This document summarizes the key findings of a study on oil and fatty acid distribution in different circles of sunflower heads. The study found: 1) Oil content consistently decreased from the outer circle to the central circle of sunflower heads during both study years. The outer circle had the highest oil content. 2) Palmitic acid accumulation showed no consistent pattern between circles or years. Stearic acid was higher in 2008 than 2007 and showed significant interaction between year and circle. 3) Oleic acid was consistently highest in the outer circle and lowest in the central circle both years. It had a significant negative relationship with circle and year. 4) Linoleic acid consistently increased from the

1. This article appeared in a journal published by Elsevier. The attached
copy is furnished to the author for internal non-commercial research
and education use, including for instruction at the authors institution
and sharing with colleagues.
Other uses, including reproduction and distribution, or selling or
licensing copies, or posting to personal, institutional or third party
websites are prohibited.
In most cases authors are permitted to post their version of the
article (e.g. in Word or Tex form) to their personal website or
institutional repository. Authors requiring further information
regarding Elsevier’s archiving and manuscript policies are
encouraged to visit:
http://www.elsevier.com/copyright

2. Author's personal copy
Oil and fatty acid distribution in different circles of sunflower head
Fayyaz-ul- Hassan, Shuaib Kaleem, Mukhtar Ahmad ⇑
Pir Mehr Ali Shah, Arid Agriculture University Rawalpindi, Pakistan
a r t i c l e i n f o
Article history:
Received 23 April 2010
Received in revised form 13 November 2010
Accepted 1 February 2011
Available online 13 April 2011
Keywords:
Oil
Fatty acid
Distribution
Circles
a b s t r a c t
Prevailing temperature at anthesis influences pollen health, fertilisation, seed filling, oil and fatty acid
accumulation in different circles of sunflower head. Field experiments were conducted, during 2007
and 2008, at Pir Mehr Ali Shah, Arid Agriculture University, Rawalpindi, Pakistan, to document oil and
fatty acid distributions in different circles of sunflower head. Hybrid S-278 was planted in randomised
complete block design with a two factors factorial experiment, with four replications. At maturity, heads
were divided into three equal circles (outer, middle and central); thereafter, oil and fatty acid distribu-
tions were separately determined in each circle. Oil and fatty acid concentrations in three circles differed
significantly. The outer circle accumulated high oil and oleic contents which decreased to a minimum in
the central circle; however, linoleic acid consistently increased, from outer to central circle, during both
the years.
Ó 2011 Elsevier Ltd. All rights reserved.
1. Introduction
Sunflower oil extracted from achenes is commonly used in food,
as a frying medium, and in cosmetic formulations, as an emollient.
Oil is light in taste and appearance. It is a combination of mono-
unsaturated and polyunsaturated fats with low saturated fat levels.
Oil is liquid at room temperature. Fatty acid composition is a major
determinant of oil quality, mainly with good percentages of oleic
and linoleic acid. Fatty acid composition is mainly affected by
genotypes and environmental conditions, temperature having a
major influence on oil quality (Izquierado, Aguirrezabal, Andrade,
& Pereyra, 2002).
Sunflower is a temperate crop but it can perform well under
various climatic and soil conditions. It is a short duration crop
maturing in 100–120 days. Temperature is a major environmental
factor that determines the rate of plant development. Fluctuations
in temperature and moisture availability affect the quantity and
quality of oil accumulation (Hassan, Manaf, & Ejaz, 2005). Variation
in unsaturated fatty acids profile is strongly influenced by both
genetics and climate. Demurin, Skoric, Veresbaranji, and Jocic
(2000) concluded that oleic acid content is essentially influenced
by temperature during seed development; each 1 °C increase of
temperature leads to about 2% increase of oleic acid. Oil and fatty
acid composition in seeds are important targets in sunflower
breeding.
A completely developed head usually has a small circular
depression in the centre while middle and outer whorls are flat.
