Floral evocation

Cytokinins are a class of phytohormones that are believed to regulate development at various times and places [6, 9, 17]. Specific aspects of development that are affected by cytokinins include shoot formation, release of axillary buds, partial floral evocation and inhibition of root elongation. However, there are some instances where cytokinins seemingly have little or no effect on these and other processes, thus producing puzzling discrepancies. These discrepancies are significant, because in order to understand how cytokinins function we need to know which processes are not effected by cytokinins as well as those that are effected. 

Quite generally, mitotic and DNA synthetic indices are far higher in shoot me-ristems during the floral transition than in both vegetative and reproductive meristems [5]. In several species this activation at floral evocation was shown to be due to the shortening of the cell cycle [1,8]. Another remarkable feature of the floral transition, caused by a transfer of plants from non-inductive to inductive daylength conditions, is the transient synchronization of the division cycle of part, at least, of the meristem cell population [1,5, 8]. 

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