Trial Results
Wheat Canopy Management
Key Outcomes
 The earliest time of sowing, on average, produced lower yields than plots sown 2
and 4 weeks later
 The second time of sowing, on average, produced the highest yields
 Naparoo was the highest yielding variety in the trial
 Lower plant densities produced yields equal to higher populations when sown early
 Seeding applications of nitrogen generally produced the highest yields
Trial Objectives: To determine optimum management strategies for different wheat
varieties based on time of sowing
Plot Size:
Replicates:
5m x 1.6m
3
Treatments
All TOS
The trial consisted of 4 times of sowing (TOS):
TOS 1 – 21st April 2011
TOS 2 – 5th May 2011
TOS 3 – 19th May 2011
TOS 4 – 3rd June 2011
4 varieties – Esto, Mace, Naparoo and Scout
4 seeding densities – 50, 100, 200 & 300 seeds/m 2
Nitrogen treatments - Nil N, 50 or 100 kg N/ha at
seeding, 100 kg N/ha Zadok’s growth stage (GS) 31.
All plots were sown with 140 kg/ha Single Super
Phosphate
Trial Results
Due to the range of treatments and combinations of
treatments in this trial, the analysis of the trial is
rather complex.
The purpose of this trial is to
determine how to manage the canopy of a wheat
crop in relation to time of sowing (TOS), variety
choice, nitrogen status and strategy and seeding
rate. Therefore we will begin by looking at what the
overall trends of the trial were across all times of
sowing. Following this, we will delve deeper into the
results to determine how each variety should be
managed according to its time of sowing.
6|Trial Results 2011
In 2011 the first time of sowing was prior to Anzac
Day, the date generally accepted as the earliest for
sowing main season wheats. This enabled us to
generate some data to see whether this “standard”
is still justified for modern wheat cultivars and what
modifications may be implemented to reduce the risk
of early sowing.. With the recent trend towards
earlier sowing (and MNHRZ data to support it!) – the
question remains: How early is too early?
Table 1: Wheat Yield & Protein vs. Time of Sowing
TOS
Yield (kg/ha)
Protein (%)
1
4674.1
10.12
2
5867.3
9.35
3
5582.4
9.95
4
4495.2
8.96
LSD (P=0.05)
390.74
0.296
From the data in Table 1, there is a significant yield
loss averaged across all varieties, associated with
sowing at the first time of sowing. This lower yield,
whilst over 1 t/ha lower yielding than the 2 nd TOS
sown 2 weeks later, may actually support sowing at
this time given the opportunity. Additionally, the
average yield at TOS 1 is not any lower than TOS 4,
which was sown 6 weeks later. Secondly, had the
dry spell in August-September continued, even
shoter season varieties sown at TOS 1 may have
been the highest yielding, as these plots had almost
completed grain fill during these poor conditions
(hence higher protein figures in Table 1). Thirdly,
the plots sown in June needed good conditions in
spring to achieve these yields. Had the end of the
year been a terminal drought, there would likely
have been large differences in yield between TOS 1
& 4. In summary, there is arguably more upside to
sowing too early as opposed to too late.
The other factor that may have contributed to poorer
yields at TOS 1 was the fungal disease eyespot that
was present in this area of the trial. With early
sowing and vigorous early growth, eyespot was able
to flourish. As it was too late to control once noticed,
this likely influenced the yields of this TOS
considerably.
Given that we now understand the general trends
associated with time of sowing in this trial, how do
we ensure that we maximise yields at each of them?
We will look into this deeper by looking at the
management of each variety at each individual time
of sowing.
TOS 1 – 21/04/2011
TOS 2 treatments had the full range of plant
densities and nitrogen applications.
Table 3 &
Figure 2, indicates there were large yield gains
associated with the optimal nitrogen strategies for
each variety. In most cases this was 50 kg N/ha at
seeding.. Scout was the exception , where Nil N
and 50N plots produced significantly yields than
either 100 kg N/ha at seeding or GS 31. Scout
appears to produce a significant amount of biomass
with the high rate at seeding N applciatons, which
may have resulted in early subsoil moisture
depletion and lower yields.
GS 31 applications of nitrogen at this time of sowing
did not perform well. Seeding densities made a
significant difference to final yield at this TOS. Both
Naparoo and Scout produced significantly higher
yields when sown at lower densities. . Reducing
the initial number of plants per unit area is an
effective way of managing this biomass early in the
season. The thinner crop takes longer to develop
the same biomass as a more densely sown crop. It
is this delay in biomass production that can save
carbohydrate and water for growth and grain filling
later in the season. This is essential if the crop is to
finish successfully in a dry season.