Anthesis (pollen shedding) begins at the periphery and proceeds
to the centre of the head (Putnam et al., 1990). Similarly, matura-
tion of sunflower seeds takes place from the perimeter to the cen-
tre of sunflower head and seeds maturing at higher temperature
would accumulate higher oil content (Weiss, 2000). Different
whorls within a head fertilise and mature differently (Alkio,
Diepenbrock, & Grimm, 2002); thus, growth of achenes mainly de-
pends on phloem transport from upper fully expanded green
leaves to the capitulum. Improved assimilate supply to growing
achenes is regarded as the main factor for increase in yield of mod-
ern sunflower hybrids (Lopez Pereira, Trapani, & Sadras, 1999).
Munshi, Kaushal, and Bajaj (2003) studied the physiochemical
properties of seeds located in different whorls of sunflower head
and concluded that the proportion of filled seeds decreased from
outer to central whorl. A 10-fold decrease in filled to un-filled seed
ratio was observed, due to which oil content was higher in the out-
er than in the middle and central whorls. The higher oil content in
the outer whorl was concluded to be the effect of environmental
conditions and the span of seed development. The accumulation
of oil during seed filling was considered to be dependent upon
an unhampered supply of photo-assimilates from the source to
the sink. Similarly, Alkio and Grimm (2003) observed poorly
developed or un-filled achenes in the central part of the sunflower
head. They further concluded that, before fertilisation and seed fill-
ing, assimilates and nutrients are required for floret development
and flowering. Following anthesis, if no fertilisation occurs or the
embryo is aborted due to environment, the assimilate demand is
reduced, ultimately causing the vascular tissues of this head region
to degenerate, leading to empty achenes, influencing oil and oil
quality. Vascular bundles originating from the stem run radially to-
ward the periphery of the capitulum and from there toward the
centre of the capitulum. The occurrence of empty achenes is
0308-8146/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved.
doi:10.1016/j.foodchem.2011.02.002
⇑ Corresponding author. Fax: +92 51 9290160.
E-mail address: ahmadmukhtar@uaar.edu.pk (M. Ahmad).
Food Chemistry 128 (2011) 590–595
Contents lists available at ScienceDirect
Food Chemistry
journal homepage: www.elsevier.com/locate/foodchem

3. Author's personal copy
highest in the centre of the capitulum and poor seed filling is
related to poor vascularisation of receptacle; thus, oil and oil qual-
ity are affected more in this portion of the head (Goffner, Cazalis,
Percie du sert, Calmes, & Cavalie, 1988).
At the time of achene maturity, heavier seeds were observed in
the outer region, probably due to the early maturation and produc-
tion of more filled seeds in the peripheral zones (Baydar & Erbas,
2005). Although quite abundant literature is available on breeding,
agronomic, physiological and quality aspects of different hybrids
grown in different parts of the world, information related to distri-
bution of oil and fatty acids in different circles of sunflower head is
scarce. The present study was designed to document how seed
position affects oil and fatty acid accumulation in different circles
of sunflower head.
2. Materials and methods
2.1. Field experimentation and soil status
Field experiments were conducted at Pir Mehr Ali Shah, Arid
Agriculture University, Rawalpindi, Pakistan, located at 33° and
38° N and 73° and 04° E, during 2007 and 2008. The soil of the
experimental site was loam-type in texture with class typic camb-
orthids having sand 43%, silt 46% and clay 11%, pH 7.4 and EC
0.66 m S cmÀ1
. Available NPK concentrations in the soil before
sowing were 300, 5.00 and 140 mg kgÀ1
, respectively.
2.2. Soil preparation and sowing methodology
Prior to sowing, the particular site was fallow during the winter
and was prepared for sowing by giving one soil-inverting plough
and, thereafter, ploughed thrice with a tractor-mounted cultivator
and planked with the last ploughing. The recommended dose of
fertiliser of 80 kg nitrogen and 60 kg P2 O5 per hectare was applied
in the form of urea and DAP at the time of last ploughing. Crop was
sown on 18th March, 2007, and 20th March, 2008. Sowing was
done with a dibbler, by putting two seeds at each pre-marked spot.
