HORTSClENCE 47(7):917-926. 2012.
Response of Higbbush Blueberry
to Nitrogen Fertilizer during Field
Establishment-II. Plant Nutrient
Requirements in Relation to Nitrogen
Fertilizer Supply
David R. Bryla1,4
U.S. Department ofAgriculture, Agricultural Research Service, Horticultural
Crops Research Unit, 3420 NW Orchard Avenue, Corvallis, OR 97330
Bernadine C. Strik2
Department of Horticulture, Oregon State University, 4017 ALS, Corvallis,
OR 97331
M. Pilar Baiiados3
Departmento de Fruticultura y En%gia, Pontijicia Universidad Cat6lica
de Chile, Casilla 306-22, Santiago, Chile
Timothy L. Righetti
University of Guam, UOG Station, Mangilao, Guam 96923
Additional index words. Vaccinium corymbosum, fertilizer rate, integrated plant nutrient
management, macronutrients, micronutrients, nutrient partitioning, plant dry matter,
reallocation
Abstract. A study was done to determine the macro- and micronutrient requirements of
young northern highbush blueberry plants (Vaccinium corymbosum L. 'BIuecrop') during
the first 2 years of establishment and to examine how these requirements were affected by the
amount of nitrogen (N) fertilizer applied. The plants were spaced 1.2 x 3.0 m apart and
fertilized with 0, SO, or 100 kg·ha-1 of N, 3S kg.ha-1 of phosphorus (P), and 66 kg·ha- 1 of
potassium (K) each spring. A light fruit crop was harvested during the second year after
planting. Plants were excavated and parts sampled for complete nutrient analysis at six key
stages of development, from leaf budbreak after planting to fruit harvest the next year. The
concentration of several nutrients in the leaves, including N, P, calcium (Cal, sulfur (S), and
manganese (M"n), increased with N fertiIizer application, whereas leaf boron (B) concentration decreased. In most cases, the concentration of nutrients was within or aboyc the range
considered normal for mature blueberry plants, although leafN was below normal in plants
grown without fertilizer in Year 1, and leafB was below normal in plants fertilized with SO or
100 kg·ha- 1 N in Year 2. Plants fertiIized with SO kg·ha- ' N were largest, producing 22% to
32% more dry weight (DW) the first season and 78% to 90% more DW the second ~eason
than unfertilized plants or plants fertilized with 100 kg·ha- 1 N.Most DW accumulated m new
shoots, leaves, and roots in both years as well as in fruit the second year. New shoot and leaf
I
DW was much greater each year when plants were fertilized with SO or 100 kg·ha- N,
I
whereas root DW was only greater at fruit harvest and only when SO kg·ha- N was ap~lied.
Application of SO kg.ha- I N also increased DW of woody stems by fruit barvest, but neltber
SO nor 100 kg.ha- I N had a si!!11ificant effect on crown, flower, or fruit DW. Depending on
treatment, plants lost 16% t: 29% of total biomass at leaf abscission, 3% to 16% when
pruned in winter, and 13% to 32% at fruit barvest. The content of most nutrients in ~be plant
folIowed the same patterns of accumulation and loss as plant DW. Howeycr, unhk~ ~W,
magnesium (Mg), iron (Fe), and zinc (Zn) content in new shoots and lea~:es was Similar
among N treatments the first year, and N fertilizer increased Nand S content m woody ~tems
mUch earlier tban it increased biomass of tbe stems. Likewise, N, P, S, and Zn content III the
crown were greater at times when N fertilizer was applied, wbereas K and Ca content were
sometimes lower. Overall, plants fertilized with 50 kg·ba- I N produced the most gro\~~h and,
from planting to first fruit harvest, required 34.8 kg.ha- I N, 2.3 ~'ha-I P, t2~,kg.ba K. 8.4
kg'ha-1 Ca, 3.8 kg.ha- Mg S.9 kg·ba- ' S 295 g·ba-I Fe, 40 g·ba B, 23 g·ba copper (Cu),
'
1273 g·ha- I Mn, and 6S g. b~-I Zn. Thus, of the total amount offertilizer ap~lied ove~ 2 years,
only 21 % of tbe N, 3% of the P, and 9% of tbe K were used by plants dunng estabhshment.
Like many crops, fertilizer practices in bluebeny (Vaccinium sp.) are routinely adjusted by
comparing the results of leaf nutrient analysis
HORTSCIENCE VOL. 47(7)
JULY
2012
at a standard time against the known optimal
ran"es of leaf nutrient concentrations. E fTectiv: fertilizer management, however, also
requires a good understanding of plant nutritional demands both in terms of the nutrient
amount (Santos, 2011) and the timing in
which each nutrient is most needed (Mattson
and van Iersel, 20 II). Biomass determination
through sequential plant excavation. coupled
with nutrient analysis of each tissue type, is
presently the most reliable way to obtain the
amounts and seasonal patterns of plant nutrient uptake (Weinbaum et aI., 2001). Nutrient
analysis of entire plants at multiple times
during annual cycles of growth and development is difficult and expensive, and only N
has been examined in detail in highbush
blueberry (Bafiados et aI., 2012; Hanson and
Retamales, 1992; Retamales and Hanson.
1989; Throop and Hanson, 1997).
Nitrogen is the predominant nutrient applied to blueberry for successful commercial
growth and production. Although the blueberry
plant is relatively small and slow·growing
compared with many temperate fruit tree
crops, the amount of N fertilizer applied to
the crop each year is comparable (Stiles and
Reid, 1991). Typical rates in Orcgon, for
example, average 50 to 100 kg·ha- ' ofN per
year during planting establishment and 100
to 300 kg·ha-' of N per year once the field
matures. Other nutrients are also applied,
largely based on soil tests and general recommendations from plant and soil testing laboratories. Hart et al. (2006) developed more
stringent guidelines for nutrient management
of blueberry based on leaf tissue and soil
analysis. However, witli-me exception of N.
the defined ranges of nutrient sufficiency were
based on experience and not on controllcd
studies of each nutrient.
Nutrient requirements in perennial fruit
crops such as blueberry depend on new biomass production in vegetative and reproductive tissues, the nutrients needed for production
of the new tissue, and the amount of nutrient,
reallocated from existing plant tissues. Mature
northern highbush blueberry plants produce
most new shoots and leaves in the spring and
early summer, before or during fruit development. and most new roots in early spring.
before budbreak, and mid· to late summer
after fruit harvest (Abbott and Gough, 1987).
