In tissue cultures roots can be induced by

The correct answer is Lower concentration of cytokinins and higher concentration of auxins

Concept:

• In plant tissue culture, the growth and differentiation of plant cells can be controlled by the use of plant growth regulators, primarily auxins and cytokinins.
• Auxins and cytokinins play crucial roles in the regulation of plant growth and development. Their relative concentrations determine the formation of roots, shoots, or callus.
• Auxins are primarily responsible for root induction, while cytokinins promote shoot formation.

Explanation:

• Only auxins and no cytokinins: While auxins are crucial for root induction, the complete absence of cytokinins may not be ideal for overall growth and differentiation. Cytokinins, even in low concentrations, can support better tissue development.
• Higher concentration of cytokinins and lower concentration of auxins: This combination is typically used for shoot induction rather than root formation. High cytokinins and low auxins promote shoot growth.
• Only cytokinins: Cytokinins alone are not effective for root induction. They are more associated with promoting cell division and shoot formation.
• Lower concentration of cytokinins and higher concentration of auxins: This is the correct combination for root induction in plant tissue culture. Higher levels of auxins promote root formation, while lower levels of cytokinins support this process.