Agricultural and Food Science, Vol. 19 (2010): 69-80

A G R I C U L T U R A L A N D F O O D S C I E N C E

Vol. 19(2010): 69–80.

Effect of substrate type on the field performance
and chemical composition of highbush

blueberry cv. Patriot

Ireneusz Ochmian1, Józef Grajkowski1 and Katarzyna Skupień2*
1Department of Pomology, West Pomeranian University of Technology, Szczecin ul. Janosika 8,

71-432 Szczecin, Poland
2Department of Plant Raw Materials Processing and Storage, West Pomeranian University of Technology,

Szczecin, ul. Słowackiego 17, 71-434 Szczecin, Poland,
*e-mail: kskupien@agro.ar.szczecin.pl

The aim of a 3-year study was to compare the effect of substrate type (peat, sawdust and cocoa husk) on
the yield, fruit quality, general and phenolic composition, and antioxidant activity of highbush blueberry
(Vaccinium corymbosum L.) cultivar Patriot. The largest berries and the highest yield were obtained from
bushes grown in sawdust (3.661 kg ha-1). Berries from bushes grown in cocoa husk had the highest content
of N (14.25 g kg-1), P (1.17 g kg-1), K (6.51 g kg-1), and Zn (8.78 mg kg-1), as well as P (1.26 g kg-1) and K
(6.99 g kg-1) in the leaves. Both the leaves and fruits of plants grown in sawdust had higher Cu concentra-
tions (3.89 and 3.01 mg kg-1). Berries from sawdust-grown bushes had the highest soluble solids (13.1%)
and total sugar (10.80 g 100 g-1) content. The fruits obtained from peat-grown bushes exhibited enhanced
antioxidant capacity (38.6 µmol Trolox g-1). However, the highest levels of phenolics were noted in berries
produced in the cocoa husk (208.29 mg 100 g-1) and peat-bed system (174.07 mg 100 g-1). Regardless of the
type of substrate used, the following phenols were identified (in descending order): anthocyanins>chlorogenic
acid>flavonols. Delphinidin-glycosides were the most abundant pigments, and cyanidin, peonidin, petunidin,
and malvidin-glycosides were also detected. Total flavonol content (quercetin derivatives and kaempferol
3-rutinoside) was not significantly affected by the type of substrate.

Key- words: Vaccinium corymbosum, yield, firmness, macro- and microelements, phenolics

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Ochmian, I. et al. Effect of substrates on highbush blueberry ‘Patriot’

A G R I C U L T U R A L A N D F O O D S C I E N C E

Vol. 19(2010): 69–80.

Introduction

Highbush blueberries (Vaccinium corymbosum
L.), among other members of the Ericaceae fam-
ily, are considered to be a rich source of phenolic
compounds and are known for their antioxidant
properties (Kalt et al., 1999, Zheng and Wang,
2003, Castrejón et al. 2008). Due to their chemical
composition, blueberries are highlighted as one of
the healthiest foodstuffs (Kader et al., 1996, Main-
land et al. 2002). Because of its value, the species
has been cultivated for years in North America.
The first breeding project was launched in 1908 in
Florida (Lyrene 1997), and soon afterwards high-
bush blueberries were imported from the USA to
Europe (Strik 2005).

In Poland, the first experiments involving
highbush blueberry cultivation were undertaken
in 1946, while the development of large-scale pro-
duction methods began in 1976. According to the
results of field trials, Patriot was one of the culti-
vars recommended for growing in Poland (Smo-
larz 2006). A considerable increase in blueberry
production has been recently observed in Poland.
In 2006 Poland took 1st place in Europe with re-
gard to the highbush blueberry growing area, and
blueberry production reached 8,000 t, which gave
us the second place after Germany (10,000 t) (In-
ternetowa giełda rolna fresh-market 2009).

The highbush blueberry requires specific grow-
ing conditions including the right site, high in or-
ganic matter, appropriate water and air drainage,
low pH, and adequate moisture (Kozinski 2006).
On the one hand, this species allows the use of
land which as a result of its high acidity is not suit-
able for other crops (Ciordia et al. 2006). On the
other hand, such soils are less and less available,
which hinders the establishment of new planta-
tions. These factors have necessitated the search
for and the development of modified soil systems.

An improvement in soil conditions can be
achieved by using organic mulch materials, like
peat with low pH, sawdust, or coniferous bark. The
application of mulches contributes to the loosen-
ing of the higher strata of soil thus improving root
penetration (Kozinski 2006). In the USA, cotton

by-products, pecan hulls (Krewer et al. 2002), leaf-
mould compost, pit-coal ash, sludge from sewage
treatment plants (Black et al. 2002), and conifer
needle litter (Entrop 2000) are used for mulching
purposes. From the practical and economic point
of view, the components used for substrates and
mulching should be relatively cheap, easily acces-
sible, and should meet the habitat requirements of
a given species. Therefore, the use of agricultural
and forest by-products for this purpose seems to
be fully justified.

The objective of the present study was to evalu-
ate the influence of three types of substrate (cocoa
husk, sawdust and peat) on the yield, fruit quality
(fruit size and firmness), bush growth rate, fruit
chemical composition (the content of soluble sol-
ids, total sugar, L-ascorbic acid, NO3

- , NO2
-, phe-

nolics, macro- and microelements, titratable acid-
ity, juice efficiency, antioxidant activity), macro-
and microelement concentrations in the leaves of
highbush blueberry cv. Patriot.

