What is new from 2016 research for the Optimised Canola Profitability project

Take home messages

  • Early sowing (early April) of canola exposes the inherent phenological differences between commercial canola varieties and as a consequence choose wisely.
  • In 2016 (a very high rainfall season) slower developing varieties maintained consistent yield across sowing dates while faster developing varieties generally achieved their highest yield from late April sowing.
  • Early sowing limited yield of fast developing varieties due to early flowering which increased exposure to fungal diseases and reduced biomass and yield potential.
  • There was a strong relationship between final biomass and grain yield.
  • Certain varieties convert biomass more effectively into grain yield (higher harvest index (HI)). 
  • Aim to plant canola in paddocks with a high starting nitrogen (N) availability or be prepared to fertilise it.

Introduction

The Optimised Canola Profitability (OCP) project is a collaborative project between NSW DPI, CSIRO, SARDI and GRDC. A strong focus of the research to date has been on investigating the interactions between sowing date and variety choice of canola as it relates to phenology, biomass accumulation, grain yield and oil concentration. Variety by sowing date experiments were planted across the Northern and Southern GRDC regions in 2016, from the Darling Downs in SE Queensland, Canowindra on the central-west slopes of NSW, Horsham in the Wimmera region of Victoria and west to the Eyre Peninsula in South Australia. This paper presents an overview of results from southern NSW, including the N trials. Further results will be available as samples are processed over the coming weeks. 
 

Results are also reported from an additional experiment at Finley in the southern Riverina of NSW that is co-funded under the ‘Southern irrigated cereal and canola varieties achieving target yield potential’ project. Irrigation was only required for establishment so the experiment was essentially a dryland site for the rest of the 2016 season.

Phenology of commercial cultivars — 2016

An understanding of varietal phenology as well as characterisation of a particular environment enables varietal choice and sowing date decisions to target optimum flowering time to reduce frost, heat and moisture stress risks during reproductive development. Radiation also influences the optimum flowering window due to the positive relationship between intercepted radiation and seed number. Record low radiation levels in 2016 together with high rainfall, warm winter temperatures and low spring temperatures made this an important issue.

To determine the varietal response to sowing date, a diverse set of varieties was sown in experiments at a range of locations in 2016 (Table 2). This paper reports on four sites — Finley (southern Riverina, NSW), Wagga Wagga (eastern Riverina, NSW), Ganmain (north-eastern Riverina, NSW) and Condobolin (central-west plains, NSW). Table 1 shows a basic description of these four sites, including available water and N. Common across these sites in 2016 was well above average (or near record) rainfall, elevated winter temperatures (relatively few frost events), cool spring temperatures (no major heat events) and very low incoming solar radiation during winter and spring (lowest on record for the period from May to October). 

Table 1. Location, fallow rainfall (Nov to March), in-crop rainfall (April to October), soil N at sowing and N applied to four canola experimental sites in 2016.

  Region  Nov 15 - Mar 16
Rainfall 
Apr 16 - Oct 16 
Rainfall*
Available N (sowing) Applied N
Finley Riverina 204mm 452mm 108kg/ha 300kg/ha
Wagga Riverina 243mm 625mm 133kg/ha 200kg/ha
Ganmain Riverina 233mm 530mm 129kg/ha 0-200kg/ha
Condobolin CW Plains 198mm 498mm 253kg/ha 0-125kg/ha

* To ensure timely establishment, Finley had 45mm applied to sowing time 1 and 2 (lateral irrigator). Wagga had 11mm applied to sowing time 1 and 2 (dripper lines). Ganmain had 15mm applied to sowing time 1 only (dripper lines), and Condobolin had 66mm applied to sowing time 1 and 2 (lateral irrigator).

Archer was the slowest variety to flower from early sowing at three sites and had the most consistent flowering date across sowing dates (Table 2). At Wagga Wagga, there was 19 days difference in flowering date of Archer between sowing on 31 March and 29 April. In contrast, there was 59 days difference in flowering date for the same sowing dates of Nuseed Diamond. The ability of Archer to flower in a tight flowering window regardless of sowing date means that it has a wide and flexible sowing window. Other varieties with a similar (but lesser) ability to regulate their flowering window at earlier sowings (early April) include ATR Wahoo, Pioneer®45Y25 RR, Hyola 725®RT and Hyola®600RR. Varieties that are generally very quick to flower from early sowing include Nuseed Diamond, ATR Stingray, IH30RR and Hyola®575CL. 

