Fast winter wheat phenology can stabilise flowering date and maximise grain yield in semi-arid Mediterranean and temperate environments

Australian wheat (Triticum aestivum) producers have been sowing crops earlier to adapt to reduced autumn rainfall, extreme spring weather and increasing farm size. Analysis of sowing date records indicate a shift of around 1.5 days/year over a 10 year period. The most suitable development patterns to maintain or increase yield at earlier sowing times have not been identified. Field experiments were conducted over two years at a range of sites and times of sowing (TOS), comparing a novel cultivar with fast-winter (FW) development to current elite spring and winter cultivars, and near-isogenic lines that differed only in major development genes. In cooler environments, the FW exhibited a more stable flowering time across a broader range of TOS compared to spring or slower developing winter cultivars. The optimal sowing window was shorter in warmer environments for the FW. Early-sown FW wheat yielded 8% more than fast-developing spring wheat sown later but flowering concurrently. FW wheat yielded 17% more than the elite mid-winter cultivar, and 18% more than elite slower developing spring cultivars when averaged across all TOS. The FW development pattern has potential to extend sowing periods while achieving 10-20% higher yields and flowering time stability. Wheat cultivars with altered development patterns must be developed to ensure crops flower during optimal periods from earlier sowing times.