133 J. Fismes et al. European Journal of Agronomy 12 2000 127–141
Table 5 N and S uptake by the whole plant excluding roots at green bud, flowering and maturity, and by the vegetative parts at maturity
of field-grown winter oilseed rape in 1995–96 A and 1996–97 B. Means within a column followed by the same letter are not significantly different at the 95
confidence level Tukey’s test Treatment
Rosette Flowering
Maturity N
S N
S N
S NS
N S
Whole plant kg ha−1 Whole plant kg ha−1
Whole plant kg ha−1 Vegetative parts kg ha−1
A S=0
Control 26.86 b
2.16 c 38.48 c
1.04 a 66.89 b
7.09 ab 9.4
6.19 b 0.60 c
AN 42.00 ab
4.85 a 110.95 a
4.06 a 160.45 a
6.82 ab 23.5
19.79 a 1.04 ab
UR 37.80 ab
3.92 ab 73.92 b
2.93 a 140.15 a
5.25 b 26.6
17.53 a 0.95 bc
S=30 ATS-S AN+S
30 53.11 a
4.85 a 97.14 ab
3.53 a 163.09 a
7.44 ab 21.9
19.88 a 1.25 ab
UR+S 30
51.21 a 4.26 ab
85.99 ab 3.62 a
147.92 a 7.12 ab
20.8 15.48 a
0.95 bc S=75 ATS-S=30+MgSO
4 -S=45
AN+S 75a
39.97 ab 3.18 bc
88.35 ab 2.19 a
162.22 a 11.33 ab
14.3 21.37 a
1.05 ab UR+S
75a 41.70 ab
3.15 bc 94.88 ab
3.09 a 151.03 a
9.16 ab 16.5
16.38 a 1.31 ab
S=75 MgSO 4
-S AN+S
75b 42.53 ab
2.64 c 85.30 ab
3.80 a 166.67 a
12.98 a 12.8
21.09 a 1.61 a
UR+S 75b
41.14 ab 2.69 c
86.91 ab 2.46 a
159.42 a 10.59 ab
15.0 20.51 a
1.08 ab B
S=0 Control
37.17 b 5.42 a
31.45 b 1.53 b
90.53 c 7.55 a
12.0 9.08 b
3.22 a AN
80.69 a 9.81 a
78.21 a 5.68 ab
178.42 ab 9.15 a
9.5 20.16 ab
2.28 a UR
59.90 ab 6.39 a
73.13 a 4.43 ab
168.62 ab 8.40 a
20.1 16.28 ab
1.63 a S=30 ATS-S
AN+S 30
59.91 ab 7.49 a
81.31 a 8.54 a
178.33 ab 9.44 a
18.9 22.29 a
3.42 a UR+S
30 69.19 ab
9.38 a 84.73 a
6.64 a 191.90 ab
9.78 a 19.6
18.82 ab 1.97 a
S=75 ATS-S=30+MgSO 4
-S=45 AN+S
75a 65.70 ab
8.15 a 76.84 a
5.91 ab 209.69 a
11.82 a 17.7
22.61 a 3.84 a
UR+S 75a
47.43 ab 7.27 a
73.51 a 3.54 ab
172.61 ab 13.75 a
12.5 16.78 ab
6.17 a S=75 MgSO
4 -S
AN+S 75b
71.14 ab 9.31 a
85.62 a 7.08 a
187.91 ab 13.40 a
14.0 21.56 a
5.84 a UR+S
75b 64.60 ab
8.11 a 77.96 a
4.79 ab 197.15 ab
12.95 a 15.2
20.25 ab 5.35 a
oil, of which the content was slightly decreased by 1996–97 when compared with the control and the
treatments with S application. Fertilization of S 4
. Unfortunately, in the second pot experiment, the GLS contents were not determined due to
increased the GLS contents but had no influence on oil contents Table 3. The results suggest a
insufficient seed samples. For this experiment, S applications at 75 kg ha−1 led to a decrease of oil
higher responsiveness of GLS than oil to the S fertilization.
content of about 10 when the soil was jointly
fertilized with ATS-S and MgSO 4
-S and about 7.5
with MgSO 4
-S exclusively. In field experiments, the average content of
4. Discussion
GLS Table 3 was found to be relatively higher for the
second year 15.07 mmol g−1 versus
4.1. Imbalanced N and S 9.44 mmol g−1 and a slight increase in average oil
content has been observed 50.7 versus 49.5
. In pot experiments using the cultivar Hybridol,
total pod abortions occurred when the soil was N applications alone decreased markedly the GLS
contents by 45.4 in 1995–96 and by 34
in fertilized only with AN or UR without S Table 2.