Table 2. Date of flowering (50% of plants with one open flower) of canola varieties sown at two or three sowing dates at four sites in NSW in 2016.

  Wagga Wagga Finley Ganmain Condobolin
  31-Mar 13-Apr 29-Apr  12-Apr  30-Apr  7-Apr  21-Apr  6-Apr  20-Apr 
Diamond  6-Jun 12-Jul  4-Aug  13-Jul  3-Aug 
ATR Stingray 10-Jun 12-Jul  2-Aug  - - 9-Jul 28-Jul  3-Jul  24-Jul 
IH30 RR 16-Jun 20-Jul  8-Aug  - - - - - -
Hyola®575CL 16-Jun 15-Jul  18-Aug  - - - - - -
Pioneer®44Y89 CL 23-Jun 22-Jul 18-Aug  25-Jul  16-Aug  22-Jul  11-Aug  12-Jul  2-Aug 
Pioneer®43C80 CL - - -  -  -  -  - - -
ATR Bonito - - - 25-Jul 16-Aug   -  - - -
ATR Gem 8-Jul 26-Jul 18-Aug   -  -  -  - - -
Pioneer®45Y86 CL - - -  -  -  -  - - -
Pioneer®45Y88 CL 12-Jul 4-Aug 29-Aug 10-Aug 21-Aug   -  - - -
Hyola®559TT 15-Jul 1-Aug 22-Aug  -  -  -  - - -
Nuseed GT50 RR 15-Jul 1-Aug 18-Aug  -  -  -  - - -
Hyola®600RR 22-Jul 2-Aug 29-Aug  -  -  -  - - -
Hyola®725RT 26-Jul 8-Aug 31-Aug   -  -  -  - - -
Pioneer®45Y25RR - - -  16-Aug 24-Aug   -  - - -
ATR Wahoo - - - - - 18-Aug 25-Aug  5-Aug  12-Aug 
Archer 12-Aug 18-Aug 31-Aug  23-Aug  30-Aug  7-Aug  15-Aug 

When should canola flower?

Preliminary research in 2016 (data to be presented in more detail at the 2017 Wagga Wagga GRDC Update) suggests that the critical stage for yield potential of canola is between 100 and 500 degree days (°C.days) after the commencement of flowering. Stress during this period has the biggest impact on yield. For an average mid-late winter day at Wagga Wagga, this would mean that the critical period commences around 10 days after the start of flowering (50% of plants with one open flower) and continues for four weeks. 

The critical growth period needs to coincide with the optimal environmental conditions (critical flowering windows), when the risk of frost, heat and moisture stress are minimised and yet there is sufficient radiation to provide energy for growth. The critical flowering window for canola across a range of environments is being characterised as part of the OCP project.   

Sowing date and grain yield — 2016

At Wagga Wagga, long season varieties such as Archer, Nuseed GT50 RR and Hyola®600RR maintained consistent grain yield across sowing dates (Table 3), and Nuseed GT50 RR was the only variety to yield above 4t/ha from each sowing date. The highest individual treatment yield was Nuseed Diamond sown on 29 April, yielding 4.8t/ha. Fast developing varieties such as Nuseed Diamond, ATR Stingray, Pioneer®44Y89 CL and Hyola®575CL yielded less from early sowing, partly because flowering occurred too early to maximise biomass and seed number.

In addition to the reduced biomass from early sowing, Nuseed Diamond and ATR Stingray had increased disease infection (despite multiple applications of fungicide). The very early flowering (June) of these varieties exposed them to infection events all through winter, with the grain yield of Nuseed Diamond reduced by Sclerotinia (approximately 25% of plants were infected) and the grain yield of ATR Stingray reduced by upper canopy blackleg infection (greater than 50% of pods were infected). 

