View of Effects of different fertilization practices on the carotene content of carrot

MaataloustieteellinenAikakauskirja Vol. 61: 7—14, 1989

Effects of different fertilization practices on the

carotene content

carrot

AINO-MAIJA EVERS

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

Abstract. The effects of different fertilization practicesonthe carotene content of carrot cv. Nantes Duke Notabene 370Sv werestudied in field experimentsin southern Finland.

Unirrigatedand irrigated placement and broadcast fertilization,NPKfertirrigationswithout basic fertilization,NPKfertirrigationswith NPKbasic fertilization, and PK placementwith Nfertirrigationswere ^{compared.Further,} single applicationwascompared to split applica- tions. Carotene determinationswere done at harvest in 1985and 66, 88 and 121(at harvest) daysfrom sowingin 1986.The resultswere studied by contrast analysis.

Weather conditions hada strongeffectonthe carotene content and inboth yearsthecaro- tene contentincreased with the length of the growing ^season. At harvestin 1985, PK place- ment withNfertirrigationshad atendency to yieldahigher carotene contentthan did broad- cast fertilization, irrigated single application, and NPKfertirrigations.The carotene content washigher when PandK wereplacement fertilized^ascompared to treatmentswherePand K werebroadcast fertilizedorfertirrigated (p⁼0.1). At the first sampling datein 1986,fertili- zation increased the carotene content (p⁼0.1).PKplacementwithN fertirrigationshad aten- dency toincrease the carotene content^ascompared to placement fertilization, single applica- tion and irrigated single application.Atthe second sampling date and at harvest in 1986no statistically significantdifferences could be found.

The results indicate that the placement of PK-fertilizer ^orNPK-fertilizer^wasfavourable to carotene production.Besides the fertilization experiment, samples from two organically cultivated fieldswerecollected 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 dependenton ^genotype (Gabelman 1974) and climate (Simon et al. 1982). The developmentalstageof_aplant (Banga ^etal.

1963, ^{Phan &} Hsu 1973, Fritz ^& Habben 1975) and temperatures during the growing 7

JOURNAL OF AGRICULTURAL SCIENCE^INFINLAND

season (Barnes 1936,^Bangaetal. 1955) also haveaconsiderable^{effectonthecarotenecon-}

tent.In addition, soil moisture (Banga ^&De

Bruyn 1964, ^Dragland 1978), the intensity of photosynthesis, shootsize,and plant den- sity (Banga ^& De ^Bruyn 1964) affect the carotene content ofcarrots.

The literaturecontainsreportsabout 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 nitrogenincreased^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) foundno differences incarotene con- tentsresulting from fertilizer levelsortheuse of organic versus inorganic fertilizers. The effects ofdifferentfertilization practices and the split application of nutrients have been studied very scarcely. The aim of thepresent study was to investigate whether unirrigated or irrigated placement and broadcast fertili- zation, fertirrigation and their combinations as wellasthe split application of nutrients af- fect thecarotene content of carrots.

Material and methods Field experiment

The field experimentwas doneon the Kot- kaniemi Experimental Farm of Kemira Oy.

inVihti, ^southernFinland, ^{in thesummersof} 1985 and 1986. Carrotcv. Nantes Duke Nota- bene370 Svwasgrown asdescribed 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 amountsin 1985

applications ^{~~~ ~} T7~ ^and 1986

mm No fertilization

Noirrigation 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 duringseason 80 29 160 3xlo

Half the NPKbasic fertilization1 ¹ before sowing and 80 32 142 3xlo 3duringseason

PK placement² 1 before sowing and 81 56 133 3xlo

3N-fertirrigations 3duringseason

4N-fertirrigations 1 before sowing^{and 155 56} 133 ^4xlo

4 duringseason

1 Half of the nutrientsweregiven by basic placement fertilization and half by NPK fertirrigations.

2 Phosphorusand potassium ^weregiven by basic placement fertilization and nitrogen by fertirrigations.

3 The nutrient amounts ^were30^% biggerin 1985than in 1986.

randomized blocks, ^with ten treatmentsper block and plots of 25

m 2

Determination

of

Thecarrotsamples for the determination of carotene werecollectedonSeptember 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, andtwo analysesweremade 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

octadecylsilane stationary phase with visible photometric detectionat wavelength 450 nm (Lancer 1976). This method measures the added aand (3 carotene content. In thetext it is termed^carotene for short. 60 grams of fresh carrot tissue was crushed in a blender

containing 100 ml CH₂C1₂and wasmixed for 10minutes, filtered and analyzedimmediate- ly by HPLC. The samples _were protected from light and oxygen because thesecan de- stroycarotene. The datawasstudied statisti- cally by contrast analysis (Steel ^& Torrie

1980).

Organically cultivatedcarrots

Simultaneously with those for the fertiliza- tion experiments, samples from twoorgani- cally cultivated fields_werecollected. These_or- ganically cultivated carrots were grown with thesameseed 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- edcarrots. Thecompostand soil analyses as well astheamounts ofcompostusedaregiv- en in a previous study (Evers 1988).

