Genetic control of wood properties of Pinus patula in southern Africa
| dc.contributor.advisor | Fossey, A. | |
| dc.contributor.advisor | Grobler, J. P. | |
| dc.contributor.advisor | Kanzler, A. | |
| dc.contributor.author | Nel, André | |
| dc.date.accessioned | 2015-09-10T09:57:38Z | |
| dc.date.available | 2015-09-10T09:57:38Z | |
| dc.date.copyright | 2013 | |
| dc.date.issued | 2013 | |
| dc.date.submitted | 2013 | |
| dc.description.abstract | English: Pinus patula is the most widely planted softwood species in Southern Africa and is utilised for various solid wood and pulp and paper products. Tree improvement programmes for forestry species started in Southern Africa during the 1950’s, with an initial focus on volume improvements. The focus for many advanced tree improvement programmes has moved to the improvement of wood properties. This quantitative genetics study utilized half-rotation age P. patula progeny material from a 5 × 5 full diallel mating design and additional factorial crosses. A radial wood sample at 1.3 m above ground level from each of 300 trees was used to study a range of wood density, tracheid cross-sectional and -dimension characteristics. A large range of family variation was found for all wood properties. The combining ability analysis indicated that general combining ability was the most predominant effect and that specific combining ability effects were absent for nearly all the investigated wood density and tracheid traits. Reciprocal, maternal and non-maternal effects were also not significant for all but a few traits. Some of the wood properties were influenced by the specific site where trees were grown. Heritability estimates for many of the important wood density and tracheid traits were moderate to high, indicating strong additive genetic control of these properties. Wood density traits were under strong genetic control, with a pith-to-bark increase in wood density traits. Latewood proportion and earlywood density had a strong effect on weighted mean wood density. There were also strong positive correlations for density traits between growth rings, indicating that early selection would be possible. Tracheid cross-sectional properties were also strongly inherited, and strong correlations were found between the cross-sectional traits and calculated pulp and paper traits. Tracheid dimension traits such as tracheid length, width and cellwall thickness had lower heritability estimates than those found for wood density and tracheid cross-sectional traits. These were, however, of higher magnitude than growth trait heritabilities. Several strong positive and negative correlations were found between growth, wood density and tracheid property traits. These negative correlations would make multi-trait selections very problematic. Predicted gains for some of the studied wood properties were substantial, but correlated responses between primary and secondary selection traits were often negative. The structuring of genetic material into wood property specific sub-populations would ensure the improvement of selected important wood properties. These different properties can then be combined by means of controlled pollinations, and be deployed via vegetative propagation. This study has provided novel information on the genetic inheritance of physical wood properties of P. patula grown in Southern Africa, and will allow tree breeders to include some of these properties in breeding programmes. | en_ZA |