Most N is acquired during shoot and fruit
development (Throop and Hanson, 1997).
and therefore split applications of granular
N fertilizer are recommended in the spring
(April to June in the northem hemisphere) for
blueberry (Hart et aI., 2006). Reallocation of
nutrients in woody plants occurs internally.
especially in early spring from storage tissues
such as the crown and woody stems and in the
fall from senescing leaves (Mohadjer et aI.,
200 I; Rempel et aI., 2004; Strik et aI., 2(04)
and externally from decomposition of plant
tissues such as senesced leaves and roots and
pruned wood (Strik et aI., 2006).
We previously found that 50kg·ha-' N per
year promoted more gro\\1h and yield than
no N fertilizer during establishment of highbush blueberry, whereas rates 100 kg·ha-' N
or greater were excessive and resulted in salt
stress and plant mortality in the young plant·
ing (Baiiados et aI., 2012). Through destructive
917
harvests and the use of depleted 15N fertilizer,
we estimated that unfertilized plants gained
1.6 g/plant of N from soil sources, whereas
fertilized plants accumulated 2.3 g/plant of
N, on average, 60% of which was from
fertilizer Nand 40% was from the soil. The
objectives of the present study were to determine the requirements of N and other
macro- and micronutrients in the young
plants and to examine how the requirements
were affected by the amount of N fertilizer
applied. Plants were excavated, separated
into relevant plant parts, and analyzed for
nutrients on six key dates from leafbudbreak
immediately after planting to the first fruit
harvest the next year.
one row ofl2 plants. The N fertilizer used was
granular ammonium sulfate (2IN-OP-OK).
Three equal applications of the fertilizer were
sprinkled around the base of the plants each
spring at a total rate equivalent to 0 (no
additional fertilizer N), 50, or 100 kg·ha- ' N
per year. A fourth set of plants was fertilized at
a rate of ISO kg·ha- ' N but was not used in the
present study as a result of severe problems in
the treatment with salt injury and plant death
---e. o·
A
Materials and Methods
(Bafiados et aI., 2012). The fertilizer was
applied on 11 Apr., 20 May, and 27 June in
2002 (Year I) and on 24 Mar., 8 Apr., and 23
June in 2003 (Year 2). Each plant was also
fertilized with 35 kg·ha- ' P and 66 kg·ha- ' K
each spring. Plants were winter-pruned in Feb.
2003 and lightly cropped the second year after
planting.
One randomly selected plant from each
treatment plot was excavated and sampled
Year 1
Year2
B
3.5
N rate (N)
3.0
Year 1"
Year 2·
N rate (N)
Year 1"
NS
Year 2
0.16
YxN'·
0.14
~
0.12
~
YxN**
Two-year-old 'Bluecrop' blueberry plants
were obtained from a commercial nursery
(Fall Creek Farm & Nursery, Lowell, OR)
and transplanted on 27 Mar. 2002 to a field
located at the North Willamette Research and
Extension Center in Aurora, OR. The plants
were delivered from the nursery in 4-L pots
filled with a mix of peat, bark, and pumice.
Both roots and the soil mix were placed in the
planting hole and packed firmly in place with
surrounding soil. Soil at the site was a Quantama fine loam (mixed, mesic Aquatic Haploxeralfs) with a pH 5.0 and 3.0% organic
matter content. The soil was amended before
planting with a 10-cm deep layer of Douglas
fir (Pseudotsuga menziesii Franco) sawdust
and 66 kg·ha- ' ofN [2IN-OP-OK ~hS04].
The sawdust and fertilizer was incorporated
0.2 m deep by cultivation in ~ I-m wide strips
to form five 50-m-Iong rows of planting beds.
Plants were spaced 1.2 m apart within rows and
3.0 m apart between rows (equal to a density of
2778 plantslha). Grass alleyways (1.1 m wide)
were planted and maintained between the
rows. The field was irrigated as needed (~25
to 38 mmlweek) from May to September each
year using overhead sprinklers.
Three N fertilizer treatments were applied
to plants during the first 2 years after planting.
The treatments were arranged in a randomized
complete block design with three replicates
per treatment. Each treatment plot consisted of
z
.,
2.5
0·······
"Cii
-'
Q
2.0
.. ~
0.10
1.5
1.0
'--'----~_ _ _.>_..1
c
1.0
~
L-..------'----L-l0.08
D
N rate (N)
Year 1'·
Year 2 NS
0.40
N rate (N)
NS
Year 1
Year 2 NS
YxN NS
~
0.8
0.35
l>
YxN'
0.30 !!l.
;s::
....
'"
~
0.25
co
~
0.20
0.6
0.15
0.4
'-'----~--_--'-..J
E
0.8
iii
-
0.6
'--'-----'-----~
N rate (N)
Year 1"
Year 2'
YxN NS
YxN NS
1200
.1:'L ....
...
~
'"
l>
900
rJ)
~
0.10
F
N rate (N)
Year l'
Year 2·
!!l.
;s::
:J
0.4
600
0.2
0.0 ~---~---~.J
G
~
'--'-----~---~o
H
600
N rate (N)
Year 1NS
Year2 NS
500
YxN NS
40
300
0·············
2····
l>
~
."
400
20
~
300
100
Received for publication 27 Feb. 2012. Accepted
for publication 14 May 2012.
We thank G. Buller, H. Rempel, and M. Resendes
for technical support and acknowledge financial
support from the Oregon Blueberry Commission
and the Northwest Center for Small Fruits Research.
Mention of a trademark, proprietary product, or
vendor does not constitute a guarantee or warranty
of the product by the U.S. Dept. of Agriculture or
Oregon State University and does not imply its
approval to the exclusion of other products or
vendors that also may be suitable.
I Research horticulturist.
lProf;:ssor and berry crop extension specialist.
'Former PhD graduate student. Department of
Horticulture, Oregon State University.
'To whom reprint requests should be addressed;
e-mail david.bryla@;ars.usda.gov.
!!l.
CIl
~
5-
200
o~------~----~
o
50
100
N fertilizer rate (k ·h -')
9 a
'--'--------~------~~100
a
50
100
N fertilizer rate (kg·ha·')
Fig. 1. Leaf (A) nitrogen (N), (B) phos horus
.
(F) manganese (Mn) (G) boron (Bf d (ii): (C) calcIUm (Ca), (D) magnesium (Mg), (E) sulfur (5).
'B!uecrop' blueben; during the
::d ) Iron (Fe) concentrations in response to N fertil!zer rate I~
eac
spnng \~ith 0, 50, or 100 kg.ha-' N and Ithe second year after planting. The plants were fertlhzed 3
(Year 2). Results from individual d eab~es were collected 24 July 2002 (Year I) and 25 July 200_
. .
an com med
I' f
.
* .. -f
nonslgmficant and significant at P <: 0 05
ana YSls 0 vanance are inset in each graph: 1'S"
three replicates and error bars
- . and 0.01, respectively. Each symbol represents the mean 0
represent ± I SE.
firs;
918
HORTSCIENCE VOL.
