Question:
Which plant bio regulator blocks the synthesis of gibberellin?
Which plant bio regulator blocks the synthesis of gibberellin?
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Prohexadione-Ca is commonly sprayed in apple orchards to manage canopy density and reduce susceptibility to secondary infections.
Updated On: Jul 10, 2026
- Abscisic acid
- Ethylene
- Benzothidiazole
- Prohexadione - Ca
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Verified By Collegedunia
The Correct Option is D
Solution and Explanation
Step 1: Understanding the Concept:
Gibberellins (GAs) are hormones responsible for cell elongation and vegetative shoot growth in plants.
Plant growth retardants are applied to limit shoot growth by targeting key enzymatic pathways of GA biosynthesis.
Step 2: Detailed Explanation:
Prohexadione-calcium (Prohexadione-Ca) structurally mimics 2-oxoglutarate, which serves as a co-substrate for enzymes.
It inhibits the late-stage dioxygenases ($3\beta$-hydroxylase and 20-oxidase) that convert inactive GAs to biologically active forms.
This enzymatic inhibition blocks active gibberellin synthesis, resulting in reduced vegetative growth without affecting fruit development.
Step 3: Final Answer:
The plant growth regulator that inhibits gibberellin biosynthesis is Prohexadione-Ca.
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