Materials and methods

The experiment was carried out in the spring of
2001 at the Experimental Station Rajkowo near
Szczecin in heavy soil of neutral reaction (pH 7.1).
The purpose of field trials was to evaluate highbush
blueberry cultivation in three different substrates
placed in the trenches, 35 cm deep and 100 cm wide
(0.35 m3 medium per m of row length). Acidic muck
soil (peat), conifer sawdust from a local sawmill,
and cocoa husk – a by-product obtained from the
Chocolate Confectionery Plant ‘Gryf’ in Szczecin
were used as substrates. In vitro potted plants of
highbush blueberry cv. Patriot were spaced 1.5 m
apart in a row and 2.5 m between the rows. The
experiment was conducted in 2005–2007. The
physical properties of the substrates tested in the
experiment are shown in Table 1. Soil samples were
taken from each replicate of substrate and from the
soil, with a sample stick, in mid-August. Among the
substrates, peat had the highest and sawdust had
the lowest field water capacity (44.8% and 31.3%

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Ochmian, I. et al. Effect of substrates on highbush blueberry ‘Patriot’

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Vol. 19(2010): 69–80.

respectively), while cocoa husk had the highest full
water capacity (85.3%). These differences neces-
sitated the use of varied watering rates.

Fertilization was limited to nitrogen supply
only, because chemical analyses of both the soil
and substrates showed a high and/or a medium
content of other nutrients. Each type of media was
fertilized with ammonium nitrate on three occa-

sions at a total dose of 30 kg N ha-1. Supplemen-
tal irrigation with acidified water (with H2SO4 up
to pH of 2.5–3.5 measured in H2O) was applied
through a T-Tape drip line. The rate of water sup-
ply was adjusted to soil moisture content based on
the results of tensiometric monitoring expressed
in pF units (pF – soil suction being the logarithm
of water height in centimeters), carried out twice
a week. Measuring tubes (30 cm) were installed
15 cm below the soil surface, and pF 2.2 was
adopted as a threshold value for irrigation. Hav-
ing reached the threshold, the soil was irrigated
to approximately pF 1.0. Due to the wide range
of substrate reaction, water used for irrigation was
acidified to a different degree. Water used for peat
irrigation had higher pH (3.72) because peat reac-
tion was suitable for blueberry cultivation, while
cocoa husk and sawdust beds were irrigated with
water with pH of 2.36 to lower the reaction of these
media (Table 2). Among the substrates tested, peat
maintained a constant pH level of 3.3–3.5 during
the field trials, while cocoa husk had the highest
reaction (pH of 4.6–6.4) (data not shown). pH and
EC were measured with a multi-function computer
device CX-741 Elmetron (Zabrze, Poland).

The content of available Ca, Na, Fe, Mn, Zn
and Cu in the soil and in the substrates was de-
termined by the AAS method (Atomic Absorption
Spectrometry) prior to sample extraction with 0.1

Table 1. Water capacity, pH and salinity of the sub-
strates used for blueberry cultivation

Peat Cocoa husk Sawdust
Field water capacitya
(% vv-1)

44.8 36.9 31.3

Full water capacitya
(% vv-1)

80.6 85.3 82.6

pHb 3.40 5.00 4.70

Soil salinity
(g NaCl kg-1)c

0.87 0.35 0.56

a Water capacity of soil was measured with the gravimetric
method in spring 2005.
bThe reaction of substrates was measured with the conductomet-
ric method in KCl at the end of highbush blueberry vegetative
season. pH values are the mean for 2005-2007.
cSoil salinity was measured with the conductometric method
and the values are the mean for 2005-2007.

Table 2. Physicochemical properties of water used in the experiment (on average for 2005–2007).

Raw water*
Acidified water for sawdust
and cocoa husk*

Acidified water to irrigate peat*

Fe+3 (mg·l-1) Ca+2 (mg·l-1) EC (mS·cm-1) pH
EC

(mS·cm-1)
pH

EC
(mS·cm-1)

0.17 94.0 0.80 7.01 2.46 2.36 2.01 3.72
* The values are the mean of 2005-2007. The measurements were carried out three times in each year of experiment. Fe3+and Ca2+
were determined by the AAS method (Atomic Absorption Spectrometry), and EC (Electrical Conductance) and pH were measured with
a conductometric method.

Table 3. The content of available macro- and microelements in the grey brown podsolic soil used in the experiment (an
average for 2005–2007).

