Scientia Horticulturae 145 (2012) 109117 [620590]

Scientia Horticulturae 145 (2012) 109–117
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Scientia Horticulturae
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Yield response, pest damage and fruit quality parameters of scab-resistant and
scab-susceptible
apple cultivars in integrated and organic production systems
Imre J. Holba,b,∗, Péter Dremákb, Klára Bitskeyb, István Gondab
aPlant Protection Institute, Hungarian Academy of Sciences, P.O. Box 102, H-1525 Budapest, Hungary
bUniversity of Debrecen, P.O. Box 36, H-4015 Debrecen, Hungary
a r t i c l e i n f o
Article history:
Received
6 May 2012
Received
in revised form 31 July 2012
Accepted
1 August 2012
Keywords:Apple scab
CalciumCodling moth
Integrated
apple
Organic
apple
Soluble
solid contenta b s t r a c t
In a 4-year Hungarian study, 10 apple cultivars (5 scab-resistant and 5 scab-susceptible) were evaluated
for yield, scab incidence, codling moth injury, soluble solid concentration, and calcium content of fruit in
high-density integrated and organic apple orchards. Yield was significantly higher in the integrated plots
compared to the organic ones in all years (mean values were 18 and 13 kg tree−1, respectively). Yield
was significantly lower on the younger trees (5–6 years old) compared to the older ones (13–14 years
old) in both production systems (mean values were 14 and 17 kg tree−1, respectively). Mean final scab
and codling moth incidences were considerably higher in the organic than in the integrated production
system, except for the resistant cultivars which had no fruit scab symptoms. Fruit of all cultivars was pro-
tected in the integrated production system (mean fruit scab and codling moth incidences were below 2.5
and
4%, respectively). Only the scab-susceptible cultivars were moderately or highly infected by harvest
in the organic production system (mean fruit scab incidence was above 5%), while all cultivars (including
scab-resistant ones) were highly damaged by codling moth by harvest in the organic production system
(mean incidence was above 20%). Mean soluble solid concentrations and calcium contents were signifi-
cantly higher in the organic production system only in one year compared to the integrated one (mean
values were 17 and 16%, and 204 and 191 mg kg−1, respectively), and cultivars of scab-susceptibile vs
scab-resistant had significant effect on soluble solid concentrations and calcium contents also in one year
(mean values were 16 vs 17 kg tree−1, and 202 vs 175 kg tree−1, respectively). Our results indicated that a
multiscale selection approach is required for choosing cultivars for integrated, and especially for organic
growing methods in order to facilitate successful apple growing in environmentally benign production
systems.
© 2012 Elsevier B.V. All rights reserved.
1. Introduction
As environmental considerations are becoming increasingly
important in apple production, interest has turned from con-
ventional to integrated and organic production systems, where
management practices differ from those in conventional pro-
duction system (e.g. Reganold et al., 2001; Peck et al., 2006 ).
By definition integrated fruit production (IFP) in pome fruits is
the economical production of high quality of fruit, giving pri-
ority to ecologically safer methods, minimizing the undesirable
side effects and use of agrochemicals, to enhance the safe-
guards to the environment and human health (Cross and Dickler,
1994 ). While organic production is defined as an approach where
the aim is to create integrated, humane, and environmentally
sustainable production system, which maximize reliance on
∗Corresponding author. Tel.: +36 52 508 444; fax: +36 52 413 385.
E-mail address: holbimre@gmail.com (I.J. Holb).farm-derived renewable resources and the management of eco-
logical and biological processes and interactions (Lampkin, 1994 ).
Synthetic products are restricted in integrated and banned in
organic apple production, e.g., in plant protection and nutrient
supply. In organic apple growing, only natural products, such as
stable manure, compost, soluble rock powder, sulfur and copper
compounds, fungicidal and botanical soaps, botanical insecticides,
traps, and biological methods, are permitted according to IFOAM
(International Federation of Organic Agriculture Movements) stan-
dards (Anon., 1989, 2001 ). Many synthetic pesticides and artificial
fertilizers can be used in conventional apple production. More-
over, especially in organic apple production, pest and nutritional
managements are less effective than in integrated and/or conven-
tional productions with one of the consequences being that disease
and pest damage are likely to be more serious in such systems
(Rader et al., 1985; Ellis et al., 1998; Holb, 2007; Holb and Scherm,
2008 ).
Many aspects of horticultural performance and fruit quality
of organic and integrated apple have been widely examined for
0304-4238/$ – see front matter © 2012 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.scienta.2012.08.003

110 I.J. Holb et al. / Scientia Horticulturae 145 (2012) 109–117
Table 1
Pedigree,
country of origin and literature citation on scab susceptibility for the 10 cultivars in the apple orchard at Debrecen–Pallag, Hungary.
Cultivar Pedigree Country of origin Literature citation on scab susceptibility
Scab-resistant‘Liberty’ ‘Macoun’ בPurdue’ USA Lamb et al. (1979)
‘Reanda’ ‘Clivia’ × Malus floribunda Germany Fischer and Fischer (1996, 1999)
‘Remo’ ‘James Grieve’ × M. floribunda Germany Fischer and Fischer (1996, 1999)
‘Retina’ ‘Apollo’
× M. floribunda Germany Fischer and Fischer (1996, 1999)
‘Rewena’ (‘Cox Orange’ × ‘Oldenburg’) × M. floribunda Germany Fischer and Fischer (1996, 1999)
Scab-susceptible
‘Idared’ ‘Jonathan’
בWagener’ USA Aldwinckle (1974); Norton (1981)
‘Jonagold’ ‘Golden Delicious’ בJonathan’ USA Aldwinckle (1974); Norton (1981)
‘Jonica’ Mutant of ‘Jonagold’ USA Aldwinckle (1974); Norton (1981)
‘Mutsu’ ‘Golden Delicious’ × ‘Indo’ Japan Aldwinckle (1974); Norton (1981)
‘Royal
Gala’ ‘Kidd’s Orange Red’ × ‘Golden Delicious’ New Zealand Norton (1981)
some apple cultivars (e.g. Reganold et al., 2001; Peck et al., 2006 ).
