CR 69:143-154 (2016)  -  DOI: https://doi.org/10.3354/cr01400

ABSTRACT: This study aimed to assess the performance of 8 agro-climate indices and wheat yield in 2030 and 2050 at 3 locations (Moree, Dubbo and Wagga Wagga) on a north-south climatic gradient in eastern New South Wales, Australia, by coupling downscaled outputs of 4 climate models with a mechanistic wheat model. These locations represent the transition of grain production systems from those with summer-dominant to those with winter-dominant rainfall. Simulation showed (1) ambiguous results in the frequency changes of frost occurrence across locations, phenophases, study period and sowing times; (2) a substantial increase in the frequency of heat stress during the flowering period across sowing times, study periods and locations; (3) a decrease in pre- and post-flowering rainfall in most cases; (4) no change in soil water deficit (SWD) in 2030 in 31 out of 42 cases (the combination of 7 sowings, 2 phenophases and 3 locations) and a decrease (by 0.2) or no change in SWD in 2050 in 18 out of 42 cases; and (5) a decrease, increase, or absence of change in wheat yield depending on locations, with sowing times in 2030 increasing more or decreasing less. Changes in wheat grain yield reflected the changing patterns of agro-climate indices. The concurrent occurrence of heat stress and terminal drought at wheat reproductive stages will pose significant challenges for sustainable development of the wheat industry in the future.

KEY WORDS: Wheat · Climate change · Frost risk · Heat stress · Soil water deficit · Flowering · Grain filling