47(7) JULY 2012
~
destructively on six key dates: leaf budbreak
(29 Apr. 2002), late July when leaf sampling
is recommended for nutrient analysis (24 July
2002; see Hart et aI., 2006), and just before
leaf abscission (29 Oct. 2002) in Year 1; and
just before winter pruning (7 Feb. 2003), leaf
budbreak (22 Apr. 2003), and late July when
fruit were first harvested (25 July 2003) in
Year 2. Each plant was dug up from the entire
width of the planting bed to a depth of 0.3 m
to recover as much of the root system as
possible. Roots were washed after digging to
remove the soil, and the plants were partitioned into new shoots, leaves, flowers and
fruit (Year 2 only), l-year-old wood, 2-yearold wood (Year 2 only), the crown, and roots.
Each part was then oven-dried at 70°C, and
dry weights were recorded after the samples
reached a constant weight. New shoots and
l-year-old wood produced in 2002 were reclassified as 1- and 2-year-old wood, respectively,
in Feb. 2003.
All dried plant parts were ground to pass
through a 40-mesh (425-llm) screen and analyzed for N using a combustion analyzer (CN2000; Leco Inc., St. Louis, MO) and for P, K,
Ca, Mg, S, Fe, B, Cu, Mn, and Zn using
inductively coupled plasma--optical emission
spectroscopy (Optima 3000DV; Perkin Elmer,
Wellesley, MA) after acid-digestion (Jones and
Case, 1990). Fruit samples were analyzed for
N but were unavailable for analysis of other
nutrients, and root samples were not analyzed
for Fe as a result of potential issues with soil
contamination.
Data were analyzed by analysis of variance using SAS Version 9.2 software (SAS
Institute, Cary, NC) and square-root transfonned when needed as determined by the
heterogeneity of variance. Any transfonned
data were back-transformed for presentation.
Means were separated at the 0.05 level using
Duncan's new multiple range test.
Results and Discussion
Leaf nutrient status. The concentration of
N in leaf samples taken in late July increased
with N fertilizer application as has been
shown by others in northern highbush
(Ballinger and Kushman, 1966; Bishop
et ai., 1971; Cummings, 1978; Cummings
et a\., 1971) and rabbiteye (V. virga tum Ait.)
(Spiers, 1983) blueberry. The leafN concentrations in this study, however, were higher
than what is considered normal (1.76% to
2.00%; Hart et aI., 2006) for northern highbush blueberry in Oregon, especially during
the first year after planting when levels averaged 2.82% in plants fertilized with 50 kg·ha-'
Nand 3.48% in those fertilized with 100
kg·ha- ' N (Fig. lA). By the second year, leaf
N concentrations were lower in N-fertilized
plants but again were still higher than nonnal,
a~eraging 2.23% with 50 kg·ha- ' Nand 2.57%
With 100 kg·ha- ' N. Without N fertilizer, leaf
N concentrations averaged only 1.42% the
first year after planting but increased to 1.76%
the second year. It is possible that current
recommendations for sufficiency of leaf N
concentration (Hart et at., 2006), generally
HORTSCIENCE VOL.
47(7) JULY 2012
used for producing plants, may need to be
increased for young, establishing plants. Leaf
N concentration has been shown to decrease
with planting age (Cummings, 1978).
The concentration of several other leaf
nutrients also increased significantly with N
fertilizer application, including P and Ca during
the first year after planting (Fig. 1B-C), Mg
during the second year after planting (P < 0.10;
Fig. ID), and Sand Mn during both the first and
the second year after planting (Fig. IE-F).
Others have found little effect of N fertilizer
rate on leaf P (Ballinger and Kushman, 1966;
Bishop et a!., 1971; Cummings et a!., 1971) in
establishing northern highbush blueberry, although variability in response has differed with
site (Cummings et aI., 1971). The effect ofN
fertilization on leafCa has likewise been sho\\TI
•
0 kg·ha·'
-0- 50 kg·ha·'
-.....- 100 kgha·'
~
:e-
A
180
~ 150
~
~
I
I
r"
Nxr**
~ 120
"0
a
p
Year 1
NNS
I
I
90
I
1;;
~
o/!
(5
0
.s::
0
60
I
30
I
I.
a
I.
I
a
Year2
0
~
I
I
r"
NxP*
I
•
I"
b
I
I
b
I
•
I
c
I
I
/
(/J
0
~
C
120
80
40
~
20
0
0
/
i
/
I
/
I
60
~
"0
-0
I
Pruned
T**
NxT**
.9
E
p
NNS
III
:e- 100
~
a
B
/
b
I
b
a
'E
III
60
C
NNS
:e-
50
~
40
E
30
.9
'"
~
"0
C
;:
e
()
.1
T**
NS
NxT
I
I
P
I
•
20
10
0
0
'E
200
c.
'"
~150
N**
r**
NxT**
"
::::
'"
E 100
~
"0
'0
0
a:
50
0
Apr.
July
Oct.
Jan.
Apr.
JUly
2002·2003
.
new shoots and leaves, (B) woody stems, (e) crown, and (D) roots of :Bluecrop·
Fig. 2. Dry weIght of (A)Ii (2002) and second (2003) year after planting. The plants were fertIlIzed each
blueberry dunng the rst ha- 1 •
(N) and pruned 7 Feb. 2003. Results from two-way anal}sls
spring. with 0, 50, or IO~ k.~e m:gi~se~ in each graph: NS, ., •• = nonsignifi~nt and significant at
ofvanance [N rate (i\) t1 .. I<DLch SYmbol represents the mean of three rephcatcs; means Without
p ~ 0.05 and 0.01, respecltne y.
ive~ date are not significantly different at the 5% level (Duncan·s
letters or with a common etter on a g
new multiple range test).
919
to vary by site as well as cultivar within a region
(Cwnmings et aI., 1971). Bishop et al. (1971)
and Ballinger and Kushman (1966) found that
Ca decreased with increasing N rates in mature
'Bluecrop' and 'Wolcott' blueberry, whereas
Cummings (1978) reported little effect of N
rate on leaf Ca in the first growing season and a
decrease \\ith N rate in the second year. Leaf
Mg was affected little by N rate in our study,
as has been reported by others (Ballinger and
Kushman, 1966; Bishopetal., 1971; Cummings
et aI., 1971). LeaH,tn concentration increased
with N fertilization. which was likely related to
a decline in soil pH (Baiiados et aI., 2012). also
observed by Townsend (1973) in a 6-year study
in 'Blueray' blueberry.
