underground plant parts may remain viable if unsprayed.
It is commonly employed for weed control in non-cultivated areas and as a desiccant prior to harvesting.
Step 3: Evaluation of Options.
- (A) Paraquat: Accurately described as a non-selective contact herbicide.
- (B) Glyphosate: A non-selective herbicide, but it acts systemically, not solely on contact.
- (C) Metribuzin: Classified as a selective, systemic herbicide, not exclusively a contact type.
- (D) Isoproturon: A selective herbicide utilized for controlling broadleaf weeds in wheat cultivation.
Step 4: Determination.
Consequently, Paraquat aligns with the definition of a non-selective contact herbicide.