In vivo grafting and in vitro micrografting of Acacia mangium: impact of ortet age

The possibilities of vegetatively propagating juvenile - 6-month-old and mature - 3 to 5 year-old - #Acacia mangium# ortets by grafting were investigated using in vivo and in vitro techniques. The average success rates obtained for in vivo topcleft grafting were 49% for scions coming from juvenile plant material and 0% when collected from mature ortets. In vitro micrografted apices gave rise to 52% and 46% of successfully established micrografts for the juvenile and the mature plant material respectively. No significant difference between juvenile and mature origins in terms of grafting success was observed for in vitro micrografting of shoot apices. However, the ones coming from the juvenile ortets elongated more readily than those from the mature origin which were more prone to rest. Overall, the in vitro micrografting technique used appeared to be an helpful tool for vegetative non-destructive propagation of mature selected Acacia mangium ortets, apparently recalcitrant to more conventional in vivo grafting techniques. These results are discussed in terms of scion size and the related potential for grafting in relation to the age ofthe ortet. (Résumé d'auteur