1.0 SummaryThe research is conducted on Shorea macrophylla which will be treated with different concentrations of indolebutyric acid (IBA) which are 0% (control), 3.0%, 5.0% and 8.0% in Semenggoh plantation, Sarawak in 12 weeks using air layering propagation method. In the first part of the experiment, IBA hormone will be prepared from powder to liquid form as a stock solution. The stock solution is then diluted to the required concentrations. After preparing the IBA solution, the air layering method on Shorea macrophylla will be carried out according to the appropriate guidelines. The result will be analyzed based on the parameters of number of new roots, root length and time taken for roots to initiate growth using analysis of variance (ANOVA). The expected result will be that different concentrations have a different effect on the root growth of Shorea macrophylla.Keywords: IBA hormone, root growth, air layering method, Shorea macrophylla2.0 IntroductionShorea macrophylla (de Vr.) Ashton is a species endemic in Malaysia and northern Borneo. It has a vulnerable conservation status which constitutes an endangered species and is crucial for its conservation. Apart from this, Shorea macrophylla is a medium-sized terrestrial timber tree, well known for its oil-bearing fruits and one of the four known Red Meranti which contains large-sized 'illipe nuts'. From this specialty, Shorea macrophylla is subject to tropical forest domestication programs (Ting Sing Teck, 2002). Shorea macrophylla belongs to the order Malvales and family Dipterocarpaceae, has a tall white buttress and produces resin when the smooth bark is cut. It is usually found in lowlands, along well-watered rivers and in periodically flooded areas. Common names of Shorea macrophylla are kawang, e...... middle of paper ......um tissue carefully and leave the interior wood. Before using sphagnum moss, it should be soaked for several hours to ensure it is damp and squeezed to rinse out excess water. Excessive moisture will lead to root rot and deterioration of plant tissues. Firmly place a handful of sphagnum moss and completely cover the area of ​​injured branches. Then, use a clear polythene bag to cover the wound area and tie it with nylon string to hold it in position. This is also to prevent any form of moisture from entering and exiting the injured area. The experience lasts 12 weeks. Throughout the experiment, record the observation of root formation and growth for each treatment. At the end of the experiments, harvest the branches and be sure to cut 1 to 2 inches from the parts to be treated. Calculate the number and length of roots and save.