A short-season, early-vigorous wheat ideotype for adaptation to a changing global climate

The changing global climate of more variable rainfall patterns and increasing temperatures is a severe threat to worldwide food security. There is need for adaptive technologies, agronomy, and crop varieties that will be capable of meeting and exceeding the projected demands of an increasing human population in the changing climate. An increase in average temperatures will result in crop cycles shortening and as such the vigour of varieties will need to increase to ensure optimum production occurs (Malhi et al. 2021). With up to ~20% of all calories consumed coming from wheat grain, it is therefore a vital component of food security and a focus for yield improvement (Erenstein et al. 2022). A proposed new wheat ideotype, of a highly early vigorous plant with a shortened lifecycle has been tested in Australian conditions, and has applicability on a global scale.
Australia is one of the largest wheat exporters, and is essential to worldwide food security. In the southern Australian wheatbelt, wheat is traditionally sown in the autumn to be grown over winter, flower in spring and then be harvested in early summer. With water availability the greatest limiter to yield, this allows for sufficient time for moisture to be harvested by the crop, and develop enough biomass before anthesis for conversion to grain yield (Richards et al. 2014). The timing of sowing in the autumn is crucial as it enables the plant’s phenological requirements of vernalisation, photoperiod, and earliness per se to be met over winter. This results in anthesis occurring in spring when the relative risks of frost and heat and drought stress are at their lowest. Mistimed flowering results in the sensitive floral parts being damaged, and a resultant drop in grain yield (Flohr et al. 2017). However, the timing of sowing in autumn, to ensure correct timing of anthesis, is often dictated by the colloquially termed autumn break. This is a flush of rainfall that growers will wait for until they sow. The autumn break provides good soil moisture, ensuring consistent and even germination of the crop. The changing climate has reduced the reliability of this rainfall and so many growers are being forced to sow into dry soil, and are encountering issues with poor germination, emergence, and crop stand establishment (Unkovich 2010). The proposed ideotype tested here negates the need for the autumn rainfall by delaying sowing into mid-winter into near guaranteed moisture. This delay in sowing requires the ideotype to have exceptionally high early vigour for biomass development, as well as hastened phenology to still time anthesis in the optimum flowering window in the spring (Chen et al. 2020). This paper covers a definition of the ideotype drawing upon global literature of short season, highly vigorous wheat varieties in addition to a multi-trait multi-environment analysis of short season wheats in Australian conditions.