Abstract:Cuttings of Coleus scutellarioides were separately exposed to red light (660 nm) and far-red light (780 nm) in order to examine root initiation and level of endogenous ABA in the cutting with immuno-assay. The results showed that red light but not far-red light could promote root initiatian from the cuttings. Level of endogenous ABA in whole and especially in the lower half of the cutting under red light was lower than that under far-red light. This change and redistribution of endogenous ABA may be related to root initiation. The effect of red light on promoting root initiation was confirmed by root/ shoot ratio enhancement of cucumber seedling exposed to red light.