A goal to close-the-gap between actual and potential yields is clearly a worthwhile objective. However, delivering enduring profitability to grain growers also requires investments aimed at further extending the yield potential and yield stability of all Australian grain crops. Extending yield potential can be achieved by increasing the genetic yield potential and by limiting the impact of yield constraints (e.g. frost, hostile soils and heat).
Maintaining yield stability under the impacts of various environmental factors is an important consideration in limiting exposure to production risk and underpins stability of supply. Investments in this area may involve relatively high risks and long timeframes to delivery.
Key investments 2019–20
Examples of investments in 2019–20 that met this objective include:
Australian Research Council Research Hub for Wheat in a Hot and Dry Climate
The ongoing investment in the Australian Research Council Research Hub for Wheat in a Hot and Dry Climate brings together wheat researchers from three Australian wheat breeding companies. Research exploits global diversity for wheat and advanced genomic technologies for faster development of heat and drought tolerant varieties, which make better use of nitrogen fertiliser for Australian grain growers. In 2019–20 this investment delivered:
- drought tolerance Quantitative Trait Locus (QTL) and heat tolerance QTL to wheat breeding partner companies
- evaluation of near isogenic lines for two heat tolerance QTL in field trials.
Introgression of heat-tolerant genes to broaden genetic variation in current wheat breeding populations
Periods of extreme high temperatures, particularly short periods of heat shock, are a major threat to wheat yield and grain quality throughout much of the Australian wheat belt. This investment aims to significantly improve the high temperature tolerance of wheat by:
- extensively phenotyping wheat populations, or improved crosses from them, for field response to high temperature using both traditional and new phenomic methods
- calculating genomic breeding values for heat tolerance to assist prediction of the best crosses to generate heat tolerant breeding lines in Australian commercial breeding programs.
Progress to date in this investment includes:
- Evaluation of 748 wheat introgression lines containing genomic segments associated with heat tolerance and a 200-line core set across three national locations. Lines with high yield and stability have been identified, genomic estimated breeding values calculated, and QTLs associated with heat tolerance identified by genome-wide association studies.
- A genomic prediction-based strategy to identify the best lines and parent combinations was trained at Narrabri and then validated in Western Australia and Victoria. By including genotype-by-environment interactions and environmental covariates, the prediction accuracy and reliability improved, and the resulting first new recombinants were tested in 2019.
- Wheat germplasm was developed with yield equivalent or higher than current elite wheat cultivars under normal growing conditions, but 20.0 per cent higher yielding under heat stress. Heat tolerant germplasm has been passed on to Australian wheat breeders for use in their programs.
Identification of wheat frost tolerance loci using a combination of genetics, biochemistry and molecular approaches
The effect of frost on wheat at flowering is sudden and the result is damaging and irreversible. Due to its sudden nature, frost can be more financially devastating to growers than droughts because growers do not have the opportunity to reduce input costs. Droughts normally establish over prolonged periods of time. As the genetic variability in the current Australian breeding stock may not be enough to achieve a significant or sufficient increase in frost tolerance, field trials will introduce more germplasm from colder parts of the world to increase the chance of identifying key cold and frost tolerance genes. This investment, in conjunction with supporting field trials, was established to address the challenges of identifying those genes using reliable phenotyping methods and knowledge-based selection methods. The field work is complemented with controlled environment experiments to map QTL and identify the molecular and biochemical basis of cold tolerance of interesting germplasm. The investment has delivered tools to support breeders in developing frost sensitivity in wheat, and have included:
- development of a phenotyping method for wheat chilling tolerance in a controlled environment
- identification metabolic markers (unsaturated to saturated lipid ratio) for chilling tolerance.
Frost risk management
Completed at the end of 2019, this investment investigated the impact of different agronomic strategies (canopy management, crop type and stubble management) on frost risk management to aid grower decision-making across southern Australia. A total of 36 trial sites across three trial series were established in the southern and western regions from 2014 to 2018. The right mix of crop type, sowing date and variety were consistently identified as key levers to maximise profitability in frost-prone environments. Meta-analyses of each trial series provided a robust basis on which to develop communications and extension tools for frost risk management.
National Paddock Survey Initiative
This project established a database of crop performance in 250 paddocks over four years across Australia, to assist with the identification of yield gaps and causes. Yield calculator tools for wheat, barley and canola, which enable assessment of the likelihood of abiotic and biotic stresses affecting crop yield, are key outcomes of investment.
Quantifying the effectiveness of cover crops as a means of increased water infiltration
Growers are increasingly looking at cover cropping to manage moisture retention, particularly during the prolonged drought conditions throughout many of the grain growing regions during 2017 to 2019.
This project assessed and quantified the effectiveness of cover crops to increase rainfall infiltration, reduce evaporation, and so increase the Plant Available Water for dryland grain. It also assessed the impact of cover crops on the subsequent infiltration of irrigation water and plant available water supply in cotton systems
Now completed, the project supported analysis of the benefits of cover cropping to mitigate erosion, improve weed management and moisture retention. This work demonstrated that the timing of cover cropping can increase available soil moisture by more than 20mm.
Optimised canola profitability—understanding the relationship between physiology and tactical agronomy management
This project delivered an extensive program of physiological and agronomic research across eastern Australia to increase profitability and reduce production risk. During 2019–20, this investment contributed to improving the understanding of the drivers of development, flowering time and the critical period for grain yield development. Outputs included tactical agronomy advice for:
- robust, high-yielding early sowing systems
- reduced production risk in low rainfall areas
- improved harvest management.
Following this work, an independent survey of 90 consultants indicated 68.0 per cent had made significant practice changes, resulting in additional income of $74 million per annum.