Question

Which one of the following conditions would, in general, be more conducive for the production of roots from callus tissue of plants under in vitro conditions?

• A. Higher cytokinin/auxin ratio
• B. Higher auxin/cytokinin ratio
• C. Lower auxin/cytokinin ratio
• D. Removal of both auxin and cytokinin from the medium

Hint:

• Auxin ↑ → Roots
• Cytokinin ↑ → Shoots
• Balanced → Callus

Answer 1

The Correct Option is B

Concept: In plant tissue culture, the ratio of plant growth regulators determines organ formation:
• High auxin : low cytokinin → Root formation
• High cytokinin : low auxin → Shoot formation
• Balanced ratio → Callus formation

Step 1: Understanding hormone effect.

• Auxins promote root initiation
• Cytokinins promote shoot development

Step 2: Analyzing options.

• Higher cytokinin/auxin: Favors shoots → Incorrect.
• Higher auxin/cytokinin: Favors roots → Correct.
• Lower auxin/cytokinin: Opposite condition → Incorrect.
• Removal of both: No differentiation → Incorrect.

Step 3: Selecting the correct answer.
Thus, root formation requires higher auxin to cytokinin ratio.