Yield proved to be generally lower in organic apple orchards com-
pared to either conventional or integrated ones (Palmer et al.,
2003; Amarante do et al., 2008; Johnsson et al., 2010 ). In general,
disease and pest damages were lower in integrated or conven-
tional orchards compared to organic ones, except for scab-resistant
cultivars where good control was achieved against apple scab
in all production systems (Rader et al., 1985; Ellis et al., 1998;
Holb, 2007; Holb and Scherm, 2008 ). In previous studies, solu-
ble solid and calcium contents varied amongst apple cultivars and
management systems (DeEll and Prange, 1994; Roth et al., 2007;
Peck et al., 2006, 2009; Roussos and Gasparatos, 2009; Holb and
Nagy, 2009; Choi et al., 2011 ). In case of soluble solid content
(SSC), some studies (Peck et al., 2006, 2009; Roth et al., 2007 )
showed that SSC were not consistently different between inte-
grated and organic production systems; however, other studies
(DeEll and Prange, 1994; Reganold et al., 2001; Amarante do et al.,
2008; Roussos and Gasparatos, 2009 ) showed that organic apples
had generally higher SSCs compared to conventional/integrated
apples. In case of calcium content, Peck et al. (2006) demon-
strated there were no differences among the fruit calcium content
between integrated and organic orchards. On the other hand, other
studies (Peck et al., 2009; Holb and Nagy, 2009 ) reported that
IFP-grown fruit contained more calcium than organically grown
fruit, and one study (Roussos and Gasparatos, 2009 ) showed that
calcium contents were higher in the flesh portion of organically
produced fruits compared to conventional apples. In general, no
clear statement could be drawn in case of soluble solid and cal-
cium contents of apple cultivars in order to give priority to either
conventional or environmentally friendly (integrated or organic)
production systems.
Most apple studies, aiming to compare production systems,
focused on only one or few apple cultivars (e.g. Reganold et al.,
2001; Peck et al., 2006, 2009, 2010; Johnsson et al., 2010 ) and
only few attempts have been made to show the major horticultural
attributes (e.g. yield, disease and pest damages, inner content of
fruit) of several disease-susceptible and disease-resistant apple cul-
tivars under the same orchard conditions in comparison between
integrated and organic production systems (Holb, 2000, 2007 ). In
addition, it would be essential to know whether the major horticul-
tural attributes of susceptible and resistant cultivars differ between
the two production systems depending on the age of the trees in a
longer life span of the orchard.
The aim of this study was to evaluate 10 apple cultivars (5 scab-
resistant and 5 scab-susceptible) for yield, scab incidence, codling
moth injury, soluble solid concentration, and calcium content of
fruit in high-density integrated and organic apple orchards. The
study was also aimed to evaluate above measurements on younger
(5–6 years old in 2001–2002) and on older life stages of the trees(13–14
years old in 2009–2010) in the same integrated and organic
orchard blocks.
2. Materials and methods
2.1. Location, plant material and orchard management
A 4-year study (2001, 2002, 2009, and 2010) was carried out in
an experimental apple orchard in Eastern Hungary. The orchard,
located in Debrecen–Pallag (47◦31/prime60/prime/primeN, 21◦37/prime60/prime/primeE), consisted of
a mixed stand of apple cultivars. Orchard soil type was brown
forest soil with alternating layers of clay. Trees were planted on
M.26 rootstock in 1996 and pruned to a spindle shape. Between-
row and within-row distances were 4 m and 1.5 m, respectively.
Bare soil, 3.2 m wide, was maintained mechanically with a disc-
tiller in the spacings between rows; and straw mulch was used
in the rows. Trees were ca. 2.0–2.8 m tall during the study period.
The orchard was divided into two equal orchard parts: one fol-
lowed the integrated and other organic production guidelines
(Cross and Dickler, 1994; Anon., 1989, 2001 ). The orchard parts
were separated by windbreaks of Italian alder (Alnus cordata ) and
by a 4 m-wide road. Thirty-nine cultivars were planted in each
orchard part with three replicate plots per cultivar in a com-
pletely randomized design (CRD) according to Gomez and Gomez
(1984) . Each replicate plot consisted of seven trees. Ten cultivars
were selected for our study (Table 1): 5 widely grown commer-
cial cultivars and 5 promising scab-resistant cultivars (Lamb et al.,
1979; Fischer and Fischer, 1996, 1999 ). The pest management pro-
gram in the integrated block followed the Hungarian integrated
fruit production guidelines, while those in the organic plots were
according to the Hungarian organic production guidelines derived
from the European IFP (Cross and Dickler, 1994 ) and the Inter-
national Federation of Organic Agriculture Movements organic
production guidelines (Anon., 1989, 2001 ). Both sets of guide-
lines had been applied since the orchard was planted in 1996.
Fungicides, insecticides, and herbicides used in the two production
systems are listed in Table 2; application schedules were similar to
those reported in a previous paper (Holb et al., 2005 ). All sprays
were applied with a Kertitox 2000 axial blower spray machine
(Debreceni Gépgyár B.V., Debrecen, Hungary) with a ceramic hol-
low cone at 1.1–1.2 MPa with a volume of 1000 l ha−1. In the organic
blocks, stable manure and compost were applied at 30 t ha−1in
November of every other year. The integrated orchards relied on
annual application of a nitrogen–phosphorus–potassium (NPK)
complex fertilizer (Péti Kevert NPK M˝utrágya, Nitrogénm ˝uvek
GmbH, Pétfürd ˝o, Hungary) at the beginning of March at a dosage of
100 kg ha−1active ingredient with 10:15:15 N–P–K ratio for nutri-
ent supply.

I.J. Holb et al. / Scientia Horticulturae 145 (2012) 109–117 111
Table 2
Fungicide,
insecticide, and herbicide active ingredients used in the apple orchard at
Debrecen–Pallag,
Hungary, 2001, 2002, 2009, and 2010a.
Integrated Organic
Fungicidescaptan, 50% calcium polysulfides, 29%
copper
hydroxide, 77% copper hydroxide, 77%
copper
sulfate, 350 g l−1copper sulfate, 350 g l−1
difenoconazole, 250 g l−1elemental sulfur, 80%
dithianon,
70% elemental sulfur, 900 g l−1
dodine, 500 g l−1
kresoxim-methyl, 50%
pyrimethanil,
300 g l−1
trifloxistrobin, 50%
Insecticides
acetampirid,
20% Bacillus thuringiensis , 3.2%
fenoxicarb, 25% mineral oil, 90%
flufenzin, 200 g l−1plant oil extract, 50%
hexytiazox,
10%
lufenuron,
50 g l−1
mineral oil, 90%
teflubenzuron,
150 g l−1
tiacloprid, 480 g l−1
triflumuron, 25%
Herbicides
glyphosinate-ammonium,
360 g l−1
aApplication schedules were similar to those described in detail by Holb et al.
