Maataloustieteellinen Aikakauskirja
Vol. 61: 7—14, 1989

Effects of different fertilization practices on the carotene content of carrot

AINO-MAIJA EVERS
Kemira Oy, Espoo Research Centre, Luoteisrinne 2,
SF-02270 Espoo, Finland

Abstract. The effects of different fertilization practices on the carotene content of carrot
cv. Nantes Duke Notabene 370 Sv were studied in field experiments in southern Finland.
Unirrigated and irrigated placement and broadcast fertilization, NPK fertirrigations without
basic fertilization, NPK fertirrigations with NPK basic fertilization, and PK placement with
N fertirrigations were compared. Further, single application was compared to split applica-
tions. Carotene determinations were done at harvest in 1985 and 66, 88 and 121 (at harvest)
days from sowing in 1986. The results were studied by contrast analysis.

Weather conditions had a strong effect on the carotene content and in both years the caro-
tene content increased with the length of the growing season. At harvest in 1985, PK place-
ment with N fertirrigations had a tendency to yield a higher carotene content than did broad-
cast fertilization, irrigated single application, and NPK fertirrigations. The carotene content
was higher when P and K were placement fertilized as compared to treatments where P and
K were broadcast fertilized or fertirrigated (p =0.1). At the first sampling date in 1986, fertili-
zation increased the carotene content (p=0.1). PK placement with N fertirrigations had a ten-
dency to increase the carotene content as compared to placement fertilization, single applica-
tion and irrigated single application. At the second sampling date and at harvest in 1986 no
statistically significant differences could be found.

The results indicate that the placement of PK-fertilizer or NPK-fertilizer was favourable
to carotene production. Besides the fertilization experiment, samples from two organically
cultivated fields were collected to obtain data concerning organically cultivated carrots.

Index words; carrot, placement fert., broadcast fert., fertirrigation, carotene, organic cultivation

Introduction

Carrot (Daucus carota L.) contains many
carotenoids, mainly tetraterpenes of the
isoprenoid group. About 60 % of the total
carotene content in carrot is (3-carotene
(Gabelman 1974). The variation in carotene

content is dependent on genotype (Gabelman
1974) and climate (Simon et al. 1982). The
developmental stage of a plant (Banga et al.
1963, Phan & Hsu 1973, Fritz & Habben
1975) and temperatures during the growing

7

JOURNAL OF AGRICULTURAL SCIENCE IN FINLAND

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season (Barnes 1936, Banga et al. 1955) also
have a considerable effect on the carotene con-
tent. In addition, soil moisture (Banga & De
Bruyn 1964, Dragland 1978), the intensity
of photosynthesis, shoot size, and plant den-
sity (Banga & De Bruyn 1964) affect the
carotene content of carrots.

The literature contains reports about the in-
fluence of macronutrients on the carotene
content the results of which are contradicto-
ry. Freeman & Harris (1951) and Habben
(1973) found that increasing the amounts
of nitrogen increased the carotene content. On
the other hand, Dragland (1978) reported
that increasing nitrogen amounts did not
affect the carotene content, and Southards
& Miller (1962) obtained the highest caro-
tene contents with low nitrogen levels. The
same contradiction has been observed for
potassium. In some studies, increasing
amounts of potassium had no significant in-
fluence on carotene content (Gallagher
1966, Habben 1973), whereas others (Sout-
hards & Miller 1962) reported that high

potassium and magnesium levels increased the
amount of carotene in carrots. Nilsson
(1979) found no differences in carotene con-
tents resulting from fertilizer levels or the use
of organic versus inorganic fertilizers. The
effects of different fertilization practices and
the split application of nutrients have been
studied very scarcely. The aim of the present
study was to investigate whether unirrigated
or irrigated placement and broadcast fertili-
zation, fertirrigation and their combinations
as well as the split application of nutrients af-
fect the carotene content of carrots.