P K Ca Mg Na Fe Mn Zn Cu

(mg·100g-1) (mg·kg-1)

12.41 35.6 70.6 5.67 1.25 102.8 66.5 17.9 2.7

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Ochmian, I. et al. Effect of substrates on highbush blueberry ‘Patriot’

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M HCl. Soil samples for phosphorus and potassium
analyses were extracted according to the Egner-
Riehm method, and the concentrations of these
elements were determined by a colorimetric and
flame atomic emission, respectively. Soil samples
for magnesium content estimation were extracted
by the Schachtschabel method, and Mg levels were
measured by the AAS

For macro- and microelement analyses in plant
material, one hundred leaves of plants grown in
the tested substrates were sampled each year at the
beginning of August. The leaves were dried, first
at room temperature in a shaded place and then at
~45 oC, and were pulverized with a WŻ-1 lab mill.
Aliquots of berry samples of each harvest in the
season were packed in polyethylene bags (250 g)
and kept frozen (–25 oC). Following fruit collec-
tion, all fruit samples for each substrate were com-
bined, thawed at room temperature, and dried (ini-
tial temperature 60–70 oC, final 105 oC). The dried
fruits were pulverized (WŻ-1). The total content
of macro- and microelements in leaves and fruits
was determined according to the Polish Standards.
After mineralization, total nitrogen content was de-
termined by the Kjeldahl method. The concentra-
tions of K and Ca were measured by flame atomic
absorption spectroscopy, whereas Mg, Cu, Zn, Fe,
and Mn content was determined by atomic emis-
sion spectrometry using SAA Solaar. Phosphorus
content was determined by the Barton method at
a wavelength of 470 nm, and sulphur content - by
the turbidimetric method at a wavelength of 490
nm, with a Marcel s 330 PRO spectrophotometer.

For plants grown in each substrate, bush growth
rate was estimated and expressed as the total annual
shoot length (cm) and the average length of one-
year shoots. Fruit yield was assessed and expressed
as kg per ha. Additionally, the mean weight of 100
fruits (g) was determined and fruit size measure-
ments (mm) at the vertical and horizontal axis were
taken. Fruit firmness was measured along the ver-
tical axis (fruit height) and along the horizontal
axis (fruit diameter) with a FirmTech 2 apparatus
(BioWorks, USA) immediately after harvest and
every 7 days during 21-day storage at 2 oC and
96% relative air humidity. The firmness of 50 ber-
ries selected randomly from every replicate was

expressed as a gram-force causing fruit surface to
bend 1 mm.

Titratable acidity, the content of total sugars,
soluble solids, L-ascorbic acid, nitrates and ni-
trites, and antioxidant capacity were determined
in fresh fruit soon after harvest. Titratable acidity
was determined by titration of the water extract of
blueberry homogenate with 0.1 N NaOH to the end
point of pH 8.1, according to PN-90/A-75101/04.
Total sugar content was determined by the Luff-
Schoorl method. Soluble solids content was deter-
mined in berry juice with the use of an Abbé re-
fractometer (PN-90/A-75101/02). L-ascorbic acid
content was determined by the iodometric method
(Samotus et al. 1982). In order to measure juice
extraction efficiency, fruits were homogenized with
a blender and heated up to 50 oC. After cooling, 3
mL of pectinase (Rapidase Super, BE, NC, USA)
per kg of pulp was added. The pulp was left to
stand at room temperature for 1 hour, and then it
was pressed for 10 min at a final pressure of 300
kPa with a laboratory hydraulic press (Oszmiański
and Wojdylo 2005). Nitrate and nitrite content was
measured with a RQflex 10 reflectometer (Merck).
Fruit antioxidant capacity was evaluated by met-
myoglobin oxidation inhibition by antioxidants
present in fruit extract and compared to that of
Trolox (Miller and Rice-Evans 1996). Total anti-
oxidant capacity was expressed as μmol Trolox per
g fruit tissue. Phenolics composition of blueber-
ries was determined in fruit samples that were kept
frozen (–32 oC) in polyethylene bags (250–300 g)
until analyzed. The 2 g aliquots of fruit (after thaw-
ing) were extracted three times with approx. 8 mL
of 80% MeOH acidified with a glacial acetic acid
(1 mL of 100% acetic acid per 1 L 80% MeOH) in
an ultrasonic bath for 15 min. The samples were
filtered and transferred to the flasks and made up
to the final volume 25 mL. Further, the extracts
were centrifuged twice at 12,000x g and 20 μL of
supernatants were injected into the HPLC system.
The HPLC apparatus consisted of a Merck-Hitachi
L-7455 diode array detector (DAD) and quater-
nary pump L-7100 equipped with D-7000 HSM
Multisolvent Delivery System (Merck-Hitachi,
Tokyo, Japan). The separation was performed on
a Cadenza CD C18 (75 × 4.6 mm, 5 mm) column

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Ochmian, I. et al. Effect of substrates on highbush blueberry ‘Patriot’

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Vol. 19(2010): 69–80.

(Imtakt, Japan). Column oven temperature was set
at 30 oC. The mobile phase was composed of sol-
vent A (4.5% formic acid), pH 2.2) and solvent
B (acetonitrile). The program began with a linear
gradient from 0% B to 21% B (0–30 min), followed
by washing and reconditioning the column. The
flow rate was 1 mL min-1 and the runs were moni-
tored at the following wavelengths: chlorogenic
acid at 320 nm, flavonols glycosides (quercetin and
kaempferol derivatives) at 360 nm, and anthocy-
anin glycosides at 520 nm. The Photo Diode Array
spectra were measured over the wavelength range
200–600 nm in steps of 2 nm. Retention times and
spectra were compared to those of pure standards
within 200–600 nm. Standards of anthocyanidin
glycosides and chlorogenic acid were obtained
from Polyphenols Laboratories (Norway), while,
kaempferol 3- rutinoside and quercetin glycosides
from Extrasynthese (France). Except for phenolics,
the all measurements of bushes, leaves and fruits
were performed for each year of the experiment.
Phenolic patterns for berries were determined in
2006 and 2007.

