Rooting Acacia mangium cuttings of different physiological age with reference to leaf morphology as a phase change marker

Capacity for adventitious rooting of Acacia mangium was assessed for shoot terminal cuttings originating from: (A) the crown and (B) sprouting stumps of 4-year-old trees growing outdoors, (C) 4-year-old hedged stock plants and (D) 1-year-old seedlings kept cultivated in containers. All these cuttings exhibited the mature phyllode morphology. For the stump sprout origin, rootabilities of juvenile-like composed leaf (B1), intermediate leaf (B2) and mature-like phyllode (B3) cuttings were also compared. Rooting potential was found to be greatly influenced by the cutting source and to lesser extent, although still significantly, by the different types of cutting morphology. In both cases, the highest average rooting rate score of 85% was obtained for the mature-like phyllodes cuttings derived from mature sprouting stumps, whereas the same origin cuttings with juvenile-like leaves were less prone to root. Exogenous auxin treatment was shown to improve noticeably the number of roots formed per rooted cutting, but had overall no effect on rooting rate with marked differences depending on the date of the experiment. These results are discussed in terms of ageing influence on the potential for adventitious rooting of Acacia mangium cuttings, with reference to leaf morphology as a phase change marker.