Using gene-based information to adapt wheat flowering time to avoid heat, frost and drought stresses in current and future climates

Abstract

Varying the timing of reproductive stages of growth relative to climatic stresses is a useful adaptation to maintain yields. In future climates, the expectation that heat, frost and drought stresses may change in their timing means requires that breeding programs start to anticipate what the consequences may be for the suite of maturities that are delivered in their commercial varieties. Using a set of controlled treatments of vernalisation and photoperiod, a model was developed to predict wheat heading time for wheat lines varying in their combination of Vrn_1A, Vrn_1B and Vrn_1D, and Ppd_D1 alleles. The lines were also characterised for a ‘residual thermal time’ that essentially represents their ‘earliness per se’. Using APSIM_wheat, simulations were then run for key locations in the wheat belt to predict the occurrence of flowering time in current and future climates, and the patterns of drought that would be experienced by wheat lines that varied for their flowering genes, but that were similar in other trait aspects. Climate scenarios predict that heat events will become more frequent and earlier in most parts of the wheat belt, with earlier flowering needed to avoid the heat. While sowing time can also be shifted earlier to partially compensate for this effect, the generally warmer winter conditions mean that ‘later genotypes’ with either a longer earliness-per-se or different photoperiod response would likely be needed to adjust to this shift. Similarly, while there is some compensation of elevated CO2 (increased water use efficiency) in future climates, this does not eliminate the increased probability of severe drought patterns in some locations.