Hyper Yielding Cereal Project - what has performed well over two contrasting seasons?

Take home messages

• In 2017 second year research results from the Hyper Yielding Cereals (HYC) project produced maximum yields of wheat of 13t/ha with above average temperatures during grain fill and a generally harder finish.
• With the barley research, despite two contrasting seasons the same three cultivars topped the yield rankings, these were RGT Planet, RGT Conquest and the faster developing cultivar Rosalind.
• Shorter season wheat cultivars Annapurna and AGTW001 performed well irrespective of sowing date with similar or higher yields to last year’s high fliers; RGT Relay, RGT Accroc, Genius, Conqueror and RGT Calabro at the first sowing date in early April.
• RGT Relay again showed good standing power and excellent Septoria tritici blotch (STB); Zymoseptoria tritici resistance but showed good yield responses to late fungicide control of leaf rust; Puccinia triticina.
• RGT Accroc has produced high yields in both 2016 and 2017 but again showed a weakness in straw strength.
• From the 2017 results it was difficult to establish a clear relationship between optimum flowering date and final yields since cultivars flowering from late October to mid November produced good yields. In part this may be related to the impact of irrigation which tends to assist cultivars that might otherwise be penalised in a dryland system because of their later development.

^ɸExtra technical comment by Protech Consulting Pty Ltd

Background

Despite a more suitable climate for grain production than the mainland and a much higher yield potential, the average yield of red grain feed wheat in Tasmania is still around 5t/ha. While this has increased relatively more than the other states in the last 20 years (ABARES) it is still felt to be well below the potential.

The Hyper Yielding Cereals (HYC) project funded 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 wheat and barley. Using the collaboration of international, national, local expertise and breeders, the five-year project is working to close the yield gap between actual and potential yields as well as using links with end users to promote the value of trading quality feed grains.

In 2017 the Hyper Yielding research centre at Hagley, Tasmania was composed of 1000 experimental research plots dedicated to identifying new cereal lines and agronomy strategies that could lift feed grain productivity.

In 2016 first year research results from the 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 during 2016 was in stark contrast to 2017 when low rainfall, higher temperatures and late frosts affected the grain fill period. In many ways the contrast of the 2016 and 2017 seasons has been useful in determining which new cultivars and lines have performed well in both seasons.

2016 and 2017 climatic conditions

2017 differed in three principal ways from 2016 at the Hyper Yielding research centre; firstly, instead of warmer temperatures over autumn and early winter, cooler minimum temperatures prevailed (Figure 1a and 1b). One of the primary initial effects was to slow down growth from the late April sown crops (27 April) relative to those sown early in April (6 April). It also resulted in significantly less leaf rust infection (Puccinia triticina) in the early wheat sowings, a fact that appeared to indicate the importance of autumn infection in order to generate severe leaf rust infections in Tasmania.

Despite the late leaf rust infection, the disease did not influence research results at the centre. Secondly, the temperatures for the grain fill period for the wheat crops in particular, was well above the long-term maximums for Tasmania. In November these high temperatures combined with below average rainfall, made it difficult for on-farm irrigation systems to keep up with soil water demand. Lastly, although regions were affected by frost during flowering and early grain fill, results were not severe at the research site as elsewhere in the state, although grain sample screenings were increased from an average of 1.5 to 2.0% in 2016 to between 4 to 6% in 2017.

Figure 1(a). 2016 climatic data for the Hyper Yielding Cereal site at Hagley, Tasmania.

Figure 1(b). 2017 climatic data for the Hyper Yielding Cereal site at Hagley, Tasmania.

Research conducted in 2017

A series of 10 field research trials covering 1000 plots were established in Year 2 to service germplasm screening and the agronomy objectives of the project. The initial 16 cultivars/lines provided by the breeders for the early sowing window (6 April) were narrowed down to four, with a further 16 cultivars that had not been sown early in 2016 tested at this sowing date for the first time. These 16 cultivars evaluated for the first time in 2017 either showed promise in the later sowing (27 April) last year or were thought to have been more suitable for early sowing due to longer season phenology (established in year 1). The four core elite cultivars plus the controls SQP Revenue and Manning were run under three different management approaches in order to further reveal their suitability or otherwise for the early April sowing date.