(2005) .
The orchard was irrigated with a drip irrigation system twice per
year during dry periods in July and August in 2001 and 2002, while
the orchard was not irrigated in 2009 and 2010. A winter pruning
before bud break and two summer prunings at the beginning of June
and August were carried out each year. Mechanical fruit thinning
(after natural thinning) was performed in early June uniformly for
all cultivars in both production systems.
2.2. Yield assessment
Fruit yield of all the 10 selected cultivars was assessed at har-
vest in each year, when all fruits of the trees form the 2nd till the
6th ones within each 7-tree replicate plot of both integrated and
organic blocks were picked and weighed. Harvest time was based
on the biological maturity of each cultivar by measuring flesh firm-
ness and fruit colouring of sample fruits. Three fruit per cultivars
were selected for maturity check. Flesh firmness was determined
by using an Effigi penetrometer (model FT327; McCormick Fruit
Tech, Yakima, WA, USA). The colouring of each fruit was rated visu-
ally as 1, 2, 3 or 4 corresponding to 0–25%, 26–50%, 51–75% and
76–100% colouring, respectively.
2.3. Scab infection period and fruit scab assessment
Potential infection periods, based on the criteria of Mills and
La Plante (1951) , were recorded with a METOS agrometeorological
station (Pessl Instrument GmbH, Weiz, Austria) from 25 March to
10 October in 2001, 2002, 2009, and 2010.
Within each replicate plot of both integrated and organic
blocks, the middle five trees of all cultivars were assessed. Assess-
ments were made on each selected tree at harvest for fruit in all
years of 2001, 2002, 2009, and 2010. Thirty randomly selected
fruits were observed on each tree. Fruits were considered to be
diseased if at least one visible scab lesion was present. Fruit scab
incidences were calculated as the percentage of diseased leaves
and fruits, respectively. Fruit scab severities were also calculated
for both production systems but since the significant differences
between production systems for severity were similar to those
for incidence and due to the frequent low severity values in theintegrated
production system, only incidence values were retained
for analysis.
2.4. Codling moth assessment
Codling moth injuries were assessed at harvest on the same trees
of all cultuvars as for apple scab. Thirty randomly selected fruits
were observed on each tree, and the presence of typical damage
symptoms associated with codling moth larvae was identified. If
symptoms were typical and/or causative larvae were present, then
injury was considered as codling moth damage.
Numbers of male Cydia pomonella were monitored with three
pheromone traps (ARCO-PHERON AM; Hungarian Kwizda Ltd.,
Budapest, Hungary) from 20 May to 30 September each year. The
traps were baited with 1 mg of synthetic codlemone (Shin-etsu
Fine Chemical Division, Tokyo, Japan) and hung 1.5–2.0 m above
ground in the trees, keeping at least a 10 m distance among traps.
Traps were checked every 2–3 days during the season and the
number of male moths captured was recorded. Pheromone baits
were changed at 5 week intervals, and the sticky capture sheets
were replaced 8–12 times per year depending on the capture den-
sity.
2.5. Soluble solid concentration
Soluble solids concentration was determined on a freshly
squeezed juice sample from 20 fruits of each year-cultivar-
production system combinations, using an Atago temperature-
compensating refractometer (model N-20E; Atago Co., Ltd., Tokyo,
Japan) calibrated before use with a 10% (w/v) sucrose solution.
Between individual fruit samples, the refractometer was rinsed
with distilled, deionized water.
2.6. Calcium content of fruit
At harvest 5 fruits per replicate, with 4 replicates for each culti-
var and management system were used to determine the calcium
concentration on the skin of fruits for each year. Fruits were care-
fully washed, and a 1 cm transverse section of the fruit was cut
at the equator, the skin was carefully separated from the cortex,
and aliquots of each tissue were prepared for analysis. For tis-
sue element determination, peels were finely cut (<1 mm thick)
and mixed. A 0.5 g aliquot was taken for mineral analyses. Atomic
absorption spectroscopy (SpectrAA-10 Plus, Varian Australia Pty
Ltd., Mulgrave, Australia) was used to measure the concentrations
of calcium in fruit skin in mg kg−1.
2.7. Data analyses
Measurements of yield, fruit scab incidence, codling moth inci-
dence, soluble solid concentration, and calcium content of fruit
were used to characterize cultivars in both production systems
and all years. All five measurements were averaged to obtain a
single value for each year, cultivar, and production system. Then,
data of each measurement were analysed by split-plot analysis of
variance (Statistical Analysis System v. 8.1; SAS Institute Inc., Cary,
NC), where the 4 years were blocks, the two production systems
main plots, and apple cultivars sub-plots. Then means for each
measurement were separated by an unprotected least significant
difference (LSD) test using LSD 0.05values. Standard errors for the
differences (SED) and degrees of freedom (d.f.) are given in the
tables if appropriate. Prior to the analyses, all incidence values were
arcsine-square root transformed in order to make the data normally
distributed.

112 I.J. Holb et al. / Scientia Horticulturae 145 (2012) 109–117
Table
3
Analysis
of variance for the effects of year (2001, 2002, 2009, and 2010), production system (organic vs integrated), and cultivar (10 apple cultivars) on yield, fruit scab
incidence,
codling moth incidence, soluble solid concentration (SSC), and calcium content in the apple orchard at Debrecen–Pallag, Hungary.
Source of variation d.f.bYield (kg tree−1) Fruit scab incidence (%)aCodling moth incidence
(%)aSSC (%) Ca content (mg kg−1)
MScP > FdMS P > F MS P > F MS P > F MS P > F
Year (Y)3 46.7 0.005 6.23 0.049 43.5 0.036 2.29 0.078 0.613 0.943
Management (M) 1 478.2 0.003 793.1 <0.001 6081.1 <0.001 4.11 0.042 6361.1 0.028
Main plot error 3 6.24 3.87 16.1 0.764 456.2
Cultivar (C) 9 14.2 <0.001 148.1 <0.001 3.66 0.158 3.79 0.048 3084.8 0.001
M × C 9 8.61 0.058 103.9 0.353 2.54 0.631 1.09 0.158 1541.1 0.075
Sub-plot
error 54 70.5 40.3 174.7 51.9 44,315.5
aBased on arcsine-square root transformed disease incidence data.
bd.f. = degree of freedom.
cMS = Mean squares.
dThe probability values associated with the F tests.
3. Results
3.1. Yield
Analyses of variance of yield indicated significant (P < 0.05)
differences amongst years, management systems, and cultivars
(Table 3). There were no significant interactions amongst treatment
factors.
The 4-year means of yield ranged from 10.4 to 22.5 kg tree−1and
from 9.8 to 16.9 kg tree−1for the integrated and organic productionsystems, respectively; and from 9.8 to 19.3 kg tree−1and from
11.1 to 22.5 kg tree−1for scab-resistant and scab-susceptible
cultivars, respectively (Table 4). The highest yield (22.5 kg tree−1)
was harvested in the integrated orchard on cultivar ‘Jonica’, while
the lowest yield (9.8 kg tree−1) was measured in the organic
block on the Vfresistant cultivar ‘Reanda’. Yields of cultivars were
significantly differred from each other depending on years and
productions systems.
Yield was significantly higher (P = 0.05) in the integrated plots
compared to the organic ones in all years (mean values were
Table 4
Yield
(kg tree−1) of 5 scab-resistant and 5 scab-susceptible apple cultivars in integrated and organic production systems at Debrecen–Pallag, Hungary (2001, 2002, 2009, and
2010).
2001 2002 2001–2002 2009 2010 2009–2010 Overall (year)
IntegratedScab-resistant‘Liberty’ 13.5 abca13.3 a 13.4 a 15.9 a 17.9 ab 16.9 ab 15.2 ab
‘Reanda’ 10.4 a 15.1 abc 12.8 a 17.3 ab 16.3 a 16.8 a 14.8 a
‘Remo’ 14.5 bcd 16.6 abcd 15.6 abc 19.3 bc 18.7 abc 19.0 abcd 17.3 abcd
‘Retina’ 11.8 ab 13.6 ab 12.7 a 18.2 ab 19.1 bc 18.7 abcd 15.7 ab
‘Rewena’ 13.1 abc 17.1 bcd 15.1 ab 17.6 ab 18.4 ab 18.0 abc 16.6 abc
Scab-susceptible‘Idared’ 18.7 e 18.1 cde 18.4 bcd 20.3 bcd 22.4 d 21.4 de 19.9 de
‘Jonagold’ 17.9 de 20.1 de 19.0 cd 21.4 cd 19.4 bc 20.4 cde 19.7 cde
‘Jonica’ 18.3 e 21.4 e 19.9 d 22.5 d 22.1 d 22.3 e 21.1 e
‘Mutsu’
17.7 e 19.8 de 18.8 cd 20.1 bcd 21.1 cd 20.6 cde 19.7 cde
‘Royal
Gala’ 16.3 cde 17.8 cde 17.1 bcd 18.9 abc 20.4 bcd 19.7 bcde 18.4 bcde
LSD 0.05b3.3 3.7 3.5 3.1 2.6 2.8 3.3
Organic
Scab-resistant‘Liberty’ 12.9 de 12.5 cde 12.7 de 11.5 a 12.5 a 12.0 a 12.4 ab
‘Reanda’
10.9 ab 9.8 a 10.4 ab 11.2 a 13.8 bc 12.5 ab 11.4 a
‘Remo’
11.7 bc 13.3 de 12.5 cde 13.8 cd 15.8 d 14.8 de 13.7 ab
‘Retina’
10.5 a 10.1 ab 10.3 a 14.6 de 16.9 d 15.8 e 13.0 ab
‘Rewena’
11.1 ab 13.9 e 12.5 cde 15.1 e 16.1 d 15.6 e 14.1 b
Scab-susceptible‘Idared’ 12.7 cde 12.0 cd 12.4 cde 12.8 bc 13.6 abc 13.2 abc 12.8 ab
‘Jonagold’
12.6 cde 13.7 e 13.2 de 13.1 c 14.3 c 13.7 b 13.4 ab
‘Jonica’
13.1 e 14.1 e 13.6 e 13.8 cd 14.5 c 14.2 d 13.9 b
Mutsu’
11.3 ab 11.1 abc 11.2 abc 12.7 b 13.8 bc 13.3 abc 12.2 ab
‘Royal
Gala’ 11.9 bcd 11.7 bcd 11.8 bcd 12.9 bc 13.1 ab 13.0 abc 12.4 ab
LSD 0.05 1.1 1.6 1.4 1.3 1.2 1.3 2.3
Overall (management system)
Scab-resistant
12.0 b 13.5 a 12.8 a 15.5 a 16.6 a 16.0 a 14.4 a
Scab-susceptible
15.1 a 15.9 a 15.5 a 16.9 a 17.5 a 17.2 a 16.3 a
LSD 0.05 2.2 3.0 2.8 3.3 2.9 3.1 2.4
Overall (cultivar)
Integrated
15.2 b 17.3 b 16.2 b 19.2 b 19.6 b 19.4 b 17.8 b
Organic
11.9 a 12.2 a 12.0 a 13.2 a 14.4 a 13.8 a 12.9 a
LSD 0.05 2.1 2.3 2.2 1.6 3.1 2.4 2.5
aValues followed by the same letter are not significantly different according to LSD test (P = 0.05).
bLSD 0.05= least significant differences at P = 0.05 level.

I.J. Holb et al. / Scientia Horticulturae 145 (2012) 109–117 113
Table 5
Final
scab incidence (%) on fruit of 5 scab-resistant and 5 scab-susceptible apple cul-
tivars
at harvest in integrated and organic production systems at Debrecen–Pallag,
Hungary
(2001, 2002, 2009, and 2010). Fruits of all scab resistant cultivars showed
no
scab symptoms in either systems or years, therefore, these data were omitted.
