INDOLE-3-BUTYRIC ACID (IBA) AND LEAF TRIMMING REGULATE THE ADVENTITIOUS ROOT FORMATION OF STEM CUTTINGS DERIVED FROM MATURE AQUILARIA CUMINGIANA

Aquilaria is known to produce agarwood, but its natural population is declining. Apart from being recalcitrant, not all Aquilaria trees are agarwood producers, hence yield is not guaranteed in plantations established from seedlings originated from seeds. Since cloning can produce progenies with similar genetic quality as parent trees, this study evaluated the effect of various leaf trimmings, indole-3-butyric acid (IBA) doses, and their interaction in rooting induction of cuttings from mature Aquilaria cumingiana. Analysis of variance revealed a significant (p < 0.001) increase in most of the rooting parameters with increasing leaf surface areas (except on shoot length) and IBA concentrations (aside from shoot length, percentage of survival and percentage of callus). Interaction between IBA (1000 ppm) and cuttings, with half of the leaf surface trimmed, detected the highest rooting percentage (46.67 %, p < 0.001), number of roots (1.16, p < 0.05), average root length (14.05 mm, p < 0.001), number of secondary roots (3.49, p < 0.001) and length of the longest roots (18.56 mm, p < 0.001). Correlations among root traits (r² = 0.11–0.95), between rooting trait and cutting size (r² =-0.09–0.09), and among cutting sizes (r² = 0.69–0.96) were found to be highly significant (p < 0.001). The results showed potential to produce high agarwood yielding A. cumingiana using low-cost cloning technique.