Germplasm Supply, Propagation and Nursery Management of Miombo Fruit Trees - Indigenous Fruit Trees in the Tropics: Domestication, Utilization and Commercialization - page 346

a way that ensures genetic quality; the efficient establishment, management of
nurseries; tree establishment and management on the farm; harvest and
postharvest handling activities; and the marketing of germplasm and tree
products.
In Malawi the majority of nurseries were of the group type (86%). This makes
it easy to train farmers in groups, and farmer training in nursery management has
been ongoing for the last 10 years. Nearly 13,000 farmers have been trained in
tree propagation, nursery establishment and management, and farm manage-
ment. Indigenous fruit tree seedlings have been disseminated to farmers in
Malawi, Zambia, Zimbabwe and Tanzania since the late 1990s. Farmer-to-farmer
exchange and farmer training have been important methods of training larger
numbers of farmers in nursery establishment and tree management. Special
emphasis has been given in each community to the training of a few people in
grafting techniques, as this is central to the domestication programme. These
trainees can then offer services to other farmers and farmer groups, as well as
manage their own commercial nurseries.
19.2.3 Germplasm conservation
For most of the species collected, live gene banks have been established, which
have conservation value as well as a utilization purpose. These are typically set
up as provenance trials, progeny trials and orchards to allow the determination
of genetic parameters.
For the conservation of genetic resources of indigenous fruits, seed must be
collected from 25 unrelated individuals, corresponding to an effective
population size of 100 (Kwesiga et al. , 2000; Eyog-Matig et al. , 2001). The
effective population size is the number of individuals in an ideal population in
which each individual has an equal number of expected progeny (assuming
random gamete distribution). The factors that determine the effective
population size include differences in fertility between individuals, non-random
mating, unequal numbers of male and female individuals in dioecious species,
such as Uapaca kirkiana and Sclerocarya birrea , and fluctuations in population
size from generation to generation (Falconer, 1989).
The traditional approach to tree improvement involves a number of
sequential steps: species selection trials; provenance trials to identify the best
sources of a species; progeny tests to identify the best mother trees to establish
seedlings and clonal orchards; and the production of high-quality germplasm
for dissemination to users (Weber et al. , 2001; Akinnifesi et al. , 2004; Leakey
and Akinnifesi, Chapter 2, this volume). This process is time-consuming and
expensive to undertake for indigenous fruit trees species, and there is a danger
that the genetic diversity may be compromised (Weber et al. , 2001). Recently,
participatory collections of germplasm (seed and scion) based on multitrait
selection were done for Uapaca kirkiana and Strychnos cocculoides in Malawi,
Tanzania, Zambia and Zimbabwe (Akinnifesi et al. , 2006). In addition,
information was collected on the ecology, soil, and geographical location and
fruit traits of the selected trees and stored. The Malawi collections involved 102