Optimising the gross return value proposition of farmer-retained OP TT vs Hybrid CT® and TT canola with varying seed size and plant population targets
Optimising the gross return value proposition of farmer-retained OP TT vs Hybrid CT® and TT canola with varying seed size and plant population targets
Author: Justin Kudnig (Pacific Seeds). | Date: 08 Mar 2021
Key messages
- Grading OP TT canola seed to >2mm increases plant establishment, grain yield and gross returns.
- Higher yielding CT® and TT hybrids provide consistently higher grain yields and gross returns than OP TT varieties.
- CT® and TT hybrids with seed sizes of greater than or equal to 2mm established at lower plant populations can produce higher grain yields and gross returns than OP TT varieties graded to >2mm at higher plant populations.
Aims
This research examined differences in plant establishment (plants/m2), harvested grain yield (t/ha) and production of five different hybrids versus three open pollinated (OP) TT varieties (farmer retained source) with various seed sizes. The overall aim was to determine the best gross return ($/ha) value propositions for growers.
Introduction
Growers perceive there is an agronomic advantage in using OP TT canola seed graded to larger seed sizes and planted at higher plant populations. However, Australian canola growers and agricultural advisors have been seeking more data and recommendations around OP TT variety performance versus new CT® and TT hybrids.
This research examined the effect of canola seed size and plant density of new CT® and TT hybrids vs OP TT varieties on harvested grain yields and gross returns.
Previous research in this area has generated variable results but, in general terms, larger canola seed size, especially of hybrids, has provided higher establishment, particularly when planted deeper.
Brill et al (2015) demonstrated that hybrid cultivars with larger seed size could maintain higher emergence rates and grain yield than OP cultivars from deep sowing. This research also showed that larger seed size of both hybrid and OP canola increased early biomass accumulation and final grain yield.
However, Harries and Seymour (2018) found seed size did not significantly affect canola emergence, yield or seed quality. Increasing seed size had a positive linear relationship with early canola biomass and 1000-seed weight, but days to flowering and days to the end of flowering had a negative linear association with seed size.
In 24 experiments conducted across a range of agricultural environments in Western Australia between 2010 and 2014, French et al (2016) reported grain yield response to crop density was adequately described by an asymptotic model (where yield approaches but never quite reaches a ceiling at very high density).
Zhang et al (2016) demonstrated that relative yield and profit of Australian hybrid compared with OP canola is largely determined by growing season rainfall.
Method
Nine field research extension sites (RCB * 3 replicates) were sown at Geraldton WA, Morbinning WA, Katanning WA, Kojonup WA, Yarrawonga Vic, Lake Bolac Vic, Horsham Vic, Wallendbeen NSW and Lockhart NSW.
These nine trial environments varied widely in seasonal rainfall, cropping history, soil type and soil pH. A combination of best management practice (BMP) and district standard practice (DSP) treatments were applied at each location, to enable data collection for accurate comparison.
A total of nine canola varieties were compared: three OP and six hybrids across two different herbicide technology groups with three different target populations. Herbicide tolerance technologies included, CT® - Clearfield® + Triazine Tolerant and TT - Triazine Tolerant.
Target population treatments were 15 plants/m2, 25 plants/m2 and 40 plants/ m2 . These were based on an estimated 75% establishment survival factorial by adjusting all seed packet weights.
1000-seed weight (TSW) values across varieties varied from 2.47 (405,000 seeds/kg) to 6.75 (148,000 seeds/kg). Effective seed size ranged from <1.8mm to >2mm in diameter.
Measurements taken included:
- plants per m2 using 4*1m row counts per plot 14 DAS and 28 DAS
- visual subjective vigour ratings at 4-6 leaf stage
- visual maturity ratings at flowering and maturity
- grain yield (t/ha) using plot harvesters
- gross return calculations using assumptions from Tables 1 and 4.
Population and yield analysis for single sites were performed by fitting Entry, Popm2, TargetPop, TSW as fixed linear factors. Spatial adjustments were performed using the auto-regressive model which gave a BLUE output for each site.
Statistical Reference: Using ASReml (Gilmour et al 2010).
In addition, yield was further investigated using single step factor analytic MET (Multiple Environment Trial) analysis with ASReml in a model with plants/m2 as a linear fixed factor with composite entry as a random factor which gave a BLUP for each site. Spatial adjustments were determined using the auto-regressive model. Significant G*E*M effects were identified by the MET analysis.
Results and Discussion
French et al (2016) showed that canola field establishment varied from 0.3 to 1 and was higher at low target densities with a median of 0.585 at a target density of 40 plants/m². This research showed that across variety by seed size treatments mean field establishment varied from 0.51 to 0.87 for the 15 plants/m2 target, 0.43 to 0.79 for the 25 plants/m2 target and 0.42 to 0.76 for the 40 plants/m2 target (Figure 1).
Figures 2 and 3 illustrate the differences between a drier seasonal growing profile compared to a wetter rainfall zone. Geraldton represents an example of one of three trial environments that clustered for both establishment and yield results, showing lower overall percentage establishment for all variety treatments and exacerbated differences between hybrid and OP varieties for plant establishment. Most of the hybrids showed excellent establishment under less optimal emergence conditions.
