CSIRO Agriculture & Food, GPO Box 1700, Canberra, ACT, 2601, Australia
Australia's climate is characterised by high variability, both temporally and geographically. Climate change may be contributing to even greater variability, at least for temperature and rainfall which are the two weather variables of particular importance for wheat cropping. This paper describes ways that several plant traits are being harnessed to improve the adaptability of Australian wheats to climate variability and a changing climate: heat, cold, too little or too much water. Flowering is a critical phase in crop yield determination and a vital means of adapting wheat in Australia to cope with temperature and rainfall variability has been to exploit variation in time to flowering. Allelic variation for photoperiod and vernalisation genes is being used by plant breeders to deliver a range of wheat varieties that allow growers to target a critical 'flowering window' for their farm district. The aim: to minimise the risk from frost damage, if flowering occurs too early, or from drought and heat, if flowering occurs too late. Water use efficiency (WUE = kg grain per unit water used in evapotranspiration) is perceived to be another critical 'trait' for wheat adaptation. Changes in the way farmers manage the variable and changing rainfall resource are contributing to significant gains in WUE. There are also several approaches to breed for improved WUE but the value of these approaches depends on the frequency, timing and extent of water limitation to yield. Because Australia's cropping climate is so variable, researchers now have access to so-called 'managed environment facilities' that provide some control over the extent and timing of water deficits. These facilities are revealing the utility of a range of traits targeting improved WUE.