Please use this identifier to cite or link to this item:
Scopus Web of Science® Altmetric
Full metadata record
DC FieldValueLanguage
dc.contributor.advisorCollins, Nicholas Charles-
dc.contributor.advisorMather, Diane Elizabeth-
dc.contributor.advisorParent, Boris-
dc.contributor.authorShirdelmoghanloo, Hamid-
dc.description.abstractHigh temperature is one of the major environmental constraints for wheat production globally. It puts significant pressure on the wheat industry around the world, compromising both the quantity and quality of wheat grain produced. The current study focussed on the impact of brief episodes of very high temperatures during vegetative and grain-filling stages of wheat development using a combined approach of plant physiology and quantitative trait loci (QTL) mapping. At grain-filling stage, wheat plants were exposed to a brief heat stress (3 days, 37/27 ºC) 10 days after anthesis and the plants evaluated for a number of morphological and physiological traits (Chapters 3, 4, and 6). At the vegetative stage (~ 4 weeks after sowing) plants were challenged with a brief heat treatment (2 days, 40/30 ºC), and growth and senescence related characters were monitored using automated imaging facilities and a SPAD chlorophyll meter (Chapter 7). In total, 37 bread wheat genotypes were evaluated for different heat responses during the grain-filling stage. Genetic variation was observed among wheat genotypes for various heat responses, particularly for single grain weight, chlorophyll retention, rate and duration of grain-filling, and water soluble carbohydrate content and mobilization (Chapters 3 and 4). Overall, the findings suggested that more than one adaptation process contributed to tolerance. Generally, genotypes with more stable grain weight under heat tended to have particular traits under stress, including the ability to maintain chlorophyll content and rate and duration of grain-filling, and stronger water soluble carbohydrate mobilization efficiency (Chapters 3 and 4). Therefore, these traits may provide appropriate selection criteria for improving heat tolerance in wheat. A genetic linkage map of a Drysdale/Waagan population was constructed using a 9K SNP array (Chapter 5) and used for QTL analysis (Chapter 6) of heat responses (evaluated using heat susceptibility index) at the grain-filling stage. A region on chromosome 3BS strongly affected heat responses of grain weight, stay-green related traits, grain-filling duration, shoot dry weight and harvest index, explaining 10 to 40% of the phenotypic variation, with Waagan contributing the tolerance allele. Most notably, the results indicated a strong genetic link between stay-green and grain weight maintenance under brief episodes of terminal high temperatures but a lack of a significant association between the Rht-B1 and Rht-D1 dwarfing loci and heat tolerance. Using high-throughput automated imaging facilities in The Plant Accelerator, considerable variation among 77 bread wheat genotypes was observed for growth rate and senescence responses to a brief heat stress at the vegetative stage (Chapter 7). A subset of 32 genotypes was also screened at the grain-filling stage (Chapter 3) which allowed a comparison of heat responses at these two developmental stages. Growth rate and senescence responses at the vegetative stage showed significant associations with grain weight maintenance and senescence responses at the grain-filling stage. These results suggested a physiological/genetic link between heat responses at the different growth stages, with implications for developing more efficient heat tolerance screening methods. The present work contributes to the understanding of physiological mechanisms of heat tolerance and its genetic basis in hexaploid wheat, and identifies assays with potential to assist heat tolerance studies and in breeding programs.en
dc.subjecttriticum aestivumen
dc.subjectheat toleranceen
dc.subjectquantitative trait locien
dc.subjectgrain fillingen
dc.subjectstay greenen
dc.titleGenetic and physiological studies of heat tolerance in hexaploid wheat (Triticum aestivum L.)en
dc.contributor.schoolSchool of Agriculture, Food and Wineen
dc.provenanceThis electronic version is made publicly available by the University of Adelaide in accordance with its open access policy for student theses. Copyright in this thesis remains with the author. This thesis may incorporate third party material which has been used by the author pursuant to Fair Dealing exceptions. If you are the owner of any included third party copyright material you wish to be removed from this electronic version, please complete the take down form located at:
dc.description.dissertationThesis (Ph.D.) -- University of Adelaide, School of Agriculture, Food and Wine, 2015.en
Appears in Collections:Research Theses

Files in This Item:
File Description SizeFormat 
01front.pdf425.25 kBAdobe PDFView/Open
02whole.pdf8 MBAdobe PDFView/Open
  Restricted Access
Library staff access only238.26 kBAdobe PDFView/Open
  Restricted Access
Library staff access only8.94 MBAdobe PDFView/Open

Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.