Accelerated Domestication and Commercialization of Indigenous Fruit and Nut Trees to Enhance Better Livelihoods in the Tropics: Lessons and Way Forward - Indigenous Fruit Trees in the Tropics: Domestication, Utilization and Commercialization - page 405

accumulation at the graft union line, leading to the possibility of early or late
rejection (Mn'gomba, 2007; Mn'gomba et al. , 2007a; Chapter 8, this volume).
Three types of assessing age need to be considered with regard to ease of
propagation and also juvenility or precocity (the period of waiting before the
first fruiting). These are chronological age (time since planting), physiological
age (cell differentiation stage and structural maturity, including level of
lignification), and ontogenetic age (state of reproductive maturity). The
implication is that if vegetative propagation is used, the appropriate location of
the propagule becomes important for trees aimed at fruit production.
Silviculturally, trees have different stages of growth: seedling , sapling , juvenile
and matured phases (Nyland, 1996). Collecting propagules for vegetative
propagation, whether roots, stem cuttings, scions for grafting or budding, will
depend on the age of the mother tree. The chronological age of a seedling
established from seed is different from a marcott collected and established from
the tree crown, i.e. branches of a mature tree. Chronologically, trees tend to be
older from the tree base and this declines with the height along the stem,
explaining why the number of rings declines along the standing height. On the
other hand, the ontological age is the reverse, being older at the crown than the
stem and youngest at the root. This is due to different stages of cell
differentiation. This is the basis for collecting scions from matured branches in
fruit trees. A tree of the seedless breadfruit ( Artocarpus altilis ) established in
southern Nigeria from a root cutting did not fruit until about 20 years later
(personal observation), whereas trees grafted from scions collected from
matured trees fruited in less than 4 years (D.O. Ladipo, unpublished data).
Farmers in south-west Nigeria use the rooting method of propagation for
Artocarpus altilis or A. communis , but the lengthy juvenile period before
fruiting can only ensure generational security, i.e. growing trees for future
generations. Lack of awareness was the major reason for the failure of farmers
to adopt efficient methods such as air-layering and grafting.
Across the regions covered in this topic, different propagation techniques
are employed. This includes asexual methods and vegetative propagation
(cuttings, grafting, air-layering, budding, etc.) techniques (Chapters 2, 6, 8 and
9). The tissue culture technique is now beginning to be used, and its
preliminary application to miombo fruit trees is highlighted in Chapter 8.
21.4 Management and Farmer Adoption of Domesticated Trees
21.4.1 Managing domesticated trees
Management of fruit trees is what makes them essentially different from those
growing in the wild. Much of the management of indigenous fruit trees has
been broadly based on experience from exotic tree crops, and there is a need
for adaptive research on IFT management. There has been some evidence that
good management can improve the fruit traits of planted indigenous fruit trees,
even for semi-domesticated trees (Maghembe, 1995; Shackleton, 2004; Leakey
et al. , 2005) but the extent of improvement in fruit traits due to management