Table 3. Grain yield of 15 canola varieties sown at two or three sowing dates across southern and central NSW in 2016

  Wagga Wagga  Finley*  Ganmain*  Condobolin* 
  31-Mar 13-Apr  29-Apr  12-Apr  30-Apr  7-Apr  21-Apr  6-Apr  20-Apr 
Nuseed Diamond 3.1 4.4  4.8  5.0  4.6 
ATR Stingray 2.6 3.4  3.9  2.4  2.4  2.8  3.5 
IH30 RR 3.4 3.1  3.9   -  -  -  -  -  -
Hyola®575CL 3.5 3.8  3.3   -  -  -  -  -  -
Pioneer®44Y89 3.4 4.2  4.3  4.2 3.8  3.2 3.1  3.5 4.2 
ATR Bonito - - - 3.4 2.6  -  -  -  -
ATR Gem 3.5 3.8  3.3   -  -  -  -  -  -
Pioneer®45Y88 CL 3.7 3.8  4.1  3.8 3.9  -  -  -  -
Hyola®559TT 3.4 3.8 3.8  -  -  -  -  -  -
Nuseed GT50 RR 4.1 4.1  4.2   -  -  -  -  -  -
Hyola®600RR 3.9 4.1  4.4   -  -  -  -  -  -
Hyola®725RT 3.0 4.0 3.5  -  -  -  -  -  -
Pioneer®45Y25 RR - - -  3.8 3.6   -  -  -  -
ATR Wahoo - - -  -  - 2.2 2.5  3.4 3.6
Archer 4.0 3.6  4.1   -  - 2.9 2.8  4.3 4.0
l.s.d. (P=0.05) 0.46 0.26 0.36 0.39

*N treatments were included at Finley, Ganmain and Condobolin. Yield results are reported for the highest N rate in each experiment.

At Finley where the earliest sowing date (12 April) was similar to the second sowing date at Wagga Wagga (13 April), Nuseed Diamond was the highest yielding variety regardless of sowing date. The slower varieties Pioneer®45Y25 RR and Pioneer®45Y88 CL had consistent yield across sowing dates but were much lower yielding than Nuseed Diamond. The results at Finley were surprising as it was assumed that Pioneer®45Y25 RR with its delayed flowering and high yield potential would capitalise on a ‘soft’ spring. One advantage for Nuseed Diamond at Finley compared to Wagga Wagga was lower Sclerotinia pressure, though this does not entirely explain the contrasting results for Nuseed Diamond between Wagga Wagga and Finley. 

At Ganmain there was no effect of sowing date on grain yield, but the hybrid Clearfield varieties Pioneer®44Y89 CL and Archer were both significantly higher yielding than the open-pollinated TT varieties, ATR Stingray and ATR Wahoo.

At Condobolin, the yield of the fast developing varieties ATR Stingray and Pioneer®44Y89 CL was reduced by early sowing (disease level not significant), but the grain yield of Archer and ATR Wahoo was consistent across sowing dates. Comparing varieties with similar phenology (and similar to the finding at Ganmain), Pioneer®44Y89 CL was higher yielding than ATR Stingray and Archer was higher yielding than ATR Wahoo

Oil concentration

For the experiments that have been analysed for oil concentration, there was no effect of sowing date on oil at Finley (average 43% oil) or Condobolin (average 43.9%). At Wagga Wagga there was an increase in oil concentration with delayed sowing (averaged across varieties). Oil concentration was 42.9% from 31 March sowing, 44.6% from 13 April sowing and 45.7% from 29 April sowing. This oil increase with delayed sowing is unusual as in most seasons it is expected that delayed sowing reduces oil concentration as the crop is exposed to more heat and moisture stress during reproductive stages.

Nitrogen response

At selected experimental sites, N ‘indicator’ experiments were sown to determine the responsiveness of the individual trial sites. Rates of N up to 1000kg/ha were included, with the N broadcast as urea in front of the seeder. Despite the physical separation of N, rates of 500kg/ha and above generally reduced establishment so only rates up to 300kg/ha are reported here.

At Finley (starting soil N 108kg/ha) and Ganmain (starting soil N 129t/ha), canola displayed its near ‘insatiable’ appetite for N, with positive grain yield responses up to N rates of 300kg/ha (652kg/ha urea) (Figure 1). Consistent with past research, increasing the rate of N reduced oil concentration at Finley (Ganmain data not yet available), with oil declining from 44.4% with nil N to 40.7% with 300kg/ha N. Despite this lower oil concentration with the high N rate at Finley, the total amount of oil produced was greatly increased with the application of N, from 1.11t/ha (nil N) to 1.45t/ha (300 kg/ha N).

