Improving water stress tolerance of triticum aestivum by means of male sterility marker assisted recurrent selection
| dc.contributor.advisor | Botes, Willem | en_ZA |
| dc.contributor.advisor | Hess, Lezaan | en_ZA |
| dc.contributor.author | Khambule, Mhlengi Sboniso | en_ZA |
| dc.contributor.other | Stellenbosch University. Faculty of AgriSciences. Dept. of Genetics. | en_ZA |
| dc.date.accessioned | 2022-11-24T12:28:48Z | |
| dc.date.accessioned | 2023-01-16T12:44:15Z | |
| dc.date.available | 2022-11-24T12:28:48Z | |
| dc.date.available | 2023-01-16T12:44:15Z | |
| dc.date.issued | 2022-12 | |
| dc.description | Thesis (MScAgric)--Stellenbosch University, 2022. | en_ZA |
| dc.description.abstract | ENGLISH ABSTRACT: Wheat is the most widely grown cereal. More than 90% of the crop is grown for direct human consumption with increasing alternative potential for starch, glutens and biofuels. Wheat agronomic and genetic improvements will increasingly play key roles in meeting current and future food security needs and/or demands, particularly in the face of climate change. With the crop’s genetic complexity, the use and potential of molecular markers in the breeding process cannot be overlooked. The aim of this study was to select crossing parents for wheat vegetative water stress improvement under low water retention. The 4th Wheat Yield Consortium Yield Trial nursery (4-WYCYT) from CIMMYT was used as a prospective donor and evaluated for vegetative water stress tolerance at different vegetative growth stages before selection and crossing with an existing MS-MARS base population. The initial evaluation was undertaken in a growth chamber setting, selection trials were undertaken in in glasshouse conditions while crossing events used a combination of these environments. Seeds resulting from the crossing events were evaluated for early vegetative vigour under glasshouse conditions. Water retention and water availability regimes facilitated various stress combinations in both the evaluation and selection trials. Water availability was a strong factor under growth chamber (GC) conditions. Early vegetative water stress survival ranged from 16-30 plants and varying across the four retention regimes under growth chamber conditions. Survival was comparable under glasshouse conditions despite growth stage of water stress onset. Evaluated entry (EE) 005 (particularly accessions 005A and 005D) performed consistently in both growth chamber trials despite stage of stress onset, and when stress occurred during early vegetative stages despite growth environment. The said entry recorded the highest evaluated average entry yield for early vegetative stress (average of yield or total seed mass performance of available accessions for a given entry) although a single accession from EE - 006 recorded the highest individual yields (significant from two other accessions of the same genotype) when stress occurred during mid-vegetative growth under glasshouse (GH) conditions. All evaluated local checks (5 in GC and 10 in GH) performed significantly below the best performing accession and/or entry for yields in both the respective glasshouse trials, with an above average performance only when stress occurred later in the vegetative growth stages. Mid-vegetative stressed trials however recorded the least yields comparatively. The 4-WYCYT was however robust and displayed varying tolerances to water stress. This informed the selection of entries of this nursery which resulted to a male fertility segregating population produced through male sterility mediated introgression. Low retention evaluated F1 male fertile seedlings were taller on average compared to their infertile counterparts. Future studies should aim to improve wheat vegetative resilience and growth in varied and relevant water stress combinations. | en_ZA |
