Hyper Yielding Cereal project – is there relevance to the mainland high rainfall zone (HRZ)?

Take home messages

• Research results from the GRDC Hyper Yielding Cereals (HYC) project have set new benchmarks for the yield performance of irrigated feed wheat with plot yields in excess of 15t/ha in 2016 and in excess of 12t/ha in 2017.
• Higher final harvest dry matter is essential for higher grain yields. Crop canopies producing 30t/ha-35t/ha dry matter at harvest have produced plot yields of 15t/ha – 17t/ha in research plots, using feed grain germplasm.
• Initial screening (50 wheat and 11 barley cultivars/lines) have shown that there are four cultivar characteristics essential for April sowing in the Tasmanian HRZ;
  • The right ‘time clock’ or phenology is important so that the key development period of stem elongation coincides with the best environmental conditions to maximise growth and yield potential.
  • For sowing prior to ANZAC day (April 25) the research has shown that winter wheat cultivars provide much safer options for maximising yield than spring wheat cultivars.
  • Disease resistance particularly to Septoria tritici blotch (STB), leaf rust and scald.
  • Good standing power is essential for achieving yields over 8t/ha.
• Research from 2018, with mid-April sowing in south-east (SE) South Australia (Millicent), has shown that results achieved in the HYC project are relevant to the longer season mainland HRZ in south-eastern Australia.
• HYC research on feed grain germplasm in Tasmania has shown that the same cultivars are outperforming the current commercial controls grown in mid-April in SE South Australia.
• These wheat cultivars were RGT Accroc, Annapurna, RGT Calabro, AGTW0002 and DS Bennett.
• With the barley research, despite three contrasting seasons, the same three cultivars topped the yield rankings these were RGT Planet, RGT Conquest and the faster developing cultivar Rosalind.

Background

Despite a more suitable climate for grain production than the mainland and much higher yield potential, the average (predominantly dryland) yield of red grain feed wheat in Tasmania is still approximately 5t/ha. While this has increased relatively more than other states in the last 20 years (Source: ABARES) it is still felt to be well below the potential. The HYC project supported by GRDC and led by FAR Australia in collaboration with Southern Farming Systems (SFS) aims to make Tasmania less reliant on grain supplied from mainland Australia through increased productivity of feed grain wheat and barley. Through the collaboration of international, national, local expertise and breeders, the five-year project is working to close the gap between actual and potential yields, as well as using links with end users to promote the value of trading quality feed grains.

Research

The irrigated Hyper Yielding Research Centre at Hagley in Tasmania has, over the last three years, used over 1000 experimental research plots each year to identify new cereal lines and agronomy strategies that could lift feed grain productivity in the Tasmanian HRZ. The concept of the research has been to explore whether the April sowing window can be used to maximise biomass and yield potential without giving rise to large increases to input costs.

In 2016, the first-year research results from the HYC project set new benchmarks for the yield performance of feed wheat with plot yields in excess of 15t/ha. The soft finish and high rainfall experienced were in stark contrast to 2017 when low rainfall, higher temperatures and late frosts affected the grain fill period and reduced maximum yields to 12t/ha – 13t/ha. In many ways the contrast of the 2016 and 2017 seasons has been useful in determining which new cultivars/lines perform well in both seasons. In 2018/19 at the time of going to press, wheat remained to be harvested but barley was producing yields in excess of 10t/ha for the third year in succession.

High harvest dry matter is essential for higher grain yields

In order to generate higher yielding cereals, it has been essential to generate high harvest dry matters. This has been clearly observed in HYC research with some of the more promising cultivars producing the higher dry matter contents. The final harvest dry matters in 2016 HYC research for the highest yielding cultivars/lines were approximately 30t/ha – 35t/ha dry matter and showed significantly higher grain yields than the control cultivars Manning, SQP Revenue and Beaufort (Figure 1). In addition to higher dry matter the same cultivars had better standing power and exhibited better resistance to STB and leaf rust.

Figure 1. Influence of cultivar/line on grain yield and dry matter (t/ha) at harvest versus commercial controls sown 6 April – HYC Research 2016/17 season.

High fertility is essential for higher yields

High yield potential is strongly linked to higher fertility, where the extra nitrogen (N) required to realise higher potential is provided by the soil not by additional fertiliser. Analysis of HYC yields and grain proteins suggest that large quantities of N, exceeding applied N fertiliser, were removed from the soil to produce high yields. In 2016 yields of 14t/ha – 17t/ha were achieved with no more than 220kg N/ha fertiliser applied, yet N offtakes in the grain alone indicated the removal of approximately 258kg N/ha – 336kg N/ha for specific cultivars and sowing dates.