Kojonup represents an example of one of the six remaining trial environments where overall rainfall and establishment conditions where more conducive to higher levels of plant establishment across all treatments. The OP TT varieties regardless of seed size, showed higher overall plant establishment compared to the Geraldton environment, however most of the hybrids again demonstrated the highest levels of establishment.
Figure 1: Mean % of target population achieved in variety by seed size treatments across nine environments.
Figure 2: Mean % of target population achieved in variety by seed size treatments for the Geraldton environment.
Figure 3: Mean % of target population achieved in variety by seed size treatments for the Kojonup environment.
French et al (2016) showed little difference between optimum densities for hybrid and OP cultivars. Optimal densities in the high rainfall zone were about 10 plants/m² higher than in low and medium rainfall zones.
This research demonstrated that site environmental conditions and variety genetics had the largest effects on final established plant numbers rather than (TSW) seed size and target plant populations.
Yield responses using the MET analysis showed that environment was the key factor, followed by genetics. The 40 plants/m2 target treatment provided the highest yields across all trial locations (Table 5).
If population establishment is known, adding seeding rate to the model does not contribute additional information to the model. However, in a real-life situation, seeding rate is the single largest seed-related factor growers can control to target a specific establishment. If pop/m2 is removed from the analysis model on individual trials, then TargetPop and TSW factors become more significant.
Catalier (2019) found in some studies, canola yield increased with seeding rate (Harker et al 2012a; 75 and 150 seeds/m2), but in other studies seeding rate did not influence yield (Kutcher et al 2013). Gan et al (2016) observed that yield response to seeding rate appeared to depend not only on environment, but also on the seeding rates or plant densities being compared - with lower seeding rates more likely to show yield responses than higher seeding rates.
Yang et al (2014) found seed yield increased with seeding rate, however yield leveled off at higher plant densities. With seed size, a yield benefit from larger canola seed was observed by Elliot et al (2008) and Brill et al (2016), while Harker et al (2015), Clayton et al (2009), Lamb and Johnson (2004) did not see a benefit of larger seed on canola yield.
The MET analyses (Table 6) showed two distinct yield clusters broadly described as Cluster 1 (higher rainfall and higher yielding) and Cluster 2 (drier, lower rainfall environments). Yields across both clusters showed CT® or TT hybrids with more widely adapted genetics with seed sizes greater than or equal to 2mm providing the highest yields at 25 and 40 plants per m2 targets compared to any of the OP TT varieties regardless of plant population target or seed size.
The gross return comparisons between hybrids and OP varieties were calculated using the most popular OP TT variety, ATR Bonito with >2mm seed size and at 40 plants per m2 target used as the baseline.
Some CT® and TT Hybrids between =2mm to >2mm seed size at the 25 or 40 plants per m2 targets compared to OP TT varieties with larger >2mm seed showed increases in average gross returns ranging between $84/ha to $321/ha in the higher rainfall environments and $36/ha to $196/ha in the medium rainfall environments.
Figure 4: 2020 analysed grain yield (t/ha) of ATR Bonito - OP TT >2mm vs <2mm seed size across three population targets
For ATR Bonito, when comparing seed size of >2mm vs <2mm, the G2mm size at 25 and 40plants/m2 population targets provided the highest yield performance in all environments. The <2mm seed size at 40plants/m2 showed yield equivalence with >2mm seed size at the 15plants/m2 population target.
Figure 5: 2020 gross return comparisons ($/ha) of ATR Bonito - OP TT >2mm vs <2mm seed size across three population targets
The gross return baseline was defined using ATR Bonito at >2mm seed size at 40plants/m2 population target which provided the highest returns across all sites. Interestingly, ATR Bonito at G2mm seed size at the 25plants/m2 target showed similar returns to the <2mm treatment at 40plants/m2, demonstrating that savings related to sowing seed can be captured by growers using graded OP TT seed to >2mm size.
Figure 6: 2020 analysed grain yield (t/ha) of ATR Bonito - OP TT >2mm vs Hyola Enforcer CT® =2mm seed size across three population targets
Hyola Enforcer CT® with =2mm seed size at 25 and 40plants/m2 population targets provided higher yields even over ATR Bonito >2mm at 40plants/m2 over all sites. Hyola Enforcer CT® with =2mm seed size at 15plants/m2 demonstrated yields equal to, slightly below or higher than ATR Bonito >2mm at 40plants/m2 target, depending on the individual environments.
Figure 7: 2020 gross return comparisons ($/ha) of ATR Bonito - OP TT >2mm vs Hyola Enforcer CT® =2mm seed size across three population targets
The gross return baseline was defined using ATR Bonito at >2mm seed size at 40plants/m2 population target. Hyola Enforcer CT® at 25 and 40plants/m2 population targets provided higher $/ha returns at all sites with the 15plants/m2 population target providing higher returns at some higher rainfall locations.