134 J. Fismes et al. European Journal of Agronomy 12 2000 127–141
This fact would be explained by the imbalanced Anderson, 1990; Sexton et al., 1998. The path-
NS uptake ratios Sweeney and Moyer, 1997, of way of S nutrition is the reduction of SO
2− 4
to which the values observed at rosette stage Table 4
cysteine in assimilatory sulfate reduction pathway are abnormally larger with 37 AN and 39 UR
Lappartient and Touraine, 1996. This pathway than those of the control 22.3 and slurry 18.
is tightly linked to assimilatory nitrate reduction According to Janzen and Bettany 1984, the
Kast et al., 1995, where O-acetyl-serine is severity of S deficiency is aggravated by higher
formed. This latter compound reacts with sulfur rates of N application. Plants receiving no N
reduced to form cysteine. In agreement with these fertilizer showed no apparent S stress, whereas
observations, the results indicate that N and S plants receiving N fertilizer, particularly at higher
taken up by rapeseed at maturity stage are associ- rate without S, showed symptoms suggesting severe
ated according to a polynomial equation of second physiological disorder in N nutrition.
order Fig. 1. This implies that N and S nutrition Sulfur
mainly enhances
the reproductive
are linked and the process would be down-regu- growth, and the proportion of the reproductive
lated when one of them quantitatively overexceeds. tissues inflorescences and pods in total dry matter
Under controlled conditions with optimum tem- was found to be significantly increased by S during
perature and humidity, the correlation coefficients pod development MacGrath and Zhao, 1996.
between N and S uptake obtained over the two Under S deficient conditions, the amount of amino
years 1995 and 1996 of experiments Table 6 acids and nitrates in leaves increases dramatically
were found to be significant at rosette stage: Hue et al., 1991 and protein degradation within
r 2=0.59 P0.05, maturity: r2=0.82 P0.01,
chloroplasts occurred Dannehl et al., 1995. and for the seeds: r
2=0.95 P0.01. By contrast, Besides, sulfur affects photosynthetic characteris-
the coefficient value was not significant at flower- tics Sexton et al., 1997; Blake-Kalff et al., 1998.
ing. This could be attributed to the early irregular According to them, S deficiency limits protein
losses of leaves which occurred in the growth synthesis by limiting the amount of methionine
chamber. Major phenomena could be related to and cysteine available for the assembly of new
plant ontogeny caused by the regularly imposed proteins.
temperature, humidity and light intensity of con- Furthermore, Sunarpi and Anderson 1997
trolled conditions which are different from the have shown that high levels of N inhibit the
usual requirements in the field Sarwar and proteolysis process in soybean and so the export
Kirkegaard, 1998. of N and S from mature leaves to developing
Similar results were obtained in field experi- leaves or developing grains. In agreement with
ments Table 6 with highly significant correlation them, our results emphasize therefore the interest
coefficients at green bud stage: r2=0.83 P0.01 of applying S fertilizer in combination with N;
and for seeds: r 2=0.72 P0.01. The lack of
otherwise, oilseed rape that grows on S-limiting statistically significant correlation between N and
soils will suppress the development of reproductive S noted at maturity may be due in part to the
organs and even lead to pod abortion MacGrath flexible system of stems for regulating the nitrogen
and Zhao, 1996; Zhao et al., 1997. Under imposed supply to regions of demand. Indeed, as shown by
conditions within the growth chamber, this work Sunarpi and Anderson 1997, stems are able to
also points out the higher sensitivity of cultivar act as a source at low levels of N supply and as a
Hybridol than Tanto to the imbalanced NS ratios. major sink of N when N supply is very high.
Further study is needed to gain a better causal Similar roles played by stems in regulating and
understanding of this different sensitivity between accumulating sulfur, especially as sulfate, have
cultivars. been reported as well Sexton et al., 1998.