The results obtained were subjected to statisti-
cal analysis using Statistica 7.1 (Statsoft, Poland).
The values were evaluated by the Duncan test and
for phenolics by the Student test. The differences
between the means at p<0.05 were considered sig-
nificant.

Results and discussion

Data relating to plant growth, yield, fruit size and
weight of blueberries cv. Patriot are presented in Table
4. Three-year observations of highbush blueberry de-
velopment showed that peat was the most stimulating
medium, superior to sawdust and cocoa husk with
regard to total annual shoot length and average one-
year shoot length. Kozinski (2006) observed a higher
growth rate of one-year-old shoots when blueberry
was grown in soil mixed and mulched with sawdust
compared to soil mixed and mulched with bark as
well as in pure mineral soil (as control treatment).

In this experiment the vegetative growth of
plants was not parallel to their productivity. Among
the substrates tested, the highest yield was obtained
from bushes grown in sawdust (3.661 kg ha-1 per
season on average), whereas plants grown in cocoa
husk were characterized by the lowest productivity
(1.315 kg ha-1 per season on average). The values
are so low due to frost damage in 2006. However,
despite of unfavorable weather conditions, this spe-
cies allows multi-annual utilization of plantings,
though its productivity is conditioned by the age
of bushes and agronomic practices involved, too.
In a study conducted by Ciordia et al. (2006), the
yield of southern highbush cultivars grown in plas-

Table 4. Growth vigour, yield, weight of 100 fruits, and fruit size of ‘Patriot’ cv. highbush blueberry depending on sub-
strate type (an average for 2005–2007)

Type of substrate Peat Sawdust Cocoa husk

Total annual shoot length (cm) 401 b 311 a 315 a

Mean length of one-year shoots (cm) 46.0 b 37.7 ab 33.0 a

Mean yield (kg·ha-1) 2,639 b 3,661 c 1,315 a

Mean weight of 100 fruits (g) 140 b 126 a 120 a

Fruit size (mm)
ha 14.50 b 15.15 b 12.15 a

øb 17.85 b 17.85 b 16.35 a

Fruit size reduction between begin-
ning and end of harvest (%)

h -34.3 -37.6 -31.6

ø -46.6 -62.1 -48.9

ha – fruit size measured along fruit height (at vertical axis)
øb - fruit size measured along fruit diameter (at horizontal axis)

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Vol. 19(2010): 69–80.

tic tunnels, measured over four years, ranged from
411.36 to 1990.90 g plant-1. Glonek and Komosa
(2006) determined an average yield of 4.530–5.557
kg per bush for 10-year-old highbush blueberry cv.
Bluecrop, depending on fertilization. Smolarz et al.
(2006) reported that the productivity of 25-year-old
‘Bluecrop’ bushes under different fertilization con-
ditions was 2.90–20.77 t per ha.

The highest weight of 100 fruits was found for
berries originating from bushes bedded in peat (140
g). Plants grown in sawdust (126 g) and cocoa husk
(120 g) provided smaller fruits. Strik et al. (2003)
noted much higher fruit weight for ‘Bluecrop’ ber-
ries, ranging from 130 to 220 g (after conversion)
and even higher for ‘Berkeley’ berries, between 180
and 260 g (after conversion). One-fruit weight meas-
ured by Heiberg and Stubhaug (2006) varied from
1.81 to 2.86 g, depending on cultivar and location.
‘Patriot’ berries are slightly flattened, which can be
seen when comparing fruit diameter and height (Ta-
ble 4). The highest dimensions were determined for
berries from bushes grown in sawdust, whereas the
lowest for those from bushes grown in cocoa husk.
However, the largest berries (sawdust) did not have
the highest weight of 100 fruits, while the small-
est berries (cocoa husk) had the lowest 100-fruit
weight. Fruit size reduction was observed towards
the end of the harvest season. Fruit diameter was

dramatically reduced, particularly in berries from
bushes grown in sawdust (by 62%), whereas fruit
height was reduced to a lesser degree (>30%). Under
field conditions, precipitation shortage or the lack
of watering at the end of the growing season sub-
stantially contribute to fruit size reduction. Ciordia
et al. (2006) tested six southern blueberry cultivars
grown in trenches under tunnels, and observed in
most varieties a decline in the weight of late-harvest
berries equal to or less than 1 g, which made them
unacceptable for the fresh fruit market.

