Creating Opportunities for Domesticating and Commercializing Miombo Indigenous Fruit Trees in Southern Africa - Indigenous Fruit Trees in the Tropics: Domestication, Utilization and Commercialization - page 153

In Zimbabwe, using PRA approaches, 416 participants (farmers, fruit
vendors and schoolchildren, 65% of them female) identified 108 superior trees of
Uapaca kirkiana in seven districts across the country. In addition, 200 participants
(50% women) from four districts identified 34 superior phenotypes of Strychnos
cocculoides . Total soluble sugar from Strychnos cocculoides trees ranged from 7
to 23% and fruit size ranged from 75 to 514 g. ICR04MapanzureZW8 had the
biggest fruits (514 g) and ICR04MafungautsiZW17 had the highest total soluble
sugar (23%). The variability of fruit characteristics was clearly illustrated in
Zimbabwe; trees with very contrasting fruits were identified as ICR02Chimani
ZW9, ICR02UrandaZW29 and ICR02MafaZW40. ICR02MafaZW40 had the
highest pulp content and greatest fruit weight, but a low sugar content. In
contrast, ICR02UrandaZW29 had small fruits that were very sweet and had high
pulp content (Akinnifesi et al ., 2006). On the other hand, although
ICR02ChimaniZW9 had large fruits, it was rejected in the selection process as it
had low pulp content, high relative shell weight and low sugar content. It also
had the highest seed weight. A consequence of domestication and cultivar
development is that trees propagated clonally from mature tissues will flower and
fruit earlier. They will therefore be smaller in stature and produce fewer fruits,
especially in the climate of miombo woodlands. To compensate for this, trees can
be grown at higher density. In our experience, marcots are bigger than grafted
trees, and trees established from seedlings tend to be taller but with a smaller
crown size compared with marcots. However, trees established from seedlings
have a longer juvenile phase than trees established from either grafted or
marcottage stocks. In high-rainfall areas of West Africa, marcots have been shown
to be bigger than plants established from seedlings (Z. Tchoundjeu, personal
communication).
However, it is important to recognize that, as in Uapaca kirkiana in
Zambia, some fruit traits, including tree fruit load and pulp content per fruit,
can be manipulated to a limited extent by management practices such as
thinning (Mwamba, 1995b). The challenge is not only of practical improvement
per se, but also of reconciling the potential genetic improvement with the
practical realities of farmers' needs and perceptions and the delivery of
germplasms (Simons, 1996), considering also intellectual property right (IPR)
environments.
Clonal propagation
Seedling propagation is not a desired approach for commercial fruit production
because of the high variability of progenies from mother trees; asexual means are
therefore preferred. Both macropropagation (conventional vegetative propagation)
and micropropagation ( in vitro culture) techniques have been applied to some
priority miombo indigenous fruits in southern Africa. Vegetative propagation is
needed to rapidly test, select from, multiply and use the large genetic diversity in
wild tree species on stations and farms. From our experience, some of the miombo
fruit trees are not amenable to propagation by juvenile stem cuttings; examples are
Uapaca kirkiana , Parinari curatellifolia and Sclerocarya birrea .