The three management levels of input were i) grazed (mechanically defoliated twice) with standard input ii) standard input alone and iii) high input where extra nitrogen, plant growth regulators (PGRs) and fungicide input were applied. The trial resulted in a significant (p=<0.001) interaction between cultivar and management applied (Table 1 and 2), meaning that cultivars responded differently to the management regimes imposed. The yields of the four elite cultivars selected from 2016 yielded between 10.02 to 11.66t/ha. The top yield of 11.66 t/ha (RGT Accroc) was 2.78t/ha less than the highest yield achieved in 2016 when RGT Relay yielded 14.44t/ha at the early sowing date. RGT Accroc was significantly higher yielding where it was grazed or treated with higher input, a result principally correlated to lower lodging in these two management regimes.

In contrast, in the stiffer strawed, slower developing, more disease resistant variety RGT Relay there were no significant differences in yield amongst the three management regimes applied, with less than 0.3t/ha difference in the three strategies. In part the slower development resulted in reduced dry matter removal from the ‘grazed’ plots and extra PGR input was not required. At the early sowing date in 2017 Relay yielded 3t/ha less than 2016.

SQP Revenue was the only cultivar to give significantly higher yields under grazing management, a result that correlated to lower levels of lodging and lower disease pressure in these defoliated crops. Protein levels were mainly in the range of 10.7 to 11.1% suggesting that yield was optimised for the site with the nitrogen levels applied. There were no significant effects of management strategy on the quality parameters of protein, test weight or screenings, but results on test weight were very variable and indicated some possible frosting damage.

Table 1. Grain yield (t/ha), % Site Mean, Protein, test weight and screenings of the elite wheat germplasm under three management levels, sown 6 April, harvested 23 January.

Notes: Figures followed by different letters are considered to be statistically different (p=0.05)

Letters following mean figures in bold are only comparable to other bold letters in the same column/row.

The input levels for the three management regimes for the 6 April sowing date are outlined in Table 2.

Table 2. Detail of management levels applied to the Management x Cultivar trial – sown 6 April
Sowing date: 6 April
Plant population: Target of 180 plants/m² (mean of 116 plants/m² established)
Sowing fertiliser: 100kg MAP

^ɸTrial purposes only as label states that Hasten is only for use with Prosara at 150ml. In commercial situations please adhere to label recommendations

In neighbouring trials looking at the 16 cultivars sown at the same early April sowing, yield results and phenology data revealed some surprising results with more rapid developing cultivars, such as AGTW001 and Annapurna either outperforming or giving comparable performance to the longer season elite lines selected from 2016 (Table 3), even though the flowering phenology of the cultivars was far earlier. Only RGT Accroc, Annapurna and AGTW001 had passed the mid flower point (GS66-71) on 1 November.

All other cultivars in Table 3 were at various stages of head emergence (GS51-59) with the exception of RGT Relay that was still at the late booting stage and did not start flowering until 17 November. RGT Calabro was at GS59 (full head emergence) on 1 November. The poor quality of the samples is part a reflection of partial frosting and partially the particular plot header. One of the major considerations for the early sowing window is stiff straw and good disease resistance when sowing early.

Since many of the cultivars tested on 6 April 2017 had not been tested at this sowing date in 2016 the varieties were also grown in an untreated screen with no PGR and fungicide applied. Only the cultivars that lodged in this screen or in the yield trials sown at the same time are featured in Figure 2.

Table 3. Grain yield (t/ha), % Site Mean, % grain protein and % screenings

Figure 2. Lodging index (severity x extent – 0 to 500 scale) of cultivars trialled under both the standard and high input management and in the untreated screening trial (with PGR or fungicide) assessed on the 23-24 January just prior to harvest (GS99). Note. Other varieties not shown did not suffer lodging.

Disease resistance when sowing early

The same untreated screen gave an excellent insight into Septoria tritici blotch, Zymoseptoria tritici susceptibility when cultivars were sown in the highest risk sowing window (Figure 3). The screen was less reliable in 2017 for generating good leaf rust differences, however there was one exception to this general observation. This concerned RGT Relay that provided excellent STB resistance and stiff straw but did succumb to a very late infection of leaf rust that was not apparent in mid-December 2017, which resulted in significant yield reduction when not controlled (Table 5).

Samples of the pathogen on RGT Relay did not reveal a new pathotype as the sample sent was not viable, but both yield and green leaf area were affected by the new year infection timing. At the same time (Jan 5) RGT Accroc, RGT Calabro and Annapurna had in the main, reached physiological maturity. This is an important observation for RGT Relay grown under irrigation, since later cultivar development combined with irrigation may make it particularly responsive to late fungicides for leaf rust control. Similar findings have been observed in New Zealand for similar cultivars grown under irrigation.

