Disclosed are compounds which are useful as the active ingredient of a cell differentiation promoter. As an example of said compounds, a compound, which is useful as the active ingredient of an adventitious root formation promoter capable of promoting rooting of a plant and improving the rooting rate thereof, can be cited. Also disclosed are a rooting method and a rooting medium, wherein an adventitious root formation promoter containing the aforesaid compound is used, for improving the productivity of clone seedlings by a cuttage method, a tissue culture method or the like.Specifically disclosed are a cell differentiation promoter which contains a compound represented by any of general formulae (1-1), (1-2), (1-3), (2-1) and (2-2) or a salt of the same, a plant shoot rooting medium which contains said cell differentiation promoter, and a method for producing clone seedlings which comprises using said cell differentiation promoter or said rooting medium.