The all berries showed higher values of firmness
when it was measured along the vertical axis (fruit
height) compared with the horizontal axis (fruit di-
ameter) (Table 5). As regards fruit hardness at diam-
eter position, berries from bushes grown in cocoa
husk (the smallest ones) showed the highest bend-
ing resistance (210 G mm-1) and the lowest drop
in firmness during 21-day cold storage (2 oC, 96%
humidity). The highest firmness measured along the
fruit height axis (492 G mm-1) and the lowest decline
in hardness (by 6.1%) were found for berries from
plants grown in sawdust (the biggest ones). Berries
from bushes bedded in peat (~as big as those from
plants grown in sawdust) showed the lowest firm-
ness measured along the horizontal and vertical axis
(184 and 440 G mm-1, respectively) and the greatest
decline in hardness (by 8.7 and 8.18%, respective-

Table 5. Changes of firmness for ‘Patriot’ blueberries after the harvest and during storage in a cold room (2 0C, 96%
relative air humidity) on average for 2005–2007.
Storage time

Substrate

After harvest
7-day

storage
14-day
storage

21-day
storage

Firmness changes after 21-day
storage (%)

Fruit firmness measured at diameter (G mm-1)

Peat 184 180 175 168 -8.70 a

Sawdust 198 195 189 183 -7.58 ab

Cocoa husk 210 207 200 195 -7.14 b

Mean 197 b 194 ab 188 ab 182 a

Fruit firmness measured at height axis (G mm-1)

Peat 440 435 429 404 -8.18 a

Sawdust 492 490 478 462 -6.10 b

Cocoa husk 472 462 456 442 -6.36 b

Mean 468 c 462 bc 454 b 436 a

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Vol. 19(2010): 69–80.

ly). Thus, in terms of handling, these berries would
be most sensitive to up- and side-pressure.

The substrates tested in this experiment differed
with respect to nutrient abundance (Table 6). In gen-
eral, cocoa husk was abundant in P and Zn, sawdust
was particularly rich in Mn and Cu but had a low
Ca and Mg content, whereas peat had the lowest
K content. Regardless of the substrate, blueberry
leaves had higher amounts of total N, Ca, Mg, Fe
and Mn, compared to fruits (Table 7). The highest
N content was found in the leaves of plants grown
in sawdust and in the fruits of plants grown in cocoa
husk. According to Hanson (2006), the optimal N
content of blueberry leaves picked in mid- summer
amounts to 1.7–2.1%. After conversion the above
data it can be seen that the N content of berry leaves

was sufficient. Fruit N content was approximately
half of leaf N content, and the values obtained were
lower compared to 1.7-2.8% determined by Skupień
(2004) in four blueberry cultivars.

In this study, plants cultivated in cocoa husk
had the highest concentration of P and K, both in
the leaves and fruits. The leaf P status varying from
1.11 to 1.26 g kg-1 was lower than that reported by
Glonek and Komosa (2006) for cv. Bluecrop (0.18-
0.20%), while leaf K levels in cv. Patriot (5.15-6.99
g kg-1) were similar to those determined by these
authors in cv. Bluecrop (0.56–0.58%). Fruit K levels
measured in this study (5.18–6.51 g kg-1) were lower
compared to the values obtained by Skupień (2004)
(0.738–0.855%).

Table 6. The available macro- and microelements content in the tested substrates on average for 2005–2007.

P K Ca Mg Fe Mn Zn Cu

(mg·100g-1) (mg·100g-1)

Peat 13.04 b 29.65 a 170.1 b 28.62 b 202 a 32.03 a 12.65 a 1.81 a

Sawdust 7.54 a 52.49 b 83.4 a 21.94 a 231 ab 56.47 b 25.93 a 7.36 b

Cocoa husk 17.16 c 51.26 b 208.5 b 26.71 b 279 b 24.13 a 51.66 b 1.58 a

Table 7. Total macro- and microelements content in leaf and fruit of blueberry ‘Patriot’ on average for 2005–2007.

Macro- and
microelementsa

Leaves Fruit

Peat Sawdust Cocoa husk Peat Sawdust Cocoa husk
(g·kg-1)

Total N 21.81 a 23.06 b 21.45 a 12.27 a 12.94 a 14.25 b

P 1.13 a 1.11 a 1.26 b 0.79 a 0.90 a 1.17 b

K 5.74 a 5.15 a 6.99 b 5.18 a 5.35 a 6.51 b

Ca 3.38 b 3.05 b 1.54 a 0.12 b 0.10 ab 0.08 a

Mg 1.71 b 1.48 ab 1.14 a 0.27 a 0.58 b 0.26 a

S 1.73 a 1.60 a 1.48 a 1.38 b 1.05 a 1.32 b

(mg·kg-1)

Cu 2.72 ab 3.89 b 1.75 a 1.53 a 3.01 b 1.87 a

Zn 9.41 a 10.16 b 9.64 a 6.60 a 5.66 a 8.78 b

Fe 58.67 a 58.93 a 52.91 a 23.67 a 21.64 a 22.78 a

Mn 199.89 b 170.46 b 121.04 a 24.49 a 23.03 a 22.73 a
a The values are calculated on dry weight basis

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Vol. 19(2010): 69–80.

In cv. Patriot, higher concentrations of Ca, Mg,
and S were recorded in the leaves of bushes grown
in peat. Glonek and Komosa (2006) determined the
following values in blueberry leaves: 0.64–0.78%
Ca, 0.15-0.16% Mg, and 0.11–0.12% S. A com-
parison of these data with our results shows that Ca
levels in the leaves of blueberries grown in the tested
substrates were distinctly lower, whereas Mg and S
content was similar. Fruit S content in ‘Patriot’ ber-
ries (>1.0 g kg-1) was higher, compared to control
lingonberries analyzed by Levula et al. (2000) (>700
mg kg-1). ‘Patriot’ berries showed a lower fruit Ca
content (0.08–0.12 g kg-1) and a higher fruit Mg con-
tent (0.26–0.58 g kg-1), in comparison with blue-
berries studied by Skupień (2004) (0.127–0.191%
and 0.016–0.018%, respectively). The low leaf Ca
and fruit Ca levels observed in this study could re-
sult from better acidification of the substrates used.
As regards between-substrate differences, ‘Patriot’
berries from plants grown in peat had the highest
Ca content. The highest fruit S levels were deter-
mined for berries originating from cocoa husk and
peat beddings, whereas berries from plants grown
in sawdust were richest in Mg.