The most marked point of our results Table 6 4.2. N and S uptake relationships
is the strongly significant correlation values obtained in field trials at flowering: r
2=0.73 The excess or the deficiency of one of both the
N and S elements may disturb protein synthesis P0.05 in 1995–96, and r
2=0.87 P0.01 in
135 J. Fismes et al. European Journal of Agronomy 12 2000 127–141
controlled conditions than in the field. The absence of correlation between N and S taken up by seeds
in the first field experiment 1995–96 would be due to the low remobilization of N and S from
the vegetative parts excluding pod walls and seeds, as clearly proved by the strong correlation
coefficient of 0.79 P0.05. Indeed, there may have been either a sink limitation for N and S
utilization within the seeds or simply a limited ability to reduce both N and S for amino acid
synthesis, as attested by the non-significant correla- tion value noted for seeds Table 6. Presumably,
climatic conditions would be one of the most important factors for such an event. As a result,
the average N uptake in this first year Table 5 was relatively lower 146.6 kg ha−1 than that in
the second year 175 kg ha−1, where strong corre- lations were recorded at each stage Fig. 1.
Therefore, monitoring N and S uptake curves during the growth could be an indicator for predic-
ting good yield production.
The almost linear curve for N and S uptake at green bud stage Fig. 1 indicates increasingly pro-
portional N and S taken up by oilseed rape. Accordingly, this suggests the synthesis of reserve
proteins in leaves which were intensively developed and almost fully expanded at this time. In parallel,
during this stage, nitrate and sulfate transported in the xylem with the transpiration stream would
be very important as well. According to Hell and Rennenberg 1998, part of the sulfate can undergo
xylem-to-phloem exchange during the xylem trans- port. Thus, its distribution within the plant in this
way may represent part of a plant internal sulfate cycle. For nitrate, this exchange during the xylem
transport is not clear. However, for oilseed rape grown with high N fertilization, Colnenne et al.
1998 observed an important accumulation of non-assimilated N in the nitrate form at this early
Fig. 1. Curves of N and S taken up by field-grown winter oilseed
stage when compared with wheat. In consequence,
rape in 1996–97 observed at green bud, flowering and maturity,
at this critical stage later autumn and early spring
and for seeds. For illustration, we present only the curves of
any deficiency of N will affect the growth of aerial
this year. The other curves show similar trends. Each datum
parts including foliar areas and stems Colnenne
point corresponds to a mean value of four replications.
et al., 1998, and S deficiency will lower the formation of reproductive organs that begin well
at spring Janzen and Bettany, 1984. 1996–97 when compared with pot trials in 1995
and 1996 NS . The explanation would be, as Under normal N and S nutrition conditions,
the trends of curves associating N and S uptake mentioned before, the larger losses of leaves under
136 J. Fismes et al. European Journal of Agronomy 12 2000 127–141
Table 6 Correlation between N and S uptake. Correlation coefficient r2 calculated on the average value of eight treatments for the 1995 pot
experiment and nine treatments for the remaining experiments, and significance level P0.05; P0.01 Stage of plant
Parts of plant Pot experiments
Field experiments 1995
1996 1995 and 1996
1995–96 1996–97
1995–96 and 1996–97 Rosette
Whole plant NS
0.80 0.59
NS 0.81
0.83 Flowering
Whole plant NS
NS NS
0.73 0.94
NS Maturity
Whole plant 0.83
0.84 0.82
NS 0.92
NS Vegetative parts
NS NS
NS 0.79
NS NS
Seeds 0.96
0.95 0.95
NS 0.89
0.72
hold across the observed growth stages as well as Therefore, if N and S transports operate simulta-
neously, the mechanisms which regulate the pas- during seed formation. This obviously implies the
same interaction mechanisms between N and S sage either between stems and pod walls or between
pod walls and seeds remain to be elucidated, even during seed protein and secondary metabolite
synthesis. In particular, this underlines again the because they evidently influence yield and seed
quality. double resilient roles of stems Sunarpi and
Anderson, 1997; Sexton et al., 1998 and pod walls Zhao et al., 1993a; Fismes et al., 1999 as sink
4.3. Apparent N-use efficiency and source for N and S in regulating transport
between both the vegetative and reproductive Without
15N as tracer, the apparent N-use efficiency: ANU=[N uptake from fertilized
parts, and therefore an optimal protein synthesis can be efficiently fulfilled within the seeds Fig. 1.
plots−N uptake
from controlsN
fertilizer applied ] can be expressed to examine the effect of
The fully expanded leaves represent the most important sink for S and N within plants Sunarpi
S supply on N uptake. The inhibitory action of ATS on N nitrification and urease activity was
and Anderson, 1996; Blake-Kalff et al., 1998. In this connection, the close relationships of N and
well proved in laboratory experiments Goos, 1985; Fairlie and Goos, 1986.