| dc.description.abstract | AFRIKAANSE OPSOMMING: Koring is die mees verboude graangewas. Meer as 90% van die gewas is vir direkte verbruik deur mense, maar daar is ‘n toenemende potensiaal vir gebruik as bron van stysel, glutenien en biobrandstof. Die verbouing van koring en die genetiese verbetering daarvan sal dus toemend ‘n belangrike rol speel ten einde huidige voedselsekerheidsbehoeftes en/of vraag in te voorsien. Veral gegewe klimaatsverandering. Met die genetiese kompleksiteit van die gewas in ag genome is die gebruik van molekulêre merkers in teling iets wat nie oor gesien kan word nie. Die doel van die studie was om kruisingsouers te selekteer vir die vegetatiewe verbetering van waterstres toleransie tydens lae water retensie. Die 4de Koring Opbrengs Konsortium Opbrengs Proef (in Engels 4th Wheat Yield Consortium Yield Trial nursery (4- WYCYT)) van CIMMYT is gebruik as moontlike donors en ge-evalueer by verskillende groeistadiums voor seleksie en kruising met die bestaande MS-MARS basispopulasie. Die aanvanklike evaluasie was in ‘n groeikabinet en opgevolg met seleksieproewe in ‘n glashuis. Saad vanuit die kruisings is ge-evalueer vir aanvanklike kiemkragtigheid tydens glashuisproewe. ‘n Aantal waterterughoudings en -beskikbaarheidskemas het verskeie stres kombinasies se toetsing help fasiliteer in beide die evaluasie asook die seleksie proewe. Water beskikbaarheid was ‘n belangrike faktor tydens groeikabinetkondisies gewees. Aanvanklike vegetatiewe groei tydens waterstres het gewissel en het verskil oor die vier terughoudingsvlakke tydens groeikabinet kondisies. Oorlewing was egter vergelykbaar onder glashuiskondisies ondanks waterstresperiodes se aanvang. Ge-evalueerde inskrywing EE-005 (veral EE-005A en EE-005D) het goed gevaar in beide groeikabinet eksperimente ondanks die begin van die stres en ook wanneer die stres plaasgevind het tydens aanvanklike vegetatiewe groei. Die betrokke inskrywings het die hoogste ge-evalueerde gemiddelde opbrengs gehad tydens aanvanklike vegetatiewe stress (gemiddeld van opbrengs of totale saadmassa van beskikbare inskrywings van ‘n betrokke inskrywing) alhoewel ‘n enkele inskrywing van EE–006 die hoogste individuele opbrengs gelewer het (betekenisvol van die twee ander inskrywings vanaf dieselfde genoptipe) wanneer stres toegepas is gedurende mid-vegetatiewe groei in die glashuis. Alle ge-evalueerde plaaslike kontroles (5 in GK en 10 in GH) het betekenisvol swakker gevaar as die beste inskrywings en/of inskrywing vir opbrengs in beide die glashuisproewe met bo-gemiddelde prestasie net wanneer die stres plaasgevind het later tydens vegetatiewe groei stadiums. Mid-vegetatiewe stresproewe het egter die laagste opbrengste aangeteken. Die 4-WYCYT was egter veerkragtig en het verskeie vlakke van toleransie teenoor waterstres getoon. Dit het die seleksie van inskrywings gerig in die kwekerye wat gelei het daartoe dat die segregerende manlikvrugbare populasie uitgebrei kon word. F1-manlikvrugbare inskrywings met lae terughoudings vlakke was oor die algemeen langer in vergelyking met vrugbare inskrywings. Toekomstige studies moet gemik wees daarop om koring se vegetatiewe veerkragtigheid en groei in ‘n reeks wisselende en toepaslike waterstres kombinasies te toets. | af_ZA |
| dc.description.version | Masters | en_ZA |
| dc.format.extent | x, 112 pages : illustrations (some color) | en_ZA |
| dc.identifier.uri | http://hdl.handle.net/10019.1/125983 | |
| dc.language.iso | en_ZA | en_ZA |
| dc.publisher | Stellenbosch : Stellenbosch University | en_ZA |
| dc.rights.holder | Stellenbosch University | en_ZA |
| dc.subject | Wheat (Triticum eastivum) -- Yields -- Effect of water levels on | en_ZA |
| dc.subject | Wheat -- Breeding -- Genetic engineering | en_ZA |
| dc.subject | Wheat -- Effect of drought on | en_ZA |
| dc.subject | Wheat -- Effect of stress on | en_ZA |
| dc.subject | Wheat -- Environmental aspects | en_ZA |
| dc.subject | UCTD | en_ZA |
| dc.title | Improving water stress tolerance of triticum aestivum by means of male sterility marker assisted recurrent selection | en_ZA |
| dc.type | Thesis | en_ZA |
Files
Original bundle
1 - 1 of 1
Loading...
- Name:
- khambule_water_2022.pdf
- Size:
- 3.46 MB
- Format:
- Adobe Portable Document Format
- Description: