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Background and Objectives:
Sulphur (S) is essential for protein formation. As a component of
amino acids such as cysteine and methionine, S contributes to the
quality of protein in wheat grain and flour. Research in Europe,
Australia, and New Zealand has shown that inadequate supplies of S
dramatically lower the breadmaking quality of wheat. In a number of
these studies, the breadmaking quality problems were especially severe
in treatments where the nitrogen (N) fertility was high.
Currently, up to 30% of cultivated soils in the Prairie Provinces are
estimated to be deficient in S for both canola and legume production (Bettany
et al. 1982) and marginally sufficient for cereal production. This
area includes a large portion of the Gray Luvisolic soils and extends
into the Dark Gray and Black Chernozemic soil zones if the soils
contain low concentrations of organic matter, are coarse-textured,
well-drained, and intensively cropped (Bailey 1987). Furthermore, the
incidence of S deficiency on the Prairies is increasing as a result of
a number of factors. As observed in other parts of the world, reduced
S inputs from the atmosphere, less indirect application of S in N and
phosphorus (P) fertilizers, coupled with accelerated rates of crop
uptake by high yielding S-using crops, leaching of sulphate from the
rooting zone, and less mineralization of organic S from soil organic
matter have contributed to increased S deficiency (Tisdale et al.
1986; Doyle and Cowell 1993; Zhao et al. 1999c).
This study was conducted to generate information regarding the
impact of S fertilization on grain yield and quality of Canada Western
Red Spring (CWRS) wheat grown under western Canadian growing
conditions. In 1999, 2000, and 2001 we conducted field trials at
eighteen sites to:
- Investigate the relationship between grain S concentration,
grain N concentration, and grain N:S ratio and grain yield and
breadmaking quality of CWRS wheat (using twelve field sites from
1999 and 2000).
- Investigate the impact of S fertilization on the grain yield and
breadmaking quality characteristics of CWRS wheat. Within this
objective, we wanted to examine whether the breadmaking quality of
CWRS wheat was improved by S fertilization in the absence of a yield
response (using twelve field sites from 1999 and 2000).
- Evaluate agronomic tools (e.g. soil tests and plant tissue
tests) which would aid western Canadian producers to predict the S
concentration and N:S ratio in grain as well as quality responses to
S fertilization (using twelve field sites from 1999 and 2000).
-
Evaluate other varieties of the CWRS wheat
class to determine if they demonstrate similar quality responses to
S fertilization as AC Barrie. We also wanted to examine if
differences in quality characteristics between varieties could be
overcome with the application of S fertilizer (using four
established sites in 2000 and six new sites in 2001).
Procedure and Project
Activities:
Canada Western Red Spring wheat (Triticum
aestivum) was grown at eighteen locations across western Canada in
1999, 2000, and 2001. In 1999, field sites were located near
Erickson, MB; Brandon, MB (Brandon South); Melfort, SK; Kelvington,
SK; and Athabasca, AB. In 2000, field sites were located near
Erickson, MB; Glenboro, MB; two sites near Brandon, MB (Brandon North
and Brandon South); Rosebank, MB; Archerwill, SK; and Athabasca, AB.
In 2001, field sites were located near Rosebank, MB; Neepawa, MB;
Brandon, MB; Shoal Lake, MB; Kindersley, SK; and Saskatoon, SK.
Nitrogen and S were applied at varying rates as
urea and granular ammonium sulphate (20.5-0-0-24), respectively. A
blanket application of 40 kg P2O5 per hectare
was also applied as monoammonium phosphate (12-51-0) to each site.
Each treatment was replicated four times in a randomized block
design. In 1999 and 2000, AC Barrie CWRS wheat was planted at all
sites. At four sites in 2000 (Archerwill, Erickson, Glenboro, and
Rosebank) and at six new sites in 2001, AC Superb and BW267 were also
planted, but only under high N conditions. Therefore, treatments were
as follows:
A.
0 kg S and 26 kg N* per hectare – AC Barrie (1999 & 2000, only)
B.
0 kg S and 100 kg N per hectare – AC Barrie (1999, 2000, &
2001)
C.