Plants cultivated in substrates rich in microele-
ments showed elevated concentrations of microele-
ments in the leaves and fruits (Table 7). The high-
est Cu levels were noted in the leaves and fruits of
‘Patriot’ bushes grown in sawdust (3.89 mg kg-1 and
3.01 mg kg-1, respectively) which was most abun-
dant in Cu. Interestingly, the leaves and berries of

plants grown in peat and cocoa husk had similar
Cu levels as the respective substrates. As regards
sawdust, leaf Cu and fruit Cu concentrations cor-
responded to the values (3.37–3.88 ppm) observed
by Glonek and Komosa (2006) for the leaves of
cv. Bluecrop, whereas fruit Cu content reported by
Skupień (2004) was much lower (0.138–0.303 mg
kg-1). The highest Zn concentrations determined in
‘Patriot’ leaves (sawdust) and fruits (cocoa husk) in
this study were correlated with Zn abundance in the
medium. Leaf Zn content at 9.41–10.16 mg kg-1 was
lower than that reported by Merhaut and Darnell
(1996) at 27-31 µg g-1, and similar to that obtained
by Glonek and Komosa (2006) at 7.98-8.38 ppm.
Fruit Zn content (5.66-8.78 mg kg-1) was higher than
that determined by Skupień (2004) at 1.081–1.30
mg kg-1.

The all substrates tested as growing media for
blueberry cv. Patriot showed high Fe concentrations
(>200 mg 100 g-1). Leaf Fe content (52.91–58.93 mg
kg-1) was very close to the range of 53.9-57.7 ppm
reported by Glonek and Komosa (2006) and higher
than the 36-37 µg g-1 range determined by Merhaut
and Darnell (1996). On the other hand, fruit Fe con-
tent in blueberry cv. Patriot was ~50% that of leaf
Fe content, however it was still higher than 14-15
mg kg-1 reported for lingonberries by Levula et al.
(2000). Despite statistical differences between the
media tested, no significant differences were found
for leaf and fruit Fe content.

Table 8. Blueberry ‘Patriot’ fruit chemical composition in dependence on the type of substrate (an average for 2005–2007).

Itema Peat Sawdust Cocoa husk

Soluble solids (%) 12.4 a 13.1 b 11.7 a
Total sugar (g·100 g-1) 9.71 a 10.80 b 9.85 a
Titratable acidity (g citric acid·100 g-1) 2.41 b 2.35 b 1.98 a

L-ascorbic acid (mg·100 g-1) 26.0 b 23.4 a 26.2 b

Juice efficiency (%) 89.98 a 90.29 a 89.88 a

N-NO2 (mg·kg
-1) 0.75 a 0.95 b 0.85 ab

N-NO3 (mg·kg
-1) 19.3 a 31.4 b 24.6 ab

TEAC (μmol Trolox·g-1) 38.6 b 35.7 a 35.3 a
aThe values are presented on fresh weight basis
TEAC – Trolox Equivalent Antioxidant Capacity

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Ochmian, I. et al. Effect of substrates on highbush blueberry ‘Patriot’

A G R I C U L T U R A L A N D F O O D S C I E N C E

Vol. 19(2010): 69–80.

The highest Mn levels were recorded in the
leaves of plants grown in peat and sawdust (Mn-
richest substrates) however the type of substrate did
not affect fruit Mn content. Leaf Mn concentrations
determined for cv. Patriot (121.04–199.89 mg kg-
1) were higher than those found for cv. Bluecrop
(107.6–128.0 ppm) (Glonek and Komosa 2006), and
both ranges were higher than the value of 44–57 µg
g-1 reported by Merhaut and Darnell (1996). On the
other hand, ‘Patriot’ berries had a low Mn content,
ranging from 21.64 mg kg-1 (sawdust) to 23.67 mg
kg-1 (peat).

‘Patriot’ berries obtained from sawdust-grown
bushes had the highest soluble solids (13.1%) and
total sugar content (10.80 g 100 g-1) (Table 8). In
the study conducted by Skupień (2004) the soluble
solids content of blueberry cultivars mulched with
sawdust was determined within a similar range of
11.6–13.8%. Prior et al. (1998) observed greater
variation in soluble solids content (10.0–19.0%),
affected by the cultivar, geographical location and
harvest date. Total sugar content found in this inves-
tigation (9.85–10.80 g 100 g-1) corresponds to the
sum of glucose and fructose reported by Wang et
al. (2008) for blueberries in a conventional culture
system (10.90 g 100 g-1). Ostrowska and Ściążko
(1996) determined a slightly lower total sugar con-
tent of blueberries, ranging from 8.36 g 100 g-1(cv.
Bluecrop) to 9.57 g 100 g-1(cv. Jersey).

