EFFECT OF INDOLE BUTYRIC-ACID (IBA) ON STEM CUTTINGS OF SHOREA-LEPROSULA

The application of auxin (indole butyric acid, IBA) significantly incr eased the rate of root emergence in single node leafy stem cuttings of Shorea leprosula taken from 10-month-old potted seedlings. A range of IBA doses (0, 20, 40, 60 and 80 mug IBA per cutting) were tested and 20 mug per cutting was found to be the best with 70% of cuttings roote d within 12 weeks. Higher doses resulted in less rooting success. IBA application also enhanced the number of roots developed on each cuttin g. The mean accumulated number of roots per rooted cutting in Week 10 on cuttings treated with 20, 40, 60, and 80 mug IBA was 5.05, 5.26, 4. 82 and 4.80 respectively compared with 3.11 for cuttings treated with only a 50% ethanol and water mixture.