INFLUENCE QF WERiENT-ELEMERT SUPPLY ON
LEAF cam-931mm AND GROWTH OF HEGHBUSH
awmm (VACCEREUM coamaosum L.) WITH

SPECIAL REFERENCE TO IMPORTANCE OF
smmm DATE 0N LEAF AND FRUIF commune»:
OF HELD GROWN BLUEBERRIES

 

Thesis for Hm Degree of DH. D.
MECEKGAH STATE UNIVERSITY

Harry James Amling
1958

 

 

FHESIS

 

 

This is to certify that the

thesis entitled

INFLUENCE OF NUTRIENT-ELEMENT SUPPLY ON LEAF COMP$ITION
AND GROWTH OF HIGHBUSH BLUEBERRY (VACCINIUM CORYMBOSUM

L.) WITH SPECIAL REFERENCE TO IMPCRTANCE OF SAMPLING
DATE ON LEAF AND FRUIT COMPCBITION OF FIELD
GROWN BLUEB ES

presente 9

Harry James Amling

has been accepted towards fulfillment
of the requirements for

Doctor's degree in Horticulture

/
. ’_ ," ,~./// ‘ (‘11-.-
fl ’ ' (“£1 ’I’é"“’ 7”)" [1/2 7/
//

Major professor

 

Date November 17, 1958

 

INFLUENCE OF NUTRIENT -ELEMENT SUPPLY ON LEAF COMPOSITION AND

GROWTH OF HIGHBUSH BLUEBERRY (VACCINIUM CORYMBOSUM L.) WITH

 

SPECIAL REFERENCE TO IMPORTANCE OF SAMPLING DATE ON LEAF

AND FRUIT COMPOSITION OF FIELD GROWN BLUEBERRIES

By

HARRY JAMES AMLING

AN ABSTRACT

Submitted to the School for Advanced Graduate Studies of Michigan

Approved

/ ’ .‘
f 7» /' \ L..z--C-c 6 ii ”9;!
_/r ‘ . Z'
J

State University of Agriculture and Applied Science

in partial fulfillment of the requirements
for the degree of

DOCTOR OF PHILOSOPHY

Department of Horticulture

1958

/‘

HARRY JAMES AMLING ABSTRACT - 1

One- and two-year-old rooted cuttings of the highbush blueberry
Vaccinium cogmbosum L. , were grown in quartz sand and in vermiculite
under varied levels of ten nutrient elements. Leaf analyses and plant re-
sponse to treatment in terms of foliar expression, root development and
growth were recorded and discussed. In addition, leaf and fruit samples
were collected biweekly in the summer of 1957 to ascertain seasonal in-
fluence on leaf and fruit composition. Commercial blueberry fields were
also surveyed for nutritional disorders. Leaf analyses, photographic and
descriptive records were collected of the nutritional disorders observed.

In sand culture the leaf content of N, P, K, Mg, Ca, B and Mn
increased as the supply of the element increased. Iron and copper increased
in the leaf only when a high external supply existed. With vermiculite only,
K and B increased in the leaf as the supply of the element increased. Mn,

Fe and. Cu leaf levels increased only when solutions containing high levels of
the elements were used.

Numerous nutrient interrelations became apparent when the concen-
tration of particular nutrient elements in solution were varied. The more
prominent relationships are as follows: (1) As the supply of nitrogen increased,
all elements except phosphorus decreased in the leaf. (2) A shortage or ex-
cess of phosphorus decreased the nitrogen level in the leaf. (3) As the supply

of potassium or magnesium increased from 0 ppm to 30 ppm or 24 ppm,

HARRY JAMES AMLING ABSTRACT - 2
respectively, the antagonistic influence of potassium on the uptake of magnes-
ium was equal in severity to the reciptoval antagonism exerted by magnesium
on potassium uptake. With further increases in the supply of these two ele-
ments, the antagonistic influence of potassium on magnesium uptake was less
severe than the reciprocal antagonism of magnesium on potassium uptake.

(4) Iron showed a strong antagonistic influence on the uptake of manganese.
Manganese did not exhibit a reciprocal relationship on iron. (5) A low level
of any one of the major elements in solution resulted in a high manganese leaf
level. (6) A low level of calcium in solution promoted the accumulation of the
heavy metal nutrient-elements, magnesium and potassium in the leaf. (7) The
potassium level in the leaf increased with increased supply of boron.