Total acid content observed in this study was
1.98–2.41 g citric acid 100 g-1 (Table 8). Higher
acidity was observed in the berries of bushes bed-
ded in peat and sawdust. Rosenfeld et al. (1999)
determined acid concentrations at 0.82% in ‘Blue-
crop’ berries stored at 4 °C. L-ascorbic acid content
determined for ‘Patriot’ berries varied from 23.4 mg
100 g-1 (sawdust) to 26.2 mg 100 g-1 (cocoa husk),
and was not affected by the type of substrate (Table
8). Łata et al. (2005) reported vitamin C content of
16.6–30.6 mg 100 g-1 in blueberries, depending on
the cultivar and seasonal variations.

Juice efficiency measured for ‘Patriot’ berries
was high (89.9–90.9%) and not medium-dependent
(Table 8). Rossi et al. (2003) obtained a lower juice
yield for blueberries, amounting to 79–81%, which
could result from a different extraction procedure.

The nitrite content of blueberries obtained from
plants grown in all media tested in the study was
below 1 mg kg-1 (Table 8), which is consistent with
Polish regulations concerning, among others, apple
juice, fruit-vegetable juices and banana-containing
products for babies and young children under three.
Blueberries are characterized by low nitrate accu-
mulation. The values obtained in this study (Table
8) confirm that blueberries are nitrate-safe product
and the amounts ranging from 19.9 mg kg-1 (peat)
to 31.4 mg kg-1 (sawdust) are fairly below the lev-
els permitted for bananas and vegetables meant for
special usage (baby food, etc.) up to 200 mg kg-1.

The antioxidant capacity of blueberries is well
substantiated in the literature (Prior et al. 1998,
Ehlenfeldt and Prior 2001). In this experiment,
blueberries showed TEAC values in the range of
35.3–38.6 μmol Trolox·g-1 (Table 8). Connor et al.
(2002) found lower antioxidant activity for ‘Patriot’
berries, varying from 20 to 29 μmol Trolox·g-1 de-
pending on the year of the experiment and location.
Ścibisz et al. (2003) observed that early harvested
berries showed 29.9 μmol Trolox·g-1, whereas late-
harvested berries – 61.8 μmol Trolox·g-1. A likely
reason is that smaller fruits of late harvest have a
higher surface:volume ratio. Since in blueberries an-
thocyanins are found in the skin only, the enhanced
amount of these compounds (apart from other phe-
nolics) in smaller berries contributes substantially to
their higher antioxidant activity.

The type of substrate exerted a significant in-
fluence on total phenolic content (Table 9). Ber-
ries from bushes grown in cocoa husk showed the
highest amounts of phenolics (208.29 mg 100 g-1),
while the lowest value was observed for sawdust-
originating berries (122.43 mg 100 g-1). Connor
et al. (2002) measured a total phenol content of
360–569 mg chlorogenic acid equivalents 100 g-1
in ‘Patriot’ berries. Prior et al. (1998) estimated
phenolic content at 181.1-390.5 mg 100g-1 in blue-
berry cultivars obtained from different sources. In
this study, the amount of total phenols was not in
accordance with TEAC values. Berries from plants
grown in sawdust and cocoa husk beddings had
almost equal antioxidant capacity (35.7 and 35.3
μmol Trolox g-1, respectively), whereas the phenol
content of berries originating from cocoa husk was

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Ochmian, I. et al. Effect of substrates on highbush blueberry ‘Patriot’

A G R I C U L T U R A L A N D F O O D S C I E N C E

Vol. 19(2010): 69–80.

1.7-fold higher than that of sawdust-grown berries.
Berries collected from peat-grown bushes showed
the highest antioxidant activity (38.6 µmol Trolox
g-1), although they had a medium phenolic content
(174.08 mg 100 g-1).

The proportions of phenolics identified in blue-
berries were as follows: for peat – 70.4% anthocy-
anins> 22.7% chlorogenic acid > 6.9% flavonols, for
sawdust – 85.3% anthocyanins > 8% chlorogenic
acid > 6.7% flavonols, for cocoa husk – 55.4% an-
thocyanins > 39.7% chlorogenic acid > 4.9% fla-
vonols. The greatest differences between berries
were observed with respect to chlorogenic acid (Ta-
ble 9). The berries from plants grown in cocoa husk
bedding were richest in chlorogenic acid (82.79 mg
100 g-1) whereas, the chlorogenic acid content of

berries from bushes grown in peat and sawdust was
~2-fold and ~8-fold lower, respectively. Zheng and
Wang (2003) determined lower chlorogenic acid
concentrations in blueberry cv. Sierra - 645.9 µg
g-1. Regardless of substrate type, delphinidin glyco-
sides dominated among anthocyanins (41.4–52.12
mg 100g-1), especially delphinidin 3-glucoside and
delphinidin 3-galactoside (Table 9). Cyanidin, peo-
nidin, petunidin and malvidin-glycosides were also
detected. Berries originating from peat had a higher
content of total anthocyanins (122.6 mg 100g-1),
whereas the lowest amounts of these pigments were
found in the fruits of sawdust-grown plants (104.45
mg 100 g-1). Connor et al. (2002) determined 140-
191 mg cyanidin 3-glucoside equivalents 100 g-1 in
‘Patriot’ berries, depending on the year of the experi-

Table 9. Influence of substrates on phenolic composition of ‘Patriot’ blueberries (an average for 2006–2007).

