ABSTRACT
Historically, research into the biology of cytokinins (CK) has been closely associated with roots and root growth. In one of the earliest examples of hormone interactions in regulating plant differentiation and morphogenesis, Skoog (1994) reported a quantitative relationship between adenine and auxin in the formation of buds and roots. Later he found that CK were much more effective than adenine as potent inhibitors of root formation. Moreover, their “push-pull” relationships with auxin, which determine the degree to which shoots or roots differentiate from dividing callus, have been exploited as well-established procedures for routine manipulation of in vitro tissue culture systems (Krikorkian, 1995).