In the UK, recent analysis of independent NIAB TAG trials show similar findings to the HYC research over the last two years. Results from a large series of wheat trials indicated that high yield potential usually comes from higher fertility, where the extra N required to realise that potential is provided by the soil, such that the total applied N needn’t be significantly higher than for crops with lower yield potential. The analysis of trials on wheat from the UK put forward ‘that for every tonne of N fertilised grain/ha, two thirds of a tonne comes from the yield without N’. This was put forward to explain ‘why the additional amounts of N required for very high yields in field trials is less than would logically be expected’ (NIAB TAG 2018). Clearly the fertility of farming systems and soil organic matters are lower in Tasmania than the UK, however from the Tasmanian results the fertility of the whole farming system is a key component to achieving higher yields.

Is there any relevance of the HYC research to the mainland HRZ?

With far less emphasis on breeding for yield in HRZ regions of Australia, does the research on germplasm and agronomic strategies in Tasmania have any relevance to the mainland? 2018 results from the SA Crop Technology Centre at Millicent run by FAR Australia in collaboration with SARDI and funded by Landmark and the wider industry would suggest the answer is yes.

Mid-April sowing (18 April) suggested that winter wheat cultivars were more suitable to secure the yield potential of this sowing date than spring wheats which developed too quickly (Table 1). The sowing date was too early for the spring wheat cultivars resulting in significant frosting, particularly where cultivars were grown ungrazed (high and standard management).

There was a significant interaction between cultivar and management with spring wheat cultivars benefitting from simulated grazing and the winter wheats showing a yield penalty from grazing. With less frosting in spring the wheat cultivars, under simulated grazing, retarded the development resulting in a partial escape from some of the frosting effects with late flowering. In addition, cultivars identified as high yielding in Tasmanian HYC trials have topped the 2018 Crop Technology Centre results. These wheat cultivars were RGT Accroc, Annapurna, RGT Calabro, AGTW0002 and DS Bennett.

High input management (five fungicides (seed treatment and four foliar sprays) and 200kg N/ha of applied N) did not significantly increase grain yields over the standard management approach based on three foliar fungicides and a 120N total. Higher yielding cultivars were associated with higher test weights and larger grain size (data not shown).

Table 1. Grain yield (t/ha) under three management levels, 2018 Crop Technology Centre, Millicent, SA

Winter – winter wheat, Spring – spring wheat, ‘Grazed’ Management – simulated grazing with mechanical defoliation.

Yield figures followed by different letters are considered to be statistically different (p=0.05), for example

a yield of 9.33 efg is considered statistically different to 8.36 h but not to a yield of 9.13 fg.

Plot yields: To compensate for edge effect a full row width (22.5cm) has been added to either side of the plot area (equal to plot centre to plot centre measurement).

Simulated grazing showed a considerable range of dry matter offtakes dependent on the date at which the cultivar reached growth stage (GS)30 (start of stem elongation). With later developing winter wheat cultivars that reached GS30 in late August, dry matter offtakes exceeded 2000kg/ha. However, these cultivars gave greater grain yield reductions as a result of simulated grazing (Table 2). With slightly faster developing winter wheat cultivars such DS Bennett, which reached GS30 in early August, the dry matter offtake associated with grazing gave only a slight yield reduction in grain yield but dry matter offtake closer to 1000 kg/ha.

Table 3. Approximate date of pseudo stem erect (GS30), mid flowering (GS65) under standard management, dry matter (DM) removed in simulated grazing (mechanical defoliation) management at GS30 and grain yield reduction associated with grazing, 2018 Crop Technology Centre, Millicent, SA

* Provisional data means presented with no statistical analysis in the express results

In conclusion, the HYC research trials have identified new cultivars and techniques that have set new benchmarks for yield performance in feed wheat with plot yields in excess of 15t/ha and barley yields over 11t/ha. In addition, 2018 research at the SA Crop Technology Centre in Millicent has found that the same lines identified as high fliers in Tasmania have been performing well in the South Australian HRZ.

Come and view the HYC research at the main Hyper Yielding Cereal Project Field Day in Tasmania on Thursday November 14 2019!

Acknowledgement

The research undertaken as part of these projects is made possible by the significant contributions of growers and agronomists through trial cooperation and provision of diseased plant materials for the isolate collection as well as the support of the GRDC, the author would like to thank them for their continued support.

Contact details

Nick Poole
FAR Australia
23 High St, Inverleigh, Victoria 3221
0499 888 066
nick.poole@faraustralia.com.au

Darcy Warren
FAR Australia
23 High St, Inverleigh, Victoria 3221
0455 022 044
darcy.warren@faraustralia.com.au