Genotypic response of South African wheat cultivars to photoperiod, vernalization and adaptation

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Date
2004
Authors
Muller, Olaf
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University of the Free State
Abstract
English: The aim of this study was to determine the response of South African bread wheat cultivars to vernalisation and photoperiod and to group the genotypes accordingly. In addition to this the way in which the response of genotypes to vernalisation and photoperiod attributes to yield stability was also investigated. Thirty South African wheat cultivars were included in two separate trials to evaluate their response to vernalisation and photoperiod treatments. The wheat cultivars were selected to represent cultivars planted in all the main wheat production regions of South Africa. The range of genotypes included cultivars with no vernalisation requirement to cultivars with very strong vernalisation requirements. The vernalisation trial consisted of 30 South African wheat cultivars subjected to eight vernalisation treatments, ranging from zero to seven weeks vernalisation. Each treatment had eight replicates on which days to heading, flowering and physiological maturity were observed. Cluster analysis was done to group the cultivars into similarity groups. Four groups were identified: 1) True winter wheats encompassing: Molen, - - SST936, SST966, SST399, and 2) Winter wheats that included Betta-ON, Caledon, Elands, Hugenoot, PAN3235, SST367, and SST983, 3) Intermediate wheats consisting of Gariep, Limpopo, PAN3211, PAN3349, PAN3377, SST124, SST363, and Tugela-ON, and 4) Spring wheats including Baviaans, Inia, Kariega, Marico, Palmiet, Steenbras, SST57, SST65, SST88, SST822, and SST876. The photoperiod trial involved 30 South African wheat cultivars subjected to three photoperiod treatments (10, 14, and 18 hours day light). Ten replicates were included for each treatment. Days to heading, flowering and physiological maturity were recorded for all cultivars. Cluster analysis was performed and four discreet response classes identified. The classes were denominated as Group 1, Group 2, Group 3, and Group 4. Group 1 consisted of only one cultivar SST399. Group 2 included all the following true winter, winter, and intermediate wheat cultivars: Molen, Betta-DN, Caledon, Elands, Hugenoot, PAN3235, SST367, Limpopo, Gariep, PAN3211, PAN3349, PAN3377, SST124, SST363, and Tugela- ON. The only cultivars in Group 3 are the hybrid wheats: SST936, SST966, and SST983. Group 4 included all the spring wheat cultivars: Baviaans, Inia, Kariega, Marico, Palmiet, Steenbras, SST57, SST65, SST88, SST822, and SST876. Data obtained from the vernalisation and photoperiod trials were used in conjunctiqn with data from cultivar evaluation trials to determine the relationship between the response to vernalisation, photoperiod and yield stability. Yield data from the three main wheat production areas: Free State (14 sites), Irrigation areas (13 sites), and the Western Cape (12 sites) were used to calculate yield stability. Correlations between response to vernalisation, photoperiodic and yield stability were found to be weak, although stronger correlations were observed between vernalisation response and yield stability in the Western Free State, Central Free State, and warmer irrigation areas. The data from this study suggest that wheat should be classes as true· winter, winter, intermediate, and spring wheats, and that trial layouts should be planned according to these classes.
Afrikaans: Die doel van hierdie studie was om die reaksie van Suid-Afrikaanse broodkoring cultivars op vernalisasie en fotoperiode behandelings te bepaal en die cultivars dienooreenkomstig te klassifiseer. Aanvullend tot die klassifikasie van broodkoring cultivars is "n ondersoek geloods na die waarskynlikheid dat "n genotipe se reaksie op vernalisasie en fotoperiode bydrae tot opbrengsstabiliteit in broodkoring. Dertig Suid-Afrikaanse broodkoring cultivars is in twee afsonderlike proewe ingesluit om hierdie cultivars se reaksie op vernalisasie en fotoperiode behandelings te evalueer. Die cultivars is gekies op grond van verteenwoordiging van cultivars in die belangrikste verbouingsstreke van Suid Afrika, wat genotipes met geen, en sterk vernalisasiebehoeftes insluit. Die vernalisasie proef het bestaan uit 30 Suid Afrikaanse broodkoring cultivars wat onderhewig was aan agt vernalisasie behandelings wat gewissel het van geen vernalisasie tot sewe weke vernalisasie behandelings. Elke behandeling het agt herhalings gehad waarop dae tot aarverskyning, blom en fisiologiese volwassenheid aangeteken is. "n Trosanalise is uitgevoer om die cultivars in verwantskapsgroepe te klassifiseer. Vier groepe is uit hierdie analise geïdentifiseer naamlik: 1) Egte winter tipes, wat Molen, SST966, SST936, SST399 en insluit, 2) Winter tipes bestaande uit Betta-DN, Caledon, Elands, Hugenoot, PAN3235, SST367 en SST983, 3) Intermediêre tipes insluitend Gariep, Limpopo, PAN3211, PAN3349, PAN3377, SST124, SST363 en Tugela-DN en 4) Lente tipes insluitend Baviaans, Inia, Kariega, Marico, Palmiet, Steenbras, SST57, SST65, SST88, SST822 en SST876. Die fotoperiode proef het 30 Suid Afrikaanse broodkoring cultivars ingesluit wat aan drie fotoperiodiese behandelings (10, 14, en 18 ure dagliglengte) blootgestel is. Elke behandeling is tien maal herhaal en dae tot aarverskyning, blom en fisiologiese volwassenheid is aangeteken. 'n Trosanalise is uitgevoer om die cultivars op grond van hulle reaksie op fotoperiode in verwantskapskiasse te deel. Die analise het vier diskrete klasse geïdentifiseer wat Groep 1, Groep 2, Groep 3 en Groep 4 genoem is. Groep 1 bestaan slegs uit een cultivar, SST399, terwyl Groep 2 die volgende egte winter, winter en intermediêre cultivars insluit: Molen, Betta-DN, Caledon, Elands, Hugenoot, PAN3235, SST367, Limpopo, Gariep, PAN3211, PAN3349, PAN3377, SST124, SST363 en Tugela-DN. Groep 3 het al die basterkoring cultivars bevat, naamlik: SST936, SST966 en SST983. Groep 4 is opgemaak uit al die lente tipes: Baviaans, Inia, Kariega, Marico, Palmiet, Steenbras, SST57, SST65, SST88, SST822 en SST876. Data wat uit die vernalisasie en fotoperiode proewe verkry is, is in samehang met data uit die cultivar evaluasie proewe gebruik, om vas te stelof daar 'n verwantskap tussen vernalisasie, fotoperiode en opbregsstabiliteit is. Opbrengsdata van die belangrikste koringproduksiegebiede: Die Vrystaat (14 lokaliteite), Besproeiingsgebiede (13 lokaliteite) en die Weskaap (12 lokaliteite) is gebruik om opbrengsstabiliteit te bereken. Korrelasies tussen vernalisasie, fotoperiode en opbrengsstabiliteit was oor die algemeen swak, maar sterker korrelasies is wel tussen die reaksie op vernalisasie en opbrengsstabiliteit in die Wes Vrystaat, Sentraal Vrystaat en warmer besproeiingsgebiede gevind. Die data wat uit hierdie studie verkry is, dui aan dat broodkoring behoort as egte winter, winter, intermediêre en lente tipes geklassifiseer te word en dat proewe binne klasverband opgestel moet word.
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Vernalization, Wheat -- Breeding -- South Africa, Wheat -- Effect of temperature on, Dissertation (M.Sc.Agric. (Plant Science (Plant Breeding))--University of the Free State, 2004
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