| dc.description.abstract | Afrikaans: Pinus patula is die mees aangeplante sagtehout spesie in Suider-Afrika en word vir verskeie soliede hout, pulp en papier produkte benut. Boomveredelingsprogramme vir bosbou spesies is in die 1950’s in Suider-Afrika begin met die fokus op verhoogde boomvolume. Vir baie van die gevorderde boomveredelingsprogramme het die toekomstige klem verskuif na die verbetering van houtkwaliteit-eienskappe. Hierdie kwantitatiewe genetika studie het van half-rotasie ouderdom P. patula nageslagsmateriaal, afkomstig van ‘n 5 × 5 volle dialleel ontwerp, asook bykomende faktoriale kruisings gebruik gemaak. Die studie het ‘n pit- tot- bas radiale houtmonster, wat geneem is op ‘n hoogte van 1.3 m van grondvlak af, benut om houtdigtheid en trageïed eienskappe te ondersoek. Al die houtkwaliteite wat ondersoek is het ‘n groot hoeveelheid familie-variasie getoon. Verdere ondersoek het aangetoon dat algemene kombineervermoë betekenisvol was vir die oorgrote meerderheid houtdigtheid- en trageïed-eienskappe. Spesifieke kombineervermoë was nie ‘n betekenisvol faktor vir die meeste eienskappe gewees nie. Resiproke, moederlike en nie-moederlike effekte was ook in die meeste gevalle nie betekenisvol gewees nie, behalwe vir enkele houteienskappe. Die spesifieke groeiplek het ‘n betekenisvolle effek op sekere van die houteienskappe gehad. Heelwat van die belangrike houtdigtheid- en trageïed-eienskappe het gemiddeld tot hoë oorerflikheidswaardes in hierdie studie getoon. Hierdie hoë waardes en die algemene kombineervermoë was ‘n aanduiding dat die eienskappe deur sterk additiewe geen-aksie beheer word. Die studie het ook bevind dat houtdigtheid, met ‘n pit- tot- bas verhoging in digtheidswaarde, onder ‘n hoë vlak van additiewe genetiese beheer was. Najaarshout-persentasie en voorjaarshout-digtheid het die grootste bydra tot beswaarde gemiddelde houtdigtheid gemaak. Daar was ook 216 hoogs betekenisvolle positiewe korrelasies tussen houtdigtheidswaardes vir die verskillende jaarringe, wat aandui dat vroeë seleksie moontlik is. Die studie het ook bevind dat trageïed dwars-snit eienskappe onder ‘n hoë vlak van additiewe genetiese beheer was, met hoogs betekenisvolle positiewe korrelasies tussen sekere van hierdie eienskappe en berekende pulp en papier eienskappe. Trageïed-afmetingseienskappe, insluitend trageïed lengte, breedte en selwanddikte was onder ‘n laer vlak van additiewe genetiese beheer as houtdigtheid- en trageïeddwars-snit eienskappe, maar was steeds hoër as boomgroei-eienskappe. Die studie het bevind dat daar verskeie sterk positiewe en negatiewe korrelasies tussen boomgroei-, houtdigtheid-, trageïed dwars-snit- en afmetings-eienskappe was. Hierdie negatiewe korrelasies tussen eienskappe gaan die keuse vir meervoudige eienskappe bemoeilik. Voorspelde teelwinste vir sekere van die houteienskappe was aansienlik hoog, maar korrelasies tussen die primêre en sekondêre eienskappe was in baie gevalle negatief. Dit het tot gevolg dat genetiese teelmateriaal in sub-populasies met spesifieke houteienskappe verdeel sal moet word, om verbetering van die belankrikste gekose eienskappe te verseker. Verskillende houteienskappe kan dan gekombineer word deur kruisbestuiwings uit te voer en plantmateriaal vegetatief voort te plant. Hierdie studie het nuwe inligting verskaf oor die genetiese oorerflikheid van fisiese houteienskappe van P. patula wat in Suider Afrika verbou is, en sal boom-telers in staat stel of van die belangrike eienskappe in te sluit in boomveredelingsprogramme. | af |
| dc.description.sponsorship | South African Pulp and Paper Industries (Sappi) | en_ZA |
| dc.identifier.uri | http://hdl.handle.net/11660/1218 | |
| dc.language.iso | en | en_ZA |
| dc.publisher | University of the Free State | en_ZA |
| dc.rights.holder | University of the Free State | en_ZA |
| dc.subject | Correlations | en_ZA |
| dc.subject | Heritability | en_ZA |
| dc.subject | General and specific combining ability | en_ZA |
| dc.subject | Tracheid properties | en_ZA |
| dc.subject | Wood density | en_ZA |
| dc.subject | Physical wood properties | en_ZA |
| dc.subject | Pinus patula | en_ZA |
| dc.subject | Pine -- Genetic engineering -- South Africa | en_ZA |
| dc.subject | Conifers -- Genetic engineering -- South Africa | en_ZA |
| dc.subject | Thesis (Ph.D. (Genetics))--University of the Free State, 2013 | en_ZA |
| dc.title | Genetic control of wood properties of Pinus patula in southern Africa | en_ZA |
| dc.type | Thesis | en_ZA |