20 kg S and 26 kg N per hectare – AC Barrie (1999 & 2000, only)
D.
20 kg S and 100 kg N per hectare – AC Barrie (1999, 2000, &
2001)
E.
0 kg S and 100 kg N per hectare – BW267 (2000 & 2001, only)
F.
20 kg S and 100 kg N per hectare – BW267 (2000 & 2001, only)
G.
0 kg S and 100 kg N per hectare – AC Superb (2000 & 2001, only)
H.
20 kg S and 100 kg N per hectare – AC Superb (2000 & 2001,
only)
*There were no 0 N treatments. The 0 N rate was
not feasible in combination with the 20 S rate because ammonium
suphate was used as the S source and MAP was used as the P2O5
source. Therefore, the low N treatment was adjusted to 26 kg N per
hectare for both S rates.
Agronomic measurements were
initiated to help identify appropriate agronomic tools (e.g. soil and
plant tissue tests) for predicting the S concentration and N:S ratio
of grain and whether or not S fertilizer should be applied to improve
grain quality. At the 1999 and 2000 sites, spring soil testing
consisted of taking three soil cores from each plot, just prior to
fertilization and seeding. Sampling depths at most sites were 0-15,
15-30, 30-60, and 60-90 cm. At Archerwill in 2000, only one composite
soil sample was collected from the 0-15, 15-30, and 30-60 cm depths
for the entire plot area prior to fertilization and seeding.
Appendices 1a and 1b summarize the soil SO4-S and NO3-N
concentrations to 60 cm for the sites in 1999 and 2000.
Mineralizeable N was also estimated on all surface samples (0-15 cm)
from 1999 and 2000 using a modification of the phosphate-borate method
developed by Gianello and Bremner (1986b). We then estimated
mineralizeable S by dividing the mineralizeable N values determined in
the phosphate-borate extraction by 8.3. This value of 8.3 was adopted
from the work of Bailey (1985) who found the average N:S ratio of soil
organic matter in Prairie Canadian soils to be 8.3:1. Midseason crop
measurements collected include concentrations of N and S in plant
tissue at 50% heading (Feekes 10.3 stage) at all sites in 1999 and
2000 and concentrations of N and S in plant tissue at the 4-6 leaf
stage (Feekes stages 1.4 to 1.6) at three sites in 2000. After
harvest, grain and straw yield at maturity plus N, S, and protein
content were also determined. With the yield and plant nutrition
data, total S accumulation in the plant was calculated.
Grain samples were taken to Agricore United for
grading. In order for grain samples to continue on to the detailed
quality analysis phase of the experiment, the samples had to meet #1
or #2 CWRS wheat quality standards. As a result, grain samples from
Brandon South and Kelvington in 1999 were rejected due to fusarium
head blight damage and frost damage, respectively. In 2000, all grain
samples from Glenboro, Erickson, and Athabasca were rejected; at
Brandon North, all low N treatment samples were also rejected. One
replicate from three treatments at Rosebank in 2000 was also
rejected. In 2001, grain from Rosebank, Neepawa, and Brandon was
rejected.
Grain samples grading #1 or #2 were milled to
flour, and flour yield was measured using a Buhler laboratory mill
after the grain was tempered to 16.5% moisture content (on 1999 and
2000 samples, only). The flour was then analyzed for total S and N.
Sodium dodecyl sulfate (SDS) sedimentation tests were conducted on 2.5
g samples of flour according to the method of Kovacs (1985). In a
previous study, SDS sedimentation volume was found to correlate
positively and strongly with loaf volume for a number of different
wheat varieties (Axford et al. 1979). Furthermore, high SDS volumes
are indicative of high gluten strength and quality (Kovacks 1985).