Mace and Estoc did not respond to reduced seeding
densities at this time of seeding.
TOS 3 – 19/05/2011
This time of sowing was a limited data set (all plots
were sown at 100 seeds/m2), therefore there is no
data associated with seeding densities higher or
lower than this. However, previous results from the
MNHRZ wheat canopy management trials suggest
that 100 seeds/m2, or lower, is no limitation to crop
yield when sown early. Because there was only one
plant population at TOS 1 there are only nitrogen x
variety interactions.
From the data in Table 2 & Figure 1, we can see
that nitrogen management is able to have a large
influence on the yield of the different varieties. Most
varieties when sown at the very early time of sowing
gave a greater response to delayed nitrogen
applications. This is most likely associated with
seeding applications of nitrogen producing too much
biomass, resulting in earlier soil water depletion
during grain fill. This was not the case for Naparoo
however, which produced greater yields with
seeding applications on nitrogen. Naparoo is a low
biomass producing variety prior to GS 31. This
delayed biomass accumulation may be another
reason why seedbed nitrogen applications did not
cause haying off like it appeared to in other varieties
tested.
TOS 2 – 05/05/2011
7|Trial Results 2011
At this time of seeding the results in Table 4 &
Figure 3 indicate important trends.
Improvement in yield associated with best
management practices is starting to decline. This is
due to the season imposing more yield limiting
factors on the crop than can be compensated for by
optimal seeding densities and nitrogen strategies.
Essentially we are hoping that spring rainfall is good
to ensure that yields will be OK.
Secondly, the number of management practices
making a significant difference to final yields in
declining.
This is again associated with
development timing of the crop being “rushed along”
by the season (increased temperatures and
daylength occur sooner, therefore less vegetative
growth). Once again, this results in crops that are
reliant on either subsoil moisture or spring rainfall to
finish adequately.
Thirdly, there is little variation in the management
strategies that promote higher yields between
varieties by this TOS. Essentially, this time of
sowing compresses the development time of the
crop into a shorter period, meaning that higher
seeding rates and higher seedbed nitrogen rates are
required to enable the crop to produce adequate
biomass and head numbers for optimal yield.
Surprisingly at this time of seeding, both Mace and
Estoc produced significantly higher yields when
sown at 100 seeds/m 2. Previous MNHRZ trial
results have suggested that higher seeding rates
were required for the later times of sowing to
produce their best possible yields. At this time of
seeding, 50 seeds/m 2 was not adequate to maximise
yields, resulting in significantly lower yields in both
Mace and Estoc.
However, later sowing reduces the impact of these
strategies, as the season tends to influence yields
more heavily than management.
Nitrogen application strategies are heavily reliant on
seedbed nitrogen applications, with all varieties
responding positively to this strategy (100 kg N/ha at
seeding was best). Early nitrogen is required at the
later times of sowing to promote tillering and
biomass production – both of which are limited early
by cooler temperatures at this time of sowing. This
strategy is very risky as high nitrogen rates and
seeding density may be detrimental should spring
conditions be less than favourable. , Conversely if
we don’t provide adequate plant numbers or
nitrogen to the crop we are likely to lose yield
anywayIn 2011 TOS 3 yields were only slightly
lower (~300 kg/ha) than the best time of sowing
(TOS 2). Late spring rains and excellent levels of
subsoil moisture leading into the dry spell in AugustSeptember ensured that this time of sowing was a
profitable one. Subsoil moisture and spring rainfall
are not factors that can be relied on every year –
even in the high rainfall zones.
Late season applications of nitrogen can be used to
successfully increase yield. They are most profitable
when sowing is early, soil nitrogen is low and plant
populations are high. Of course all nitrogen
applications are more profitable in favourable
seasons can be used to increase grain protein.
TOS 4 – 03/06/2011
Again, this time of sowing was able to produce
respectable yields in 2011 due to sub soil moisture
levels and spring rain. Data in Table 5 & Figure 4
indicates the management strategies still had some
bearing on the final yields achieved, albeit very
minor. Again higher densities and seedbed nitrogen
are required to produce good yields at this TOS.
Although not tested in this trial, short season wheat
varieties such as Axe, do provide some flexibility if
sowing later in the season, as their basic vegetative
period is shorter, meaning that less yield is lost
when later sown. The use of such varieties could be
considered useful on farms that have larger areas to
cover.and by necessity, a longer sowing period.
