Grain dormancy in fixed lines of white-grained wheat (Triticum aestivum L.) grown under controlled environmental conditions
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Pre-harvest sprouting (PHS) in wheat (Triticum aestivum L.) can be a significant problem, causing deleterious effects on grain quality. However, the adverse impacts of PHS can be reduced by introgressing genes controlling grain dormancy into white-grained bread wheat. Screening for grain dormancy typically involves germination testing of harvest-ripe grain grown in a glasshouse or field. However, the more uniform environmental conditions provided by temperature controlled glasshouses (i.e. controlled environmental conditions—CEC) may provide significant benefits for the assessment of grain dormancy. In this study, the dormancy phenotype of grain grown under CEC incorporating an extended photoperiod, was compared with 2 years of data from field grown material. Four dormant double haploid lines (derived from SW95-50213 and AUS1408) and two locally adapted non-dormant cultivars EGA Gregory and EGA Wills were compared in three replicated experiments grown under CEC (22 ± 3°C and 24 h photoperiod). The germination response of harvest-ripe grain was examined to assess the expression of grain dormancy. Two measures of germination, the predicted time to 50% germination (G 50) and a weighted germination index, both clearly differentiated dormant and non-dormant lines grown under CEC. In addition, levels of grain dormancy were similar to field-grown plants. These results demonstrated that CEC with an extended photoperiod can be used for rapid and reliable characterisation of grain dormancy in fixed lines of bread wheat.
KeywordsControlled temperature glasshouse Extended photoperiod Germination index Germination response Phenotypic screen Pre-harvest sprouting Wheat breeding
This work was supported by the Grains Research and Development Corporation of Australia by providing an Undergraduate Honours Scholarship and was a collaborative project between the University of Queensland and the Queensland Department of Primary Industries and Fisheries. The authors also wish to acknowledge the valuable assistance of Associate Professor Stephen Adkins for use of his laboratory and equipment, Dr. Christopher Lambrides for detailed comments on early drafts of this manuscript, and support provided by the glasshouse managers at the St. Lucia campus of The University of Queensland.
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