2001 2002 2009 2010 Overall(year)
IntegratedScab-susceptible‘Idared’ 0.2 aa0.5 ab 0.4 a 0.7 b 0.5 b
‘Jonagold’ 0.8 b 1.1 cd 1.3 b 1.2 c 1.1 c
‘Jonica’ 0.8 b 0.7 bc 1.1 b 1.3 c 1.0 c
‘Mutsu’ 1.6 c 1.8 e 2.4 c 1.9 d 1.9 d
‘Royal Gala’ 1.3 c 1.4 de 2.1 c 1.9 d 1.7 d
LSD 0.05b0.4 0.5 0.4 0.5 0.3
Organic
Scab-susceptible‘Idared’ 5.6 b 7.9 b 8.1 b 8.0 b 7.4 b
‘Jonagold’
10.1 c 13.2 c 14.4 c 13.2 c 12.7 c
‘Jonica’ 9.7
c 12.1 c 13.2 c 14.3 c 12.3 c
‘Mutsu’ 16.7 e 19.3 e 23.2 e 21.5 e 20.2 e
‘Royal
Gala’ 13.4 d 15.7 d 19.4 d 17.4 d 16.5 d
LSD 0.05 2.4 1.7 2.7 2.5 2.2
Overall (management system)
Scab-resistant 0.0 a 0.0 a 0.0 a 0.0 a 0.0 a
Scab-susceptible 6.0 b 7.4 b 8.6 b 8.1 b 7.5 b
LSD 0.05 4.1 4.8 5.6 5.2 5.5
Overall (cultivar)
Integrated
0.5 a 0.6 a 0.7 a 0.7 a 0.6 a
Organic
5.6 b 6.9 b 7.8 b 7.4 b 6.9 b
LSD 0.05 4.3 5.1 6.1 5.7 5.7
a,bFor explanation see Table 4, footnotes ‘a’ and ‘b’.
17.8 and 12.9 kg tree−1, respectively) and scab-susceptibile vs scab-
resistant cultivars had significant effect on yield only in 2001
(mean values of 12.0 vs 15.1 kg tree−1, respectively) (Table 4). Yield
was significantly lower on the younger trees (2001–2002) com-
pared to the older ones (2009–2010) (mean values were 14.2 and
16.6 kg tree−1, respectively, P = 0.047) (Table 4).
3.2. Scab infection period and fruit scab incidence
Weather conditions were suitable for the development of scab
epidemics in all years. The numbers of Mills infection periods was
21, 26, 30, and 29 occasions in 2000, 2001, 2009, and 2010, respec-
tively, from end-March until early-October.
Analyses of variance of fruit scab incidence indicated significant
(P < 0.05) differences amongst years, management systems, and
cultivars (Table 3). There were no significant interactions amongst
treatment factors.
The 4-year means of fruit scab incidence at harvest ranged from
0.0 to 2.4% and from 0.0 to 23.2% for the integrated and organic
production systems, respectively; and from 0.2 to 23.2% for scab
susceptible cultivars (Table 5). Mean final scab incidences were sig-
nificantly higher in the organic than in the integrated production
system in all years, except for the resistant cultivars which had
no fruit scab symptoms in either production system. Fruit of all
cultivars were successfully protected against apple scab in the inte-
grated production system (final scab incidence was below 2.5%), but
all scab-susceptible cultivars (‘Idared’, ‘Jonagold’, ‘Jonica’, ‘Mutsu’,
and ‘Royal Gala’) were moderately or highly infected by harvest in
the organic production system (Table 5).
3.3. Codling moth incidence
Analysis of variance of codling moth incidence indicated signifi-
cant (P < 0.05) differences amongst years and management systemsTable 6
Final
codling moth incidence (%) on fruit of 5 scab-resistant and 5 scab-susceptible
apple
cultivars at harvest in integrated and organic production systems at
Debrecen–Pallag,
Hungary (2001, 2002, 2009, and 2010).
2001 2002 2009 2010 Overall(year)
IntegratedScab-resistant‘Liberty’ 3.1 4.1 2.4 3.4 3.2
‘Reanda’
4.8 3.5 3.1 2.9 3.6
‘Remo’ 3.6 2.3 3.3 4.1 3.3‘Retina’ 3.3 3.9 2.5 4.4 3.5
‘Rewena’ 4.6 4.2 3.5 2.6 3.7
Scab-susceptible‘Idared’ 5.4 3.4 3.6 3.6 4.0
Jonagold’
4.4 2.7 2.1 4.2 3.4
‘Jonica’ 4.6 4.3 2.3 2.9 3.5‘Mutsu’ 5.2 2.8 2.5 2.6 3.3
‘Royal
Gala’ 4.4 3.5 3.5 4.1 3.9
LSD 0.05ansbns ns ns ns
Organic
Scab-resistant‘Liberty’ 21.2 17.6 18.3 21.9 19.8
‘Reanda’
20.4 22.7 19.2 22.3 21.2
‘Remo’
25.2 22.3 15.7 24.6 21.9
‘Retina’
24.2 17.4 21.4 16.5 19.9
‘Rewena’ 27.5 21.3 16.2 23.5 22.1
Scab-susceptible‘Idared’ 21.3 20.2 16.9 24.6 20.8
‘Jonagold’ 24.5 22.4 20.2 20.3 21.9
‘Jonica’
25.6 20.9 15.3 21.4 20.8
‘Mutsu’
21.8 17.5 19.2 16.9 18.9
‘Royal
Gala’ 25.3 22.9 17.9 24.7 22.7
LSD 0.05 ns ns ns ns ns
Overall (management system)
Scab-resistant
13.8 11.9 10.6 12.6 12.2
Scab-susceptible 14.3 12.1 10.4 12.5 12.3
LSD 0.05 ns ns ns ns ns
Overall (cultivar)
Integrated
4.3 ac3.5 a 2.9 a 3.5 a 3.5 a
Organic 23.7
b 20.5 b 18.0 b 21.7 b 21.0 b
LSD 0.05 1.7 1.6 1.4 2.1 2.8
aFor explanation see Table 4, footnote ‘b’.
bns = nonsignificant at P = 0.05.
cFor explanation see Table 4, footnote ‘a’.
(Table 3). No significant effects were found amongst cultivars. There
were no significant interactions amongst treatment factors.
The 4-year means of codling moth incidence ranged from 2.1 to
5.4% and from 15.3 to 27.5% for the integrated and organic produc-
tion systems, respectively; and from 2.4 to 27.5% and from 2.1 to
25.6% for scab-resistant and scab-susceptible cultivars, respectively
(Table 6). The highest codling moth incidence (27.5%) was har-
vested in the organic orchard on the Vfresistant cultivar ‘Rewena’,
while the lowest codling month incidence (2.1%) was measured in
the integrated block on cultivar ‘Jonagold’.
Mean codling moth incidences were significantly higher in the
organic than in the integrated block in all years (mean values were
21.0 and 3.5%, respectively). Fruits of all cultivars were satisfactorily
protected against codling moth in the integrated production sys-
tem (mean final codling moth incidence was below 4%), while all
cultivars were highly damaged by harvest in the organic produc-
tion system (mean final codling moth incidence was above 20%,
Table 6).
