Preharvest sprouting is a problem in many regions of the world, resulting in
downgrading of quality, substantial economic losses to wheat growers, and
difficulties for grain handling and marketing agencies. Improvements in
tolerance from the introduction of better grain dormancy at, or near,
harvest-ripeness would be expected to have a significant impact on the
incidence and severity of sprouting. Intermediate levels of dormancy in older
Australian wheats, such as Halberd, and a small number of current cultivars
could be used in the short term while more extreme dormancy is being
introgressed into locally adapted germplasm. A doubled haploid population
derived from Cranbrook (extremely non-dormant, very susceptible to sprouting)
x Halberd (intermediate dormancy, moderately tolerant to preharvest sprouting)
was grown in replicated experiments and ripe grain harvested for assessment of
dormancy, measured as a germination index. Consistent differences were
observed between the parents in both experiments. For the bulk of the progeny,
the germination index fell within a range defined by Cranbrook at the upper
and Halberd at the lower end. Significant quantitative trait loci, all
contributed by the very susceptible parent, that explained 11%,
9%, and 9% of the phenotypic variation were identified on
chromosome arms 2AL, 2DL, and 4AL, respectively. These QTLs offer the
opportunity to develop molecular markers for grain dormancy and to develop a
better understanding of the mechanisms involved in this trait.
Effects of long-term high-temperature stress on reproductive growth and seed development in development in Brassica napus