Dough mixing and rheological characteristics were evaluated on the
farinograph, mixograph, and extensigraph. The farinograph and
mixograph are physical dough testing tools that measure the physical
properties of dough during the mixing process (Kunerth and D’applonia
1985). The extensigraph is a load-extension instrument that measures
the strength and extensibility of dough during the stretching process
(Shuey 1975). Farinograph tests were conducted with a 10 g Brabender
Farinograph using the constant flour weight method (Approved Method
54-21, AACC, 2000). In 1999 and 2000, mixograph tests were conducted
with a 2-g Micromixograph using a modification of the method developed
by Pon et al. (1989), where 2 g of flour were used instead of 10 g and
using a fixed water absorption of 65% instead of 62%. In 2001, the
mixograph tests were conducted using a 10-g mixograph. Extensigraph
tests were conducted with a 2-g Micromixograph and Texture Analyzer
according to the method of Suchy et al. (2000). A hook speed of 3.3
mm/second and water absorption level of FAB + 6% were used. The
optimized long-fermentation bake test (Approved Method 10-10B, AACC,
2000), on 100-g flour samples (14% mb) at a water level of FAB – 3%,
was used to evaluate the baking potential of the flour samples.
Finally, in 1999 and 2000 the flour protein was separated into
fractions of insoluble glutenin, soluble glutenin, monomeric protein,
and residual protein according to the method of
Suchy et al. (2002).
To examine the relationships between
grain S concentration, N concentration, and N:S ratio and wheat
quality and yield, simple linear and partial correlation coefficients
were determined for the pooled data from 1999 and 2000 using the PROC
CORR procedure (SAS Institute Inc. 1999). To examine grain yield and
quality responses to S fertilization at all sites independently,
analysis of variance (ANOVA) and calculation of least significant
difference values (LSD’s) were conducted using the PROC GLM procedure
(SAS Institute Inc. 1999). Single degree of freedom contrasts were
used to further analyze treatment effects. Using the 1999 and 2000
data to evaluate the predictive value of the plant tissue tests,
linear, polynomial, and logarithmic regression equations were
determined for each predictive variable, including plant tissue S
concentration, N concentration, and N:S ratio at 50% heading and 4-6
leaf stages, with grain S concentration, N concentration, and N:S
ratio as the response variables. To evaluate the predictive value of
the soil SO4-S test, linear and polynomial regression
equations were determined with grain S concentration and total S
accumulation in the plant as the response variables. Soil SO4-S,
NO3-N, and fertilizer S and N were also used in correlation
analysis to determine how they predicted the N to S ratio in grain.
Multiple regression analysis was used to determine the predictability
of grain S concentration and total S accumulation using three
potential sources of S (fertilizer S, soil SO4-S, and
estimated mineralizeable S).
Results and Discussion:
Objective #1: To investigate the relationship between
grain S concentration, grain N concentration, and grain N:S ratio
and grain yield and breadmaking quality of CWRS wheat.
Appendix 2 summarizes the correlation coefficients for the
relationships between grain S concentration, grain N concentration,
and grain N:S ratio with the measured yield and quality parameters.
Analysis of grain samples for total S, N, and N:S ratio accurately
predicted the concentration of S, N, and N:S ratio in flour. The
initial quality analysis of a producer’s wheat is traditionally
determined on grain, not on flour. Therefore, the N and S
concentration in grain was used as the basis for discussing the
relationship of N, S, and N:S ratio with yield and quality
parameters. Furthermore, the grain S and N concentrations were
positively correlated (Table 3.6). Therefore, similar to the methods
of Moss et al. (1981), partial correlation coefficients were also
determined for grain S concentration and grain N concentration with
each dependent variable. Partial correlation coefficients make it
possible to examine the relationship between grain S concentration and
the measured quality variables at a constant grain N concentration and
vice versa.
Grain S concentration and N:S ratio
were weakly correlated with both absolute and relative grain yield
(Appendices 2, 3a, and 3b). Of the three measurements of N and S
content, grain S concentration was most strongly and positively
correlated with loaf height, loaf volume, and oven spring; grain N:S
ratio was negatively, but more weakly, correlated with these baking
parameters (Appendices 2 and 4a). The improvements in baking quality
with rising grain S concentrations and declining grain N:S ratios were
accompanied by an increase in dough extensibility and a reduction in
dough strength. Grain S concentration was positively correlated with
dough extensibility and negatively correlated with maximum dough
resistance (Rmax), mixograph peak time, and work input to
peak (Appendices 2, 4b, and 4c). Grain N:S ratio was negatively
correlated with dough extensibility and positively correlated with Rmax
and work input to peak.
