Trial Results
Canola Agronomy
Key Outcomes
 The Clearfield varieties 46Y83 and Hyola 474CL were consistently the highest
yielding in the trial
 100 kg/ha of nitrogen was needed to maximise yields at Time of Sowing (TOS) 2,
while 50 kg/ha N was adequate to maximise yields at TOS 1.
 Garnet and Agamax produced higher oil contents than all other varieties tested
 100 kg/ha of nitrogen resulted in significantly lower oil contents
Trial Objectives: To test the performance of a range of canola varieties and to
determine optimum nitrogen management strategies for them
Plot Size:
Replicates:
10m x 1.6m
3
Treatments
The trial consisted of 2 times of sowing (TOS):
TOS 1 – 5th May 2011
TOS 2 – 27th May 2011
All plots were sown with 60 kg/ha of MAP.
9 varieties –Conventional: Garnet, Hyola 50, CBAgamax, Triazine Tolerant: Crusher, ATR-409,
Hyola 555TT, Clearfield: Hyola 575CL, 46Y83 and
Hyola 474CL
3 Nitrogen treatments - Nil N, 50 or 100 kg N/ha 6
weeks after emergence.
All plots were analysed for oil and protein content
following harvest.
Trial Results
Yield
Time of Sowing
There was no response to time of sowing in the trials
this year due to excellent reserves of plant available
water at sowing (>50mm). This was despite TOS 2
being sown 3 weeks later than TOS 1. This data
underpins the need to know plant available water
levels in paddocks/areas to be sown to canola, as
water stored in the profile is of comparable value to
growing season rainfall for canola yield. This is in
direct contrast to MNHRZ canola trials over the last
4 years, where early sowing has always been a
major advantage for high yields.
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Variety
The Clearfield varieties 46Y83 and Hyola 474CL
consistently produced the highest yields in the trial.
These yields however, were often not significantly
different from other varieties that were tested
including some of the Triazine Tolerant lines (See
Figure 1). The Clearfield varieties did perform
exceptionally well at TOS 2, yielding more than the
majority of other varieties tested.
In contrast to the trials in previous years, Garnet and
Hyola 50 did not perform as well. The trial site in
2011 had both Garnet and Hyola 50 stubbles from
2010 within 500m of it. Blackleg infection may have
been a contributing factor for the lower yields in
these varieties. Crusher too, has similar genetics to
Garnet, which may have been the reason for its
relatively poor yield performance in this trial.
Agamax was a solid performer in these trials, being
the highest yielding conventional variety at both
times of sowing. However, this has not been the
case in past trials, and was not significantly higher
than Garnet or Hyola 50 at either TOS.
Of the Triazine Tolerant lines tested, ATR-409 again
produced good yields. It yielded equivalent to or
better than any other variety at TOS 1, but with later
sowing suffered yield decline as the vegetative
growth period length declined. This was similar to
what occurred with Hyola 555TT, unlike Crusher
which yielded more at the later TOS.
The
photosynthetic inefficiency that exists with the
Triazine Tolerant genetics appears to be decreasing
as newer varieties are released. Early releases of
TT varieties often produced 20-30% lower yields,
however new varieties now are only 2 - 10% lower
yielding than imi tolerant and conventional varieties.
Nitrogen
Responses to nitrogen in the trial were heavily
influenced by TOS (See Table 1). When sown
early, there was no advantage to applying nitrogen
above 50 kg N/ha. This was most likely due to the
high soil levels of N at the site (136 kg N/ha 090cm). Early sowing allowed for rapid growth of the
roots and consequently excellent exploration of the
soil profile for nitrogen. This is contrast to TOS 2,
where the crop was highly responsive to increased
rates of nitrogen, as root exploration may have been
poorer when sown 3 weeks later into cooler
conditions.
Table 1: Canola Yield (kg/ha) vs. Time of Sowing
and Nitrogen rate (kg N/ha)
TOS 1
TOS 2
LSD (P=0.05)
Nil N
2165.6
2206.6
50N
2593.0
2606.8
100N
2778.7
2919.0
186.57
This data demonstrates the value of knowing initial
soil nitrogen levels and using them as a base for
making in season decisions for nitrogen application.
