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dc.contributor.advisorLabuschagne, M. T.
dc.contributor.advisorVan Biljon, A.
dc.contributor.authorLindeque, Robert Crowther
dc.date.accessioned2016-11-24T09:20:46Z
dc.date.available2016-11-24T09:20:46Z
dc.date.issued2016
dc.identifier.urihttp://hdl.handle.net/11660/4799
dc.description.abstractEnglish: In field crops the measurement of any yield or quality parameter by a single factor that is inherently sensitive to the environment, may skew the result and have no application. Two classical examples exist in the wheat industry where firstly, grain yield alone does not fully reflect and determine the on-farm profitability of a wheat variety. The parameters that are part of the grading scale (hectolitre mass, grain protein content and falling number) together with grain yield and price per ton form the components responsible for the ultimate farm gate price. Secondly, grain protein content is mostly inadequate for explaining flour quality of wheat which is critical for determining sustainability of the milling and baking industry. Protein quality, referring to the concentrations and ratios of glutenin, gliadin and albumin protein fractions are proving to be more important than protein quantity. Wheat varieties from the irrigation region in the medium and low ranking group were a clear example thereof as these genotypes obtained Grade 2 (< 12% grain protein content) and Grade 3 (< 11% grain protein content) but produced loaf volumes well within the allowed 10% variation from the loaf volume of the quality standard. In irrigated wheat and rainfed wheat of the summer rainfall region and winter rainfall region, E had the largest impact on flour protein and grain protein content. E contributed most to the variation of soluble glutenin in total protein for irrigation whereas G x E interaction resulted in the highest variation for rainfed SRR and WRR. Soluble α/β, γ gliadin in total protein were primarily affected by E for irrigation and G for both rainfed in the SRR and in the WRR. E contributed most to the variation in soluble albumin/globulin in total protein for irrigation, rainfed SRR and rainfed WRR wheat. For the insoluble fractions, E largely determined the variations of insoluble glutenin in total protein for irrigation, rainfed SRR and rainfed WRR. Insoluble α/β, γ gliadin in total protein were primarily determined by E in irrigation and rainfed SRR whereas G determined variation in the rainfed WRR. Insoluble albumin/globulin in total protein were primarily determined by the E of irrigation and rainfed WRR whereas G x E determined variation in the rainfed SRR region. Glutenin concentrations were highest in wheat from the rainfed WRR, α/β, γ gliadin in rainfed SRR wheat and albumin/globulin in irrigated wheat. No clear and repeating trends regarding the concentrations and ratios of protein fractions could be established with correlations in any of the three production regions, which underlines the enormous role of the environment on protein quality. For example, large insoluble glutenin in total protein of irrigated and rainfed SRR wheat only correlated strongly and positively with high flour protein, whereas in rainfed wheat of the WRR large insoluble glutenin in total protein correlated positively and strongly with high flour protein, high grain protein and high loaf volume. The examples become more extreme with insoluble small glutenin proteins of irrigated wheat correlating strongly and positively with low loaf volume, whereas in rainfed SRR small soluble and insoluble glutenin correlated negatively with low loaf volume. In rainfed wheat from the WRR, small insoluble glutenin in total protein correlated negatively with high grain protein, but positively with low loaf volume. The climatic environment of the three production regions differs significantly in regard to annual rainfall and seasonal temperatures which wheat producers cannot control. Management of the environment by wheat farmers should focus on the production environment through selection of adapted wheat varieties, soil moisture conservation and optimal fertilising practises. These factors determine grain yield but also determine the protein composition that eventually affects wheat flour quality.en_ZA