Plant to plant distance was maintained 25 cm, and row to row
75 cm, in a net plot size of 5 Â 3 m2
. The sunflower hybrid S-278
was sown by using seed at 5 k/ha. After complete emergence,
one plant was maintained per hill. Weeds were kept under control
by hand-weeding throughout crop life cycle.
2.3. Data recording and treatments
Ten randomly selected heads from central rows in each plot and
three replications were harvested on the 8th of July, 2007 and the
11th of July, 2008 and sun-dried for five days. Heads were equally
divided (Fig. 1) into three circles Outer (O), middle (M) and central
(C). The two years (2007 and 2008) were considered as factor A and
three equal circles (outer, middle and central), thus making three
treatments, as factor B. Meteorological data during the course of
the experiment were also recorded (Table 1).
2.4. Oil extraction and fatty acid determination
Achenes from each circle were separated by hand. Achenes from
each circle were separately analysed for oil content by NMR, Model
MQA-7005, Oxford Institute, USA, by standardising the equipment
with six different oil contents (samples previously analysed). Thus
oil contents in each circle were recorded (Warnsely, 1998). The
fatty acids in oil were analysed by a gas chromatograph (AIML-NU-
CON) after intersterilification with methanolic KOH. In this meth-
od, fatty acids were converted to methyl esters prior to analysis
by gas chromatography (GC). Oil samples (50 ll) were methylated
in 4 ml of 1 M KOH for one hour at room temperature. The resul-
tant fatty acid methyl esters (FAME) were extracted with high per-
formance liquid chromatography-grade hexane and analysed by
GC using a fused capillary column (WCOT fused silica
30 m  0.25 mm coating CPWAX 52 CBDF = 0.25 lM, CP8713), a
flame ionisation detector (FID) and nitrogen gas as carrier
(3.5 ml/min). FAMEs were injected manually. Fatty acids were de-
tected by chromatographic retention time and by comparison with
authentic standards (Paquot, 1988).
2.5. Statistical analysis
The collected data were subjected to statistical analysis by
using analysis of variance with the help of MSTATC, separately
for both the years (Freed & Eisensmith, 1986). Least significant dif-
ference (at 5% probability) was used to compare the means (Mont-
gomery, 2001). Multiple regression analysis was performed by
using STATGRAPHICS software while Box-and-Whisker plots were
generated by using original recorded data (StatPoint Technologies
Inc., 2009).
3. Results
3.1. Oil content
Oil content consistently decreased from outer to central circle
during both the years. Statistical differences for oil content were
recorded among circles for both the years, 2007 and 2008 (Table
2). The maximum oil content (48.87%) was obtained from the outer
circle which was statistically (p < 0.05) similar to the middle circle
(47.55%) but statistically (p < 0.05) different from the central circle
(45.19%). Comparison of the years showed statistically non-signif-
icant differences for oil content. Interactions of years  circles
were statistically significant. The outer circle accumulated the
maximum (48.85%, 47.70%) oil contents during both years of
experimentation, respectively, while the central circle gave the
minimum (44.26%, 46.12%) values during the two years, respec-
tively. Similarly, the output of the multiple linear regression model
to describe the relationship between oil contents and two indepen-
dent variables, i.e. years (Y) and sunflower head circles (C), de-
picted a negative relationship (Oil content = 50.285 À 0.13 Â
Y À 1.5425 Â C). Since the p-value was less than 0.05, a statistically
significant relationship existed between the variables. The
R-Squared and adjusted R-squared statistics indicated 51.08% and
44.56% variability in oil content, respectively, with standard error
Fig. 1. Circles of sunflower head.