The improvements in dough quality
with rising grain S concentrations and declining grain N:S ratios were
associated with an increase in the proportion of soluble glutenin in
flour and a reduction in the ratio of insoluble to soluble glutenin in
flour. Grain S concentration was positively correlated with the
proportion of soluble glutenin and negatively correlated with the
ratio of insoluble to soluble glutenin in flour. Grain N:S ratio was
negatively correlated with the proportion of soluble glutenin and
positively correlated with the ratio of insoluble to soluble glutenin
in flour. These correlations indicated that the improvements in dough
quality due to improved S nutrition were probably due to the enhanced
concentration of gluten proteins rich in cysteine, improving the
dough’s capacity to form intermolecular disulphide and other types of
bonds.
Objective #2: To investigate the impact of S fertilization
on the grain yield and breadmaking quality characteristics of CWRS
wheat. Within this objective, we wanted to examine whether the
breadmaking quality of CWRS wheat was improved by S fertilization in
the absence of a yield response.
&
Objective #3: To evaluate agronomic tools (e.g. soil tests and plant
tissue tests) which would aid western Canadian producers to predict
the S concentration and N:S ratio in grain as well as quality
responses to S fertilization.
Appendices 5 and 6 summarize the
analysis of variance and contrasts for the treatment effects for 1999
and 2000. In 1999 and 2000, application of 20 kg S ha-1
significantly improved grain yield at only two of twelve sites
including only two of the seven sites where grain quality evaluation
was conducted. However, application of S fertilizer improved the
overall quality of wheat at four of seven sites. All four sites where
consistent quality improvements were observed contained between 26 and
40 kg SO4-S ha-1 prior to fertilization,
concentrations of soil S regarded to be marginally deficient to
sufficient for grain yield. Also, at these four marginal S sites, the
S concentration and N:S ratio of plant tissue samples collected at 50%
heading was < 0.15% S and > 17:1, respectively, for the high N, zero S
treatment. Sulphur
fertilization increased the concentration of S in grain and reduced
the N:S ratio in grain at these four sites, even though S
fertilization improved grain yield at only two of the sites. The
improvements in grain S nutrition were accompanied by significant
improvements in loaf volume at two of the four marginal S sites when S
fertilizer was applied in combination with 26 or 100 kg N ha-1,
and at one more site where 100 kg N ha-1 was applied.
Sulphur fertilization increased loaf height and oven spring at three
of the four sites. Application of S fertilizer also significantly
increased dough extensibility at all four marginal S sites and reduced
Rmax and mixograph peak time at three of the four marginal
S sites. Mixograph peak time was significantly reduced at the other
site only in the presence of 100 kg N ha-1. Furthermore, S
fertilization reduced the viscoelastic ratio and mixograph work input
to peak at all four marginal S sites. Sulphur fertilization increased
the proportion of soluble glutenin in flour and reduced the ratio of
insoluble to soluble glutenin in the flour at three of four marginal S
sites. Sulphur fertilization in the presence of 100 kg N ha-1
only, increased the proportion of soluble glutenin in flour and
reduced the ratio of insoluble to soluble glutenin in the flour at the
other marginal S site. Finally, at the three sites where soil SO4-S
concentrations were > 40 kg ha-1, no yield and few
consistent breadmaking and dough quality improvements were observed in
response to S fertilization. At these high S sites, S fertilization
increased the S concentration in grain under the low N fertilization
treatment and reduced the N:S ratio in grain at one site, only.
Where the concentration of soil NO3-N
was low, the majority of quality improvements due to S fertilization
occurred only when 100 kg N ha-1 was applied. Where soil
NO3-N concentrations were medium to high, most quality
responses to S fertilization were observed when either 26 or 100 kg N
ha-1 was applied, providing evidence that grain quality
responses to S fertilization are enhanced at high concentrations of
plant available N due to the balancing effect of S fertilization on
the N:S ratio in grain.
