QTL mapping of chromosomal regions conferring reproductive frost tolerance in barley ( Hordeum vulgare L.). 
Spring radiation frost is a major abiotic stress in southern Australia, reducing yield potential and grain quality of barley by damaging sensitive reproductive organs in the latter stages of development.  Field-based screening methods were developed, and genetic variation for reproductive frost tolerance was identified.  Mapping populations that were segregating for reproductive frost tolerance were screened and significant QTL identified.  QTL on chromosome 2HL were identified for frost-induced floret sterility in two different populations at the same genomic location.  This QTL was not associated with previously reported developmental or stress-response loci.  QTL on chromosome 5HL were identified for frost-induced floret sterility and frost-induced grain damage in all three of the populations studied.  The locations of QTL were coincident with previously reported vegetative frost tolerance loci close to the vrn- H1 locus.  This locus on chromosome 5HL has now been associated with response to cold stress at both vegetative and reproductive developmental stages in barley.  This study will allow reproductive frost tolerance to be seriously pursued as a breeding objective by facilitating a change from difficult phenotypic selection to high-throughput genotypic selection.