Figure 8: 2020 analysed grain yield (t/ha) of ATR Bonito - OP TT >2mm vs Hyola 350TT >2mm seed size across three population targets
Hyola 350TT with >2mm seed size at the 15, 25 and 40plants/m2 population targets provided higher yields over ATR Bonito >2mm seed size at all three population targets over all nine trial environments. ATR Bonito with >2mm seed size showed the highest yields at 40plants/m2 over 25 and 15 plants/m2 population targets across all trial sites.
Figure 9: 2020 gross return comparisons ($/ha) of ATR Bonito - OP TT >2mm vs Hyola 350TT >2mm seed size across three population targets
The gross return baseline was defined using ATR Bonito at >2mm seed size at 40plants/m2 population target. Despite the higher seed costs associated with the larger hybrid seed, Hyola 350TT at 25 and 40plants/m2 population targets provided higher $/ha returns at nearly all trial sites and importantly at the 15plants/m2 target, provided similar gross returns to OP TT >2mm baseline at 40plants/m2.
Figure 10: 2020 analysed grain yield (t/ha) of three OP TT varieties with >2mm at 40plants/m2 vs 2 hybrids =2mm and >2mm seed size at 25plants/m2 across three population targets
The hybrids, Hyola Enforcer CT and Hyola 350TT at the 25 and 40plants/m2 targets provided higher yields over all three OP TT varieties with >2mm at the 40plants/m2 target over all yield environments.
Figure 11: 2020 gross return comparisons ($/ha) of three OP TT varieties with >2mm vs 2 hybrids =2mm and >2mm seed size across three population targets
The gross return baseline was defined using ATR Bonito at >2mm seed size at 40plants/m2 population target. Hyola Enforcer CT at the 25plants/m2 target provided higher $/ha returns at all sites compared to all three OP TT varieties with >2mm seed size at 40plants/m2.
Despite the higher seed costs associated with the larger hybrid seed, Hyola 350TT at the 25plants/m2 target population provided comparable to higher returns to all three OP TT varieties with >2mm seed size at 40plants/m2.
Figure 12: 2020 analysed grain yield (t/ha) of three OP TT varieties with >2mm at 40plants/m2 vs four hybrids ranging from <1.8mm to >2mm seed size at 40plants/m2 across three population targets
Three of the four hybrids at 40plants/m2 showed higher yields than all three OP TT varieties across all locations with many of these being significantly higher. CT200251, a longer season experimental hybrid with <1.8mm small seed size at 40plants/m2 showed high yields in higher rainfall environments but yielded less competitively at individual lower yielding sites.
Figure 13: 2020 gross return comparisons ($/ha) of three OP TT varieties with >2mm at 40plants/m2 vs four hybrids ranging from (<1.8mm to >2mm) seed size at 40plants/m2 across three population targets
Hybrids, Hyola Enforcer CT® and HyTTech® Trophy at 40plants/m2 delivered higher gross returns than all three OP TT varieties at 40plants/m2 across all sites, whereas two other hybrids showed variable gross return responses due to influences from background genetics, plant maturity, individual site rainfall, seed size and related sowing costs.
Conclusion
This study highlights that G X E X M interactions are very complex and dynamic. Genetics (G) is the biggest controllable factor, i.e. varietal choice; Environment (E) is the most significant factor by far. Management (M) will influence to a small degree in some environments, but for every environment where M has a significant effect, there are many environments where it does not. From a profitability perspective, the main consideration is “Genetics by Multi-Environment” relationships.
In relation to addressing canola growers’ ongoing requests for further research on validation of grading OP TT seed to >2mm, this research showed the >2mm seed across three OP TT “farmer sourced” varieties, increased plant establishment by up to 35%, provided significant yield increases of up to 433kg per hectare and effectively lifted gross returns by up to $255 per hectare compared to the <2mm seed size.
Several CT® or TT hybrids across all nine environments whether =2mm or >2mm seed size, demonstrated up to 35% higher establishment than all the OP TT varieties whether <2mm or >2mm seed size. Grain yields of several CT® or TT hybrids were significantly higher than all OP TT varieties irrespective of seed size, measured up to 560kg per hectare.
Whether the trial locations received a medium or high growing seasonal rainfall, several CT® or TT hybrids, even with the lower plant population targets, provided higher gross returns in dollars per hectare than all three OP TT varieties with the >2mm seed size in conjunction with the highest target population.
This effectively validates that CT® or TT hybrids with higher yielding genetic backgrounds now provide a strong positive value proposition in $/ha for canola growers by consistently providing higher returns than graded larger seed of farmer retained OP TT canola seed.
Acknowledgments
2020 Trial Development, design and analysis by Dr David Tabah, Crop Research Lead (Canola), Advanta Seeds 2020 Trial planting, maintenance, spraying and harvest across Australia by Kalyx Australia, Synergy (SLR research & Extension), Crop Circle Consulting and TrialCo
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Paper reviewed by
Dr David Tabah, Crop Research Lead (Canola) – Advanta Seeds Australia