S uptake across the main growth stages obtained in this study support the hypothesis of simulta-
In pot trials, ATS had a significant impact only at the highest rate of 75 kg S ha−1. The ANU
neously coordinated phloem transport of N and S as various amino acids andor small peptides from
value obtained with the treatment slurry+ATS was 62
versus 43 with slurry alone. Similar
mature leaves to other plant parts Sunarpi and Anderson, 1997. In agreement with them, the
results were recorded with chemical fertilizers for which the averaged values shifted from 25
with transport of both elements is a common mecha-
nism because the putative transport from mature N-only application to about 40
when S was added Fig. 2. Thus, S applied at the highest dose
leaves of nitrogen as nitrate andor ammonium and sulfur as sulfate, after proteolysis, would
of 75 kg S ha−1 increased significantly N taken up by rapeseed in pot but not in field trials.
involve at least two mechanisms. In addition, in agreement with Sunarpi and Anderson 1997, our
Agronomically, the dose advised for ATS is 10 vv, which corresponds to an equivalent of 30 kg
results suggest that this proteolysis is promoted when either N or S becomes limiting. However,
S ha−1 Goos, 1985. In field experiments, the values of ANU varied from 41.6
with N alone comparisons of N versus S as to the relative
intensity, the duration and the efficiency of remobi- to 49.5
with N plus S. Based on these low values of ANU, our results confirm those of Schjoerring
lization remain to be clarified. As previously shown, N and S can be abnormally sequestered
et al. 1995, indicating that oilseed rape is appa- rently a N-inefficient plant compared with cereal
and stored in the vegetative parts upon maturity.
137 J. Fismes et al. European Journal of Agronomy 12 2000 127–141
Fig. 2. Apparent N-use efficiency values from pot trial in 1996 and the two-year field trial 1995–96 and 1996–97. The results from the pot trial in 1995 are not presented due to pod abortions. Each datum represents the mean of eight values for the pot trial one
year and 16 values for the field trials two years. The bar corresponds to the standard error ±S.E.. For the legends, see Table 4 B and Table 5 A and B.
crops, of which the values are generally higher and under conditions of S deficiency, sulfate-S is still
present in a considerable proportion to total S in can reach the range of 75 to 90
Delogu et al., 1998. This is proved by the fact that oilseed rape
oilseed rape. In contrast, the amount of S in GLS is small in vegetative tissues under the conditions
is unable to withdraw all N from leaves before they
are lost
Schjoerring et
al., 1995.
of abundant supply of S. In addition, the ineffective xylem-to-phloem transfer of SO
2− 4
, because of its Furthermore, Shepherd and Sylvester-Bradley
1996, by referring to N response in grain yield, higher accumulation in the vacuoles in the mature
leaves compared with the middle or younger ones have demonstrated that for each 100 kg N ha−1
applied, the rapeseed provides N equivalent to Blake-Kalff et al., 1998, may contribute to this
inefficiency as well. The results evidently suggest 30 kg N ha−1 for the following cereal. This argu-
ment again confirms oilseed rape as a N-inefficient that the oilseed rape crop is inherently inefficient
in N and S utilization within the plant. plant, and so its beneficial effects on succeeding
cereal crops through increasing soil fertility and disease progression are amply pleaded by Sieling
4.4. Seed glucosinolate and oil contents and Christensen 1997.
The same tendency was obtained for the appar- Sulfur applications increased the level of GLS
ent sulfur-use efficiency see data in Table 5 with compared with the soil receiving only N fertiliza-
low values not exceeding 8 results not shown.
tion. Under controlled conditions, the GLS In fact, the calcareous soil used is rich in organic
content amounted to 13.5 mmol g seed−1, a value S about 1300 kg S ha−1, which level is largely
1.5-fold higher than the treatment receiving only superior to the limit of 400 kg S ha−1, above which
slurry without S. However, the values are very soils are considered to be well sufficient in S
close to those of the controls. Globally, the content Merrien, 1987. Therefore, our results compare
of GLS from field experiments varied between 8 favorably with values varying between 10 and 15
and 18 mmol g seed−1 and in any case, the observed obtained from the S-sufficient soils Zhao et al.,
values do not exceed the threshold limit of 1993b. Likewise, oilseed rape is considered also a
18 mmol g−1 fixed by the European norm. Over S-inefficient plant MacGrath and Zhao, 1996.
