Germplasm Supply, Propagation and Nursery Management of Miombo Fruit Trees - Indigenous Fruit Trees in the Tropics: Domestication, Utilization and Commercialization - page 348

period once dispersed. In the miombo woodlands, U. kirkiana seeds normally
germinate as soon as the fruit ripens (Prins and Maghembe, 1994).
Uapaca kirkiana has desiccation-sensitive non-orthodox seeds, with a high
water content and active metabolism. Studies in Malawi (Ngulube and
Kananjii, 1989) also showed that the viability of U. kirkiana seeds carefully
stored in cold room conditions was lost within a month of collection. The
embryo would deteriorate quickly during storage because of the high water
content of the seed and its active metabolism, which encourages the internal
production of heat and the rapid growth of microorganisms, especially storage
fungi (Hans, 1981). During the short-term storage of non-orthodox seeds, the
proliferation of microorganisms must be curtailed to keep the seeds viable
(Sutherland et al. , 2002).
Many other miombo fruit tree species have orthodox seeds. Orthodox
seeds are seeds that can remain viable for long periods if processed and stored
in the appropriate manner; normally seed should have a low moisture content
and be kept at low temperature (Dawson and Were, 1997). For example,
Azanza garckeana , Flacourtia indica , Sclerocarya birrea and Parinari
curatellifolia have orthodox seeds, and their seed may store well for a year or
more (Teichman et al. , 1986; Msanga, 1998). In orthodox seeds, ageing (which
results in loss of viability) is a function of time, temperature and moisture
content; with a controlled storage environment seed survival can be prolonged.
A dry, cool environment normally lowers the risks of fungal proliferation and
infestation by seed pests that affect the viability of orthodox seeds.
Seeds of Strychnos cocculoides are intermediate between the orthodox and
recalcitrant types (Msanga, 1998). Mkonda et al. (2004) monitored the viability
of four S. cocculoides provenances from Zambia stored for 0-15 months at
room temperature and

4°C and found significant differences between
provenances and storage temperatures. The provenance Kalulushi had lower
viability under both storage conditions. When stored at room temperature, it lost
viability more quickly compared with the other provenances. Over 70% of the
seeds of Kasama and Serenje provenances remained viable for up to 15 months
when stored at 4°C, while their viability dropped dramatically within 9 months

of storage at room temperature (Mkonda et al. , 2003).

19.3.2 Seed pretreatment and germination

Seeds of some miombo fruit tree species germinate immediately, while others
require special seed pretreatment. For example, up to 80% germination can be
achieved by simply cleaning and soaking the seeds of Diospyros mespiliformis ,
Strychnos spinosa , Syzygium cordatum , Uapaca kirkiana , Ziziphus abyssinica
and Ziziphus mauritiana , while less than 20% germination could be achieved
with different pretreatments of seeds of Flacourtia indica and Parinari curatellifolia
(Prins and Maghembe, 1994). Nicking the seeds of Azanza garckeana to partially
remove the seed coat gave 100% germination (Maghembe, 1995). For Ziziphus
spp . , Tamarindus indica , Parkia filicoides and Bridelia cathartica , direct sowing of
seeds after removing pulp gave 93-100% germination (Maghembe, 1995). For