Peat Sawdust Cocoa husk
mg·100g-1

Chlorogenic acid 39.52 b 9.78 a 82.79 c
Cyanidin -3-arabinoside 5.43 3.85 2.75
Cyanidin-3-galactoside 6.14 5.37 3.56
Cyanidin-3-glucoside 5.90 5.13 3.78
Delphinidin-3-arabinoside 10.94 9.74 9.64
Delphinidin-3-galactoside 15.91 14.21 18.27
Delphinidin-3-glucoside 19.52 17.51 24.21
Peonidin-3-arabinoside 6.92 5.47 3.09
Peonidin-3-galactoside 5.92 5.57 7.19
Peonidin-3-glucoside 6.71 5.20 3.50
Petunidin-3-arabinoside 7.18 2.38 11.67
Petunidin-3-galactoside 1.81 4.97 3.05
Petunidin-3-glucoside 3.92 4.89 6.41
Malvidin-3-arabinoside 9.79 7.45 9.36
Malvidin-3-galactoside 10.56 8.36 4.95
Malvidin-3-glucoside 5.95 4.35 3.88
Sum of anthocyanins 122.6 b 104.45 a 115.31 ab
Quercetin-3-galactoside 5.93 4.01 5.83
Quercetin-3- glucoside 1.44 1.04 1.17
Quercetin-3- ramnoside 2.07 1.46 1.94
Kaempferol-3-rutinoside 2.52 1.69 1.26
Sum of flavonols 11.96 a 8.2 a 10.2 a
Total 174.07 b 122.43 a 208.29 b

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Vol. 19(2010): 69–80.

ment and the growing area. In an experiment per-
formed by Prior et al. (1998), the total anthocyanin
content of blueberries varied over a wide range of
93.1 to 235.4 mg 100 g-1. Quercetin derivatives and
kaempferol 3-rutinoside were also identified, and
quercetin 3-galactoside was found to be a predomi-
nant flavonol. The total of quercetin derivatives var-
ied from 6.51 mg 100 g-1 (sawdust) to 9.44 mg 100
g-1 (peat), and these values were higher compared
with the data obtained for blueberries of different
varieties and sites by Häkkinen and Törrönen (2000)
– 2.2-4.7 mg 100 g-1, but lower than those reported
by Zheng and Wang (2003) for cv. Sierra (248.7
µg g-1). However, in the present study the type of
medium did not significantly affect total flavonol
content (8.2–11.96 mg 100 g-1).

Conclusions

A three-year study of substrates tested as growing
media for highbush blueberry cv. Patriot showed
that the most intensive bush growth was observed
when plants were grown in peat, while the highest
yield (on a 3-year average) was attained in plants
grown in sawdust. The berries of bushes bedded
in sawdust were largest, but they showed the most
disadvantageous fruit size reduction as the picking
period progressed. On the other hand, these berries
demonstrated the highest firmness measured along
the vertical axis (fruit height), whereas the berries of
bushes grown in cocoa husk had the highest firmness
measured along the horizontal axis (fruit diameter).

Irrespective of the substrate used, the leaves of
‘Patriot’ plants contained larger amounts of N, Ca,
Mg, Fe and Mn than the fruits. As regards particular
media, the concentrations of macro- and microele-
ments in leaves and fruits varied, except for leaf Fe,
fruit Fe and fruit Mn content which showed no cor-
relation with the substrate.

Berries originating from sawdust contained the
highest amounts of soluble solids and total sugars,
and the lowest L-ascorbic acid levels. For all ber-
ries, juice efficiency was high and not substrate-de-
pendent. The accumulation of nitrates and nitrites in

blueberry cv. Patriot was low and did not exceed the
permissible levels for food items designed for babies
and young children.

Berries originating from peat had the highest
antioxidant capacity and the highest total anthocy-
anin content. Delphinidin-glycosides were pre-
dominant anthocyanins in all berries. The following
phenolics were identified in ‘Patriot’ berries (in de-
scending order): anthocyanins > chlorogenic acid >
flavonols. The proportions of individual compounds
were substrate-dependent. Berries originating from
the cocoa husk bedding showed the highest content
of chlorogenic acid and total polyphenols. On the
other hand, the amount of total flavonols was not
affected by the type of substrate.

From the quantitative point of view, the best pro-
ductivity (yield) and consumer attractiveness (fruit-
size) were observed for ‘Patriot’ blueberries grown
in sawdust. These berries were richest in N, P, K,
Zn, total sugars and soluble solids. However, their
most undesirable characteristic was a considerable
fruit size reduction at the end of the harvest season,
and lower concentrations of anthocyanins and total
phenols, compared with berries grown in peat and
cocoa husk respectively.
Acknowledgments. The study was supported by the grant of
the Scientific Research Committee No.0395/P06/2004/26.

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Effect of substrate type on the field performance and chemical composition of highbus hblueberry cv. Patriot
Introduction
Materials and methods
Results and discussion
Conclusions
References