Material and methods

Field experiment

The field experiment was done on the Kot-
kaniemi Experimental Farm of Kemira Oy.
in Vihti, southern Finland, in the summers of
1985 and 1986. Carrot cv. Nantes Duke Nota-
bene 370 Sv was grown as described by Evers
(1988). The experiment was arranged in four

Table 1. The fertilization treatments

Treatment Number and time Macronutrient amounts Irrigation water
of fertilizer in 1986' kg/ha amounts in 1985
applications ~~~ ~ T7~ and 1986

mm

No fertilization
No irrigation 0 0 0 0 0
Irrigation 0 0 0 0 3xlo

NPK placement
No irrigation 1 before sowing 80 35 133 0
Irrigation 1 before sowing 80 35 133 3xlo

NPK broadcast
No irrigation 1 before sowing 80 35 133 0
Irrigation 1 before sowing 80 35 133 3xlo

NPK fertirrigations
Without basic fertilization • 3 during season 80 29 160 3xlo
Half the NPK basic fertilization 1 1 before sowing and 80 32 142 3xlo

3 during season
PK placement2 1 before sowing and 81 56 133 3xlo

3N-fertirrigations 3 during season
4N-fertirrigations 1 before sowing and 155 56 133 4xlo

4 during season

1 Half of the nutrients were given by basic placement fertilization and half by NPK fertirrigations.
2 Phosphorus and potassium were given by basic placement fertilization and nitrogen by fertirrigations.
3 The nutrient amounts were 30 % bigger in 1985 than in 1986.

8



randomized blocks, with ten treatments per
block and plots of 25 m 2 (Table 1).

Determination of carotene
The carrot samples for the determination of

carotene were collected on September 30, 1985
(117 days from sowing) and August 12, 1986,
on September 3, 1986 and October 6, 1986
(66, 88 and 121 days from sowing, respective-
ly). Six consecutive carrots were sampled
from each plot, from a randomized place,
and two analyses were made for each sample.
In 1985 samples were collected from two
blocks, in 1986 from four blocks. Carotene
was determined by high-performance liquid
chromatography (HPLC) on SPHERISORB
10 ODS 2 250x4.6 mm I.D. column, a bonded
octadecylsilane stationary phase with visible
photometric detection at wavelength 450 nm
(Lancer 1976). This method measures the
added a and (3 carotene content. In the text
it is termed carotene for short. 60 grams of
fresh carrot tissue was crushed in a blender

containing 100 ml CH 2C12 and was mixed for
10 minutes, filtered and analyzed immediate-
ly by HPLC. The samples were protected
from light and oxygen because these can de-
stroy carotene. The data was studied statisti-
cally by contrast analysis (Steel & Torrie
1980).

Organically cultivated carrots

Simultaneously with those for the fertiliza-
tion experiments, samples from two organi-
cally cultivated fields were collected. These or-
ganically cultivated carrots were grown with
the same seed material, but the geographical
locations (Varkaus and Rantasalmi) and soil
characteristics differed from those of the fer-
tilization experiments. In any case, these sam-
ples gave information of organically cultivat-
ed carrots. The compost and soil analyses as
well as the amounts of compost used are giv-
en in a previous study (Evers 1988).

Fig. I. The effect of different fertilization practices on the carotene content of carrots at harvest in 1985 and 1986.

9



Results

Weather conditions

Weather conditions had a strong effect on
the carotene content of carrots. The carotene
contents of carrots cultivated in 1985 were
lower than in 1986 irrespective of the fertili-
zation treatments (p<o.ool***) (Fig. 1).

Developmental stage

The carotene content of carrots increased
with the length of the growing season (Fig. 2).
At the first sampling date, 66 days from sow-
ing, the carrots were about 10 cm long, with

an average weight per carrot of 27.0 grams.
In these young and small carrots, the carotene
content was low, the average for all treatments
being 2.6 mg/100 g fresh weight (FW). At the
second sampling date, 88 days from sowing,
the average weight per carrot was 76.5 g, the
mean carotene content being 4.3 mg/100 g
FW. At harvest, 121 days from sowing, the
corresponding values were 106 gand 6.1 mg/
100 g FW.

Fertilization

The statistical analysis method used in this
study did not reveal any significant differences

Fig. 2. The effect of different fertilization practices on the development of the carotene content of carrots in 1986.

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between fertilization practices or between un-
fertilized and fertilized treatments on level
p<0.05. At harvest in 1985, PK placement
with N fertirrigations had a tendency to yield
a higher carotene content than did broadcast
fertilization, irrigated single application, and
NPK fertirrigation (p = 0.1). There was also
a tendency for a higher carotene content when
P and K were placement fertilized as com-
pared to treatments where P and K were
broadcast fertilized or fertirrigated (p =0.1).

At first sampling date in 1986, fertilization
increased the carotene content (p = 0.1). PK
placement with N fertirrigations had a ten-
dency to increase the carotene content as
compared to placement fertilization, single ap-
plication and irrigated single application
(p = 0.1). At the second sampling date and at
harvest in 1986 no statistically significant
differences could be found.

