Canola shatter reduction with PodGuard®

By BCG Staff and Contributors
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Take home messages

  • Varieties with the PodGuard® trait were better able to withstand pod shattering in an extreme
    event than varieties that did not contain the trait.
  • PodGuard® canola can help with harvest logistics as it gives confidence to windrow when almost mature or direct head with no desiccation, without fear of large shattering losses.
  • Delaying desiccation can allow for greater yields and better quality in all varieties, this comes with added risk of shattering, PodGuard® trait can mitigate these losses.

Background

Pre-harvest shattering is a major contributor to canola yield loss and productivity, with significant yield and oil losses incurred by harvesting canola too early (Hertel 2013; Street 2013). Desiccation or windrowing operations are timed to maximise yield and oil content while minimising yield loss from shattering, a balance which proves a constant management challenge.

As a result, Bayer CropScience have developed PodGuard®, a new trait technology which strengthens canola pods and greatly reduces the risk of pod shatter (Bayer Australia 2016). It is being progressively introduced into new Bayer hybrid canola varieties such as IH 51 RR and InVigor® R 5520P, with claims that the trait provides increased flexibility, potentially widening the windrow or direct heading window.

Since 2014, research has shown that the PodGuard® trait allows varieties to retain more seed in the pod than varieties without the trait (Bayer 2016; McClelland and Pratt 2014). This has been tested in a range of environments and rainfall areas with consistent results.

Currently, the PodGuard® trait is only available in Roundup Ready® (RR) varieties which incur higher seed costs and a receival price reduction. The PodGuard® trait could improve the profitability of growing Roundup Ready® canola in low to medium rainfall zones by removing windrowing costs and improving yield and oil.

Note: Two trials were established at Warmur and Longerenong. These trials were managed under different protocols due to timing and harvest logistics. Subsequently, these trials are discussed separately.

Trial 1 – Southern Mallee (Warmur)

Aim

To determine whether a range of windrowing/desiccation timings has an effect on yield and oil of canola varieties with and without the PodGuard® trait.

Paddock details

Location: Warmur
Annual rainfall: 444mm
GSR (Apr-Oct): 371mm
Soil type: clay loam
Paddock history: 2014 wheat, 2015 fallow

Trial details

Crop type: Canola
Treatments: Refer to Table 1
Target plant density: Seeding equipment:
Seeding equipment: Knife points, press wheels, 30cm row spacing
Sowing date: 4 May
Replicates: Four
Harvest date: Refer to Table 1 and 2 for harvest timings

Trial inputs

Fertiliser: At sowing Granulock Supreme Z + Impact @ 50kg/ha, 100kg/ha SOA
at two-leaf, and 100 and 60kg/ha of urea applied as a split application
at six-leaf and budding
Herbicide: Managed to best practice
Reglone® @ 3L/ha + BS 1000 @ 0.25% (over first harvest timing)
Insecticide: Managed to best practice; no insect damage was observed
Fungicide: Low levels of blackleg were present in each trial
Seed treatment/inoculant: All certified and treated by seed companies

Methods

A split block replicated trial was sown at Warmur. The trial had six varieties which compared
desiccation timing and subjection to a (simulated) shattering event (Table 1).

Table 1. Treatment descriptions at the Warmur site.

Canola shatter reduction with Podguard table 1

On the day of desiccation (Timing 1), varieties ranged between 30 to 90 per cent seed colour change, depending on maturity. The colour change percentage of each variety was recorded on the day of spraying (Table 2).

Timing 2 was not desiccated at all and was harvested when all varieties had matured naturally. There was minimal natural shattering of all varieties in this second timing. The simulated shattering events were carried out before each harvest timing with two passes of PVC pipe through plots.

Assessments at both locations included establishment scores, NDVI, colour change when spraying, and grain yield and quality parameters.

Yields and oil percentage was corrected to the average canola moisture of each desiccation timing.

Results and interpretation

Yield and oil percentage were affected greatly with the standard desiccation timing, all varieties increased (in both yield and oil) when left to mature naturally (Table 2).

The PodGuard® lines were equal top performing varieties at both times of harvest in terms of yield. Timing 1 yielded less than Timing 2 across all varieties, demonstrating that early desiccation of any variety decreased yield.

Increases in yield between desiccation timings varied between varieties. The varieties were at different per cent colour change when desiccated. Hyola 559TT, which had the lowest per cent colour change (30 per cent) when sprayed, experienced the greatest increase in yield. Stingray at 80 per cent colour change when desiccated was the variety with the lowest increase in yield between desiccation timings (Table 2).