3.4. Soluble solid concentration
Analysis of variance of soluble solid concentration data set
indicated significant (P < 0.05) differences amongst management
systems and cultivars (Table 3). No significant effects were found

114 I.J. Holb et al. / Scientia Horticulturae 145 (2012) 109–117
Table 7
Soluble
solid concentrations (%) of 5 scab-resistant and 5 scab-susceptible apple cul-
tivars
at harvest in integrated and organic production systems at Debrecen–Pallag,
Hungary
(2001, 2002, 2009, and 2010).
2001 2002 2009 2010 Overall(year)
IntegratedScab-resistant‘Liberty’ 18.6 ba15.9 c 16.1 ab 15.5 ab 16.5 abc
‘Reanda’
16.5 a 18.5 e 16.5 abc 15.3 ab 16.7 abc
‘Remo’
16.1 a 17.9 de 18.6 d 17.8 cde 17.6 c
‘Retina’ 16.4
a 16.1 c 15.2 a 16.9 bcde 16.2 abc
Rewena’ 16.5 a 16.9 cd 16.8 abc 17.9 de 17.0 bc
Scab-susceptibleIdared’ 16.2 a 13.8 a 16.4 ab 15.5 ab 15.5 a
‘Jonagold’
15.8 a 15.7 bc 17.2 bcd 18.3 e 16.8 abc
‘Jonica’
16.9 ab 15.8 c 18.1 cd 16.1 abc 16.7 abc
‘Mutsu’ 15.8
a 15.4 bc 16.5 abc 16.3 bcd 16.0 ab
‘Royal
Gala’ 15.5 a 14.2 ab 17.1 bcd 15.1 ab 15.5 a
LSD 0.05b1.9 1.5 1.6 1.7 1.5
OrganicScab-resistantLiberty’ 18.1 c 17.6 bc 17.8 bc 15.8 a 17.3 ab
‘Reanda’ 16.4 abc 16.7 ab 18.9 c 15.8 a 16.9 ab
‘Remo’
17.8 bc 18.4 c 16.5 ab 17.2 abc 17.5 b
‘Retina’
15.9 ab 16.2 ab 15.6 a 16.2 ab 15.9 a
‘Rewena’
15.3 a 17.1 ac 16.7 ab 17.1 abc 16.6 ab
Scab-susceptible‘Idared’ 15.6 a 15.9 a 17.7 bc 16.8 abc 16.5 ab
‘Jonagold’ 16.3
abc 16.5 ab 19.2 c 18.3 c 17.6 b
‘Jonica’ 15.9 ab 16.7 ab 17.7 bc 16.1 ab 16.6 ab
‘Mutsu’ 16.1 ab 16.9 ab 16.9 ab 18.2 c 17.0 ab
‘Royal Gala’ 16.7 abc 17.3 bc 17.8 bc 17.6 bc 17.4 b
LSD 0.05 2.0 1.4 1.9 1.5 1.4
Overall (management system)
Scab-resistant
16.8 a 17.1 b 16.9 a 16.6 a 16.8 a
Scab-susceptible 16.1 a 15.8 a 17.5 a 16.8 a 16.5 a
LSD 0.05 0.8 0.9 0.9 1.1 0.9
Overall
(cultivar)
Integrated 16.4
a 16.0 a 16.9 a 16.5 a 16.4 a
Organic 16.4 a 16.9 b 17.5 a 16.9 a 16.9 a
LSD 0.05 0.8 0.8 0.9 0.9 0.9
a,bFor explanation see Table 4, footnotes ‘a’ and ‘b’.
amongst years. There were no significant interactions amongst
treatment factors.
The 4-year means of soluble solid concentration ranged from
13.8 to 18.6% and from 15.3 to 19.2% for the integrated and organic
production systems, respectively; and from 15.2 to 18.9% and
from 13.8 to 19.2% for scab-resistant and scab-susceptible culti-
vars, respectively (Table 7). The highest soluble solid concentration
(19.2%) was measured in the organic orchard on cultivar ‘Jonagold’,
while the lowest soluble solid concentration (13.8%) in the inte-
grated block on cultivar ‘Idared’.
Mean soluble solid concentrations were significantly higher in
the organic production system only in 2002 compared to the inte-
grated one (mean values were 16.9 and 16.0%, respectively), and
cultivars of scab-susceptibile vs scab-resistant had significant effect
on soluble solid concentrations also in 2002 (mean values were 15.8
vs 17.1 kg tree−1, respectively) (Table 7).
3.5. Calcium content of fruit
Similarly to soluble solid concentration data set, analyses of
variance of calcium content of fruit indicated significant (P < 0.05)
differences amongst management systems and cultivars (Table 3).
No significant effects were found amongst years. There were no
significant interactions amongst treatment factors.
The 4-year means of calcium content of fruit ranged from 117
to 250 mg kg−1and from 116 to 251 mg kg−1for the integrated
and organic production systems, respectively; and from 116 toTable 8
Calcium
content (mg kg−1) of 5 scab-resistant and 5 scab-susceptible apple culti-
vars
at harvest in integrated and organic production systems at Debrecen–Pallag,
Hungary
(2001, 2002, 2009, and 2010).
