Ownclasses

Root development is promoted by

  • abscisic acid

  • auxin

  • gibberellin

  • ethylene

Answer

B.

auxin

The higher concentration of auxin causes inhibition of root elongation, but the number of lateral branches in the root is considerably increased. In plant tissue cultures, relatively amounts of auxin and cytokinin induce the development of root, shoot or undifferentiated mass of tissues. High auxin to cytokinin ratio favours the root development high cytokinin to auxin ratio favours shoot development, while intermediate concentration results in the formation of undifferentiated cell mass. 

The higher concentration of auxin causes inhibition of root elongation, but the number of lateral branches in the root is considerably increased. In plant tissue cultures, relatively amounts of auxin and cytokinin induce the development of root, shoot or undifferentiated mass of tissues. High auxin to cytokinin ratio favours the root development high cytokinin to auxin ratio favours shoot development, while intermediate concentration results in the formation of undifferentiated cell mass.