The effects of indole -3- butyric acid( IBA) rooting hormone on the rooting of campor( ocotea usambarensis) coppice stem cutting

Abstract

Ocotea usambarensis Engl. is a high value timber tree that is threatened in Kenya due to overexploitation and poor natural regeneration. It seeds once in eight to ten years but most of its fruits are lost pre-maturely due to pest attack. In addition its seeds are recalcitrant. Alternative methods of propagation should be developed to complement the few seed available. A rooting trial was set up to determine the ability of Indole-3-butyric acid (IBA) to promote rooting in O. usambarensis coppice stem cuttings. The experiment was laid out in a complete randomised design and cuttings treated with IBA at 0, 60, 90 and 120mg/l concentrations. Each IBA concentration was replicated 3 times and each replicate had 10 cuttings. The experiment was incubated in a non-mist propagator with vermiculite as the rooting medium. Assessment for rooting was done on 84th, 104th and 136th day. Data on rooting, number of roots and the length of the longest root and sprouting was collected and analysis done using Genstat. The highest rooting was 43.5% at 60 mg/l IBA and the least 6.7% in both 90 and 120 mg/l concentrations. However, the difference was not significant (p=0.264). The number of roots and length of the longest root were not significantly influenced by IBA treatment. However, the proportion of cutting that sprouted, the number and growth of sprouts were significantly decreased with increase in IBA concentration. The lack of significant positive increase in the rooting with IBA treatment suggests that O. usambarensis may have a relatively high level of endogenous auxins.