dc.description.abstractAfrikaans: Die akkurate meting van opbrengs of kwaliteit in gewasproduksie deur ‘n enkel parameter wat gevoelig is vir omgewingstoestande, kan ‘n verwronge beeld skep en eindelik die resultate ontoepaslik maak. Twee baie duidelike voorbeelde hiervan bestaan in die koringbedryf waar eerstens, die plaashek winsgewendheid van ‘n koringkultivar nie alleenlik deur graanopbrengs bepaal word nie. Graderingskriteria soos hektolitermassa, proteïeninhoud en valgetal bepaal saam met graanopbrengs en die heersende koringprys die finale prys. Tweedens, blyk proteïeninhoud onakkuraat te wees om die meelkwaliteit van koring, noodsaaklik vir die voortbestaan van die bak en maalbedryf, te omskryf. Proteïenkwaliteit, verwys na die konsentrasie en verhoudings van glutenien, gliadien en albumien/globulien, lyk belangriker te wees as die hoeveelheid proteïen. ‘n Sprekende voorbeeld hiervan is die koringkultivars uit die besproeiingsgebied in die medium en lae proteïeninhoud groepe wat ten spyte van ‘n Graad 2 (< 12% graanproteïen) en Graad 3 (< 11% graanproteïen) broodvolumes geproduseer het wat gemaklik binne die 10% variasie van die kwaliteitstandaard se broodvolume val. Die omgewing (E) het die grootste invloed gehad op die variasie in graanproteïen en meelproteïen van besproeiingskoring en droëlandkoring uit die somerreënval en winterreënvalgebiede. Omgewing het ook die meeste bygedra tot die variasie in oplosbare glutenien in totale proteïen vir besproeiingskoring terwyl die omgewing en genotipe interaksie (G x E) die mees prominente faktor was wat variasie van droëlandkoring in die somerreënval en winterreënvalgebiede bepaal het. Variasie in die oplosbare α/β, γ gliadien in totale proteïen in besproeiingskoring is primêr deur E bepaal terwyl genotipe (G) die primêre faktor was wat variasie in droëlandkoring van die somerreënval en winterreënvalgebiede bepaal het. E was ook primêr verantwoordelik vir die variasie in oplosbare albumien/globulien in totale proteïen van koring afkomstig uit die besproeiingsgebiede en droëlandkoring van die somerreënval en winterreënvalgebiede. Vir die onoplosbare fraksies was E weereens verantwoordelik vir die variasie van onoplosbare glutenien in totale proteïen van koring uit al drie die produksiegebiede. Variasie in die onoplosbare α/β, γ gliadien in totale proteïen van besproeiingskoring en droëlandkoring uit die somerreënvalgebied is hoofsaaklik deur E bepaal terwyl G die variasie in droëlandkoring van die winterreënvalgebied bepaal. Variasie in die onoplosbare albumien/globulien in totale proteïen van besproeiingskoring en droëlandkoring uit die winterreënvalgebied is primêr deur E bepaal terwyl G x E hoofsaaklik verantwoordelik was variasie in droëlandkoring van die somerreënvalgebied. Die glutenien konsentrasies was die hoogste in droëlandkoring uit die winterreënvalgebied, α/β, γ gliadien die hoogste in droëlandkoring van die somerreënvalgebied en albumien/globulien die hoogste in besproeiingskoring. Geen duidelike of herhalende tendense in die konsentrasies en verhoudings van die proteïenfraksies in koring uit enige van die drie produksiegebiede is deur korrelasies uitgewys nie, wat die groot invloed van omgewing op proteïenkwaliteit beklemtoon. ‘n Voorbeeld hiervan is dat die groot onoplosbare glutenien in totale proteïen van besproeiingskoring en droëlandkoring uit die somerreënvalgebied slegs positief met hoë meelproteïen gekorreleer het terwyl groot onoplosbare glutenien in totale proteïen van droëlandkoring uit die winterreënvalgebied positief met hoë meelproteïen, hoë graanproteïen en hoë bakvolume gekorreleer het. ‘n Ander voorbeeld van uiterstes is die sterk en positiewe korrelasie van klein onoplosbare glutenien van besproeiingskoring met lae broodvolume terwyl droëlandkoring uit die somerreënvalgebied negatief met lae broodvolume korreleer. Klein onoplosbare glutenien in totale proteïen van droëlandkoring uit die winterreënvalgebied het weer negatief met hoë graanproteïen gekorreleer maar positief met lae broodvolume. Die klimaatsomgewing van die drie produksiestreke verskil drasties van mekaar in terme van jaarlikse reënval en temperature waaraan ‘n koringprodusent niks kan doen nie. Bestuur van die omgewing berus dus grootliks op die produksie-omgewing wat ‘n koringboer kan manipuleer deur keuse van kultivars wat goed aangepas is, vogbewaring en optimale bemestingtoediening. Hierdie faktore bepaal nie alleen net graanopbrengs nie maar ook die samestelling van proteïen wat noodsaaklik is vir goeie meelkwaliteit.af
dc.language.isoenen_ZA
dc.publisherUniversity of the Free Stateen_ZA
dc.subjectThesis (Ph.D. (Plant Sciences (Plant Breeding))--University of Free State, 2016en_ZA
dc.subjectWheaten_ZA
dc.subjectGrain -- Qualityen_ZA
dc.titleProtein quality vs. quantity in South African commercial bread wheat cultivarsen_ZA
dc.typeThesisen_ZA
dc.rights.holderUniversity of the Free Stateen_ZA


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