Genotype x environment interaction for Sunflower Hybrids in South Africa

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dc.contributor.advisor Geerthsen, Peter J.M. en
dc.contributor.advisor Roux, Carl Z. en
dc.contributor.postgraduate Leeuwner, Danie Verster en
dc.date.accessioned 2013-09-06T14:28:52Z
dc.date.available 2006-03-10 en
dc.date.available 2013-09-06T14:28:52Z
dc.date.created 2004-11-19 en
dc.date.issued 2007-03-10 en
dc.date.submitted 2006-03-10 en
dc.description Dissertation (MSc (Genetics))--University of Pretoria, 2007. en
dc.description.abstract When testing nine different sunflower cultivars in 32 South African environments (location x year), an Additive Main Effects and Multiplicative Interaction analysis (AMMI) identified sizeable genotype by environment (GxE) interaction. The first two Interaction Principal Components Axes (IPCA1 and IPCA2) were highly significant (p<0.001), but all the factors responsible for the GxE interaction could not be identified, as the causes of interaction seems to be of complex nature. IPCA1 captured 34% of the interaction SS with only 15.3% of the degrees of freedom, while IPCA2 captured 22.5% of the interaction SS with 14.5% of the degrees of freedom. This indicates that the AMMI2 model fits the data well and is parsimonious. Both cultivars and environments grouped together in quadrants according to their length of season when their respective IPCA1 and IPCA2 scores were plotted against each other. Environments from the warmer dry Western and Northern regions, including the Dry Highveld Grassland, Northern Arid and Central Bushveld, grouped in opposite quadrants, 1 and 3, while environments from the cooler moist Eastern regions, including the Moist Highveld Grassland grouped in opposite quadrants, 2 and 4. The factors responsible for the division between quadrants 1 and 3, as well as those responsible for the division between quadrants 2 and 4 could not be identified. The long-season cultivars were better adapted to the Northern and Western environments, while the medium-season cultivars were better adapted to the Eastern environments. Each quadrant was dominated by a different cultivar. Because the environments and cultivars could not be sufficiently described according to the factors responsible for the observed GxE interaction, cultivars can not be advised for specific environments. It is therefore presently recommended that cultivars which are more widely adapted to South African conditions, be selected. en
dc.description.availability unrestricted en
dc.description.department Genetics en
dc.identifier.citation Leeuwner, D 2004, Genotype x environment interaction for Sunflower Hybrids in South Africa, MSc dissertation, University of Pretoria, Pretoria, viewed yymmdd < http://hdl.handle.net/2263/23082 > en
dc.identifier.upetdurl http://upetd.up.ac.za/thesis/available/etd-03102006-142125/ en
dc.identifier.uri http://hdl.handle.net/2263/23082
dc.language.iso en
dc.publisher University of Pretoria en_ZA
dc.rights © 2004, University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. en
dc.subject Gxe interaction en
dc.subject Interaction en
dc.subject Sunflower en
dc.subject UCTD en_US
dc.title Genotype x environment interaction for Sunflower Hybrids in South Africa en
dc.type Dissertation en


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