2001 2002 2009 2010 Overall(year)
IntegratedScab-resistant‘Liberty’ 206 ca247 c 191 bc 250 d 223.5 c
‘Reanda’
155 b 142 a 177 ab 220 cd 173.5 ab
‘Remo’ 117
a 247 c 189 abc 158 ab 177.8 abc
‘Retina’ 157 b 188 b 194 bc 189 bc 182.0 abc
‘Rewena’ 143 ab 231 c 202 bc 215 c 197.8 abc
Scab-susceptible‘Idared’ 135 ab 249 c 213 c 218 c 203.8 bc
‘Jonagold’
168 b 162 ab 197 bc 141 a 167.0 a
‘Jonica’ 137
a 147 a 159 a 166 ab 152.2 a
‘Mutsu’ 211 c 231 c 203 bc 148 a 198.2 abc
‘Royal
Gala’ 206 c 222 c 207 bc 204 c 209.8 bc
LSD 0.05b37.5 33.2 32.5 31.5 48.2
Organic
Scab-resistant‘Liberty’ 116 a 239 d 121 a 221 bcd 174.3 a
‘Reanda’
176 cde 175 abc 131 ab 189 ab 167.8 a
‘Remo’
142 abc 238 d 145 abc 211 bc 184.0 ab
‘Retina’
137 ab 165 ab 179 cd 191 a 168.0 a
‘Rewena’ 191
e 183 abc 222 ef 189 a 196.3 abc
Scab-susceptible‘Idared’ 185 de 219 cd 251 f 247 d 225.3 bc
‘Jonagold’ 129 a 194 abcd 167 bcd 161 a 162.8 a
‘Jonica’
174 bcde 209 bcd 196 de 211 bc 197.5 ab
‘Mutsu’
148 abcd 162 a 175 cd 191 ab 169.0 a
‘Royal
Gala’ 236 f 234 d 257 f 229 cd 239.0 c
LSD 0.05 37.4 46.8 40.1 32.7 46.6
Overall (management system)
Scab-resistant
154.0 a 205.5 a 175.1 a 203.3 a 184.5 a
Scab-susceptible 172.9 a 202.9 a 202.4 b 191.6 a 192.5 a
LSD 0.05 31.2 34.8 26.1 29.3 28.7
Overall (cultivar)
Integrated
163.5 a 206.6 a 193.2 a 190.9 a 188.6 a
Organic 163.4
a 201.8 a 184.3 a 204.0 b 188.4 a
LSD 0.05 32.6 34.8 32.9 24.5 26.3
a,bFor explanation see Table 4, footnotes ‘a’ and ‘b’.
250 mg kg−1and from 129 to 251 mg kg−1for scab-resistant and
scab-susceptible cultivars, respectively (Table 8). The highest cal-
cium content (251 mg kg−1) was measured in the organic block
on cultivar Idared’, and the lowest calcium content (116 mg kg−1)
also in the organic block but on the Vfresistant cultivar ‘Lib-
erty’.
Mean calcium contents were significantly higher in the organic
than in the integrated production system only in 2010 (mean values
were 204.0 and 190.9 mg kg−1, respectively), and scab-susceptibile
vs scab-resistant cultivars had significant effect on calcium con-
tents only in 2009 (mean values were 202.4 vs 175.1 kg tree−1,
respectively) (Table 8).
4. Discussion
In this study, yield, soluble solid concentration, calcium con-
tent, scab and codling moth damages of five scab-susceptible and
five scab-resistant apple cultivars were determined on 5–6 and
13–14 years old trees in the same high-density integrated and
organic orchard blocks. Data on yield and scab incidence showed
clear differences among cultivars, production systems and years
but other horticultural attributes responded variously to charac-
teristics of cultivars, production systems and tree ages.
In this study, yield was significantly lower in the organic plots
compared to the integrated plots (Table 4) resulting in a mean yield

I.J. Holb et al. / Scientia Horticulturae 145 (2012) 109–117 115
reduction of 27% in the organic production system. In contrast, mul-
tiyear studies in Washington State showed that cumulative yields
of fruit were not different between organic and integrated systems
or were inconsistent for organic production (Reganold et al., 2001;
Peck et al., 2006, 2010 ). Similarly to the present study, Palmer et al.
(2003) demonstrated that cultivar ‘Braeburn’ showed a significant
yield per tree reduction of 12% in the treatments containing sul-
fur compared to the non-sulfur treatments. Peck et al. (2006) also
showed a yield reduction of 50% for cultivar ‘Galaxy Gala’ in the
organic production system compared to the integrated one. Then
Johnsson et al. (2010) reported that accumulated yield for culti-
vars ‘Aroma’ and ‘Karin Schneider’ was lower (ranging from 15 to
33% and from 5 to 20%) in the organically grown trees compared
to integrated ones, which was mainly due to a smaller amount
of fruit in the organically grown trees. Yield reduction and great
alternance of fruit bearing in organic production may associate to
several factors such as fruit-thining effect of sulphur-containing
fungicides (e.g. Johnsson et al., 2010 ), significant fruit loss caused
by higher disease and pest pressures (e.g. Holb, 2007; Holb and
Scherm, 2008 ), and/or unbalanced nutritional status of leaf and fruit
tissues (e.g. Peck et al., 2006 ) in the organic orchards. The above
examples indicate that more advanced orchard management prac-
tices are needed for higher and/or consistent yields in organic apple
production.
Our study indicated that tree age influenced yield attributes.
Yield was significantly lower on the 5–6 years old younger trees
compared to the 13–14 years old older ones (mean values were
14.2 and 16.6 kg tree−1, respectively, Table 4). This was due to that
the younger trees were smaller in size compared to older trees,
thus these trees produced less amount fruits than the older and
larger once. Tree age, however, has no significant effect on other
measured parameters. This was due to that tree age was unlikely
to influence the efficacy of fungicide and insecticide sprays as well
as soluble solid concentrations and calcium contents in our exper-
iments.
Results of this study demonstrated that the amount of fruit
scab on scab-susceptible cultivars was 10–20 times greater in the
organic blocks compared to the integrated ones (Table 5). This may
be due to the differences in the efficacy of fungicides in the two
production systems. Copper and sulphur fungicides used in organic
fruit production provide less effective disease control compared to
synthetic fungicides approved in the integrated fruit production
(e.g. Ellis et al., 1998; Holb et al., 2003a,b, 2005 ).
Previous studies revealed that European fruit market standards
accept a maximum threshold of 1% fruit incidence of scab at har-
vest in the integrated production system (Scheer, 1980; Holb et al.,
2003a ). Our study showed that scab control efficacy in the inte-
grated production system was close to reach this standard for all
the cultivars studied. However, it needs to be noted that the spray
program (9–15 annual sprays) of this study was adjusted to the
most susceptible cultivars. Recommendations in Western Euro-
pean countries suggest three to four treatments of scab-resistant
cultivars with broadspectrum fungicides to prevent infection by
sooty blotch and flyspeck secondary attacks as well as possible
resistance breaking by scab itself (e.g. Fischer and Fischer, 1999;
Gessler et al., 2006 ). Therefore, the scab-resistant cultivars could
probably be protected with fewer spray applications in the inte-
grated production system than demonstrated here. This would
reduce costs and any negative environmental impacts of chemical
sprays.
