[Truncated abstract] Wheat (Triticum aestivum L.) is the most important grain crop in Australia. Around 36% of its production comes from the Mediterranean-type environment of southwestern Australia. Climatic changes predicted for this region for the year 2050, such as increase in the average temperatures (up to 2.7°C), reduction in rainfall (at least 7%) and increase in carbon dioxide (CO2) concentration, threaten future wheat grain yields. The objectives of the studies reported in this thesis were to examine the impact of the above components of climate change on growth and grain yield of commercial cultivars and breeding lines of wheat with high-yielding traits. The study was conducted during three consecutive growing seasons (2010 to 2012) at The University of Western Australia’s, Shenton Park Field Research Station, and the crops were grown in tunnel houses that controlled atmospheric CO2 concentration, air temperature and watering regime in the field. The first experiment was conducted in 2010, where elevated CO2 (ECO2; 700 μL L 1) was combined with three levels of high temperature (HT; 2, 4 and 6°C above ambient temperature) and terminal drought. The hypothesis that ECO2 ameliorates the negative effects of terminal drought on biomass and grain yield was tested in a vigorous line 38- 19 and in a non-vigorous cultivar Janz, both with potential adaptation to climate change. Reductions of approximately 50% biomass and 45% in grain yield caused by terminal drought were less severe (37 and 41%, respectively) under the combination of ECO2, and temperature 2°C above ambient. This amelioration resulted from changes in the carbon source:sink relationship such as 63% increase in the rate of leaf net photosynthesis in the vigorous line 38-19 and 39% increase in tiller number and leaf area in the non-vigorous cultivar Janz. However, differences in the phenology between the two cultivars may also have influenced these responses and did not allow major comparison between vigorous and non-vigorous wheat...
|Qualification||Doctor of Philosophy|
|Publication status||Unpublished - 2014|