Speaker
Description
Introduction
The adaptation of wheat and barley to different growing environments is underpinned by an understanding of crop phenology. The importance of an optimal flowering period (OFP) to ensure the critical period for yield development coincides with favourable seasonal conditions has been demonstrated, whereby the combined risk of frost, heat and drought is minimised, and grain yield potential is maximised (Flohr et al., 2017). Whilst this concept provides useful targets for growers to mitigate risk of abiotic stresses, they remain a major limitation to yields of wheat and barley in Australian rainfed cropping systems (Hochman and Horan, 2018). Future climate predictions increase the complexity of cultivar selection and sowing decisions and present a challenge for breeders, to release new cultivars that combine improved adaptation and stress tolerance, and for growers, to improve farming systems and agronomic practices to capture genetic gains. We consider an integration of genotype (G), environment (E) and management (M) to rethink flowering time in wheat and barley to better enable growers to adapt to climate variability and attain new yield frontiers.
Methods
A comparative analysis was conducted in a series of field experiments across 31 locations in the Australian cropping region from 2010–2022, whereby annual rainfall ranged from 117–978 mm. Grain yield was recorded with respect to flowering time (phenology) to enable us to investigate yield-flowering date relationships in locations where frost, heat and drought are major sources of variation in crop yield, and a significant concern for growers. We applied the field data to test the wheat and barley models in APSIM Next Generation, and conducted long-term simulations of genotype, environment, and management to identify differences in flowering and yield responses.
Results
Grain yield ranged from 0.5–11.8 t/ha, with barley maintaining higher yields than wheat across all yield levels. However, there is evidence to suggest that current genetics is limiting the yield potential of barley in high yielding environments. The OFP for barley was earlier and broader than for wheat, with genotype × sowing time responses observed to be less apparent in barley than for wheat.
Discussion
Our comparative analysis indicates differences in flowering and yield in response to sowing date for wheat and barley. The ability of barley to achieve grain yields greater than wheat at comparative flowering dates suggests wider adaptation of barley in Australian rainfed cropping systems. This may be in part due to the narrow range in phenology responses of current commercial barley cultivars than for wheat, differences in accumulation of biomass and partitioning, or differences in tolerance to frost, drought and/or heat stress. An improved understanding of these species-specific differences will improve future crop model predictions and provide information to growers to refine crop management and reduce the risk associated with sowing time decisions.
References
Flohr, B. M., Hunt, J. R., Kirkegaard, J. A., & Evans, J. R. (2017). Water and temperature stress define the optimal flowering period for wheat in south-eastern Australia. Field Crops Research, 209, 108-119. https://doi.org/https://doi.org/10.1016/j.fcr.2017.04.012
Hochman, Z., & Horan, H. (2018). Causes of wheat yield gaps and opportunities to advance the water-limited yield frontier in Australia. Field Crops Research, 228, 20-30. https://doi.org/https://doi.org/10.1016/j.fcr.2018.08.023
| Keywords | Phenology, optimal flowering period, wheat, barley, yield |
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