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Estimation of genetic parameters and correlations for growth, rooting and frost tolerance in Eucalyptus grandis x Eucalyptus nitens hybrids
Brink, W. A. 2023. Estimation of genetic parameters and correlations for growth, rooting and frost tolerance in Eucalyptus Grandis x Eucalyptus Nitens hybrids. Unpublished masters thesis. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/0864975d-594a-4e1e-86...
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| Language: | English |
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Stellenbosch : Stellenbosch University
2023
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| access_status_str | Open Access |
| author | Brink, Willie Andries |
| author2 | Du Toit, Ben |
| author_browse | Brink, Willie Andries Du Toit, Ben |
| author_facet | Du Toit, Ben Brink, Willie Andries |
| author_sort | Brink, Willie Andries |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Brink, W. A. 2023. Estimation of genetic parameters and correlations for growth, rooting and frost tolerance in Eucalyptus Grandis x Eucalyptus Nitens hybrids. Unpublished masters thesis. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/0864975d-594a-4e1e-86db-3d640282d144 |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/129439 |
| institution | Stellenbosch University (South Africa) |
| language | English |
| last_indexed | 2026-06-10T12:40:57.522Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2023 |
| publishDateRange | 2023 |
| publishDateSort | 2023 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/129439 Estimation of genetic parameters and correlations for growth, rooting and frost tolerance in Eucalyptus grandis x Eucalyptus nitens hybrids Brink, Willie Andries Du Toit, Ben Van den Berg, Gert Nel, Andre Stellenbosch University. Faculty of AgriSciences. Dept. of Forest and Wood Science. Eucalyptus -- Breeding -- South Africa Forest genetics -- South Africa Forest microclimatology -- South Africa Renewable natural resources -- South Africa UCTD Brink, W. A. 2023. Estimation of genetic parameters and correlations for growth, rooting and frost tolerance in Eucalyptus Grandis x Eucalyptus Nitens hybrids. Unpublished masters thesis. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/0864975d-594a-4e1e-86db-3d640282d144 Thesis (MSc)--Stellenbosch University, 2023. ENGLISH ABSTRACT: Rapid growth, frost tolerance and good rooting are key requirements for the commercial clonal deployment of Eucalyptus on colder temperate sites in South Africa’s summer rainfall forestry area. Hybridising Eucalyptus grandis with Eucalyptus nitens produces progeny which may contain the combined favourable traits of both parents. Eucalyptus grandis exhibits good growth, stem form, wood properties and rooting ability in vegetative propagation. Eucalyptus nitens displays superior cold tolerance, including superior frost and snow tolerance, as well as high wood density. Eucalyptus hybrids developed specifically for improved cold tolerance tend to produce fewer viable hybrid progeny and are more recalcitrant rooters when compared to their sub-tropical counterparts. To overcome these challenges a novel testing strategy was developed and used to identify promising varieties for commercial deployment. As a result, a large population of Eucalyptus grandis x nitens hybrids was developed through controlled pollinations, propagated via mini-cuttings and established in field trials to investigate growth and adaptability. Rooting records, growth measurements and in-field frost screening data were analysed to determine genetic parameters and correlations between traits. Combined-site broad sense heritability for DBH, height and volume were 0.39, 0.46 and 0.35, respectively, indicating a moderate level of genetic control. This, in conjunction with large genetic coefficients of variation (CVg = 20%, 16% and 41% for DBH, height and volume respectively) shows that substantial gains can be made through selection. As expected, strong correlations between DBH and Height existed (RG)= 0.98). Combined-site Type B genetic correlations for DBH, height and volume were 0.71, 0.68 and 0.65, respectively, indicating notable genotype by environment interaction. Pairwise comparisons of rBg for volume showed large variation in the correlations of clonal rankings between trials, with rBg ranging from 0.00 to 0.90. Based on the results obtained in this study, higher genotype by environment interaction for the growth in the top half of the population indicates that the current strategy of selecting ‘generalists’ for the entire cool temperate region may need to be revised. It suggests that hybrid seedling selection blocks would reduce the number of poor varieties included in later trials and re-emphasizes the importance of clone by site interaction trials in determining niche requirements of specific clones. Broad sense heritability for rooting was 0.21, indicating that rooting in this population was under moderate levels of genetic control. Based on the results obtained in this study, optimization of nursery rooting protocols, as well as selection for at least a minimum level of clonal rooting, is recommended in Eucalyptus grandis x nitens. Combined-site broad sense heritability for frost tolerance was calculated to be 0.20. Type-B genetic correlations were relatively low (rB = 0.59) indicating that the there were notable rank changes for common clones over the annual frost screenings. Frost rankings have been generated enabling breeders to select clones with frost tolerance from this population. No significant correlation between rooting success, volume and frost tolerance was found, indicating no direct compromise required when selecting for all