In general. P and S concentrations were
lower in the N-fertilized plants in the second
year than they were in the first, declining by
an average of 0.4 to 0.5 mg'g-' and 0.8 to 2.6
mg.g", respectively, whereas Ca, Mg, and
Mn concentrations were higher the second
year after planting, increasing by an average
of 1.3 to 1.4 mg·g", 1.3 to 1.6 mgK', and
468 to 564 IlgK', respectively. An increase
in leaf Mg. Ca, and Mn over time has been
reported by others (Cwnmings, 1978; Townsend,
1973). In our study, only leaf P and Ca concentrations were within the range each year
considered optimum for blueberry (i.e., 0.10%
to 0.40% for P and 0.41 % to 0.80% for Ca;
Hart et aI., 2006), and this was the case
whether plants were fertilized with N or not.
LeafMg and Mn concentrations, on the other
hand, were higher than recommended (i.e.,
0.13% to 0.25% for Mg and 30 to 350 Ilg·g"
for Mn; Hart et aI., 2006) the second year
after planting, regardless ofN treatment, and
leaf S concentrations were higher than recommended (0.11% to 0.16%; Hart et aI.,
2006) in both years but only when N fertilizer
was applied [as (NH 4hS04].
Leaf B concentration was also significantly affected by N fertilizer application,
but in this case, the response differed between
years (P < 0.05; Fig. IG). In the first year
after planting, leaf B concentrations increased from 48 Ilg·g" without N fertilizer
to 62Ilg'g-' with 50 kg·ha" Nand 59 Ilg'g"
with 100 kg·ha" N. The next year, the opposite was true, and leaf B decreased from
in blueberry has been previously reported
(Cummings, 1978).
Most DW accumulated in new shoots
leaves, and roots in both years (Fig. 2) a~
well as in fruit the second year (Table I). The
total of these parts combined represented
76% to 80% of the total DW by the end of
the first season and 71% to 75% by fruit
harvest of the second season. New shoot and
leaf DW was much higher each year with N
fertilizer (Fig. 2A), whereas root DW was
only higher at harvest and only when 50
kg·ha" N was applied (Fig. 2D). Application
of 50 kg·ha-' N also increased DW of woody
stems by fruit harvest (Fig. 2B), but neither
50 nor 100 kg·ha" N had any significant
effect on crown (Fig. 2C) or flower and fruit
DW (Table I). Not surprisingly, unfertilized
plants allocated relatively more biomass to
roots and less biomass to shoots than fertilized plants, but only during the first growing
season. By the end of the first year, the rootto-shoot ratio in unfertilized plants averaged
0.85 g of root DW per gram of shoot DW
(including all aboveground parts plus the
crown), whereas in plants fertilized with 50
and 100 kg·ha" N, the ratio averaged 0.61
and 0.48 g.g", respectively. By contrast, the
second year, the ratio was similar among
treatments, averaging 0.34 to 0.39 g-g" at
fruit harvest. Root-to-shoot ratios often decline with N fertilizer application and plant
Accumulation and partitioning of plant age (Gregory, 2006); however, excavation of
biomass. Plants fertilized with 50 kg·ha" N the root system also becomes more difficult as
were the largest among the three N treatments the plants grow and mature. Such difficulty
and, by the end of the first growing season, likely reduced the percentage of roots recovproduced 0.36 kg of total DW and weighed ered in the present study and perhaps partlY
22% more than plants fertilized with 100 accounted for the lower root-to-shoot ratios
kg·ha-' N and 32% more than unfertilized and the lack of treatment differences observed
plants. By fruit harvest the next season the during the second year after planting.
difference was even greater as plants' ferThree major losses of DW occurred durtilized with 50 kg·ha" N averaged 0.70 kg ing the first 2 years after planting. The first
of total DW per plant, whereas those with was at leaf abscission in early to mid-Nov.
100 kg·ha" N or no fertilizer averaged only 2002. Leaf abscission resulted in a net loss of
0.~9 and 0.37. k~plant, respectively. Clearly, 43 g of DW or 16% of the total biomass in
SOli N was lImIted at the site, but adding unfertilized plants, 92 g or 25% of the total
~ 00 kg'h~" N was excessive for this plant- biomass in plants fertilized with 50 kg·ha" N,
mg denSIty and resulted in reduced plant and 86 g or 29% of the total biomass in pla.nts
gro\~h [see Baiiados et al. (2012) for further fertilized with 100 kg·ha-' N. At this pomt,
detaIls and additional harvest dates]. Re- fertilization with more N resulted in a greater
duced gro\\1h with excessive N fertilization allocation of biomass to leaves and therefore
68Ilg·g" with no N to 30 Ilg·g" with 50 kg·ha-'
Nand 28 IlgK' with 100 kg·ha-' N. LeafB
was not deficient (less than 20 Ilg·g") in
either year, whether plants were fertilized
with N or not, but levels were slightly less
than optimum (i.e., 31 to 80 IlgK'; Hart
et aI., 2006) the second year after planting
when N fertilizer was added.
Leaf concentrations of the remaining
nutrients, including K, Fe, Cu, and In, were
unaffected by N fertilizer application and,
with the exception of Fe (Fig. IH), remained
more or less the same during the first 2 years
after planting. LeafK concentration averaged
0.78% over each treatment and year, and leaf
Fe, Cu, and In concentrations averaged 333,
5, and 9 Ilg'g-', respectively. Both Cu and In
were within a range considered adequate for
these nutrients (5 to 15Ilg'g" for Cu and 8 to
30 for IlgK' for In; Hart et aI., 2006),
whereas K and Fe were higher than adequate
(i.e., 0.41% to 0.70% for K and 61 to 200
Ilg·g" for Fe; Hart et aI., 2006). Although
others have reported an increase in leaf K
concentration with N fertilization in highbush blueberry (Bishop et aI., 1971; Cwnmiogs,
1978; Cwnmiogs etaI., 1971; Townsend, 1973)
and an increase in leaf K as plants aged
(Cummings, 1978), fluctuations in leafK are
often associated with fruiting; these plants
produced no fruit in Year I and only a small
crop in Year 2.
Table I. Effects of nitrogen (N) fertilizer rate on flower and fruit dry weight and macro- and m'
t' .
.
dyear
after planting.'
