Reproductive biology and utilisation of Berchemia discolor (Klotzsch) Hemsley (Rhamnaceae)

[摘要] ENGLISH SUMMARY: Berchemia discolor is an indigenous African fruit tree species with potential in terms ofcommercialisation and domestication. Indigenous fruit tree species play a role in the socioeconomicwell being of small-scale farmers and rural communities. To facilitate the processof domestication and commercialisation of B. discolor, it is important to learn more about thebiology of the species, nutritional value of the fruit, and if potential markets exist for the fruit.Fieldwork was carried out in Caprivi and Omusati in northern Namibia in order to study thereproductive phenology and the floral and pollination biology of the species. Analysis of thenutritional value of the fruit was carried out on the dry fruit pulp to assess the nutrients,minerals and vitamins contained in the fruit. In addition to this a socio-economic survey wascarried out to assess the current trade in fruit and the utilisation of the tree and its products.The length of the reproductive phase during the 1996-97 season extended from mid Octoberto end of March in Caprivi and from beginning of November to early April in Omusati.Vegetative growth and flower bud formation in Omusati occurred just after the onset of thefirst rain whereas in Caprivi it occurred two weeks prior to the onset of the rain.The flowers of B. discolor are dichogamous and protandrous. Pollinators are probablyattracted to the flowers by olfactory stimuli, however visual stimuli also play a role as theflowers are greenish-yellowish in colour and several flowers are borne together in theinflorescence. Insect visitors to the flowers were identified as belonging to four differentorders (Hymenoptera, Diptera, Coleoptera and Heterophera). Three of these orders havegenera which may represent potential pollinators of B. discolor. Stigma receptivity probablyoccurred only after the elongation of the pistil subsequent to the presentation of pollen.The dry fruit pulp of B. ·discolor is rich in carbohydrates, calcium, sodium, iron, magnesiumand potassium, but it is not a good source of phosphorus, fat, protein and ascorbic acid. Thefruit trade is important for generating income, which is used to acquire other goods andservices by the rural people. B. discolor could, subject to improvements on fruit quality andmarketing become one of the commercial fruit in northern Namibia.

[发布机构] Stellenbosch University