Fayyaz-ul- Hassan et al. / Food Chemistry 128 (2011) 590–595 591

4. Author's personal copy
of 1.35. Similarly, distribution of oil among different circles, with
median, was elaborated by Box-and-Whisker Plot, which showed
that oil contents were greater in the outer circle and decreased sig-
nificantly to middle and inner circles (Fig. 2).
3.2. Palmitic acid
Palmitic acid accumulation in different circles showed a small
increase from outer to central circle during 2007; however, no con-
sistent pattern was visible during 2008. Statistically (p < 0.05) sim-
ilar results were exhibited, among circles, for palmitic acid (Table
2). Comparison of the years showed statistical (p < 0.05) differ-
ences for palmitic acid. Comparatively higher (5.81%) palmitic acid
was accumulated during 2007 as compared to 2008 (5.61%). The
interaction (years  circles) were also statistically (p < 0.05) non-
significant. The regression analysis for palmitic acid, among differ-
ent sunflower circles and years, revealed that it increased from
outer to inner circle but decreased during the second year (palmitic
acid = 5.875 À 0.2 Â Y + 0.0675 Â C). However, the p-value was
greater or equal to 0.05, and hence depicted a statistically non-sig-
nificant relationship, with standard error of 0.66. The trend of pal-
mitic acid was further elucidated by Box-and-Whisker Plot (Fig. 3).
3.3. Stearic acid
Statistically (p < 0.05) similar results were exhibited among cir-
cles regarding stearic acid for both the years (Table 2). Comparison
of the years showed statistical differences for stearic acid. A com-
paratively higher (3.52%) value was obtained during 2008 than
2007 (2.65%). The interaction (years  circles) was statistically
(p < 0.05) significant with regard to stearic acid. The maximum
(2.82%, 3.24%) stearic acid was recorded for the middle circle
during 2007 and for the outer circle during 2008, respectively,
while the minimum (2.53%, 2.87%) value was obtained for the cen-
tral circle during 2007 and 2008, respectively. The output of
regression analysis showed that stearic acid increased significantly
during the second year; on moving from outer to middle circle, it
decreased (stearic acid = 1.885 + 0.87 Â Y À 0.0525 Â C). Since the
p-value for the regression model was less than 0.05, a statistically
significant relationship existed between the variables. The
R-squared statistic indicated 40.44% of variability in stearic acid
due to variables while the adjusted R-squared statistic showed a
variability of 32.49% with standard error of 0.58. The Box-and-
Whisker plot (Fig. 4) further explained the trend of stearic acid
among sunflower circles with deviation from mean.
3.4. Oleic acid
Oleic acid consistently decreased from outer to central circle
during both the years. Statistical differences for oleic acid were re-
corded among circles during 2007 and 2008 (Table 2). The maxi-
mum oleic acid (53.3%) was accumulated in the outer circle
which was statistically (p < 0.05) different from rest of the circles,
Table 1
Meteorological data for crop duration (2007 and 2008).
Month 2007 2008
Temperature (°C) Rainfall (mm) RH (%) (mean) Sunshine
(mean h)
Temperature (°C) Rainfall (mm) RH (%) (mean) Sunshine
(mean h)
Max (mean) Min (mean) Max (mean h) Min (mean)
March 23.10 9.00 143.20 47.00 7.40 29.67 11.78 19.10 57.00 7.90
April 34.00 15.90 18.00 44.00 10.70 29.70 15.77 92.90 59.33 7.71
May 37.30 19.80 80.60 42.00 10.00 37.16 20.76 10.10 40.00 9.92
June 37.60 23.00 22.30 51.00 9.50 35.57 22.29 225.00 62.43 7.47
July 35.20 21.50 95.50 68.00 9.30 35.01 22.75 240.00 69.61 7.38
Table 2
Oil and fatty acid distribution in different circles of sunflower head during 2007 and 2008.
