The role of phenology in environmental adaptation of winter wheat

The stable flowering time of winter wheat in response to varied sowing dates potentially limits its adaptation across environments with different optimal flowering periods (OFPs). This study assessed the importance of diverse phenology for yield adaptation of winter wheat to environments with varied OFPs. A reciprocal cross between two spring wheat cultivars was made; twelve recombinant inbred winter wheat lines were derived and divided into three phenology groups – very quick, quick and mid-winter types. Lines were sown at three environments with contrasting OFPs across south-eastern Australia, with eight field experiments conducted between 2018 and 2020. Environments were categorised as early OFP (late August to early September), mid OFP (mid-September) or late OFP (early October). Heading date, yield and yield components were measured at all sites. Growing season rainfall was variable between sites, especially at the early OFP environment (82 – 265 mm) and late OFP environment (195–408 mm). Observed phenology of the different lines was consistent across years and between OFP environments, while yield was strongly influenced by seasonal climatic conditions. Across all sites, very quick lines yielded 15 – 16 % more than other phenology groups in the early OFP environment, and displayed good adaptation to mid and late OFP environments (407–482 g m−2). Quick lines also yielded well at sites with mid (465 g m−2) and late OFPs (507 g m−2), while yield of the mid phenology group was low in all environments (233–467 g m−2). Results indicate that quick and very quick developing winter wheat has broad adaptation to diverse OFPs, and phenology may be less important for adaptation to different OFP environments than previously thought. This is in part due to seasonal variation in OFP within environments.