At all four sites where grain
contained
£
0.17% S and an N:S ratio > 17:1, for the high N, zero S treatment,
quality improvements due to S fertilization were consistently observed
when combined with the high rate of N fertilization (Appendix
6). At the three sites where grain contained S concentrations
³
0.17% S and N:S ratios < 17:1, for the high N, zero S treatment,
breadmaking and dough quality responses to S fertilization at the high
rate of N fertilization were infrequent (Appendix
6).
The S concentration of whole plant
samples collected at the 50% heading stage was poorly correlated to
the S concentration in grain (Appendix 7).
The S concentration of whole plant samples collected at the 4-6 leaf
stage was not correlated to the S concentration in grain. However,
grain N:S ratio correlated well with the ratio of N to S in the plant
tissue samples collected at the 50% heading stage.
In the absence of S fertilization, soil SO4-S
concentration to 60 cm was moderately correlated with the S
concentration in grain and with total S accumulation in the plant
(Appendices 8a and 8b). However, when two additional sources of S,
including fertilizer S and estimated mineralizeable soil organic S,
were included in multiple regression analysis for the prediction of
grain S concentration and total S accumulation in the plant, the
relationships were weak (Appendix 9:
Equations 9a and 9b). Finally, when the soil N:S ratio,
calculated with the soil NO3-N and SO4-S values,
was plotted against grain N:S ratio, for the low N, zero S treatment,
there was a modest correlation (Appendix
10a). When the fertilizer treatments were added to the soil NO3-N
and SO4-S concentrations in the calculation of the soil N:S
ratio, the correlation improved but was not strong (Appendix
10b).
Objective #4: To evaluate other varieties of the CWRS wheat class to
determine if they demonstrate similar quality responses to S
fertilization as AC Barrie. We also wanted to examine if differences
in quality characteristics between varieties could be overcome with
the application of S fertilizer.
Appendices 11 and 12 summarize the S and varietal
(V) effects and contrasts for the sites where AC Barrie, AC Superb,
and BW267 were grown and graded #1 or #2 CWRS. Of these four sites,
only one site, Archerwill in 2000, where an overall grain yield
response to S fertilizer was observed, demonstrated consistent quality
responses to S fertilization; at the sites of Kindersley, Saskatoon,
and Shoal Lake, no consistent responses to S fertilization were
observed. At Archerwill, for the three varieties, S fertilization
increased the S concentration and reduced the N:S ratio in grain and
flour. As a result, even though differences between varieties were
present for a number of quality characteristics, S fertilization
affected the breadmaking and dough quality of all three varieties at
this site. For example, S fertilization significantly increased SDS
sedimentation volume, loaf volume, oven spring, loaf height, and dough
extensibility for all three varieties. Sulphur fertilization also
reduced the viscoelastic ratio for three varieties (significant for
only two, AC Barrie and AC Superb) and reduced mixograph peak time for
two of three varieties (AC Barrie and BW267). Finally, although flour
protein fractionation was conducted on the flour from Archerwill in
2000, only, for all three varieties, S fertilization significantly
increased the concentration of soluble glutenin in flour and reduced
the concentration of monomeric protein and the ratio of insoluble to
soluble glutenin in flour.
However, it is also important to note that the
varietal differences for many quality parameters were relatively large
and frequently unaffected by S fertilization, so most quality
differences between varieties were not offset by S fertilization.
Therefore, it is evident that S fertilization is not a “cure-all” for
grain quality problems. Furthermore, S fertilization for the quality
improvement of a specific variety should be selective for the type and
degree of quality problems for that variety. For example, if a
variety produces overly weak and extensible dough, S fertilization,
which generally causes a decrease in dough strength and an increase in
dough extensibility is unlikely to increase the overall quality of
that variety. However, if the variety produces dough that is
extremely strong and not extensible, S fertilization may reduce the
strength and increase the extensibility of the dough creating a better
balance between the two, which may ultimately improve the overall
baking quality of that variety.