Characteristic leaf pigmentation of N, P and Mg deficiencies appeared
sooner and were more conspicuous under high amounts of solar radiation. Un-
der low amounts, these same symptoms faded, or in the case of magnesium
deficiency, developed completely different characteristics. A shortage of any
one of the nutrient elements, except nitrogen and phosphorus, and an excess of
all nutrient elements, except phosphorus, were associated with the occurrence
of a chlorosis or necrosis, or both.
There appeared to be an increased requirement for most major nutrient

elements, except potassium, as the amount of solar radiation increased. Cor-

respondingly, there was an increased requirement for potassmm when the

 

HARRY JAMES AMLING ABSTRACT - 3
amount of solar radiation decreased. Under low solar radiation the high
potassium treatment induced the greatest amount of growth, while under high
solar radiation the high phosphorus treatment resulted in the greatest amount
of growth.

Low nitrogen levels in solution stimulated root growth, while high
N, B, Mn, Fe and Zn and low Ca, B, Mn solution levels noticeably reduced in
root development. The high phosphorus treatment induced the most desirable :
root system.

Blueberry plants were found to grow well in agricultural vermiculite
if supplied with nitrogen and phosphorus. Plants growing in vermiculite showed
noticeable reductions in growth when supplied with potassium or iron.

Definite seasonal trends existed for all nutrient elements in the leaves
except boron. ~N, K, P, Cu decreased, while Mg, Ca, Fe, Mn and Zn increased
in varying degrees as the season progressed. The biweekly leaf sampling study
also indicated that the greatest consistency in the leaf content of all nutrient
elements occurred during the three week period prior to, and including, the
first week in which 35 percent of the crop could be harvested.

Considerably more manganese was found in leaves of the Jersey variety
than in leaves of the Rubel variety. Foliar symptoms of magnesium deficiency
Were associated with a much higher medial leaf content of magnesium with

RUb61 than with Jersey. This was interpreted to mean that Rubel has a higher

HARRY LINES Al. L
scream: for r.“ .2 ;

cf K and X, and 1.x.t ;

finer than avenge
. 1i nutrzt-x'.
Trre were, hum w.
risen element 5.
tests period prxor :
9‘59percent;P -
Ci1'24 percent: at:
Ecreased sigmfisa:
The nutrm.

agesofN’ P, Mg an

HARRY JAMES AMLING ABSTRACT - 4
requirement for magnesium than Jersey. Rubel fruit contained higher amounts
of K and N, and lower amounts of Ca and Mn than did Jersey fruit. Rubel fruit
showed lower keeping quality than Jersey when N and K were higher, and Ca
lower than average.

All nutrient elements in the fruit declined with increased maturity.
There were, however, considerable differences in the magnitude of decline
between elements. The percent decrease of these elements during the six
weeks period prior to harvest were as follows: Mn - 73 percent; B - 61 percent;
Ca — 59 percent; P - 55 percent; N - 54 percent; Mg - 41 percent; Fe — 29 percent;
Cu - 24 percent; and K - 20 percent. During the harvest period N, K and Ca
decreased significantly.

The nutritional disorder survey indicated the existence in 1957 of short-

ages of N, P, Mg and Ca, and excesses of N, K and Mn in commercial fields.

SFLUENCE 0F NLTRI
GROWTH OF HICHBCS
SEEM. REFEREXL

A.\D FRUIT C Q

summed to the 3.?
State Unit-n
in pa rm

INFLUENCE OF NUT RIENT-ELEMENT SUPPLY ON LEAF COMPOSITION AND

GROWTH OF HIGHBUSH BLUEBERRY (VACCINIUM CORYMBOSUM L.) WITH

 

SPECIAL REFERENCE TO IMPORTANCE OF SAMPLING DATE ON LEAF

AND FRUIT COMPOSITION OF FIELD GROWN BLUEBERRIES

By

HARRY JAMES AMLING

A THESIS

Submitted to the School for Advanced Graduate Studies of Michigan
State University of Agriculture and Applied Science
in partial fulfillment of the requirements
for the degree of

DOCTOR OF PHILOSOPHY
Department of Horticulture

1958

ACKNOWLEDGEMENTS

The author wishes to express his sin -ere appreciation to Dr. A. L.
Kenworthy for his generous help, encouragement and guidance throughout
the investigation.