The reason put forward by these authors was, even the 2-year experiment, the content of GLS pro-
138 J. Fismes et al. European Journal of Agronomy 12 2000 127–141
Table 7 Correlation between NS uptake ratio values on the whole plant basis excluding roots and the variables of glucosinolates from
field-grown winter oilseed rape. Significant level P0.05; P0.01 Glucosinolate
Alkenyl glucosinolate 1995–96
1996–97 1995–96 and 1996–97
1995–96 1996–97
1995–96 and 1996–97 NS uptake
NS NS
− 0.51
− 0.69
− 0.68
− 0.56
duced in response to 30 and 75 kg S ha−1 as ATS-S GLS contents relies on the balanced fertilization
of both N and S. or MgSO
4 -S varied between 12 and 18 mmol g
seed−1. These results are in agreement with those As for the seed oil content, results from field
trials indicate nearly constant values with the obtained by Zhao et al. 1997, indicating for an
application of 50 kg S ha−1, a higher elevation of fertilized treatments. But, the marked point is that
in 1995–96, the percentage of oil was on average GLS from 10 to 20 mmol g−1 on S-deficient sites
versus 15 to 17 mmol g−1 on S-sufficient sites. This about 1.2
lower than that of 1996–97. In fact, the mean value of seed N content see Table 3 in
shows again the richness of S in the soil used and therefore the narrower variations of GLS pro-
1995–96 was slightly higher 3.11 than in 1996–
97 2.99 , which consequently leads, in accor-
duction in response to S fertilization. Our results show significant correlations existing between NS
dance with Andersen et al. 1996, to a decrease in oil content observed in 1995–96. The main
uptake ratio values and the content of GLS Table 7 and Fig. 3, especially the alkenyl GLS,
causes contributing to such a diminution of oil content would be likely attributed to the drought
which are the predominant group present in seeds. Their higher correlation coefficients observed
conditions which directly influence the partitioning of C assimilated during the pod-filling phase
prove their higher responsiveness to S addition, because they are synthesized from chain-elongated
Bouchereau et al., 1996. Moreover, the non- distribution of N and S from the vegetative parts
homologues of methionine Zhao et al., 1997, the outcome product of N and S assimilatory pathway.
previously noted at maturity stage Table 6 explains well this diminution.
These results clearly imply that a better control of
Fig. 3. Correlation curves between NS uptake ratio values at maturity on the whole plant basis excluding roots, and the variable of glucosinolates from the two-year field experiment. Each datum point represents a mean value of four replications.
139 J. Fismes et al. European Journal of Agronomy 12 2000 127–141
According to Andersen et al. 1996, seeds may optimal level conditions the process is synergistic
and becomes antagonistic under the extreme condi- be regarded as consisting of nitrogen-free struc-
tural material, stored proteins and stored oil. The tions of excessive level of N or S. Monitoring the
uptake of both elements across principal phenolog- proportion of structural material is expected to
decrease with increasing seed weight, while protein ical stages would be useful for predicting yield
from fertilizer testings. N application alone to this and oil may compete for the remaining space in
seeds. Accordingly, these authors showed that the calcareous soil rich in organic-N and -S gave the
same seed yield of field-grown oilseed rape as content of oil Oc is positively correlated with
seed weight Sw and negatively correlated with treatments with S application, and also the oil
contents in seeds were not influenced by S, in nitrogen
content Nc
as follows:
Oc= 63.3−7.37Nc+1.31Sw
r 2=0.89, n=92. We
contrast to glucosinolates, the contents of which were clearly increased by S fertilizers. In pot experi-
found similar significant results as expressed by the equation: Oc=68.0−5.74Nc−0.17Sw r
2= ments, higher S application significantly increased
the ANU, which was not the case in field trials. 0.71, P0.05, n=9. In our case, the slightly
negative relation with seed weight Sw would be There was only a non-significant tendency of S
improving the ANU. linked to the restricted observation numbers. But
also, this means that seed nitrogen-free structure is more subject to intrinsic or year-to-year
variations.
Acknowledgement
In general, N fertilization without S reduced total oil production due to the decrease in yield
This work was carried out as part of a research Joshi et al., 1998. Besides, water shortage occur-
program funded by the Commission of the ring during the flowering or pod-filling stages may
European Community
Contract AIR
favor increased protein content and thereby 3-CT94-1953.
decreasing oil content Bouchereau et al., 1996. Consequently, climatic conditions could also be
considered as a determining factor for oil pro-
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5. Conclusions