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

Results

Weather conditions

Weather conditions had_{a strong} effect_on thecarotene content ofcarrots.Thecarotene contents of carrots cultivated in 1985were lower than in 1986 irrespective of the fertili- zation ^treatments (p<o.ool***) (Fig. 1).

Developmentalstage

The carotene content ofcarrots increased with the length of the growingseason(Fig. 2).

At the first samplingdate,66 days fromsow- ing, thecarrots were about 10cm long, with

anaverageweight per carrot of27.0 grams.

In these young and smallcarrots, thecarotene contentwaslow,the average for alltreatments being 2.6mg/100g freshweight (FW).At the second samplingdate, 88 days from sowing, the average weight percarrotwas 76.5 g, the mean carotene content being 4.3 mg/100 g FW. At harvest, 121 days from sowing, the corresponding valueswere 106 g and 6.1 mg/

100g FW.

Fertilization

The statistical analysis method used in this study didnotreveal any significant differences

Fig. 2. The effect of different fertilization practices^onthe development of^thecarotene contentof carrotsin 1986.

between fertilization practicesorbetween un- fertilized and fertilized ^{treatments on level} p<0.05. At harvest in 1985, PK placement with N fertirrigations had ^atendencyto yield a highercarotene content than did broadcast fertilization, irrigated single application, and NPK fertirrigation (p⁼0.1). There was also atendency for_ahigher_carotenecontent^when P and K were placement fertilized as com- pared to treatments where P and K were broadcast fertilizedorfertirrigated (p⁼0.1).

At first sampling date in 1986, fertilization increased thecarotene content (p⁼0.1). PK placement with N fertirrigations had a ten- dency to increase the carotene content as comparedtoplacementfertilization, ^singleap-

plication and irrigated single application (p⁼0.1). At the second sampling date andat harvest in 1986 no statistically significant differences could be found.

In both years, four treatments gavegood results (Fig. 1). These wereplacement fertili- zation,NPK fertirrigation with NPK basic fer- tilization and PK placement with N fertirri- gations. In both years NPK fertirrigations without basicfertilization ^{yieldedalowcaro-}

tene content.Broadcast fertilization gavecon-

tradictionary results in two years. As com- paredto the averagecarotene content of_un- fertilized treatments, placement fertilization increased thecarotene contentby 35^% in 1985 andby9^% in 1986, NPK fertirrigations with NPK basic fertilization increased thecarotene contentby 28 °7o in 1985 and by 9 ^% in 1986, and PK placement with 3N fertirrigations in- creased thecarotene contentby44^% in 1985 and by 10^% in 1986.

Carotene yield

The order of superiority for thetreatments wasroughly similar whether thecarotenecon- tentwascalculatedonthe basis of freshmat- ter (Fig. 1) or dry matter (Table 2). When the resultswerestudiedasthe calculatedcaro- tene yield per hectare (Table 2), some dif- ferences were observed for 1986. Irrigated placement fertilization produced arelatively lowcarotene content, but thecarotene 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 practicesonthe carotene content of carrots calculated on dry weight basis andas acarotene yield^per hectare.

Treatments Carotene content Carotene yield

mg/100g dry weight g/ha

1985 1986 x 1985 1986 x

Unfertilized 42.554.2 48.3 1620 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 2520

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

PKplacement with 3N fertirrigations 55.4 58.8 57.1 2 090 3 070 2 580

PKplacement with 4Nfertirrigations 50.456.7 53.5 1 760 3 140 2 450

x 44.957.7 51.3 1570 3 060 2320

Organicallycultivated, location 1 66.7 3 240

Organicallycultivated, location 2 64.6 2 570

x 65.6 2 ⁹¹⁰

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Organically cultivated^carrots

Thecarotene contents werehigh forcarrots grownatboth locations, being 7.0 mg/100 g FW atlocationone and6.2 mg/100 g FW at location _two. The _{contents were} high also when calculatedon the dry weight basis (Ta- ble 2). When the^carotene yields _were calcu- lated (Table 2), theywerelower in organical- lycultivated ^carrots than in the fertilizer ex- periment.

Discussion Genotype

The main variation in thecarotene content of carrots depends on genotype (Gabelman 1974) and climate (Simon etal. 1982). In the presentstudy,cv.Nantes Duke Notabene370 Svwas used; the averagecarotene content of alltreatmentsand fortwoyears^atharvest was 5.2 mg/100 g FW. ^Bajaj et al. (1980) stud- ied 23 cultivars ofcarrot; 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

8.50 mg/100 g^FW).Thus in the climaticcon- ditions of southernFinland, this variety can reach thesame carotene levelas in India.

Weather conditions

There was a clear difference in themean carotene contentbetween thetwo years. The average carotene content for all treatments was 41.2^% higher in 1986 than in 1985. In 1985, themeandaytemperatureand thenum- ber ofsunshine 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 northernFinland, ^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 etal. 1977).