Icronu nent content m 'Bluecrop' blueberry dunng the secon
N rate (kg-ha")
Flowers
0
50
100
Significance'
Dry
\\1
(g/plant)
4.1
4.2
3.1
1'>S
N
Macronutrient content (g/plant)
Phosphorus Potassium Calcium Magnesium
0.13
0.21
0.16
0.02
0.03
0.02
0.06
0.08
0.06
0.02
0.02
1'>S
1'>S
NS
NS
om
Micronutrient content (mg/plant) _
Boron Copper Manganese _~
Sifu
u r
Iron
om
0.01
0.02
0.01
0.8
1.4
1.0
0.4
0.2
NS
NS
NS
0.01
O.QI
OJ
0.2
0.1
0.1
1.1
3.9
2.7
NS
NS
NS
OJ
OJ
0.2
ss
Fruit'
116
0.88
0.10
0
0.80
0.05
0.04
0.7
0.08
3.8
4.2
0.9
2.34
171
0.3
0.15
50
1.19
0.07
0.Q7
1.0
0.12
5.6
6.1
1.4
0.88
55
0.05
0.4
100
0.37
0.02
0.02
OJ
0.04
1.7
\.9
0.4
Significance'
~
0.1
'Flowers were collected on 22. Apr. 2003, and fruit were harvested on 25 July 2003.
'Results from one-way analYSIS ofvanance: NS and § = nonsignificant and P < 0.10 res t' I
.
' content except N
. the average of2 years of data 'collect
pec dIve
'All fruit
nutnent
I
was ca Icu Iate d usmg
f iY
'
,
.
d
rom
200 kg·ha" N (unpublished results). The plants were growing at the same site and sampl de th
mature Bluecrop' plants fertilized each yearWlth 0, lQO,an
e
e same years as those used m
. the present study.
920
HORTSCIENCE VOL. 47(7) JULY
2012
a relatively greater loss of total biomass at
leaf abscission. The next loss of OW occurred
during winter pruning in which 28 g of wood
was removed from unfertilized plants, but
only 9 and 4 g of wood were removed from
plants fertilized with 50 and 100 kg·ha- 1 N,
respectively. Unfertilized plants required
more pruning than fertilized plants because
this treatment had a lot of weak and twiggy
wood. Twiggy wood typically has thinner
and shorter new growth and produces small
berries and therefore is often removed during
pruning (Strik et aI., 1993). The final loss of
OW occurred at harvest when an average of
55 to 171 g of fruit per plant was picked
(Table 1). Although production was variable,
plants fertilized with 50 kg·ha- 1 N tended to
produce more fruit than those fertilized with
100 kg·ha- I N. Plants also lost a small amount
of DW (less than 3 to 4 g/plant) at fruit set as
the flower petals senesced (Table I).
Accllmlilation and partitioning ofnlltrit'lIIs.
In most cases, nutrient content in each plant
part followed the same pattern of accumulation as ow (Figs. 3 to 6). Thus. many differences among N treatments were similar.
For example, nutrient content in new shoots
...•
0 kg'ha-' N
--0- 50 kg'ha-' N
-...- 100 kgha" N
'E
rn
a.
:§
z
A
Year 1
3
N'
T"
NxT"
iii
2
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B
4
Year 2
Year 1
~
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o
"a
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// a
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r:rT"
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ta
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•
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fi .'
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;,
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TNxT-
0.0
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00
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/56
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or
(J)
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?
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b
Year 2
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a
a
(f)
I
N'
N"
T"
NxT"
00
I
!.
~
10
0.4
I
Year 1
Year 2
;:r
0.6
1a
H
G
(f)
a
Year 2
a
0.0
rn
a
Year 1
Year 2
Year 1
en
'E
~
0.0
0.0
'Ern
::!.
~
0
I
I
1
. b
•
/,
h
/.
~
T"
NxT"
NxT-
0.05
~
a
0.00
Year 2
T"
1
1 a
1
1
1
/
NxT"
•
/
/.
0.15
0.10
/
o
a
})
Year 1
p
/
020
/ a
/
0
1.4
a
N'
T"
NxT'
.-0
a
en
Year 2
~
/
I
/
•b
CIl
4
,t!
'3
<fl.
2
/,
/
a
"C
/if
.5
0
0
a
'E
rn
~
E.
Year 1
120
N'
T"
NxT-
c
~
'lii
2
""-0
0
.s::
90
I
/.
,$
/.
.b
July
I
I
I
I.
b
•
Oct
Jan_
Apr.
Year 2
T"
N"
T"
NxT'
/
I
..- ,0 a
Year 1
~
/a
I
a
a ,
30
0
Apr.
N"
T"
NxTI
60
en
I
Year 2
(J)
J
0
150
p-:/ •
/.
b
•
/,
Apr.
I
la
f
I.
/
July
a
/,
Oct
July
Jan.
~
2.0
""
Apr.
1.5
1.0
b
::r
2.5
})
0.5
1D
~
N
::>
'3
'"-0or
~
00
July
2002-2003
.
2002-2003
.
Fig. 3. New shoot and leaf A) nitrogen (N), (B) phosphorus.(Pl· (C) po~s~;~:;~
K
D
I'urn (Ca) (E) magnesium (Mg). (F) sulfur (S). (G) Iron (Fe). (HI
first (2(io2) and the se.cond (2003)year ?fter planting:
)'JuJn~~~
The.pl;~~
~oronf,(8~, .(1) mangane~~ (M?), and~ z;n~o(~;.~~~~~~':s!~u::~Ptwo-way~alysis o~\':::~~~:e~~;a:~~e~~~:~ i~~~~tl~~:~~::~~h :~o~mon
J)
n:re. er.tfilhzed each.sp,:,ng with ~ ~ ~~ and 001 respectively. Each symbo! represen~tt. ~ range test) Shoot and leaf copper (Cu) content increased to an
nSlgnl cant and Significant at - .
. - , t th 50!. )evel (Duncan s new mu Ip e
.
letter on a given date are not significantly ddfen:nt ~ e b~ was unaffected either year by Nor N x T.
2
average of 0.6 g/plant in Year I and 0.7 glplant III ear
921
0
HORTSCIENCE VOL.
47(7) JULY 2012
lEaLI
content when no fertilizer was applied (Figs.
4C, 4H, and 41). In addition, the content of
several nutrients in the crown differed among
N treatments, in which N, P, S, and Zn content
was higher at times with N fertilizer (Figs. 5A,
5B, 5F, and 5J), whereas K and Ca content was
sometimes lower (Fig. 5C-O). Basically, differences in root N, P, K, Mg, S, Cu, and Mn
content were similar to differences in root
3J), largely as a result of a higher concentration of each in unfertilized plants (P :::; 0.05).
Another exception was that wood Nand S
content was higher in fertilized plants much
earlier than OW, and this occurred whether 50
or 100 kg·ha- 1 N was applied (Figs. 4A and
4F). Wood K, Cu, and Mn content also
differed among treatments before harvest
and, in one instance, wood had a higher Cu
and leaves was generally higher each year in
fertilized plants than in unfertilized plants
(Fig. 3). Likewise, like with OW, the content
of many nutrients in wood and roots was often
highest in fertilized plants (Figs. 4 and 6).
However, there were a number of exceptions.
