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 s hoot terminal cuttings originating from: (A) the crown and (B) sprouti ng stumps of 4-year-old trees growing outdoors, (C) 4-year-old hedged stock plants and (D) 1-year-old seedlings kept cultivated in container s. All these cuttings exhibited the mature phyllode morphology. For th e stump sprout origin, rootabilities of juvenile-like composed leaf (B 1), intermediate leaf (B2) and mature-like phyllode (B3) cuttings were also compared. Rooting potential was found to be greatly influenced b y the cutting source and to lesser extent, although still significantl y, by the different types of cutting morphology. In both cases, the hi ghest average rooting rate score of 85% was obtained for the mature-li ke phyllodes cuttings derived from mature sprouting stumps, whereas th e same origin cuttings with juvenile-like leaves were less prone to ro ot. Exogenous auxin treatment was shown to improve noticeably the numb er of roots formed per rooted cutting, but had overall no effect on ro oting rate with marked differences depending on the date of the experi ment. These results are discussed in terms of ageing influence on the potential for adventitious rooting of Acacia mangium cuttings, with re ference to leaf morphology as a phase change marker.