In both years, four treatments gave good
results (Fig. 1). These were placement fertili-
zation, NPK fertirrigation withNPK basic fer-
tilization and PK placement with N fertirri-
gations. In both years NPK fertirrigations
without basic fertilization yielded a low caro-
tene content. Broadcast fertilization gave con-

tradictionary results in two years. As com-
pared to the average carotene content of un-
fertilized treatments, placement fertilization
increased the carotene content by 35 % in 1985
and by 9 % in 1986, NPK fertirrigations with
NPK basic fertilization increased the carotene
content by 28 °7o in 1985 and by 9 % in 1986,
and PK placement with 3N fertirrigations in-
creased the carotene content by 44 % in 1985
and by 10 % in 1986.

Carotene yield

The order of superiority for the treatments
was roughly similar whether the carotene con-
tent was calculated on the basis of fresh mat-
ter (Fig. 1) or dry matter (Table 2). When
the results were studied as the calculated caro-
tene yield per hectare (Table 2), some dif-
ferences were observed for 1986. Irrigated
placement fertilization produced a relatively
low carotene content, but the carotene yield
calculated as g/ha was very good. On the
contrary, broadcast fertilization produced a
surprisingly high carotene content, but the
carotene yield calculated as g/ha was low.
The same was true for PK placement with N
fertirrigations (Fig. 1, Table 2).

Table 2. The effect of different fertilization practices on the carotene content of carrots calculated on dry weight
basis and as a carotene yield per hectare.

Treatments Carotene content Carotene yield
mg/100 g dry weight g/ha

1985 1986 x 1985 1986 x

Unfertilized 42.554.2 48.3 1 620 2 760 2 190
Unfertilized and irrigated 35.153.4 44.2 1190 2 620 1900
Placement fertilized 49.760.0 54.9 1 850 3 190 2 520
Placement fertilized and irrigated 43.755.6 49.7 1 520 3 230 2 380
Broadcast fertilized 42.461.6 52.0 1620 3 150 2 380
Broadcast fertilized and irrigated 38.360.1 49.2 1060 2 970 2 020
NPK fertirrigations, without basic 41.456.8 49.1 1190 3 050 2 120
NPK fertirrigations, half the basic 50.560.2 55.3 1 830 3 460 2 650
PK placement with 3N fertirrigations 55.4 58.8 57.1 2 090 3 070 2 580
PK placement with 4N fertirrigations 50.456.7 53.5 1 760 3 140 2 450

x 44.957.7 51.3 1570 3 060 2 320
Organically cultivated, location 1 66.7 3 240
Organically cultivated, location 2 64.6 2 570

x 65.6 2 910

11



Organically cultivated carrots

The carotene contents were high for carrots
grown at both locations, being 7.0 mg/100 g
FW at location one and 6.2 mg/100 g FW at
location two. The contents were high also
when calculated on the dry weight basis (Ta-
ble 2). When the carotene yields were calcu-
lated (Table 2), they were lower in organical-
ly cultivated carrots than in the fertilizer ex-
periment.

Discussion

Genotype

The main variation in the carotene content
of carrots depends on genotype (Gabelman
1974) and climate (Simon et al. 1982). In the
present study, cv. Nantes Duke Notabene 370
Sv was used; the average carotene content of
all treatments and for two years at harvest was
5.2 mg/100 g FW. Bajaj et al. (1980) stud-
ied 23 cultivars of carrot; in their study this
variety contained 4.95 mg |3-carotene/100 g
FW. The overall mean of 23 varieties was
5.67 mg P-carotene/100 g FW (range 0.85—

8.50 mg/100 g FW). Thus in the climatic con-
ditions of southern Finland, this variety can
reach the same carotene level as in India.

Weather conditions

There was a clear difference in the mean
carotene content between the two years. The
average carotene content for all treatments
was 41.2 % higher in 1986 than in 1985. In
1985, the mean day temperature and the num-
ber of sunshine hours in June and July were
lower than in 1986 and lower than the long-
term averages (Evers 1988). Barnes (1936)
and Banga et al. (1955) reported that high
temperature favours carotene synthesis.
Härdh (1975) reported that the (3-carotene
content of carrots is higher in southern Fin-
land than in northern Finland, a difference
that is mainly due to higher temperatures in
the southern part of the country. Similar

results were also obtained in Norway and
Sweden (Härdh et al. 1977).