New shoot and leafMg, Fe, and Zn contents,
for example, were similar among treatments
the first year after planting (Figs. 3E, 3G, and
...
o
kgha" N
-D- 50 kg·ha" N
- y - 100 kg·ha" N
c
!!l
"'-
~
1.2
0.9
Pruned
A
N"
T"
NxT-
a
0
0
~
0.6
0.3
b
0.0
0.30
C 0,25
'"
~
Ci
~
-0
0
0
~
0.20
..
b
•
Pruned
0.12
t
a
./
..
Z
-0
B
N'
T"
NxT'
t
./
./
•
•c
...
-D
b
C
.
9
Pruned
N-
t
r'
NxT"
/
/ ab
,
a
...
a
/
•
l·
~ ..
'\ ..
I.e
'\
\-,
l
D
N'
T"
NxT NS
..
b
{
t..
::;:
'" 0.03
-0
0
0
~
0.02
€
0.04
iil
i':
-0
0.02
0.25
0.20
~
8.
(')
/,
0.15 '"
/-
<0
h
0.10
0.05
0,00
0,04
0.06
Pruned
0.05
~
0
0.00
0.10
0.06
~
0.08 ~
b
a
0,15
C
!!l 0.05
0.10
~
i':
0.00
Pruned
E
F
t
NNS
•
T"
NxT-
........•
•
•
0.01
Pruned
0.12
a
-
,,9
_~//
b
a
•
~
g
a.
0.095!!
/
/
/0
.....•..........
0,00
0.15
a
a
b
,9
t
N"
TNxT"
co
-0-
..
a
•
b
b
0.06 iil
•c
b
i':
0.03
0.00
2.5
C
'"
Ci
0,
£
2.0
G
H
NNS
NNS
T"
NxT NS
Pruned
t
}J-.,
1.5
CD
-0
0
0
~
1.0
I.
&
..
•
TNxT-
Pruned
t
12
a
•
a
/0
/:. .e_ ........
0.5
_-0
,/
..
b
0.0
b
~
10
0
0
8
C
6
4
2
a.
(')
3'
co
-0iil
:>
.0
0
a
C
80
!!l
a.
0,
60
£
o
,,
NTNxT'
Pruned
ta
40
/
20
//
A
•
.......
ab.....
I
/
/
/
,
J
Pruned
t
0
I
b
I
l-
•
··b
I
•
2.5
~
2,0
"'-
1.5
3'
0
1.0
b··.
0.5
July
Oct
Jan.
Apr.
July
0
N
:>
ce.
-0
iii'
E:
AP;r.~~J-;:-u:;:-Iy-:-~o~c'::t~,~-:-JaJ..n-,~---,-~~-,-...J 0.0
Apr.
2002-2003
July
2002-2003
Fig, 4. Woody stem (Al nitrogen (N), (B) phosphorus (p), (C) potassium (K) (D) I'
(Cu,l., (I) manganese (Mn). and (J) zinc (Zn) content in 'B\uecrop' bluebe~ d:n~l~~ (Ca), (El magnesium (Mg), (F) sulfur (S), (G) boron (B), (D) copper
fertlhzed each spnng WIth 0,50, or 100 kg·ha- ' N. Results from two-wa
I ':
first.(2002) and the second (2003) year after planting. Theplant5 \\ere
" f icant an d'
Y ana YS1S of vanance [N rate (N) x time (1)] are inset in each graph: NS, • ' ., '"
nonslgm
slgm'ficant at P --< 00. ) an dO .01, respectively. Each symbol
Ietter on a given
.
date are not slgm
' .ficantIy d'Iflierent at the 5% level (Duncan's
.
represents the meano fthree replicates; means without letters or with a coromon
new'
but was unaffected by Nor N x T.
multiple range test). Wood iron (Fe) content ranged from 4 to 17 mglplant
922
HORTSCIENCE VOL.
47(7) JULY 20P~
..•
0 kg·ha-' N
--0- 50 kgha-' N
1.:-_____---:-____----'Y-_~100 kg·ha-' N
0.7
~---------------
A
a
:g
0.6
N'
0.
'"
0.5
NxT'
z
0.4
~
0.3
E?
c
~
B
a
P'
..
a
/
....
0.2
.............•
a
7
•
b
b
0.14
0.12
:e-'" 0.10
~
'"
~
0.04
~
0.00
D
C
NNS
T"
NxT'
N'
P'
NxT"
a
•
0
/
r-..
0.06
0.04
0.02
n
a
0.05
'\.
...
.
... ~
6
0.08
~ 0.06
~
:>
0.02
00
:g
n
0.08 ~
0.062'
b
0.1
0.10
~
0.04 n
OJ
0.03 iO
-0
0.02 ~
0.01
~~~~-'---'~---'-~-'---~-'--.....J 0.00
_ 0.05
c:
~ 0.04
E?
.. ..
NNS
T-
NxT NS
./
/
...
~ 0.02
e
u 0.01
<II
~
1.5
1.2
§. 0.9
C
e
u
NxT"
/
"a
....
•
H
G
P'
:>
0.06~
0.04
'"~
NS
-.""'/
e
~
3 (')
c
2 ]'
-0
0.6
ii>
:>
•
....
0--"-
0_3
.a
4 n
NNS
TNS
NxT
NNS
NxT
(')
0.08 ~
b
0.02
b
'--"-~J-~-L~~'---'-~--'--~-'------J 0.00
ID
~
0.10
a
T-
p
~ 0.03
:g
F
N'
E
.e
0.0
J
:g
30
<II
E-
25
P'
§.
20
NxT
O)
c
:::;
NNS
NS
'/
V
15
'P
•
~
7
6
/,a
7
a
..
c
U
a
0
(')
N'
TNxT'
10
5
4
•
b
3
2
~:>
N
:>
'3
~OJ
~
b
5
0
July
Oct
Jan.
Apr.
2002-2003
July
Apr_
July
Oct
Apr.
Jan.
July
2002·2003
r 19.~. Crown (A) nitrogen ~, (8) phosphorus (P), (C) potassium (K), (D) calcium (Ca), (E) magnesium (Mg), (f) sulfur (S), (~) boron (B). (II) copper (Cu)' (ll
angan~se (Mn), and (J) Zinc (Zn) content in 'Bluecrop' blueberry during the first (2002) and the second (2003) year after planll1lg. The plant~ were fertilized each
~~g WIth 0,50, or 100 ~.ha-l N. Results from two-way analysis ofvariance ~ rate (N) x time (1)] are inset in.each graph: NS, ., •• ~ ~ignificant and significant at
di - 0.05 and 0.01, respectively. Each symbol represents the mean of three replicates; means "lthout letters or Wlth a common letter on a given date are not significantly
fferent at IDe 5% level (Duncan's new multiple range test). Crown iron (Fe) content ranged from 3 to 29 mg/plant but was unaffected by Nor Nx T.