three traits. AFRIKAANSE OPSOMMING: Vinnige groeitempo’s, ryp weerstandigheid en maklike beworteling van steggies is sleutelvereistes vir die kommersiële klonale ontplooiing van Eucalyptus op kouer gematigde groeiplekke in Suid-Afrika se somerreënval bosbougebied. Die verbastering van Eucalyptus grandis met Eucalyptus nitens produseer ʼn nageslag wat die gekombineerde gunstige eienskappe van beide ouers kan bevat. Eucalyptus grandis vertoon goeie groei, stamvorm, hout eienskappe en goeie bewortelingsvermoë in vegetatiewe voortplanting. Eucalyptus nitens vertoon uitstekende koueverdraagsaamheid, insluitend uitstekende ryp- en sneeu weerstandigheid, sowel as hoë houtdigtheid. Bloekom basters wat spesifiek ontwikkel is vir verbeterde koueverdraagsaamheid is geneig om ʼn minder lewensvatbare hibriede nageslag te produseer en vertoon swak beworteling van steggies in vergelyking met hul subtropiese eweknieë. Om hierdie uitdagings te oorkom, is 'n nuwe toetsstrategie ontwikkel en gebruik om belowende variëteite vir kommersiële ontplooiing te identifiseer. Gevolglik is 'n groot populasie van Eucalyptus grandis x nitens basters ontwikkel deur beheerde bestuiwing, gepropageer via mini-steggies en gevestig in veldproewe om groei en aanpasbaarheid te ondersoek. Bewortelingsrekords, groeimetings en siftingsdata vir rypbestandheid in veld eksperimente is ontleed om genetiese parameters en korrelasies tussen eienskappe te bepaal. Die oorerflikheidsindeks (in die breë konteks, gekombineer oor alle groeiplekke) vir DBH, hoogte en volume was onderskeidelik 0.39, 0.46 en 0.35, wat 'n matige vlak van genetiese beheer aandui. Dit, in samehang met groot genetiese variasiekoëffisiënte (CVg = 20%, 16% en 41% vir DBH, hoogte en volume onderskeidelik) toon dat aansienlike vordering deur seleksie gemaak kan word. Soos verwag, het sterk korrelasies tussen DBH en hoogte bestaan (RG = 0.98). Gekombineerde-groeiplek Tipe B genetiese korrelasies (rBg) vir DBH, hoogte en volume was onderskeidelik 0.71, 0.68 en 0.65, wat noemenswaardige genotipe x omgewingsinteraksie aandui. Gepaarde vergelykings van rBg vir volume het groot variasie in die korrelasies van klonale rangorde tussen proewe getoon, met rBg wat gewissel het van 0.00 tot 0.90. Gebaseer op die resultate wat in hierdie studie verkry is, dui hoër genotipe x omgewingsinteraksie vir die groei in die boonste helfte van die bevolking aan dat die huidige strategie om basters wat aangepas is by “gemiddelde kondisies” vir die hele koel gematigde streek te selekteer dalk hersien moet word. Dit dui daarop dat bastersaailing seleksieblokke die aantal swak variëteite wat in latere proewe ingesluit is, sal verminder en beklemtoon weer die belangrikheid van kloon x groeiplek interaksie proewe in die bepaling van nisvereistes van spesifieke klone. Breë sin oorerflikheid vir beworteling was 0.21, wat aandui dat steggie beworteling in hierdie populasie onder matige vlakke van genetiese beheer was. Gebaseer op die resultate wat in hierdie studie verkry is, word optimering van kwekery bewortelingsvoorskrifte, sowel as seleksie vir ten minste 'n minimum vlak van klonale beworteling, aanbeveel in Eucalyptus grandis x nitens. Die oorerflikheidsindeks (in die breë sin, gekombineer oor groeiplekke) vir ryp weerstandigheid is bereken as 0.20. Tipe-B genetiese korrelasies was relatief laag (rB = 0.59) wat aandui dat daar noemenswaardige rangveranderings vir gewone klone oor die jaarlikse ryp siftings datastelle was. Ryp weerstandigheid rangordes is opgestel, wat telers in staat stel om klone met groter ryp weerstandigheid uit hierdie populasie te selekteer. Geen betekenisvolle korrelasie tussen suksesvolle beworteling van steggies, volume groei en ryp weerstandigheid is gevind nie, wat aandui dat geen direkte kompromie nodig is wanneer vir al drie eienskappe geselekteer word nie. Masters 2023-11-28T16:17:00Z 2024-02-20T11:40:12Z 2023-11-28T16:17:00Z 2024-02-20T11:40:12Z 2023-11 Thesis https://scholar.sun.ac.za/handle/10019.1/129439 en Stellenbosch University 93 pages : illustrations application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Eucalyptus -- Breeding -- South Africa Forest genetics -- South Africa Forest microclimatology -- South Africa Renewable natural resources -- South Africa UCTD Brink, Willie Andries Estimation of genetic parameters and correlations for growth, rooting and frost tolerance in Eucalyptus grandis x Eucalyptus nitens hybrids |
| title | Estimation of genetic parameters and correlations for growth, rooting and frost tolerance in Eucalyptus grandis x Eucalyptus nitens hybrids |
| title_full | Estimation of genetic parameters and correlations for growth, rooting and frost tolerance in Eucalyptus grandis x Eucalyptus nitens hybrids |
| title_fullStr | Estimation of genetic parameters and correlations for growth, rooting and frost tolerance in Eucalyptus grandis x Eucalyptus nitens hybrids |
| title_full_unstemmed | Estimation of genetic parameters and correlations for growth, rooting and frost tolerance in Eucalyptus grandis x Eucalyptus nitens hybrids |
| title_short | Estimation of genetic parameters and correlations for growth, rooting and frost tolerance in Eucalyptus grandis x Eucalyptus nitens hybrids |
| title_sort | estimation of genetic parameters and correlations for growth rooting and frost tolerance in eucalyptus grandis x eucalyptus nitens hybrids |
| topic | Eucalyptus -- Breeding -- South Africa Forest genetics -- South Africa Forest microclimatology -- South Africa Renewable natural resources -- South Africa UCTD |
| url | https://scholar.sun.ac.za/handle/10019.1/129439 |
| work_keys_str_mv | AT brinkwillieandries estimationofgeneticparametersandcorrelationsforgrowthrootingandfrosttoleranceineucalyptusgrandisxeucalyptusnitenshybrids |