Dragland (1978) reported that low soil
moisture content increases the carotene con-
tent of carrot roots. Also Banga & De Bruyn

(1964) reported that the carotene synthesis in-
creases in dry soil. They concluded that evi-
dently in such case, primary vegetative root
growth is suppresed by the low soil moisture
content, causing the root to ripen at a smaller
root size. This means that protein synthesis is
also reduced and it is consuming less carbo-
hydrate compounds. Consequently, most of
the carbohydrate compounds available can be
used for other consumption processes, such
as carotenoid synthesis. Banga et al. (1963)
also studied whether the soil moisture content
affected the carotenoid synthesis directly or
indirectly by lowering the soil temperature.
They found that the soil moisture content had
a direct effect. Further Banga & De Bruyn

(1964) concluded that an oxygen content un-
der 6 % in the soil atmosphere reduces carote-
noid synthesis.

In the present field experiments, in 1985 the
precipitation was equal to the long-term aver-
ages, and in 1986 the precipitation was heavi-
er than the long-term averages except in June,
which was sunny and drier than average
(Evers 1988). In both years there were heavy
rains in September; the soil was very moist and
perhaps also had a low oxygen content.
Precipitation probably does not explain the
difference in the carotene contents between
years, as in both years the soil remained moist
throughout the growing period (except June,
1986). It is more likely that the higher tem-
perature in 1986 is the main reason for the
higher carotene contents in 1986 than 1985.

Developmental stage
There is general agreement in the literature

that the carotenoid content of carrots in-
creases when the plant is ripening (Banga et
al. 1963, Phan & Hsu 1973, Fritz & Habben
1975). Also in the present study, the carotene
content increased as the growing season
proceeded.

12



Fertilization
Because most of the variation in carotene

content is genetically controlled or is depen-
dent on climate, it is obvious that there can
be no clear differences between fertilization
practices. In more unfavourable year 1985
there was, however, a tendency for the place-
ment of PK fertilizer to increase the carotene
content. In future studies it would be intrest-
ing to investigate whether it is P or K that in-
creases the carotene content and the way in
which the nutrient affects the carotene con-
tent.

According to the literature, contradictory
results have been obtained with increasing
nitrogen amounts (Freeman & Harris 1951,

Southards & Miller 1962, Habben 1973,
Dragland 1978). In the present study, the
surplus nitrogen in treatment PK placement
with 4N fertirrigations did not significantly af-
fect the carotene content as compared to the
average of other fertilized treatments, where
the N amount applied was thought to be op-
timal on the basis of the yield. Thus this study
could find no response that depended on the
nitrogen amount.

Acknowledgement. I warmly thank Ms. Oili Uusitalo
for her excellent technical assistance. I am grateful to
Prof. E. Kaukovirta and Prof. A-L. Varis for their valu-
able comments on the manuscript. The financial support
of the Academy of Finland and Kemira Oy is gratefully
acknowledged.

References

Bajaj, K.L., Kaur, G. & Sukhua, B.S. 1980. Chemical
composition and some plant characteristics in rela-
tion to quality of some promising cultivars of carrot
(Daucus carota L.). Qual. Plant. PI. Foods Hum.
Nutr. 30: 97—107.

Banoa, 0., De Bruyn, J.W. & Smeets, L. 1955. Selec-
tion of carrots for carotene content. 11. Subnormal
content at low temperature. Euphytica 4: 183—189.

, De Bruyn, J.W., Van Bennekom, J.L. & Van Keu-

len, H.A. 1963. Selection of carrots for carotene
content. V. The effect of the soil moisture content.
Euphytica 12: 137—146.

, & De Bruyn, J.W. 1964. Carotenogenesis in carrot
roots. Neth. J. Agric. Sci. 12: 204—220.

Barnes, W.C. 1936. Effects of some environmental fac-
tors on growth and color of carrots. Cornell Univ.
Agric. Exp. Sta. Mem. 186: 1—36.

Dragland, S. 1978. Nitrogen- og vassbehov hos gulrot.
Forskn. Förs. Landbr. 29: 139—159.

Evers, A-M. 1988. Effects of different fertilization prac-
tices on the growth, yield and dry matter content of
carrot. J. Agric. Sci. Finl. 60: 135 —152.

Freeman, J.A, & Harris, G.H. 1951. The effect of nitro-
gen, phosphorus, potassium and chlorine on the caro-
tene content of the carrot. Sci. Agric. 31: 207—211.