A deep N test on canola paddocks can quantify
levels of N and soil water prior to sowing the crop
that can be used during the season to make better
decisions on applications to produce optimum yields.
crop throughout the season will aid in these
decisions.
Table 2: Canola Oil Content (%) vs. Time of Sowing
and Nitrogen rate (kg N/ha)
TOS 1
TOS 2
Nil N
47.6
46.4
LSD (P=0.05)
50N
47
47.1
100N
45.8
45.4
0.68
Varieties also differed considerably in grain oil
contents (See Figure 2). The conventional varieties
Garnet and Agamax consistently produced the
highest oil contents in the trial, especially at TOS 2,
when all other varieties were lower. At TOS 1, the
Clearfield varieties also produced high oil , however
they dropped off significantly with later time of
sowing. All of the triazine tolerant varieties and
Hyola 50, had significantly lower oil contents when
compared to the other varieties tested. Whilst the
difference in yield between triazine tolerant and
other canola varieties appears to be reducing, oil
content is still significantly lower in triazine lines.
Choosing varieties that produce higher oil contents
is another key decision that needs to be made – one
which can make a large difference to profitability at
the end of the season.
Putting It Into Practice
Oil
Oil content was significantly influenced by TOS,
variety and nitrogen management. The earliest time
of sowing produced significantly higher grain oil
compared to later sown tretaments for all varieties
except the conventional types where oil content was
higher at the second time of sowing.
Nitrogen also had a significant effect on grain oil
content (See Table 2).
100kg N/ha produced
significantly lower oil than Nil and 50 kg N/ha. This
is a result of higher grain protein contents
associated with the higher N rates. Canola, in a
similar way to cereals, produces higher grain protein
contents at the expenset of oil (or carbohydrate in
the case of cereals). This data contrasts previous
MNHRZ results where there has been little
difference between nitrogen treatments for oil
content. Understanding this interaction between
nitrogen and grain oil content is one of the key
management decisions that needs to be considered
with canola. Over fertilising with nitrogen will reduce
oil content whilst under-fertilising may cost yield.
Understanding the soil nitrogen and soil water of the
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Variety choice is still the primary factor governing
yield potential and oil content of canola in the high
rainfall areas.
Yield differences between the
conventional and herbicide tolerant canola varieties
seems to be narrowing, so choices should be made
more so on what weeds are present, blackleg
resistance and oil content.
Nitrogen applications to canola should remain
flexible in order to prevent excessive expenditure on
the crop for little or no gain or even detriment if oil
content drops considerably. Measuring nitrogen
levels in the soil prior to sowing and the use of
nitrogen rich test strips in the paddock are both
effective ways of assessing the amount of nitrogen
available to your crop. When this is matched with
the amount of plant available water that you have at
a particular point in the year, well informed
management decisions on in -crop nitrogen needs
can be made.
Acknowledgements

Pat and Mary Connell for allowing the MNHRZ
group trials on their land

Viterra, Tarlee (Robin Mansell) for oil and
protein testing
Funding Body
Australian Government – Caring for Our Country
initiative
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Figure 1: Canola yield (kg/ha) vs. Variety and Time of Sowing
3500.0
TOS 1
LSD (P=0.05) = 323.15
TOS 2
3000.0
2500.0
2000.0
1500.0
1000.0
500.0
0.0
46Y83
Agamax
ATR-409
Crusher
Figure 1: Canola Oil Content (%) vs. Variety and Time of Sowing
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Garnet
Hyola 474CL
Hyola 50
Hyola 555TT
Hyola 575CL
51.0
TOS 1
LSD (P=0.05) = 1.18
TOS 2
50.0
49.0
48.0
47.0
46.0
45.0
44.0
43.0
42.0
41.0
40.0
Garnet
Agamax
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Hyola 50
Hyola 555TT
ATR-409
Crusher
Hyola 575CL
46Y83
Hyola 474CL