Germplasm Supply, Propagation and Nursery Management of Miombo Fruit Trees - Indigenous Fruit Trees in the Tropics: Domestication, Utilization and Commercialization - page 355

nutrients, minerals and carbohydrates through the intact xylem and phloem to
the rooting area.
Air-layering has been found to be feasible for many of the miombo
indigenous fruit tree species, especially Uapaca kirkiana , in which a success rate
of about 63% was obtained (Mhango and Akinnifesi, 2001; Akinnifesi et al .,
2006). The best time to set Uapaca kirkiana marcotts is between August and
October. Our results with Uapaca kirkiana showed that no root-initiation
hormone was required for rooting. However, the survival of established marcotts
may pose a minor challenge, as mortality increases with time in the first 6-12
months in some cases (Akinnifesi et al. , 2006). Where field survival is good,
trees established from air-layers were more vigorous than grafted trees, and
produced more fruits starting after 24 months in Makoka, Malawi. Similar results
were obtained in the humid zones of Cameroon (Tchoundjeu et al ., 2006).
19.4.4 Propagation by cuttings
The use of cuttings is the simplest and probably the most important form of
vegetative propagation in the developing world. For species that can be
propagated by cutting, it has numerous advantages (Hartmann et al. , 1997).
The success of cuttings depends on their ability to produce adventitious roots
that can be easily acclimatized to the environment after rooting. The
advantages of cuttings include the following: (i) the method is inexpensive,
rapid and simple compared with other vegetative propagation methods; (ii)
many new plants can be established in a limited space from a few stock plants;
(iii) no special skills are required, unlike in grafting, budding, air-layering and
micropropagation; (iv) the problem of incompatibility due to poor union of
stock and scion in grafted plants is avoided; and (v) the plants produced are
more uniform because the variation imposed by the stock in grafting is
avoided. Stem, leaf or root cuttings can be used. Stem cuttings are classified
according to the nature of the wood, i.e. the degree of lignification: hardwood,
semi-hardwood, soft wood or herbaceous.
Rooting of juvenile stem cuttings seems to be more successful than mature
cuttings for most miombo indigenous fruit tree species. Rooting success of
cuttings of up to 60% has been observed in Parinari curatellifolia (R. Swai,
personal communication). Few of the miombo woodland indigenous fruit trees
have been tested with leaf cuttings under macropropagation.
Azanza garckeana and Vitex mombassae respond favourably to
propagation by root cuttings. In Botswana, attempts at propagating Sclerocarya
birrea by cuttings have not succeeded either in the open or under 50% shade
netting (Taylor et al. , 1996). Although cuttings in the propagation box
responded favourably in terms of vegetative growth within 3 weeks, no roots
were observed after 3 months in the box, and rooting hormone (Seradix No. 2)
did not seem to induce rooting (Taylor et al. , 1996).
Likewise, cuttings of Strychnos cocculoides sprouted within 3 weeks under
50% shade, but no root development was observed (Taylor et al. , 1996). For
Sclerocarya birrea , the use of truncheons (hardwood cuttings) has been found to