Question

Which phytohormone is regarded as an anti-stress promoter and growth bio-stimulator?

• A. Jasmonic acid
• B. 1-MCP
• C. Melatonin
• D. Prohexadione -- Ca

Hint:

Melatonin in plants is emerging as a key molecule that:
Enhances tolerance to various stresses (anti-stress).
Promotes growth and development (growth bio-stimulator).
Jasmonic acid: Primarily defense.
1-MCP: Ethylene inhibitor.
Prohexadione-Ca: Growth retardant.

Answer 1

The Correct Option is C

Step 1: Jasmonic acid mainly drives defence signalling, not general growth promotion.
Step 2: 1-MCP only blocks ethylene action, and Prohexadione-Ca actively retards growth.
Step 3: Melatonin acts as an antioxidant under stress and separately promotes germination, roots and flowering.
Step 4: Only melatonin fits both anti-stress and growth bio-stimulator roles, so it is the correct answer.