Dragland (1978) reported that low soil moisturecontent increases thecarotene con- tentofcarrot roots.Also ^Banga&De ^Bruyn (1964) reported that thecarotene synthesis in- creases in dry soil. They concluded that evi- dently in suchcase, primary vegetativeroot growth is suppresed by the low soil moisture content,causing theroot toripen at asmaller root size. Thismeans that protein synthesis is also reduced and it is consuming less carbo- hydrate compounds. Consequently, ^most of the carbohydrate compounds availablecanbe used for other consumption processes, such as carotenoid synthesis.^Bangaet al. (1963) also studied whether the soil moisturecontent affected the carotenoid synthesis directlyor indirectly by lowering the soil temperature.

They found that the soil moisturecontenthad a direct effect. Further Banga ^&De ^Bruyn (1964) concluded thatanoxygen content un- der6 ^%in the soil atmosphere reduces carote- noid synthesis.

In thepresentfield experiments, in 1985 the precipitation wasequal tothe long-termaver- ages, and in 1986 the precipitationwas heavi- erthan the long-term averagesexceptin June, which was sunny and drier than average (Evers 1988). In both years there wereheavy rains in September; the soilwasvery moist and perhaps also had a low oxygen content.

Precipitation probably doesnot explain the difference in the carotene contents between years,asin both years the soil remained moist throughout thegrowing period (except June, 1986). It is morelikely that the higher tem- perature in 1986 is the main _reason for the higher carotene contents in 1986 than 1985.

Developmentalstage

There is generalagreement 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 thepresent study, thecarotene content increased as the growing season proceeded.

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Fertilization

Because most of the variation in carotene content is genetically controlledoris depen- dent_on climate, it is obvious that therecan be no clear differences between fertilization practices. In ^more unfavourable year 1985 therewas, however, a tendency for the place- mentof PK fertilizerto increase thecarotene content.In future studies it would be intrest- ingto investigate whether it is P orK that in- creasesthe carotene content and the way in which the nutrient affects the carotene con- tent.

Accordingto 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_treatmentPK placement with 4N fertirrigations didnot significantly af- fect thecarotene content ascompared to the average of other fertilized treatments, where the Namount applied _wasthought tobe op- timal_on the basis of the yield. Thus this study could find _noresponse thatdepended onthe

nitrogen amount.

Acknowledgement.Iwarmlythank Ms. Oili Uusitalo for ^her excellent technical assistance. I ^am grateful to Prof.E.Kaukovirta^andProf.A-L.Varis for theirvalu- able commentsonthe manuscript. The financialsupport of the Academy of Finland and Kemira Oy is gratefully acknowledged.

References

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Nutr. 30:97—107.

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,De Bruyn, J.W.,^VanBennekom, ^{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.Carotenogenesisin^carrot

roots. Neth. J. Agric. Sci. 12: 204—220.

Barnes,W.C. 1936.Effects ofsomeenvironmental fac- tors on growthand color of carrots. Cornell Univ.

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Dragland,S. 1978.Nitrogen-ogvassbehov ^hosgulrot.

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

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& N.Selwey). p. 147—155.^{New York.}

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and quality of carrots.^Proc. 8. Intern. Potash Inst.

Congr.p. 257—263. Brussel.

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Ms received

SELOSTUS

Eri lannoitustapojen vaikutusporkkanan karoteenipitoisuuteen

Aino-Maija Evers

Kemira Oy, Espoontutkimuskeskus.

Luoteisrinne2, 02270Espoo

Erilannoitusmenetelmien vaikutusta porkkanalajikkeen NantesDuke Notabene 370Sv karoteenipitoisuuteen tut- kittiin kenttäkokeissa 1985ja 1986Kotkaniemen koeti- lalla Vihdissä. Vertailtavina menetelminä olivat sijoitus- ja pintalannoitus(ilmankastelua jakastelun kera), NPK- kastelulannoitus ilman peruslannoitusta, NPK-kastelulan- noitus,jossa puoletravinteista annettiin peruslannoituk- sena, sekäN-kastelulannoitus,jossa_Pja_Kannettiin si- joittaen peruslannoituksena.Kokeessa verrattiin myös kerta-annostelua jaksotettuunravinteiden antoon. Pork- kananäytteet karoteenimäärityksiin kerättiin sadonkor- juun yhteydessä 1985sekä66, 88ja121(sadonkorjuu) päivänkuluttua kylvöstä 1986.Tulosten analysointiin käy- tettiin kontrastianalyysiä, jossa ei verratayksittäisiäkoe- jäseniätoisiinsa^vaanvoidaan verrata asiakokonaisuuksia.

Vuonna 1985sadonkorjuun yhteydessä koejäsenissä, jotkasaivat^P;nja^K;n sijoittaen peruslannoituksena ja N:nkastelulannoituksena kasvukaudella, oli korkeammat

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

Vuonna ¹⁹⁸⁶vain ensimmäisellä näytteenottokerralla (66 vrk kylvöstä) lannoitus lisäsi karoteenipitoisuutta (p⁼0.1). Lannoitustapa, jossaPjaKannettiin sijoittaen keväälläja Nkastelulannoituksena kasvukaudella,lisäsi suuntaa-antavasti (p⁼0.1) karoteenipitoisuutta verrattuna sijoituslannoitukseen, yhteenantokertaan jakasteltuun yhteenantokertaan.

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

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