It could be quickly assumed that all canola growers should apply more N to their crops to increase grain yield potential, as similar results have been widely observed in previous seasons. The medium to long term strategy should be to target paddocks with relatively high soil N. For many low to medium rainfall zones, having a good N profile could be as important as having a good moisture profile to reduce the production risk associated with growing canola in a more variable climate.

Figure 1. Effect of nitrogen (N) rate on grain yield of canola at Ganmain and Finley; and on oil concentration at Finley only in 2016.

Figure 1. Effect of nitrogen (N) rate on grain yield of canola at Ganmain and Finley; and on oil concentration at Finley only in 2016.

Importance of timing of biomass accumulation

In the previous two years (2014-2015) of experiments, data showed that biomass at maturity had a positive linear relationship with grain yield. This was again demonstrated in 2016 (Figure 2) however, when growth was divided into that which occurred pre-flowering (flowering biomass) and post-flowering, data shows that post-flowering growth had a greater influence on grain yield than pre-flowering growth.

Only at the waterlogged site at Ganmain was there a relationship between flowering biomass and grain yield. At Ganmain there was a linear relationship between biomass at flowering and grain yield but only for biomass levels below 5t/ha.

Management tactics that optimise post-flowering growth will be further investigated in future years of research, but are likely to include timing of flowering, N management and variety choice.

Figure 2. Relationship between grain yield and biomass at flowering, growth post-flowering and biomass at maturity in canola trials at Wagga Wagga (×), Finley (▪), Ganmain (▲) and Condobolin (◊) in 2016.

Figure 2. Relationship between grain yield and biomass at flowering, growth post-flowering and biomass at maturity in canola trials at Wagga Wagga (×), Finley (▪), Ganmain (▲) and Condobolin (◊) in 2016. 

Harvest index and biomass accumulation

Some varieties can achieve a higher grain yield per unit of total biomass grown, referred to as a harvest index (HI). At Wagga Wagga in 2016, ATR Stingray had the highest HI but had the lowest biomass at maturity, so its grain yield was at the lower end of the varieties (averaged across sowing dates). Nuseed Diamond stands out as a variety that grows at least moderate levels of biomass but also has a high conversion of that biomass into grain. Nuseed Diamond grew a similar amount of total biomass as Pioneer®45Y88 CL, Pioneer®44Y89 CL, Hyola®725 RT and Nuseed GT50 RR but had a 17%, 10%, 21% and 10% higher HI, respectively over these varieties. The ability of some varieties to grow good quantities of biomass and then convert this biomass more efficiently into grain yield will be a focus of future research.

Conclusion

The OCP project has demonstrated that there are some varieties that have a wide planting window, allowing sowing opportunities to be captured when they arise, that can often match the yields of later-sown varieties. Such varieties may not always be the highest yielding but do offer greater flexibility to the farming system. In contrast there are fast developing varieties that should only be planted late in the sowing window to avoid reduced grain yield potential and increased disease risk.

The 2016 season has reinforced the importance of adequate N for canola. The best variety choice and sowing date management without appropriate N management is a lost opportunity. Growers need to ensure that approximately 80kg/ha of N is available to the crop per tonne of targeted grain yield. With declining levels of soil fertility generally, this means N requirements are being met more and more by fertiliser rather than soil reserves. Aiming to plant canola in high N situations will greatly reduce the risk associated with growing canola. 

Acknowledgements

This research is a collaborative project between the GRDC, NSW DPI, CSIRO and SARDI. 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 author would like to thank them for their continued support.

Thanks also to all technical staff for their assistance with these experiments, including Sharni Hands, Warren Bartlett, Danielle Malcolm, Jess Simpson, Nick Hill, Adam Coleman and Daryl Reardon.

Grower co-operators, including the McLeod family at Finley, Ben Beck at Wagga Wagga and Dennis and Dianne Brill at Ganmain are also thanked.

Contact details 

Rohan Brill
Wagga Wagga Agricultural Institute
02 6938 1989
rohan.brill@dpi.nsw.gov.au

GRDC Project Code: CSP00187, DAN00198,