Oil content (%) Palmitic acid Stearic acid (%) Oleic acid (%) Linoleic acid (%)
2007 2008 2007 2008 2007 2008 2007 2008 2007 2008
O 48.85a 47.7ab 5.56ab 5.06b 2.60 3.24NS 52.4a 54.1c 35.3e 32.3c
M 48.10a 47.00ab 5.77ab 5.00b 2.82 2.89 51.4b 52.3d 36.1d 35.0b
C 44.26c 46.12b 6.10a 5.69ab 2.53 2.87 51.0b 45.1d 36.4d 41.0a
LSD (5% probability) 1.034 0.972 – 1.013 0.359
Any two means not sharing a letter in common differ significantly. O = outer, M = middle, C = central.
Outer circle
Middle circle
Inner circle
43 45 47 49 51
Oil contents (%)
Fig. 2. Multiple Box-and-Whisker plot showing relationship between oil contents
and head circles with median vertical line.
Palmitic acid (%)
Outer circle
Middle circle
Inner circle
4.6 5 5.4 5.8 6.2 6.6 7
Fig. 3. Multiple Box-and-Whisker plot showing relationship between palmitic acid
and head circles with median vertical line.
592 Fayyaz-ul- Hassan et al. / Food Chemistry 128 (2011) 590–595

5. Author's personal copy
while the minimum (48.1%) value was obtained for the central cir-
cle. Comparison of the years showed statistical differences for oleic
acid. Comparatively higher values were obtained during 2007 than
during 2008. Interactions of years x circles were statistically
(p < 0.05) significant. The maximum (52.4%, 54.1%) oleic acid was
recorded for the outer circle during 2007 and 2008, respectively,
and the minimum (51.0%, 45.2%) value for the central circle during
2007 and 2008, respectively. The regression analysis revealed that
oleic acid contents decreased during 2008 and from outer to cen-
tral circle (oleic acid = 57.86 À 1.07 Â Y À 2.595 Â C). Similarly, p-
value regression analysis was less than 0.05; therefore statistically
significant relationships exited between variables. The R-squared
and adjusted R-squared statistics indicated 55.2% and 49.3% vari-
ability in oleic acid, respectively, with a standard error of 2.15. Sim-
ilarly, the trend of oleic acid among sunflower head circles was
further elaborated by a Box-and-Whisker plot (Fig. 5).
3.5. Linoleic acid
Contrary to oleic acid, linoleic acid consistently increased from
outer to central circle for both the years (Table 2). The maximum
linoleic acid (38.7%) accumulated in the central circle was statisti-
cally (p < 0.05) different from the rest of the circles, while the min-
imum (33.8%) value was observed for the outer circle. Comparison
of the years showed statistically non-significant differences for lin-
oleic acid. However, the interaction of years  circles was statisti-
cally (p < 0.05) significant. The maximum (36.4%, 41.0%) linoleic
acid was recorded for the central circle during 2007 and 2008,
respectively, while the minimum (35.3%, 32.3%) accumulated in
the outer circle during 2007 and 2008, respectively. The output
of regression analysis showed that linoleic acid contents increased
among years and head circles (linoleic acid = 30.88 + 0.16 -
Y + 2.44 Â C). Since the p-value of regression analysis was less than
0.05, a statistically significant relationship existed between the
variables. The R-squared statistic indicated 55.7% variability in lin-
oleic acid while the adjusted R-squared statistic showed a value of
49.8% with standard error of 1.95. Similarly, distribution of linoleic
acid among different circles with median was elaborated by Box-
and-Whisker plot, which showed more linoleic acid recorded for
the central circle (Fig. 6).
4. Discussion
In temperate regions, sunflower requires approximately 11 days
from planting to emergence, 33 days from emergence to head visi-
ble, 27 days from head visible to first anther, 8 days from first to last
anther, and 30 days from last anther to maturity (Putnam et al.,
1990). The difference (of eight to ten days from first to last anther)
indicates that temperature/environmental conditions varied for an-
ther shedding on different days, thus creating a basis for difference
in seed setting, development and oil accumulation.
