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 402

In the last decade, researchers have been making considerable changes
in approach and there has been an impressive accumulation of data on
quantitative characterization involving more participatory domestication and
clonal selection (Leakey et al. , 2003, 2005; Akinnifesi et al. , 2006a; Tchoundjeu
et al. , 2006; Chapters 8, 9, 21, this volume). All the chapters in this topic have
showcased extensive quantitative data and field experiences in Asia, Africa,
Oceania and Latin America.
Leakey et al. (2004, 2005) examined tree-to-tree variation in trees that had
been semi-domesticated by farmers in order to explore the opportunities for
multi-trait selection. They found that when species have been subjected to
truncated selection and breeding, they may bear little resemblance to their wild
origins, while some of their wild relatives may have become extinct through
clearance and genetic pollution through outcrossing with farmer-selected
varieties. On the other hand, cultivated horticultural crops have been
domesticated for thousands of years. For instance, kiwi fruit ( Actinidia spp.),
which is one of the best-known commercial horticultural crops, has a history of
utilization and cultivation in China of more than 1000 years. However,
improvement work began only in the late 1970s (Xiao, 1999). It was then
disseminated to New Zealand, cultivated and selected by farmers (and later
scientists) until it became a major export crop yielding more than 1 million t per
year world-wide (Berry, 1997; Xiao, 1999). In contrast, the domestication of
indigenous fruit and nuts is more recent in the tropics (Leakey and Simons,
1998), probably beginning less than three decades ago. In the conventional
forestry approach, early stages of domestication of timber species involve
species elimination, performance trials, followed by provenance and progeny
selection involving the transfer of geographically discrete subpopulations to
new environments (Akinnifesi et al. , 2004a, 2006; Leakey et al. , 2004) which
are usually based on an environment similar to the natural range; known as the
'homocline' concept (Nyland, 1996). This requires a long regeneration period
and cycles of breeding. However, wild fruit tree domestication cannot depend
on such a unilinear domestication process and an innovative approach to
short-circuit the process is warranted that will combine diversification and
technology change. These aspects have been the focus of Chapters 2, 8 and 9.
Domestication aims at taking advantage of variation in the wild. In study of
tree-to-tree variation in Sclerocarya birrea in South Africa, Leakey et al. (2005)
reported from a sample of 15 trees that oil yield per nut ranged from 5 to 53 g
per nut and protein content in the fruit pulp ranged from 30 to 112 g per fruit.
Such variation is the major interest in domestication. It has long been
suggested that semi-domesticated trees have superior fruit characteristics than
those of wild origins (Maghembe, 1995; Leakey et al. , 2005; Akinnifesi et al. ,
2006). In an early species-screening trial at Makoka, Maghembe (1995) found
that the average fruit of Vangueria infausta was ten times bigger than those
found in the wild. In Peru, Weber et al. (2001) reported that farmers were able
to visually identify superior peach palm trees that have better products (e.g. red
fruits with waxy coats, which have a higher oil content than red or yellow fruits
without waxy coats). Farmers' knowledge was taken as a hypothesis, tested,
and proved to be correct (Weber et al. , 2001).