Nursery results on genetic variation, vegetative propagation and other growth factors of importance for domestication of Pterocarpus Angolensis DC.

Kasumu, Exildah Chibengele Chisha (1998-02)

Thesis (M. Sc.) -- University of Stellenbosch, 1998.

Thesis

ENGLISH SUMMARY: Pterocarpus angolensis is an important indigenous timber tree species occurring in warm and summer rainfall areas of southern and central Africa. It belongs to the family Fabaceae, a subfamily of Leguminosae. Phenotypically superior trees are exploited by subsistence and commercial timber using industries. Local people found in areas where P. angolensis grows, use it for medicinal and boat, mortar and pestle manufacture. Exploitation of the species is at a high rate, however, not much research on its silviculture, tree improvement and domestication has been done. Some problems associated with the species are: slow natural regeneration, difficulty in rooting cuttings and requirement of seed treatment prior to germinating it in order to break the dormancy. Four Provenances from Chimanimani (Zimbabwe), Masese, Mufumbwe and Solwezi (Zambia) and eleven families from Masese provenance were investigated for their existing variations in terms of seedling growth rates. The trials were conducted at the Faculty of Forestry nursery, University of Stellenbosch. The objectives were to study (i) the response of the four provenances to soil sterilisation and inoculation (ii) existing seedling growth variations (iii) the shooting and rooting ability of cuttings. There were significant differences in seed germination rates, mean seedling height, root collar diameter and total above and below ground biomass between provenances, families, soil sterilisation and inoculation treatments. Mufumbwe provenance had a significantly higher mean height from time of planting to 217 days of seedling growth. Chimanimani provenance had higher above and below ground biomass than other provenances but had the lowest seedling mean height. Seedling growth variations were observed in the eleven families from one provenance. Soil inoculation, unlike sterilisation, was found to be more beneficial to seedling growth. Almost all cuttings produced shoots easily but with no root development. Shoots were not maintained for a long period. Only diameter class 3 - 4.9 cm had surviving shoots by day 104 of the experiment. There is need to continue with research work on P. angolensis otherwise it is under extinction threat and industries relying on the species would suffer.

AFRIKAANSE OPSOMMING: Pterocarpus angolensis is 'n belangrike inheemse houtsoort wat in die warm en somer reenvalgebiede van suider- en sentraal Afrika voorkom. Dit behoort tot die familie Fabaceae, 'n sub-familie van Leguminosae. Fenotipies superieure borne word ontgin deur bestaans- en kommersiele houtgebruikersindustriee. Plaaslike inwoners in die gebiede waar P. angolensis groei gebruik dit vir medisinale, boot en stamper-en-vysel vervaardiging. Oorbenutting van die spesie vind teen 'n hoe tempo plaas, maar daar word nie baie navorsing in verband met die boskultuur, veredeling en domestikasie van die spesie gedoen me. Sommige van die probleme wat geassosieer word met die spesie is: stadige tempo van natuurlike regenerasie, probleme om steggies te laat wortel en die behandeling van saad voor ontkieming om dormansie te breek. Vier herkomste van Chimanimani (Zimbabwe), Masese, Mufumbwe en Solweni (Zambie) en elf families van die Masese herkoms is ondersoek vir bestaande variasies in terme van saailing groeitempos. Die eksperimente is uitgevoer in die kwekery van die Fakulteit van Bosbou van die Universiteit van Stellenboseh. Die doelstellings van die studie was om (i) die reaksie van vier herkomste op grondsterilisasie en -inokulasie, (ii) bestaande saailing groeivariasies en (iii) loot- en wortelvorming van steggies te bestudeer. Daar was beduidende verskille in saailing ontkiemingstempos, gemiddelde saailinghoogtes, wortelkraagdeursnee en totale bo- en ondergrond biomassas tussen herkomste, families, grondsterilisasie en -inokulasie behandelinge. Die gemiddelde hoogtes van die Mfumbwe herkoms was beduidend hoer vanaf die tyd van plant tot 217 dae van saailinggroei. Die Chimanimani herkoms het hoer bo- en ondergrond biomassa, maar het die laagste gemiddelde saailinghoogte. Variasies in groei is waargeneem in die elf families van een herkoms. Die inokulasie van die grond, anders as sterilisasie, was meer voordelig vir saailinggroei. Byna al die steggies het maklik lote geproduseer, maar daar was geen wortelontwikkeling. Die lote het nie lank oorleef nie. Slegs in die deursnee klas 3 - 4.9 em het lote teen dag 104 van die eksperiment nog oorleef. Dit is noodsaaklik dat navorsingswerk op P. angolensis voortgesit moet word, want dit word deur uitsterwing bedreig en die industriee wat daarop staatmaak sal dan swaarkry.

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