HPPD inhibitors like tembotrione and mesotrione are often called "bleaching herbicides" because they stop carotenoid synthesis, causing target weeds to turn completely white before dying. Maize has high tolerance to these compounds.
Step 1: Understanding the Concept:
Selectivity is a key property of agricultural herbicides, allowing them to control target weeds within a crop without damaging the crop itself. Tembotrione is a relatively modern post-emergence herbicide. Step 2: Detailed Explanation:
Let us analyze the chemical class and selectivity of tembotrione:
Tembotrione belongs to the triketone chemical family of herbicides.
It acts as an inhibitor of the enzyme p-hydroxyphenylpyruvate dioxygenase (HPPD).
Inhibiting HPPD blocks the synthesis of plastoquinone, which is an essential cofactor for carotenoid biosynthesis.
Without carotenoids to protect the photosynthetic apparatus, chlorophyll is rapidly destroyed by sunlight, causing a characteristic bleaching (whitening) of the weed leaves, followed by necrosis.
Maize (corn) has high natural tolerance to tembotrione because it can rapidly metabolize the herbicide into inactive compounds.
Consequently, tembotrione is registered and widely used as a selective, post-emergence herbicide to control broadleaf and grassy weeds specifically inmaize crops.
Thus, tembotrione is registered for use in maize. Step 2: Final Answer:
The correct option is (B), representing Maize.