Putting It Into Practice
Canopy management is the use of a range of
management tools to promote optimal yields in
different varietal types. The tools available are
dependent on when the crop is sown. They include
variety
choice,
seeding
density,
nitrogen
management and other management factors.
8|Trial Results 2011
Early sowing is essential to optimise yields and
provides flexibility for seasonal conditions and in
season management of the crop.
Each variety has its own traits that can be
manipulated to produce high yields and quality.
Acknowledgements

Pat and Mary Connell - for allowing the MNHRZ
group trials on their land

Dan Vater, AGT – for supplying some of the
seed used in the trials
Funding Body
Australian Government – Caring for Our Country
initiative
Table 2: Best practice management strategies and associated yield increases for TOS 1
Variety
Estoc
Mace
Naparoo
Scout
Best Nitrogen
100N GS 31
100N GS 31
100N Seeding
100N GS 31
Trend
+ 500 kg/ha
+ 800 kg/ha
+ 800 kg/ha
+ 600 kg/ha
Table 3: Best practice management strategies and associated yield increases for TOS 2
Variety
Estoc
Mace
Naparoo
Scout
Best Density
300 Seeds
100 seeds
50, 100, 200 Seeds
100 seeds
Trend
+ 200 kg/ha
< 100 kg/ha
+ 400 kg/ha
+ 300 kg/ha
Best Nitrogen
50 & 100N Seeding
50 & 100N Seeding
50 & 100N Seeding
Nil & 50N Seeding
Trend
+ 900 kg/ha
+ 800 kg/ha
+ 500 kg/ha
+ 300 kg/ha
Table 4: Best practice management strategies and associated yield increases for TOS 3
Variety
Estoc
Mace
Naparoo
Scout
Best Density
Trend
100, 200, 300 Seeds+ 500 kg/ha
100 Seeds
+ 500 kg/ha
100 Seeds
< 100 kg/ha
300 Seeds
< 100 kg/ha
Best Nitrogen
Trend
100N Seeding & GS 31
+ 200 kg/ha
100N Seeding
+ 500 kg/ha
100N Seeding
+ 500 kg/ha
100N Seeding
+ 500 kg/ha
Table 5: Best practice management strategies and associated yield increases for TOS 4
Variety
Mace
Naparoo
Scout
Best Density
300 Seeds
100 Seeds
200 Seeds
Trend
< 200 kg/ha
< 100 kg/ha
< 200 kg/ha
Best Nitrogen
100N Seeding
50N Seeding
100N Seeding
Trend
+ 300 kg/ha
< 100 kg/ha
< 200 kg/ha
- Denotes statistically significant (P=0.05)
- Denotes statistically significant (P=0.1)
Figure 1: TOS 1 Variety Yield (kg/ha) vs. Nitrogen strategy
9|Trial Results 2011
8000.0
Estoc
Mace
Naparoo
Scout
7000.0
LSD (P=0.05) – NS
6000.0
Yield (kg/ha)
5000.0
4000.0
3000.0
2000.0
1000.0
0.0
Nil N Seeding
50N Seeding
Figure 2: TOS 2 Variety Yield (kg/ha) vs. Nitrogen strategy
10 | T r i a l R e s u l t s 2 0 1 1
100N Seeding
100N GS 31
8000
Estoc
Mace
Naparoo
Scout
7000
6000
Yield (kg/ha)
5000
4000
3000
2000
1000
0
Nil N Seeding
50N Seeding
Figure 3: TOS 3 Variety Yield (kg/ha) vs. Nitrogen strategy
11 | T r i a l R e s u l t s 2 0 1 1
100N Seeding
100N GS 31
8000
Estoc
Mace
Naparoo
Scout
7000
LSD (P=0.1) – 437.69
6000
Yield (kg/ha)
5000
4000
3000
2000
1000
0
Nil N Seeding
50N Seeding
Figure 4: TOS 4 Variety Yield (kg/ha) vs. Nitrogen strategy
12 | T r i a l R e s u l t s 2 0 1 1
100N Seeding
100N GS 31
8000
Mace
Naparoo
Scout
7000
LSD (P=0.05) - NS
6000
Yield (kg/ha)
5000
4000
3000
2000
1000
0
Nil N
13 | T r i a l R e s u l t s 2 0 1 1
50N Seeding
100N Seeding
100N GS 31