Factors affecting the rooting ability of Dryobalanops oblongifolia and Shorea splendida (dipterocarpaceae) stem cuttings

Dipterocarp propagation research to date has mainly focused on vegetative (asexual) methods. Studies on several important timber species have shown that unique propagation conditions are needed for each species. Two species, Dryobalanops oblongifolia ("kapur paya") and Shorea splendida ("engkabang bintang"), were chosen for this study because they have potential economic and ecological importance, and their propagation conditions have not hitherto been analysed. Two important parameters for rooting success of dipterocarp stem cuttings are propagation medium and exogenous application of auxins. This study tested the effects of four propagation media, three indole butyric acid (IBA) treatments, and two Benlate treatments on rooting and mortality of D. oblongifolia and S. splendida leafy stem cuttings. Cuttings of S. splendida had a significantly higher rooting percentage than those of D. oblongifolia (p < 0.001), but also showed a higher overall mortality. This could be due to a higher metabolic rate in the former species. No significant differences were observed among the medium and auxin treatments, suggesting that other parameters (e.g. condition of stock plant individuals) could be more important for the rooting of these species. The Benlate significantly lowered the initial rate of mortality for S. splendida, with the 0.10% solution showing reduced mortality (at week 12) over the 0.05% solution and the control (p < 0.05). By week 16 however, the total mortality rates were the same. Periodically repeated applications of fungicide could reduce overall mortality rates of S. splendida cuttings.