DW, although sometimes the differences occurred in the 50 and 100 kg·ha- 1 N treatments
anfted, unlike root DW usually occurred more
o ntha .
6F
6H, nJust at fruit 'harvest (Figs. 6A-C, 6E,
,
and 61)
The conten~ of many nutrients in the
Woody
.
(29 0 stems lIlcreased
over fall and winter
.
ct. 2002 to 7 Feb 2003' Fig 4A-J) The
IDcreasf
.,.'
tre trn eoN, P, K, and Mg in almost all
a ents from fall to late winter may have
been a result of remobilization of nutrients
from senescing leaves or additional plant
uptake during this time period. Copper
content likely increased as a result of a
copper sulfate fungicide (see subsequently).
The content of Ca in the woody stems
increased over fall/winter; because this nutrient is not mobile, it is unlikely this increase
was from remobiIization before leaf abscission. In the crown tissues, only N, P, and K
content in the unfertilized plants increased
over winter, perhaps a result of added nutrient
uptake during this period. In the roots, N
content increased in the unfertilized plants
and P in those fertilized with 100 kg·ha- ' N,
perhaps a result of the lower soil pH in this
treatment (Baiiados et al., 2012). which would
have increased availability of soil P. Losses in
nutrient content over this time period may
have been caused by a reduction in efficiency
923
HORTSCIENCE
VOL. 47(7) JULY 2012
•
0 kg'ha- 1 N
-{)- 50 kg'ha- 1 N
-...- 100 kg'ha- 1 N
A
1::
3
m
a.
:§
z
a
N"
P"
/
/
~<
1)
0.15
b
/
I.
•
•
/
b
b
/.
0
0.5
1::
m
a.
:§
><:
(5
a
rx:
0.4
;0
/
/
/
/
....... ~---
0.25
0.20 ~
/
/
a
(5
/
NxT"
/
2
0
TO>
/ a
NxT""
rx:
o
~--------------I
B
a
P
N'
<0
-0
0.10 ~
c
0.05
0.00
a
C
D
N'
o
/
N"
T"'
NxT'
I
T"
/
/
/ .• -- .>......,
• 1
NS
."
I
b
/
.....
......... . . .
/.
0.1
1.2
;0
0
1.0
.,(')
0.8
0---"9-..
b
/
I'
0.2
NxT
/
r,
0.3
1.4
.....
0-- •.
~
0.6
<0
-0
0.4
c"
or
0.2
0.0
0.5
'E
-[
0.4
:§
'"
:2
g
0.0
E
N"
F
NO.
a
T"
NxT'
/
fa
/
NxT"
a
/
0.3
0.8
a
T"
?
a
/
/
0.2
/
rx:
....
b
0.1
c
'"
a.
en
.s
ttl
(5
4
:::J
c
•
b
0.2
0.0
H
NNS
NNS
TO>
3
C/l
or
/
/,
t
~
2-
<0
0.4 -0
/
b
G
;0
0
0.6
o
NS
NxT
NxP'
J.
2
/,
a
a
p
T"
I
I
•
rx:
0
2-
6
'3
<0
4
•
•
b
b
::0
8
()
c
I
i·
10
-0
or
:::J
2
c
0
150
C
a.
'"
en
120
.sc
90
(5
60
:2
J
N"
T""
NxT"
I
0
rx:
lab
I
30
•
b
0
Apr.
I
a
A,
July
Oct
,
,
2002-2003
a
0
15
b
6
3
Apr.
July
2N
:::J
9
I
I
::0
a
12
I
..
Jan.
NNS
T"
NxT NS
Apr.
July
Oct
Jan.
Apr.
'3
<0
-0
or
Eo
0
July
2002-2003
Fig. 6. Root (A) nitrogen (N), ~B) phosphorus (P): (C) potas,sium (K), (D) ~alcium (Ca), (E) magnesium (Mg), (F) sulfur (S), (G) boron (B), (H) copper (CW~~J
manganese (Mn), and (J) zmc (Zn) content
m Bluecrop blueberry dunng the first (2002) and the second (2003) year after planting. The plants were .fe~
t
I
each-spring with 0,50, or 100 kg·ha- N. Results from two-way analysis of variance [N rate (N) x time (1)] are inset in each graph: NS, *, ** =
and significant at P ~ 0.05 and 0.0 I, respectIvely. Each symbol represents the mean of three replicates; means without letters or with a common Ie e
a give~ date are not significantly different at the 5% level (Duncan's new multiple range test).
nonslgn~fi~~n
of harvesting the entire root system as plants
1
aged.
Like DW, plants fertilized with 50 kg·haN tended to have a higher fruit N content
(Table I). As mentioned earlier, other fruit
nutrients were not measured, but measurements
done on fruit from mature 'B1uecrop' plants
gro\\ing at the same site an~ f~ilized with 0,
I
100, and 200 ka·haN indIcated
:;,
. that
. N
treatment had no effect on frUIt nutnent
concentrations beyond fruit N [which increased with N fertilization (1.02% to 1.28%
N; Baiiados, 2006), as previously reported by
others (Ballinger and Kushman, 1966; Bishop
et aI., 1971)]. In this case, fruit averaged O.W/o
P, 0.69% K, 0.04% Ca and Mg, 0.07% S, 33
I1g-g-1 Fe, 8 I1g'g- 1 B,2 Jlg.g-I Cu, 36 I1g-g-1
1
Mn, and 6I1g'g- Zn (Strik et aI., unpublished
data). Assuming nutrient concentrations were
similar in the present study, the fruit would
have contained 0.9 to 2.3 g/plant 0 fN·04to
, p' ell,
1.2 g/plant of K; less than 0.2 g/plant of : and
Mg, and S; 2 to 6 mg/plant of Fe and ~i I)
less than 2 mg/plant ofB, Cu, and Zn (Ta ~ ;
With the exception of Cu, total nu~e~
uptake by the plants increased from n:it
budbreak to leaf abscission (Year I~ O~any
harvest (Year 2) and was higher. m Fig.
cases when plants were fertilized With N ~ IS
7). With N fertilizer, uptake of some nutnen
924
HORTSCIENCE VOL.
47(7)
JULY
2012
...•
0 kgha" N
-()- 50 kgha" N
'E
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8
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r:-__________-_T_- _100 kgha" N
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2002-2003
Apr.
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2002-2003
,g'(i) Total plant (A) nitrogen (N), (B) phosphorus (P), (C) potassium (K), (D) calcium (Ca), (E) magnesium (Mg), (F) sulfur (S), (G) boron (B), (II) copper (Cu).
