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English: High oleic acid sunflower hybrids have been available on the market for a few years, but research on the stability of these genotypes for oil quality traits in South African production areas is limited. General aims of this study were to compare oil quality traits of high oleic sunflower against traditional sunflower genotypes in different environments, over seasons and under heat stress conditions and to identify possible genetic markers related to the oleic acid trait that would be useful in breeding programmes. Combined ANOVAs of oil, linoleic, oleic, palmitic and stearic acid content of 16 genotypes tested in a total of nine trials over eight locations and three seasons showed highly significant differences between genotype, environment and GXE. Significant GXE suggested differential response of genotypes across testing locations and years and the need for stability analyses. Stability analyses were performed for all oil traits using AMMI. Stability analyses indicated that high oleic genotypes 6 and 8 could be considered stable across environments and seasons for oil and oleic acid content and genotype 9 for palmitic and stearic acid content. Sunflower oil quality is affected by genotype and environmental conditions with temperature as a major influence. The effect of heat stress on seed yield and oil quality traits was investigated by applying a maximum temperature of 36ºC to plants during the critical seed-filling stage. This information was needed to define a breeding strategy to further improve seed oil quality in environments where heat stress may occur. All traits measured were significantly influenced by heat stress. The low heritability estimates observed for seed-related yield traits indicated that genetic improvement for these traits would be difficult. Oil and linoleic acid contents were significantly reduced by heat, while oleic acid content was significantly increased in traditional hybrids. The oleic acid content of the high oleic acid hyb, Afrikaans: Hoë-oleïensuur sonneblombasters is al vir ‘n geruime tyd kommersieel beskikbaar, maar byna geen navorsing is gedoen om die stabiliteit van hierdie genotipes ten opsigte van olie-kwaliteitseienskappe in Suid-Afrikaanse produksiegebiede te ondersoek nie. Die doel van hierdie studie was om die olie-kwaliteitseienskappe van Suid-Afrikaanse hoë- oleïensuur sonneblomgenotipes met dié van tradisionele sonneblomgenotipes te vergelyk en om die effek van verskillende omgewings, seisoene en temperatuurstoestande op hierdie genotipes te bepaal. ‘n Verdere doel was om moontlike molekulêre merkers, wat aan die hoë-oleïeneienskap gekoppel is en in teelprogramme gebruik kan word, te identifiseer. Die gekombineerde variansie-analises vir palmitiensuur, steariensuur, oleïensuur, linoliensuur en olie-inhoud het aangetoon dat vir ‘n totaal van 16 genotipes, wat in nege proewe in agt lokaliteite oor ‘n tydperk van drie jaar ontleed is, daar hoogs betekenisvolle verskille vir genotipe, omgewing en genotipe-omgewing interaksie was. Betekenisvolle genotipe-omgewing interaksie het aangetoon dat genotipes verskillend in verskillende omgewings en oor jare gereageer het en stabiliteitsontledings was dus nodig. Die stabiliteit van al die olie-eienskappe is deur middle van additiewe hoofeffek en multiplikatiewe en interaksie analise (AMMI) bepaal. Hierdie ontledings het aangetoon dat die hoë-oleïensuur genotipes 6 en 8 hoogs stabiel oor omgewings en seisoene was vir olie- en oleïensuurinhoud, terwyl genotipe 9 stabiel vir palmitiensuur- en steariensuurinhoud was. Sonneblomolie-kwaliteit word grootliks deur die omgewing beïnvloed en temperatuur speel die belangrikste rol. Die effek van hittestremming op saadopbrengs- en olie- kwaliteiteienskappe is bestudeer deur sonneblomplante aan ‘n maksimum temperatuur van 36ºC gedurende die mees kritieke stadium van lipiedbiosintese bloot te stel. Hittestremming het ‘n betekenisvolle invloed op al die eienskappe gehad. Lae oorerflikhede van saadop, National Research Foundation (NRF), Oilseeds Advisory Committee more...