All varieties increased in oil content from Timing 1 to Timing 2. Hyola 559TT, which had the lowest colour change at desiccation, experienced a high oil content at both timings. This is an anomaly as all other varieties increased in oil content when left to mature naturally. Some varieties were below the required receival standard of 42 per cent when desiccated. Oil percentage increased to above this standard in all varieties when allowed to mature naturally (Table 2).

The results suggest that there is a clear advantage in delaying desiccation or windrowing to as close to maturity as possible. By doing this, and subsequently maximising oil percentage, a premium price can be achieved from the oil bonus.

Table 2. Yield (t/ha) and oil content (%) of the canola varieties after desiccation and maturing naturally.

Canola shatter reduction with Podguard table 2

The other influencing factor at the Warmur site was an extreme simulated shattering event at each harvest timing (Table 1). A three-way interaction between variety, desiccation timing and shattering was very close to the 95 per cent confidence interval. Together with visual observations at the time of harvest and when applying the treatments, it is highly plausible that there is an interaction between all treatments (Figure 1).

When considering the simulated shattering event in Treatment 3, the PodGuard® lines experienced less shattering than all other varieties for both Timing 1 and Timing 2. For all varieties, the later the shattering event, the greater the grain losses (Figure 1). At the time of the simulated shattering it was observed that any grain loss in the PodGuard® lines was due to the entire pod dropping and not the pod itself shattering. This dropping of pods was observed across all varieties, but combined with shattering losses in non-PodGuard® lines, the grain losses were amplified.

Canola shatter reduction with Podguard figure 1

Figure 1. Mean grain yield (t/ha) of canola varieties at Warmur. The overlayed grey bars indicate the grain yield (t/ha) and yield loss (%) from the non shattered treatments. Error bars indicate significant difference for the three way interaction variety x harvest timing x shattering. Stats: P=0.066, LSD=0.38t/ha, CV=9.6%.

Trial 2 – Wimmera (Longerenong)

Aim

To determine whether delaying harvest has an effect on yield and oil of canola varieties with
and without the PodGuard® trait.

Paddock details

Location: Longerenong
Annual rainfall: 508mm
GSR (Apr-Oct): 373mm
Soil type: clay loam
Paddock history: 2015 faba beans

Trial details

Crop type: Canola
Treatments: Refer to Table 1
Target plant density: 50 plants/m²
Seeding equipment: Knife points, press wheels, 30cm row spacing
Sowing date: 2 May
Replicates: Four
Harvest date: Refer to Table 1 and 2 for harvest timings

Trial inputs

Fertiliser: Granulock Supreme Z + Impact @ 50kg/ha at sowing, 90kg/ha SOA at
two-leaf, and 200kg/ha of urea applied as a split application at four-leaf
and eight-leaf
Herbicide: Weeds managed to best practice

Reglone @ 3L/ha + BS 1000 @ 0.25% (over first harvest timing)

Insecticide: Managed to best practice; no insect damage was observed
Fungicide: Low levels of blackleg were present in each trial
Seed treatment/inoculant: All certified and treated by seed companies

Methods

A split block replicated trial was sown at Longerenong. Each trial had six varieties comparing optimum and delayed harvest (Table 1 and 2). Treatment 2, an optimum harvest and delayed harvest treatment, were selected to adapt to and incorporate adverse weather events (rainfall and high wind, Figure 2). Subsequently, the trial aim for Longerenong differs to the Warmur trial by comparing yields when harvested on time versus late. Yields and oil percentage were corrected to the average canola moisture of each harvest timing.

Assessments at both locations included establishment scores, NDVI, colour change when spraying, and grain yield and quality parameters.

Table 3. The treatment descriptions at the Longerenong site.

Canola shatter reduction with Podguard table 3

Canola shatter reduction with Podguard figure 2

Figure 2. Weather conditions between optimal harvest timing 6 December and delayed harvest 23 December 2016. The line graph represents the maximum wind gust speed registered on that particular day, the bar graph represents the amount of rainfall received on a particular day.

Results and interpretation

45Y25 achieved the highest yield at the site when harvested at the optimal time. Both PodGuard® lines yielded second highest followed by Bonito, Hyola 559TT then Stingray (Figure 3).

Plots harvested at the optimal time yielded better than the delayed harvest treatment across all varieties. Yield losses between harvest timings was lower for the PodGuard® lines than for other varieties. InVigor R 5520P was the highest yielding variety in the delayed harvest timing.

Canola shatter reduction with Podguard figure 3

Figure 3. Mean grain yield (t/ha) of canola varieties and effect of delaying harvest at
Longerenong. LSD bars indicate significant difference for the two way interaction between variety x harvest timing Stats: P=0.002, LSD=0.29t/ha, CV=6%.

