Domestication of Irvingia gabonensis (Aubry Lecomte) by air layering

Abstract

Irvingia gabonensis is one of the most important indigenous fruit tree species in African humid tropics. Methods have been developed for phenotypic selection and vegetative propagation of this species; but techniques for the capture of desired traits through inexpensive technological methods are still lacking. A series of experiments were conducted to assess the effects of auxin (Seradix-2) application (treated and untreated marcotts), branch diameter (2-3cm, and 4 - 5 cm), and position in the crown (lower, middle and upper) on the rooting of marcotts on one hand; and the combined effect of branch length and diameter (50 cm length, 2 - 3 cm diameter), (50 cm length, 4 - 5 cm diameter), (100 cm length, 2 - 3 cm diameter), (100 cm length, 4 - 5 cm diameter), (150 cm length, 2 - 3 cm diameter), (150 cm length, 4 - 5 cm diameter) on the survival of rooted marcotts on other hand. After 12 months, the proportion of rooted marcotts was significantly higher (P < 0.05) for untreated (50 ± 7.3%), than for treated marcotts (31 ± 6.7%). Marcotts of 3 - 5 cm diameter rooted significantly better (46.9 ± 5.1%) than those of 2 - 3 cm of diameter (32.1 ± 5.2%). Branch position in the crown did not affect rooting ability of marcotts. After 8 weeks, the highest survival rate of weaned marcotts (40%) was observed for those with 100 cm length and 2 - 3 cm diameter while the highest mortality rate was obtained for those with 150 cm length and 4 - 5 cm of diameter (90%). It can be therefore concluded from this study that I. gabonensis is amenable to air-layering but further studies are needed to improve the survival rate during the weaning period. Key words: Irvingia gabonensis, domestication, marcotting, rooting ability, auxin, branch diameter, length and position