Increase of 1 °C in temperature, during flowering to maturity, of
sunflower, caused increase of 1% in oil content of sunflower
(Demurin et al., 2000). Similarly, high oleic sunflower oil had great-
er thermal stability than did normal sunflower oil (Smith, Robert &
Min, 2007). In the present investigations, progressive reduction of
oil content, from outer to central circle of the crop, is in line with
the findings of Munshi et al. (2003) who concluded that seeds in
the outer region grew at a slow rate than those in the central re-
gion; thus, time available to outer region seeds was more than that
available to seeds in the central region. Slow accumulation, for a
longer period of time, would increase the total oil content. The
opposite relationship (Fig. 7) between head circles and oil content,
for both the years, is supportive of the above assumption. An over-
all higher percentage of oil was found from the 2007 crop than that
for 2008 crop. Lower achene oil content during 2008 may be due to
comparatively lower temperature during seed development and
maturation as compared with the high temperature prevailing dur-
ing 2007 (Table 1). Thus, results of the present study are consistent
with the findings of Weiss (2000) who concluded that crops matur-
ing at higher temperature would accumulate higher oil contents.
Inconsistent patterns for palmitic acid accumulation were ob-
served among circles in the present study. Comparison of the years
regarding palmitic acid revealed less accumulation during 2008
than 2007. The smaller palmitic acid values during 2008 might
be due to the low temperature prevailing during seed development
and maturation (Table 1) which accords with the findings of
Rehmatalla, Babiker, Krishna, and Tiny (2001) who concluded that
fatty acid compositions of oilseeds are modified by the duration of
seed development and prevailing environmental conditions. Simi-
larly, inconsistent patterns of stearic acid accumulation in the pres-
ent investigation are similar to the findings of Baydar and Erbas
(2005) who found that the accumulation pattern for saturated fatty
acid was similar, with slight fluctuations. Similar to our findings
(Roche et al., 2010) reported that higher temperature prevailing
Outer circle
Middle circle
Inner circle
2 2.4 2.8 3.2 3.6 4
Stearic acid (%)
Fig. 4. Multiple Box-and-Whisker plot showing relationship between stearic acid
and head circles with median vertical line.
Oleic acid (%)
Outer circle
Middle circle
Inner circle
45 47 49 51 53 55
Fig. 5. Multiple Box-and-Whisker plot showing relationship between oleic acid and
head circles with median vertical line.
Outer circle
Middle circle
Inner circle
32 34 36 38 40 42
Linoleic acid (%)
Fig. 6. Multiple Box-and-Whisker plot showing relationship between linoleic acid
and head circles with median vertical line.
Fayyaz-ul- Hassan et al. / Food Chemistry 128 (2011) 590–595 593

6. Author's personal copy
during seed formation had affected oil contents of sunflower
significantly.
Our results reveal that outer circles accumulated higher oleic
acid during both years, which progressively decreased from outer
to central circles. Pollination, seed development and seed matura-
tion take place from the peripheral toward the central whorl on a
single head. These processes take place at different intervals of
time at different temperatures. Progressive reduction of oleic acid
from outer to central circle is in accordance with results of Munshi
et al. (2003) who concluded that peripheral seeds mature earlier at
higher temperatures, then middle and centre last; thus, all three
whorls, maturing on different days, with varying maturing temper-
ature, accumulated various oleic contents. Similarly, Hernandez
and Palmer (1992) concluded that, at the time of photo-assimilate
distribution in capitulum during anthesis and seed filling, gener-
ally, peripheral florets start to import earlier and they incorporate
higher amounts of carbohydrates, oil and oleic contents than do
the central ones. In our investigations, relatively higher oleic acid
was observed during the 1st year than during the 2nd year. Lower
oleic acid during the 2nd year may be attributed to low tempera-
ture prevailing at the time of achene development, in addition to
other environmental factors (e.g. sunshine hours). Our findings
are in line with the earlier findings of Izquierado, Aguirrezabal,
Andrade, and Cantarero (2006) who observed a linear relationship
between oleic acid concentration and temperature and recorded a
higher concentration of oleic acid at warmer temperature in the
spring season due to reduced or limited activity of de-saturase en-
zyme, responsible for the conversion of oleic acid to linoleic acid.
