Assessment of traits related with water productivity in the Australian wheatbelt using an improved version of the APSIM-Wheat model.

Abstract

Traits related with water productivity in dryland cropping interact in complex ways to influence final grain yield. Over the last decades, the APSIM-Wheat model has proved useful to address how to best combine traits for region-specific and management-specific adaptation of new genotypes. An improved wheat model using the plant model framework (PMF) from APSIM Next Generation has been developed to allow simulation of genotypic variation in early vigour, tillering rate and senescence, leaf development, growth and senescence, and transpiration efficiency. The new model allows more accurate predictions of major traits related to canopy development (e.g. tiller number and leaf area index) during the growing season. The new model was calibrated using seven field experiments from four seasons at two sites and included different management practices (i.e. early/later sowing, low/high nitrogen, irrigated/rainfed conditions). The model was successfully tested with experimental data from the APSIM validation dataset. The new model was used to assess the yield impact of traits associated with canopy growth and development (e.g. phenology, early vigour, tiller number) and transpiration efficiency. Over 5 millions of simulations were conducted for different combinations of traits at 60 sites across Australian wheatbelt from 1957 to 2018 for different managements (i.e. sowing date and nitrogen fertilization). The values of traits were reported for each site, region and the whole wheatbelt as well as for different management practices. The results are available to inform breeders about the potential trait value on wheat productivity across the Australian wheatbelt.