Conclusion #1 – directed at the entire CWRS wheat industry
This study has demonstrated and confirmed results from previous
studies that the S nutrition of wheat grain, measured as S
concentration and N:S ratio, is an important factor affecting the
breadmaking quality of CWRS wheat. High grain S concentrations and
low grain N:S ratios were associated with increased concentrations of
soluble glutenin in flour and reduced ratios of insoluble to soluble
glutenin in flour. As a result, there were probably more cysteine
residues available for the production of disulphide and other types of
bonds, producing dough that was more extensible and pliable,
ultimately producing bread loaves of better quality (e.g. higher loaf
volume). According to these results, it is evident that the S
nutrition of grain, measured as total S concentration and N:S ratio
should be considered, in addition to the concentration of N, in the
quality evaluation of CWRS wheat grain grown in western Canada.
However, in the evaluation of grain for quality, N:S ratio should be
used with caution because the same ratio of N to S can be obtained at
totally different N and S concentrations in grain and the surplus of
one nutrient may falsely indicate a deficiency of the other nutrient.
Conclusion #2 – directed at commercial processors of CWRS
wheat
In relation to “conclusion #1”, this study has demonstrated that
CWRS wheat grain containing £ 0.17% S and an N:S ratio > 17:1 contains
deficient S levels and will frequently demonstrate quality responses
to S fertilization. These thresholds are most accurate when used in
combination to avoid the limitations associated with using each
individually. For example, the combination of these criteria avoids
the limitation associated with using the N:S ratio, alone, as an
indicator of grain S nutrition, where the surplus of one nutrient may
falsely indicate a deficiency of the other nutrient or where the
deficiency of one nutrient may falsely indicate the sufficiency of the
other nutrient. Furthermore, the combination avoids the problem of
relying on grain S concentration, alone, which provides no indication
of the balance, or lack of, between N and S in the grain. These
thresholds are of greatest value for the commercial processors of CWRS
wheat because an indication of inadequate supplies of S in grain at
maturity does not provide the producer with the opportunity to correct
the S deficiency with the application of S fertilizer.
Conclusion #3 – directed at western Canadian producers of
CWRS wheat
- Sulphur fertilization will frequently improve the breadmaking
and dough quality of CWRS wheat where soils contain < 40 kg ha-1
SO4-S and are regarded as marginally sufficient for wheat yield.
Under these conditions, quality responses to S fertilization can be
expected in the presence and absence of a yield response.
- Sulphur fertilization will frequently improve the breadmaking
and dough quality of CWRS wheat where whole plants collected at 50%
heading contained < 0.15% S and an N:S ratio > 17:1. However,
further research is required to determine if the application of S
fertilizer this late in the season improves the quality of CWRS
wheat.
- Adding S fertilizer under high N fertility conditions improves
the balance between N and S, leading to enhanced dough quality and
breadmaking performance of CWRS wheat. However, in the Canadian
wheat industry, the price of CWRS wheat is currently determined by
grade and grain N concentration (grain N concentration x 5.7 =
protein concentration), only. In other words, producers receive
quality premiums for adding N fertilizer, but not for adding S
fertilizer. This policy ignores the quality improvements from S
fertilization and increases the potential for imbalances of N to S
in grain. However, until S is measured and rewarded as an important
factor for determining the overall breadmaking quality of CWRS
wheat, producers should apply S fertilizer only if they expect a
grain yield response.
Conclusion #4: directed at producers and commercial processors of
CWRS wheat
The plant tissue and soil analyses
used in this study showed only modest capability to predict the
concentration of S in wheat grain and total S accumulation in wheat.
The N:S ratio of plant tissue selected at 50% heading provided a
reasonably accurate estimate of N:S ratio in grain because the ratio
of N to S is more stable than the absolute concentrations of each
nutrient between the two stages. Estimation of the mineralizeable
fraction of soil organic S in the phosphate borate extraction for
mineralizeable N did not provide a good indication of S that may
become available to the crop throughout the growing season and did not
improve the predictability of grain S nutrition. More research is
required to develop a tool that accurately predicts the S nutrition of
wheat and to measure the mineralization of organic S throughout the
growing season and its contribution to the S nutrition of wheat.
However, until a better soil test is developed, the measurement of
water extractable NO3-N and SO4-S to 60 cm will
provide a crude estimate of N:S ratio and S concentration in grain.
