Grain yield response to sowing time, how many different response curves and maturity groups are there? Developing maturity type grain yield response curves to sowing time in Western Australia

Document Type

Conference Proceeding

Publication Date


Conference Title

System Solutions for Complex Problems: Proceedings of the 20th Australian Agronomy Conference - 18-22 September 2022

Place of Publication



frost, heat, modelling, varieties, time of sowing, flowering time


Agronomy and Crop Sciences


Current agronomic recommendations for variety maturity descriptions are based on flowering response to sowing date rather than grain yield yet yield response to sowing date is what is most important to industry in making variety by sowing date decisions. Flowering and grain yield to sowing date response curves were compared for ~45 wheat varieties sown over 8 sowing dates from mid-April to mid-June from 2015-2018. Varieties were grouped using a novel statistical approach where statistical cluster analysis was implemented on spline coefficients of the response curves. Four distinct flowering date and grain yield responses to sowing date were developed. Flowering date clusters were robust and repeatable across site and season but did not always cluster varieties into the same group as grain yield response. The grain yield response curve clusters were not as consistent across seasons with swap over between quick and mid-season spring varieties but more consistent for longer season varieties (mid-slow spring to winters). Ultimately a varieties grain yield response to sowing date should be the basis for maturity type agronomic recommendations for industry rather than flowering date, but ongoing work is required to develop consistent approaches for variety grain yield response groupings.