Fritz, D. & Habben, J. 1975. Determination of ripeness
of carrot (Daucus carota L.). Acta Hort. 52:
231—238.

Gabelman, W.H. 1974. The prospects for genetic en-
gineering to improve nutritional values. Nutrition
qualities of fresh fruits and vegetables. (Eds. P. White
& N. Selwey). p. 147—155. New York.

Gallagher, P.A. 1966. The effect of potassium on yield

and quality of carrots. Proc. 8. Intern. Potash Inst.
Congr. p. 257—263. Brussel.

Habben, J. 1973. Einfluss der Stickstoff- und Kalium-
diingung auf Ertrag und Qualität der Möhre (Dau-
cus carota L.). Landw. Forsch. 26: 156—172.

Härdh, J.E. 1975. Der einfluss der umwelt nördlicher
breitengrade auf die qualität der gemiise. Qual. PI.
25: 43—56.

HArdh, J.E., Persson, A.R. & Ottosson, L. 1977. Qual-
ity of vegetables cultivated at different latitudes in
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Lanoer, K. 1976. Trennung von Carolinoiden mit Hilfe
der HPLC. Dissertation. Friedrich Alexander Univer-
sität. Niirnberg.

Nilsson, T. 1979. Avkastning, lagringsförmäga, kvalitet
och kemisk sammansättning hos möröt, vitkäl och
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Trädg. Vet. Rapp. 7: 3—52.

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Ms received

13



SELOSTUS

Eri lannoitustapojen vaikutus porkkanan
karoteenipitoisuuteen

Aino-Maija Evers
Kemira Oy, Espoon tutkimuskeskus.
Luoteisrinne 2, 02270 Espoo

Eri lannoitusmenetelmien vaikutusta porkkanalajikkeen
Nantes Duke Notabene 370 Sv karoteenipitoisuuteentut-
kittiin kenttäkokeissa 1985 ja 1986 Kotkaniemen koeti-
lalla Vihdissä. Vertailtavina menetelminä olivat sijoitus-
japintalannoitus (ilman kastelua jakastelun kera), NPK-
kastelulannoitus ilman peruslannoitusta, NPK-kastelulan-
noitus, jossa puolet ravinteista annettiin peruslannoituk-
sena, sekä N-kastelulannoitus, jossa P jaK annettiin si-
joittaen peruslannoituksena. Kokeessa verrattiin myös
kerta-annostelua jaksotettuunravinteiden antoon. Pork-
kananäytteet karoteenimäärityksiin kerättiin sadonkor-
juun yhteydessä 1985 sekä 66, 88 ja 121 (sadonkorjuu)
päivän kuluttua kylvöstä 1986. Tulosten analysointiin käy-
tettiin kontrastianalyysiä, jossa ei verrata yksittäisiä koe-
jäseniä toisiinsa vaan voidaan verrata asiakokonaisuuksia.

Vuonna 1985 sadonkorjuun yhteydessä koejäsenissä,
jotkasaivat P;n jaK;n sijoittaen peruslannoituksena ja
N:n kastelulannoituksena kasvukaudella, oli korkeammat

karoteenipitoisuudet kuin pintalannoituksen, kertalannoi-
tuksen kastelun kera tai NPK-kastelulannoituksen saa-
neissa koejäsenissä. Karoteenipitoisuudet olivat myös kor-
keammat koejäsenissä, jotka saivat P:n ja K:n sijoitus-
lannoituksena, kuin koejäsenissä, joissa P:tä ja K:ta ei
annettu sijoituslannoitustekniikalla. Tulokset olivat suun-
taa-antavia tasolla p =0.1.

Vuonna 1986 vain ensimmäisellä näytteenottokerralla
(66 vrk kylvöstä) lannoitus lisäsi karoteenipitoisuutta
(p = 0.1). Lannoitustapa, jossaP ja K annettiin sijoittaen
keväällä ja N kastelulannoituksena kasvukaudella, lisäsi
suuntaa-antavasti (p =0.1) karoteenipitoisuutta verrattuna
sijoituslannoitukseen, yhteen antokertaan jakasteltuun
yhteen antokertaan.

Kaikkien koejäsentenkaroteenipitoisuus nousi kasvu-
kauden edetessä. Vuoden säätekijöillä oli selvä vaikutus
karoteenipitoisuuksiin.

14