Figure 3. Disease severity of Septoria tritici blotch (STB) (whole plot score), assessed on 23 August (GS26-32), 21 September (GS31-51) and 01 November (GS47-71)

Yield potential of early versus late April sowing (6 April versus 27 April) – which was higher yielding in 2017?

In 2016 the late (27 April) sown wheat trials were 2 to 3t/ha higher yielding than the early (6 April) sown wheat trials, with yields in excess of 16t/ha at the later sowing date. A soft finish and higher leaf rust pressure affecting the early sowings appeared to be two primary considerations in 2016 affecting yield. This raises the question whether under a shorter growing season in 2017 with a hotter grain fill period in November was there any advantage to 6April sowing compared with 27 April sowing growing irrigated wheat at the research centre? Although trials were in the same paddock the following results cannot be statistically compared but represent the best yields from both sowing dates (Table 4).

The differences between the two sowing dates in 2017 was relatively small (0.3t/ha) with 13t/ha achieved in both sowing date blocks, and in both cases the same shorter season wheat cultivars were the optimum performers despite the differences in estimated flowering dates between the two sowings. Unfortunately, AGTW001 has been discontinued by the breeder since its stem rust resistance was very poor and not acceptable for the mainland, however Annapurna has been carried through for more detailed agronomy evaluations at the site for 2018/19.

At both sowing dates it was difficult to suggest a strong relationship between flowering date and final yield since at the first sowing date Genius and RGT Calabro performed similarly to AGTW001 in terms of yield, but were considerably later to flower than AGTW001. At the second sowing date the differences between flowering dates was much smaller however AGTW001 and Annapurna performed significantly better than RGT Accroc and RGT Calabro (Table 4).

The exact timing of the late frosts interacting with both flowering date and cultivar may help explain some of these differences but it is worth indicating that irrigation itself may obviate some of the differences that might be commonly seen with regard to optimum flowering dates and the relationship with yield in dryland crops. That stated the Tasmanian NVT results for wheat sown in late April/early May concur with the Hyper yielding performance results indicating high yields from RGT Accroc and RGT Calabro.

Table 4. Grain yield (t/ha), % Site Mean, % grain protein and % screenings of the top five cultivars sown in trials on 6 and 27 April.

The lack of a relationship between flowering date and yield in these irrigated trials was further confounded by the performance of RGT Relay in the early sown fungicide and nitrogen research trials. These trials produced maximum yields of 12.5 to 13.0t/ha, despite a mid-November flowering date (Table 5). As stated earlier RGT Relay while being very resistant to STB, succumbed to a late leaf rust infection in the new year. Samples sent for pathotying were not viable so it remains to be seen whether this is a new issue, however it was not observed in 2016 when early leaf rust pressure was much higher. In 2017 control of late leaf rust gave significant benefits to fungicide programmes based on triazoles, SDHI and strobilurin as opposed to triazole alone.

Table 5. Grain yield (t/ha), % Site Mean, % grain protein, test weight (kg/hl) and % screenings (selected treatments from larger trial)

Higher barley yields compared to 2016

Unlike the wheat trials where yields during 2017 were back to 13t/ha from maximums of 16 to 17t/ha in 2016, the shorter growing season with a hotter grain fill period favoured barley performance at the site. In 2016 the highest yields were generated by RGT Planet, RGT Conquest, and Rosalind in a soft finish. In 2017 despite a season in stark contrast to 2016 the same three cultivars topped the performance charts but this time with a harder finish and higher yields overall. The different rotation position of ex pyrethrum may have helped, compared to process peas in 2016, however the results were very encouraging not only because of the consistency of variety performance but also the production of yields in excess of 11t/ha.

In the 2018/19 season the HYC project will undertake in depth, agronomic research on the following wheat cultivars: Annapurna, DS Bennett and the RGT lines Accroc, Calabro and Relay (sown 5 April and 26 April, 2018). With the barley component of the research, new winter germplasm sown at the same time is being tested alongside RGT Planet, RGT Conquest and Rosalind for the very first time.

Come and view the research on Thursday November 15, 2018!

Acknowledgements

The research undertaken as part of this project is made possible by the significant contributions of growers through both trial cooperation and the support of the GRDC — the authors would like to thank them for their continued support.

Contact details

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

Tracey Wylie
23 High St, Inverleigh, Victoria 3221
0499 888077
tracey.wylie@faraustralia.com.au