F'
fe m,anganese (M~), and (J) zinc (Zn) content in 'Bluecrop' blueberry dunng th~ first (2.0.02) and the second(2003) year .after planting. The plants were
n r!tl~ze? each spnn: with .0, 5.0, or 1.0.0 kg.ha- 1 N, Resul~s from two-way analYSIS of vanance [N rate (I") x. tIme (nJ are tnset III each graph: M. *, .. ~
g
I onSlgnlficant and slgmficant at P:=; .0..05 and .0,.01, respectIVely. Each symbol represents the mean of three rephcates; means WIthout letters or with a common
cttcr on a given date are not significantly different at the 5% level (Duncan's new multiple range test).
Such
.
.
y as Ca" S an d B was general1y higher
III
(:ar I at the beginning of the growing season
OcPnl to July) than later in the season (July to
tober), whereas uptake of other nutrients
M
M
.
suchasK,g,
th
n, and
Zn was '
higher later III
e season. However when no N fertilizer
' was limited later in
wasaPP rled, plant growth
th
nu~ .seaso~ (Fig. 2), and uptake of many
nents, Including N P K, Ca S and B
Was
" " ,
Unl~educed, and only Cu uptake was higher.
e other nutrients, Cu uptake also increased
over winter between the first 2 years after
planting, whether N was applied or not (Figs.
4 and 7). The plants were sprayed with copper
sulfate fungicide (Bordeaux) after pruning,
a common practice in blueberry to control
bacterial canker (Strik et aI., 1993).
Loss and net gain of nutrients. Loss and
net gain of nutrients in plants fertilized with
50 kg·ha- ' N are summarized in Table 2.
Total nutrient losses, including leaf abscission, pruning, and fruit harvest, averaged 4.85,
0.28,2.38,0.82,0.25, and 0.54 glplantofN. P,
K Ca, Mg, and S, respectively, and 5U, 5.20,
0.57, 42.4, and \.71 mglplant of Fe, B, Cu.
Mn, and Zn, respectively. At a density of2691
plantslha, each loss was equivalent to 13.1
kg·ha- ' N, 0.8 kg·ha- ' P, 6.4 kg,ha- 1 K, 2.2
kg·ha- 1 Ca, 0.7 kg·ha- 1 Mg, 1.5 kg'ha~l S, 138
g·ha~l Fe, 14 g·ha- 1 B. \.5 g·ha- ' Cll, 114
g.ha- 1 Mn, and 4.6 g·ha- ' Zn. More than half
the N, P, K, Cu, and Zn was removed during
fruit harvest, whereas most Ca, Mg, S, Fe, M;.
925
HORTSClENCE VOL. 47(7)
~
JULY
2012
Table 2. Loss and net gain of macro- and micronutrients in 'Bluecrop' blueberry during the first 2 years after planting.'
Macronutrients (g/plant)
Potassium Calcium Magnesium Sulfur IronY
Micronutrients (mg/plant)
Boron Copper Manganese
Zinc
Loss
0.09
38.2
3.55
0.39
24.1
0.17
0.69
OJI
1.09
Leaf abscission'
0.10
2.18
7.3
0.25
0.03
12.2
0.01
0.06
0.40
0.10
Pruning
0.04
0.33
lAO
5.6
0040
0.12
6.1
0.07
0.07
1.00
Fruit harvest
1.19
2.34
0.15
Gain
2.38
39.2
1.36
0.50
145
0046
ll.8
0.24
0.92
Bud break to leaf abscission (Year I r
0.56
2.55
7.36
6.64
1.16
19.3
285
0.69
lAO
10.5
Bud break to harvest (Year 2)"
0.33
1.69
5.54
'Plants were fertilized each spring with 50 kg·ha- ' nitrogen.
'Net iron gain does not include iron in the roots.
'Estimated from leaves collected on 29 Oct. 2002.
·Calculated as the difference in wood sampled just before pruning (7 Feb. 2003) and wood sampled at budbreak (22 Apr. 2003).
'Calculated as the difference in nutrients of whole plants (minus any leaf nutrients) sampled just before leaf abscission (29 Oct. 2002) and whole plants sampled at
budbreak (29 Apr. 2002).
"Calculated as the difference in nutrients of whole plants (minus any fruit nutrients) sampled at harvest (25 July 2003) and whole plants (minus any flower
nutrients) sampled at budbreak (22 Apr. 2003).
Nitrogen
Phosphorus
om
W
and B was lost during leaf abscission. Although the nutrients in senesced leaves may be
lost from plants in the short term, if leaves
drop into the row, the nutrients would likely be
available to plants again once leaves decompose (Strik et a!., 2006).
The relative losses of nutrients were
similar in plants fertilized with 0 and 100
kg·ha- I N, although unfertilized plants (which
allocated 32% total biomass to fruit) tended to
lose proportionally more nutrients during harvest, whereas plants fertilized with 100 kg·ha- I
(which allocated only 13% total biomass to
fruit) lost most nutrients during leaf abscission (data not shown).
Net nutrient gains averaged 8.09, 0.57,
2.25,2.32, LIS, and 1.66 glplant ofN, P, K,
Ca. Mg, and S, respectively, and 58.5, 9.74,
8.00, 431, and 22.3 mg/plant of Fe (not
including roots), B, Cu, Mn, and Zn, respectively (Table 2). When combined with the
losses, plants fertilized with 50 kg·ha- I N
required the equivalent of 34.8 kg·ha- I N,
2.3 kg·ha- I P, 12.5 kg·ha- I K, 8.4 kg·ha- ' Ca,
3.8 kg·ha- I Mg, 5.9 kg·ha- I S, 295 g·ha- I Fe,
40 g·ha- I B, 23 g·ha- I Cu, 1273 g·ha- I Mn, and
65 g·ha- I Zn over 2 years. Thus, the relative
amount of N, P, and K fertilizer used during
establishment, including the N added during
sawdust incorporation and in the nursery potting media at planting, was 21%, 3%, and 9%,
respectively. Because plants were smaller,
fewer nutrients were required when 0 or 100
kg·ha- I N was applied and therefore percent
fertilizer used in these treatments was even less.
This study has generated the first comprehensive nutrient accumulation data set from
planting to fruit harvest for establishing highbush blueberry. The information was used to
determine nutrient requirements of the young
plants, a useful tool for developing efficient
fertilizer management practices during the
critical stage of field establishment. Plant
uptake of most nutrients increased throughout
the growing season, indicating that it is best to
apply the majority of fertilizers in the spring;
however, K. Mg, Mn, and Zn uptake was
higher later in the season and therefore it may
be better to apply these nutrients, ifneeded., in
early or midsummer. Next, we plan to evaluate
nutrient requirements in relation to N supply
in mature plants.
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roC-
M:
zoo!.
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