Conclusion #5: directed at producers and commercial processors of
CWRS wheat
We have provided
some evidence to demonstrate that other varieties, in addition to AC
Barrie wheat, within the CWRS wheat class will demonstrate quality
responses due to S fertilization. However, with only one site
demonstrating consistent responses to S fertilization, more research
is probably required to confirm these preliminary results.
Furthermore, varietal differences for many quality parameters can be
quite large and may not be affected by S fertilization. Therefore, S
fertilization is not a “cure-all” for quality problems. Finally, S
fertilization for the quality improvement of a specific variety should
be selective for the type and degree of quality problems observed in
that variety.
Acknowledgements:
Funding for this study was provided by Agicore United, Agrium Inc.,
and the Agri-food Research and Development Initiative (ARDI).
Additional financial support, in the form of scholarships, was also
provided by the Natural Sciences and Engineering Research Council of
Canada as well as the University of Manitoba in combination with the
Lord Selkirk Association of Rupertsland (Lord Selkirk Association of
Rupertsland Agricultural Scholarship). We thank Kevin McCallum and
Jim Dyck, from Agricore United’s Proven Seed group, Lenz Haderlein
from Agrium, and Dr. Adrian Johnston and Dr. Sukdev Malhi from the
Agriculture and Agri-Food Canada Research Station at Melfort for their
assistance with establishing and maintaining field sites for this
study. We also thank Pat Greer from the Agricore United Quality
Control Lab and Kathy Adams from the Agriculture and Agri-Food Canada
Research Station in Winnipeg for their assistance with measuring grain
quality.
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Science of Food and Agriculture.
Tisdale, S. L., Reneau, R. B., and Platou, J. S. 1986. Atlas of
sulfur deficiencies. Pages 295-322 in M. A. Tabatabai, ed. Sulfur in
Agriculture. Agronomy Monograph no. 27. ASA – CSSA – SSSA, Madison,
WI., U.S.A.
Zhao, F. J., Hawkesford, M. J., and McGrath, S. P. 1999. Sulphur
assimilation and effects on yield and quality of wheat. J. Cer. Sci.
30: 1-17.
Appendices:
-
Appendix
1a. Physical and chemical characteristics of soils used in 1999
field studies
-
Appendix
1b. Physical and chemical characteristics of soils used in 2000
field studies
-
Appendix 2. Simple linear and
partial correlation coefficients between grain S concentration, N
concentration, and N:S ratio and grain yield and quality
characteristics
- Appendix 3. Relationship
between S concentration in grain and (a) absolute grain yield and
(b) relative grain yield
-
Appendix 4. Relationship between S
concentration in grain and (a) loaf volume,
(b) dough extensibility, and (c)
maximum dough resistance (Rmax)
-
Appendix
5. Summary of the analysis of variance for the N and S
fertilization effects and the N x S interactions on the different
yield and quality parameters in 1999 and 2000
-
Appendix
6. Summary of site characteristics and contrasts for the effect
of sulphur fertilization at the different levels of N fertilization
for selected quality parameters in 1999 and 2000
-
Appendix
7. Equations for the prediction of grain and whole plant
nutrition using plant tissue samples collected at the 50% heading
and 4-6 leaf stages
-
Appendix
8. Relationship between soil SO4-S concentration and (a) S
concentration in grain and (b) total S accumulation (for the 0 S
and 100 kn N ha-1
treatments, only)
-
Appendix
9. Equation 9a. Regression equation for the relationship
between grain S concentration and the three sources of soil and
fertilizer S (for high N treatments only) Equation 9b.
Regression equation for the relationship between total S
accumulation and the three sources of soil and fertilizer S (for
high N treatments only)
- Appendix 10. Relationship
between (a) nitrate:sulphate ratio in soil and N:S ratio in grain
(for 0 S and 26 kg N ha-1
treatments, only) and (b) nitrate plus fertilizer N : sulphate plus
fertilizer S in soil and N:S ratio in grain (for all fertilizer
treatments)
-
Appendix 11. Effect of sulphur fertilization (S) and wheat
variety (V) on quality characteristics in 2000 and 2001
-
Appendix 12. Summary of contrasts for the effect of sulphur
fertilization on three varieties for selected quality parameters in
2000 and 2001
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