Agriculture Reference
In-Depth Information
operators and the inadequacy of extension services to facilitate the acquisition
of such skills.
Research into the propagation of indigenous fruit trees through seeds and
vegetative material has been investigated for the past decade in southern Africa
(Maghembe, 1995; Mhango and Akinnifesi, 2001). Some advances have been
made in the nursery management of selected miombo fruit trees. Significant
progress has been made in the establishment of fruit tree nurseries (Akinnifesi
et al. , 2004, 2006, Chaper 8, this volume). Since the early 1990s, ICRAF has
been promoting decentralized germplasm production and distribution systems
at the grass roots level, where support to farmer nurseries is emerging as one of
the main pathways (Böhringer et al. , 2003).
In this chapter we review the state of knowledge about germplasm delivery
and the propagation and nursery management of miombo fruit trees in Africa.
The chapter will be limited to examples relevant to small-farm agroforestry
systems in southern Africa as opposed to highly intensive monocultural orchard
production systems. We discuss the factors involved in determining the most
appropriate methods of propagation for particular species, and the associated
constraints and limitations in scaling up the domestication of indigenous fruit
trees in southern Africa.
19.2 Germplasm Delivery and Conservation
Germplasm may be defined as genetic material, which can be seed, pollen,
vegetative propagules or other material, though it is normally thought of as seed
(Dawson and Were, 1997). The supply of germplasm in sufficient quantities and
quality at the small-scale user's level is one of the factors that limit agroforestry
development (Simons, 1996). While the trend in the past has been to put more
emphasis on central supply systems such as national tree seed centres and
government nurseries, policies are now being adopted to encourage the
decentralized supply of seeds, seedlings and vegetative propagules. Germplasm
quality has a direct impact on tree survival, growth and production. Tree
germplasm quality has physical, genetic and physiological components
(Mulawarman et al. , 2003). Valuable tree genetic resources are declining around
farming communities in southern Africa, especially in Malawi, where annual
deforestation is very high (1%), therefore limiting options for livelihoods and
economic development. The ICRAF Medium Term Plan 1998-2000 states that
domestication is not about breeding per se and that many advances are made
through studies of indigenous knowledge, the dynamics of germplasm utilization
on farms, nursery techniques, genetic selection, pomology, marketing and
processing (ICRAF, 1997, p. 26). Through an understanding of both supply of
and demand for superior germplasm of priority species, it is possible to increase
the rate of adoption of agroforestry technologies. To promote the adoption of
quality germplasm, information has to be disseminated along with the materials.
Propagation by seed (sexual propagation) is often the easiest, cheapest and
most common means for most agroforestry trees, and is generally considered the
default approach (Mudge and Brennan, 1999). On the other hand, vegetative
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