European fruit market standards can accept a maximum thresh-
old of 5% fruit scab incidence at harvest in the organic production
systems (Holb and Heijne, 2001; Anon., 2001; Holb, 2007 ). This
study demonstrated that this standard could not be met for the
scab-susceptible cultivars. However, scab control was sufficient
for all resistant cultivars in this study in agreement with thestudies
of Ellis et al. (1998) , Fischer and Fischer (1999) , Sandskär
and Gustafsson (2004) and Holb (2007) . Resistant cultivars were
notable for the absence of all visible fruit scab symptoms in this
study. However, Kühn et al. (2003) noted that low susceptibility
of cultivars to diseases and/or pests is usually not combined with
adequate yield, fruit size and fruit quality. The yield and fruit
quality of most Re-cultivars and cultivar ‘Liberty’ are acceptable
for processing and/or fresh market (Lamb et al., 1979; Fischer
and Fischer, 1996, 1999 ); therefore, most of these cultivars are
suggested for commercial organic production. However, organic
apple producers need to be warned not to plant only one cultivar
as populations of V. ineaqualis are able to adapt to a cultivar and
become more aggressive on a particular cultivar planted in a large
area (MacHardy, 1996; MacHardy et al., 2001; Dewdney et al.,
2003; Gessler et al., 2006; Holb, 2009 ). A mixed cultivar-stand is
recommended to reduce infection pressure.
Our study demonstrated that fruit scab incidence showed sig-
nificant differences between scab-resistant and scab-susceptible
cultivars (0 and 7.5%, respectively) in an overall evaluation (includ-
ing years and management systems, Table 5). However, no
differences were detected in those of yields (14.4 and 16.3 kg tree−1,
respectively, Table 4). The differences may due to that the fungus
caused mainly fruit quality loss rather than quantity loss in our
experiments. In addition a pin-point symptom type of scab lesions
(MacHardy, 1996 ) was frequent on the fruits, which did not largely
influence individual fruit weight and overall fruit yield per tree.
Our study demonstrated that cultivars had no effect on codling
moth damage of fruit as all cultivars showed similar levels of dam-
age depending on productions systems and years (Table 6). In
agreement with our study, Sandskär (2003) and Kühn et al. (2003)
also demonstrated that the percentage of fruit damage caused
by codling moth was not different among cultivars in an organic
orchard. Our study, in agreement with the studies of Holb and
Scherm (2008) and Peck et al. (2010) , clearly demonstrated that
codling moth incidences were significantly higher in the organic
than in the integrated block (mean values of this study were 21.0
and 3.5%, respectively). Holb and Scherm (2008) showed that fruit
injury, which was caused primarily by C. pomonella , was 6.1 and
19.2% in the integrated and organic treatments, respectively. Peck
et al. (2010) showed that the IFP-grown apples had between 3
and 6% insect damage while the organically grown had between
3 and 25%. Indeed, codling moth is perceived the most limiting
factor in organic apple production worldwide (e.g. Wearing, 1993;
Wearing et al., 1995; Judd et al., 1997 ). Most commonly, Bacillus
thuringiensis , granulosis viruses, rotenone, and summer oils are rec-
ommended as season-long spray applications against Lepidoptera
insects such as codling moth in organic production systems (e.g.
Wearing, 1993; Anon., 2001; Holb and Scherm, 2008 ). Addition-
ally, use of the sterile male technique (Dyck and Gardiner, 1992 ),
postharvest fruit removal, tree banding, mating disruption (Judd
et al., 1997 ), and exlusion nets (Dib et al., 2010 ) have been sug-
gested. Based on economic considerations, only B. thuringiensis and
oils were used against insects in the organic blocks in this study,
resulting in relatively high codling moth damage.
This study demonstrated that mean soluble solid concentrations
were significantly higher in the organic production system only in
one year compared to the integrated one (mean values were 17
and 16%, respectively, Table 7). Production systems did not affect
soluble solid concentrations of fruit in all other years. Peck et al.
(2006, 2009) and Roth et al. (2007) showed that differences in
soluble solid concentrations were usually <1◦Brix and were not
consistently different between fruit from integrated and organic
production systems. However, studies of DeEll and Prange (1994) ,
Reganold et al. (2001) , Amarante do et al. (2008) , and Roussos and
Gasparatos (2009) showed that organic apples had generally higher
soluble solid concentrations compared to conventional/integrated

116 I.J. Holb et al. / Scientia Horticulturae 145 (2012) 109–117
apples. Various and inconsisitent data from the present and pre-
vious studies indicate that soluble solid concentrations of apple
fruit may not be a differentiating factor between integrated and
organic production systems. Other fruit quality parameters, such as
flesh firmness, colour, crispness and flavour, were not thoroughly
measured in this study which needs to be investigated in further
studies in integrated vs organic production systems as consumer
preference highly rely on these attributes of certain cultivars.
Similarly to soluble solid concentrations, mean calcium contents
were significantly higher in the organic production system only in
one year compared to the integrated one (mean values were 204
and 191 mg kg−1in 2010, respectively, Table 8). Production systems
did not affect calcium contents of fruit in all other years. Previous
reports are inconsistent in calcium contents of fruit in environmen-
tally benign production systems. Peck et al. (2006) demonstrated
there were no differences among the fruit calcium content of culti-
var ‘Galaxy Gala’ between integrated and organic orchards. Then
Peck et al. (2009) reported that IFP-grown fruit of cultivar ‘Lib-
erty’ contained more calcium in all years than organically grown
fruit. Similary to this report, Holb and Nagy (2009) also showed that
calcium contents were higher in the integrated orchard compared
with the organic one in all years and cultivars, while Roussos and
Gasparatos (2009) showed that calcium contents were higher in the
flesh portion of organically produced fruits compared to conven-
tional apples. Varius and inconsisitent data from the present and
previous studies indicate that more research is needed whether
there are differences in calcium contents of fruit between IFP and
organically grown apple.
In summary, our results showed that the above five horticul-
tural attributes responded variously to characteristics of cultivars,
production systems and tree ages. This indicates that a multiscale
selection approach is required for choosing cultivars for inte-
grated, and especially for organic growing in order to facilitate
successful apple growing in environmentally benign production
systems.
Acknowledgements
The author thanks Dr. Andrew Fieldsend (University of Debre-
cen, Centre for Agricultural Sciences and Engineering) for his critical
reading of the manuscript. Thanks are due to the following peo-
ple for their excellent co-operation in this research: J Holb, Sr,
Á. Szíjártó, R. Veress, L. Krizsai, and G. Varga. This research was
partly supported by grants of the Hungarian Scientific Research
Fund (K78399) and the NKTH-OM-00227/2008 as well as by a János
Bolyai Research Fellowship awarded to Imre J. Holb.
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