Increased concentration of oleic acid, because of rising tempera-
ture during 2007 (Table 1), may improve oil quality in the form
of oxidative stability during storage and frying (Smith et al., 2007).
The results for linoleic acid in different circles of sunflower hy-
brids were contrary to those observed for oleic acid. Results in Ta-
ble 2 revealed that the central circle accumulated more linoleic
acid this progressively increased from outer to central circles for
both the years of experimentation. Results of the present study
are in line with the findings of Baydar and Erbas (2005) who con-
cluded that position of seeds on sunflower head had a strong effect
on fatty acid contents. As peripheral seeds mature earlier at higher
temperatures than middle and centre last, outer seeds accumulate
lower linoleic contents than do central seeds (being matured at rel-
atively low temperature). Relatively higher linoleic acid was ob-
served during the 2nd than during the 1st year of study. Higher
linoleic acid content during the 2nd year may be attributed to
low temperature conditions prevailing at the time of achene devel-
opment (Table 1). At low temperature, the enzyme de-saturase be-
comes active, which is responsible for the conversion of oleic to
linoleic acid (Baux, Hebeisen, & Pellet, 2008). Similarly, Demurin
et al. (2000) reported a negative correlation between oleic and lin-
oleic acid percentages (which are essentially influenced by temper-
ature). An inverse relationship between oleic acid, and linoleic acid,
for circles in the present study, is supportive of the above conclu-
sions (Fig. 8).
5. Conclusion
Distribution of oil and fatty acids in different head circles is a
combined function of growth, development and overall plant
structure, affected by environmental conditions. At present, all
the hybrids under cultivation have heads with different maturity
times, which ultimately affect oil quality and quantity. Therefore,
a broader, comprehensive, meaningful breeding and hybridisation,
agronomic and physiological strategy, for the development of new
hybrids with enhanced vascular connections, is needed, so that
assimilates may partition actively and equally in all the regions/
circles of the head. This equal distribution of assimilates and matu-
rity at one time may enhance the proportion of fully filled seed,
improving oil and fatty acid accumulation percentage down to
the centre of the capitulum.
References
Alkio, M., Diepenbrock, W., & Grimm, E. (2002). Evidence for sectorial
photoassimilate supply in the capitulum of sunflower (Helianthus annuus L).
New Phytologist, 156, 445–456.
Alkio, M., & Grimm, E. (2003). Vascular connections between receptacle and empty
achenes in sunflower (Helianthus annuus L). Journal of Experimental Botany, 54,
345–348.
Baux, A., Hebeisen, T., & Pellet, D. (2008). Effects of minimal temperatures on low
linolenic rapeseed oil fatty acid composition. European Journal of Agronomy, 29,
102–107.
Baydar, H., & Erbas, S. (2005). Influence of seed development and seed position on
oil, fatty acids and total tocopherol contents in sunflower (Helianthus annuus L.).
Turk Journal of Agriculture, 29, 179–186.
Demurin, Y., Skoric, D., Veresbaranji, I., & Jocic, S. (2000). Inheritance of increased
oleic acid content in sunflower seed oil. Helia, 23, 87–92.
Freed, R. D., & Eisensmith, S. P. (1986). MSTAT Microcomputer Statistical Program.
Michigan, USA: Michigan State University of Agriculture and Applied Science.
