SIMULATION OF OPTIMAL DEVELOPMENT FOR SPRING WHEAT AT 2 LOCATIONS IN SOUTHERN AUSTRALIA UNDER PRESENT AND CHANGED CLIMATE CONDITIONS

A wheat model was used to study yield rind yield variability of spring wheat grown at two locations in southern Australia, Mildura and Wagga Wagga. Different genotypes were simulated by varying the duration fro m sowing to stem extension and/or from sowing to anthesis, It was foun d that long-season genotypes have mon: variable grain yield than short -season ones. An increase in [CO2] alone was shown to increase mean cr op yield by 10-30% with little effect on variability, whereas a 3 degr ees C increase in temperature alone would reduce mean crop yield by up to 50% and its coefficient of variation by up to 30%. Optimal genotyp es were identified that minimise the variability of yield while exceed ing a yield threshold specified for each location. These optima will m aintain the present yield variability or increase the mean crop yield for relatively longer-season genotype under warmer, higher CO2 conditi ons.