The oil percentage increased slightly from 41.4 to 42.7 per cent with a delayed harvest (P=0.02, LSD=0.85). There was no significant interaction between varieties and harvest timing for oil (P=0.61). An increase in oil percentage corresponds with a decrease in moisture content. As the first timing of harvest had an average moisture content of 6.3 per cent compared to 5.8 per cent at the second harvest, this may account for the slight increase. The oil did not increase as much at the Longerenong site as it did at Warmur. This may be due to timing of the first desiccation as the Longerenong trial was sprayed when varieties were much closer to full maturity.

Commercial practice

The Warmur trial showed that desiccating (or windrowing) at the standard 40-60 per cent seed colour change can incur significant yield penalties. As both the simulated shattering events at Warmur and natural shattering at Longerenong show, however, the gains made by delaying desiccation can be quickly lost. This is why desiccation or windrowing traditionally occurs when it does.

The reduced losses of the PodGuard® lines shown in these trials potentially shifts management towards a later desiccation/windrow timing than currently practiced. This not only offers growers increased potential yields but also increased harvest flexibility. For example, if two varieties are of equal maturity, the PodGuard® line could be left to stand until the other is windrowed. Also, if direct-heading, barley may be preferentially harvested in front of forecast wet weather to maintain quality as PodGuard® lines will not shatter as much as conventional varieties in wind. This effect was seen at BCG’s Nhill Canola Varieties in 2016 where harvest was delayed due to logistics. InVigor® R 5520P yielded highest in this trial (Lemon, 2016).

In all instances, delaying harvest increased the oil content achieved by varieties. Delaying windrowing to achieve this may leave standard varieties at greater risk of shattering loss, thus negating any economic benefit.

The PodGuard® trait is effective in protecting canola from pod shatter. As the canola plant matures, all varieties become more susceptible to grain loss but PodGuard® prevents excess losses in an extreme weather event at a single point in time. Varieties with the PodGuard® trait allow delayed windrowing (80-90 per cent colour change) or desiccating a paddock to be direct headed when the crop is fully mature. This will maximise yield and oil content without substantial grain loss. The trait does not allow delaying harvest past the point of maturity, but will mitigate losses in such event.

What the PodGuard® trait offers growers is a greatly reduced production risk when utilising the Roundup Ready® system. With canola being the highest input crop in the rotation, reduced risk of losses using PodGuard® offers growers a tool to reduce their overall risk when using canola in the rotation.

On-farm profitability

At the Warmur site, letting the crop mature naturally increased the average profitability of all varieties by $378/ha. Bonito, although not the top yielding variety, had the largest return of all varieties at $1681/ha. InVigor® R 5520P was second highest at $1563/ha.

By not desiccating and delaying harvest, shattering loss risk increases for non-PodGuard® varieties. After a simulated shattering event, InVigor® R 5520P was the least affected of all varieties, returning $1192/ha (a $366/ha decrease) compared to Bonito decreasing in returns to $691/ha ($990 decrease), a difference of $506/ha (Table 4).

When comparing Roundup Ready® varieties in the medium to high rainfall zones, InVigor® R 5520P is a viable option economically, especially in the presence of an extreme weather event. However, given the additional costs associated with current Roundup Ready® technology, PodGuard® lines are not necessarily more profitable at this point in time.

Table 4. Partial Gross margin of the canola varieties at the Warmur site.

Canola shatter reduction with Podguard table 4

Assumptions are; canola sold at $512/t and $460/t for GM canola (Beulah, Nov 30 2016). Oil bonus has been added according to individual varieties (Table 2). Varieties have been corrected to different seed costs, hybrid seed $23kg and open pollinated $5kg, and sowing at 2.5kg/ha and 3kg/ha respectively. Bonito also has been corrected for an EPR of $5/tonne and RR varieties licences have been accounted for. No other management costs have been included.

References

McClelland A., Pratt T., 2014, FarmLink 2014 Research Report, ‘PodGuard® Demonstration with FarmLink’ pp. 51-53.

Bayer Crop Science, 2016, InVigor® R 5520P Factsheet, ‘Combining extra yield potential with PodGuard flexibility’ pp. 1-4.

Street M., 2013, GRDC Update Papers, ‘Harvesting canola in 2013 – to windrow or direct head?’.

Hertel K., Potter T., Street M., Wythes T., Breust P, 2013, GRDC Direct Heading Canola Fact Sheet, ‘EarlyPlanning Key To Direct Heading’.

Lemon J., 2016, 2016 BCG Season Research Results, ‘Canola varieties’ pp. 79-85.

Acknowledgements

This research was funded by Bayer CropScience.

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