Improving productivity of Australian wheat by adapting sowing date and genotype phenology to future climate

With global food demand predicted to grow by 50-80% by 2050, timely strategies are required to best adapt to the projected changes in agriculture. In this study, we illustrated how adaptation strategies not requiring additional inputs (sowing date and genotype choice) could be used to minimise the impact of projected stresses and raise wheat productivity in Australia. Yield and abiotic stresses impacting productivity of wheat crops were quantified in silico for the 1990s (1976-2005) and the 2050s (2036-2065) across the Australian wheatbelt using a modified version of the Agricultural Production Systems sIMulator (APSIM) and 33 Global Circulation Models (GCMs) under the Representative Concentration Pathways (RCP) 8.5. Two adaptation strategies were assessed: adaptation of sowing dates and/or adaptation of cultivars of contrasting phenology (i.e. fast-spring, mid-spring, slow-spring and fast-winter cultivars). For a given cultivar, optimum sowing windows associated with highest long-term yield were projected to shift to earlier dates by 2050 at most locations, with an average shift of 9.6 days for a mid-spring cultivar. Sowing early maturing cultivars enabled further increase in projected yield in major parts of the wheatbelt. In the tested conditions, sowing and cultivar adaptation allowed simulated crops to minimise the impact of abiotic stresses while limiting the shortening of the grain filling period due to global warming. Thanks to CO2 fertilisation and proper adaptation, the frequency of severe frost, heat and drought stress was reduced in all regions, except in the West where severe drought was projected to occur more frequently in the 2050s. This allowed a national yield increase of 4.6% with reduced risk of crop failure at most locations. While the study focused on stress avoidance through adaptations (sowing dates and choice of cultivar phenology), breeding for enhanced drought and heat tolerance appeared promising avenues to further improve wheat productivity.