Goffner, D., Cazalis, R., Percie du sert, C., Calmes, J., & Cavalie, G. (1988). 14
C photo
assimilate interception and seed production in sunflower as influenced by
temperature and radiation. Australian Journal of Plant Physiology, 11, 255–265.
Hassan, F. U., Manaf, A., & Ejaz, M. (2005). Determinants of oil and fatty acid in
peanut. International Journal of Agriculture and Biology, 7, 895–899.
Hernandez, L. F., & Palmer, J. H. (1992). Incorporation of 14
C labelled metabolites into
the developing sunflower capitulum. Proceedings of 13th international sunflower
conference. Pisa, Italy, Toowoomba, Australia: International Sunflower
Association. http://www.statgraphics.com/statpoint.htm.
Izquierado, N., Aguirrezabal, L., Andrade, F., & Cantarero, M. (2006). Modelling the
response of fatty acid composition to temperature in a traditional sunflower
hybrid. Agronomy Journal, 98, 451–461.
Izquierado, N., Aguirrezabal, L., Andrade, F., & Pereyra, V. (2002). Night temperature
affects fatty acid composition in sunflower oil depending on the hybrid and the
phenological stage. Field Crop Research, 77, 115–126.
Lopez Pereira, M., Trapani, N., & Sadras, V. O. (1999). Genetic improvement of
sunflower in Argentina between 1930 and 1995. II. Phenological development,
growth and source-sink relationship. Field Crop Research, 6, 247–254.
Montgomery, D. C. (2001). Design and Analysis of Experiments (5th Ed.). New York:
John Willy and Sons. pp. 64–65.
Munshi, S. K., Kaushal, B., & Bajaj, R. K. (2003). Compositional changes in seeds
influenced by their positions in different whorls of mature sunflower head.
Journal of Science Food and Agriculture, 83(15), 1622–1626.
y = -1.54x + 50.083
R² = 0.9137
44
45
46
47
48
49
50
51
0 1 2 3 4
Oilcontent(%)
Head circles
Fig. 7. Relationship between head circles and oil content (means of two years).
y = -2.595x + 58.848
R² = 0.9401
y = 2.45x + 28.67
R² = 0.9742
30
32
34
36
38
40
42
44
43
45
47
49
51
53
55
57
0 1 2 3 4
Linoleicacid(%)
Oleicacid(%)
Head circles
Oleic acid Linoleic acid
Fig. 8. Relationship between oleic and linoleic acid.
594 Fayyaz-ul- Hassan et al. / Food Chemistry 128 (2011) 590–595

7. Author's personal copy
Paquot (1988). Standard Methods for Analysis of Oils, Fats and Derivates. Paris, France:
Pergamon Press.
Putnam, D. H., Oplinger, E., Hicks, D., Durgan, B., Noetzel, D., Meronuck, R., et al.
(1990). Sunflower. Alternative Field Crops Mannual. Madison, Wl 53706:
Extension Co-operative Service, University of Wisconsin.
Rehmatalla, A. B., Babiker, E. E., Krishna, A. G., & Tiny, A. H. (2001). Changes in fatty
acid composition during growth and physiological characteristics of oil
extracted from four sunflower cultivars. Plant Food and Human Nutrition, 56,
385–395.
Roche, J., Marion, A., Andree, B., Muriel, C., Zephirin, M., Felicity, V., et al. (2010).
Sterol content in sunflower seeds (Helianthus annuus L.) as affected by
genotypes and environmental conditions. Food Chemistry, 121, 990–995.
Smith, S. A., Robert, E. K., & Min, D. B. (2007). Oxidative and thermal stabilities of
genetically modified high oleic sunflower oil. Food Chemistry, 102, 1208–1213.
Warnsely, J. (1998). Simultaneous determination of oil and moisture in seed by
NMR. Lipid Tech, 10, 6.
Weiss, E. A. (2000). Oil Seed Crops. London: Langman Group Ltd..
Fayyaz-ul- Hassan et al. / Food Chemistry 128 (2011) 590–595 595