Effects of heat exposure from late sowing on the agronomic and technological quality of tetraploid wheat

Background and objectives: Heat stress is a major limiting factor to wheat yield that also impacts on grain quality, and its incidence is likely to increase. Thirty-seven durum wheats were grown in irrigated replicated field trials over two seasons in Australia, normal sown (NS) or a 2-month late sown (LS). Agronomic and technological quality traits were examined. Findings: Later sowing exposed the crop to more days at temperatures of 30°C and above indicating more heat stress while the irrigation ensured no drought stress. Relative to NS, LS reduced yield, grain weight, test weight, and milling yield but grain vitreousness and hardness either increased or decreased depending on the trial. However, LS had positive effects on increasing protein content, dough quality indicators, and increased the proportion of high molecular weight gluten polymer. LS also enhanced pasta end-use traits, increasing pasta yellowness and firmness and decreasing cooking loss. Genotypes that showed relatively stable yield and grain characteristics under LS were identified (Caparoi, Jandaroi, Kalka, Kronos, Saintly, and WID802). Conclusions: These findings suggest that the heat stress experienced enhanced dough and pasta quality, despite having a negative impact on yield and physical grain characteristics. Genotypes were identified that represent potential sources of heat tolerance that could be useful in breeding to help limit the undesirable effects of heat stress on durum production. Significance and novelty: Late sowing of wheat is a good strategy to obtain exposure to heat stress in the Australian environment and can be used to select genotypes with better yield and quality stability.

Mike Sissons, Denise Pleming, Julian D. Taylor, Livinus Emebiri, Nicholas C. Collins