Grateful acknowledgement is expressed to Dr. H. B. Tukey Sr. , for
his inspiration; to Dr. H. K. Bell for his valuable advice and constructive
criticism of the manuscript; to Dr. E. J. Benne and Mr. S. T. Bass, and
staff, for carrying out the chemical analyses of the leaf and fruit samples;
and to Dr. F. Davis for his editing of the manuscript.

The author is grateful to Mr. John Nelson for his enthusiastic encour-
agement and help; to the Michigan Blueberry Growers Association for provid-
ing the financial assistance; and to those particular growers of the association
who donated time, labor and crop to make possible the investigation.

An expression of immeasurable gratitude is given to the author's wife,

Jeanne, for her continuous encouragement, assistance and sacrifices.

TABLE OF CONTENTS

Page
INTRODUCTION...................... 1
REVIEWOFLITERATURE..... . 2

EXPERIMENTAL PROCEDURE . . . . . . . . . . . . . . . 12

Experiment I . . . . . . . . . . . . . . . . . . . . 13
Experiment II . . . . . . . . . . . . . . . . . . . . 16
Experiment III . . . . . . . . . . . . . . . . . . . . 18
Experiment IV . ...... . . . . . . . . . . . . . 20

RESULTS 22

Experiments land 11 . . . . . . . . . . . . . . . . . 22
Leaf Nutrient-Element Composition . . . . . . . 24
Foliar Symptoms . . . . . . . . . . . . . . . . 30
Plant Growth . . . . . . . A. . . . . . . . . . . 36
Root Systems. . . . . . . . . . . . . . . . . . 43
Vermiculite as a Growing Media . . . . . . . . . 44

Experimentlll.................... 46
Leaf Nutrient Element Composition. . . . . . . . 47
Foliar Symptoms . ..... . . . . . . . . . . 52

PlantGrowth.................. 55

TABLE OF CONTENTS CONT'D

Page

Experiment IV. . . . . . . . . . . . . . . . . . 57

Seasonal Influence on Leaf Composition . . . . 58

Seasonal Influence on Fruit Composition . . . . 61
Nutritional Disorder Survey . . . . . . . . . . 62 a,
DISCUSSION....................... 66 I
SUMMARY 84 ‘T

LITERATURECITED.................. 89

APPENDIX 92

INTRODUCTION

The highbush blueberry Yaccinium corymbosum L. differs from

 

most other fruit crops by requiring an acid soil of high water-holding capa—
city. The availability of many nutrient-elements in such soils would be
considered in short or in excess supply for most fruit crops. The adapta-
bility of the blueberry to these soil conditions suggests that it differs funda-
mentally from other fruit crops in nutritional requirements.

The most reliable tool at present for diagnosing the nutritional
status of woody plants is plant analyses. Its use, however, depends largely
on a thorough understanding of the factors influencing plant composition.

At present, little information is available on the factors influencing the leaf
and fruit composition of the highbush blueberry.

The purpose of this investigation of the highbush blueberry was to
evaluate the influence of nutrient-element shortages and excesses on leaf

composition and growth, and to gain a better understanding of the seasonal

changes in leaf and fruit composition.

 

REVIEW OF LITERATURE

Doehlert and Shive (1936) published one of the earliest reports in
which sand culture techniques were employed to evaluate the nutrient require-
ments of the highbush blueberry. They studied the growth responses of the
Rubel highbush blueberry in sand culture under varied amounts of monopotas-
sium phosphate, calcium nitrate, ammonium sulfate, and magnesium sulfate.
Although unable to segregate the influence of individual nutrients, their data
showed that the best yield and tip growth was obtained from using solutions
low in monopotassium phosphate and high in nitrogen which were supplied
with boric acid and manganese sulfate. The authors suggested that the blue—
berry requirement for magnesium was slight and excesses of it may retard growth
processes. They further implied that nitrate nitrogen was superior to ammonia-
cal nitrogen.

Kramer and Schroder (1942) reported a study on the effects of nutrient
deficiencies, superimposed peat, and growth substances on rooted cuttings of
the Cabot blueberry grown in sand culture. The authors used the nutrient solu-
tion proposed by Doehlert and Shive. Modifications of this nutrient solution
were used to obtain solutions deficient in N, P, K, Mg, Ca, Fe, S. Mn and B.

In the superimposed peat-on-sand cultures, no symptoms of calcium, iron or

sulfur deficiency were observed during the course of the experiment, and

symptoms of boron deficiency were late in appearing. In straight sand cul-
tures, iron deficiency sumptoms, also, were late in developing. With these
exceptions, deficiency symptoms appeared after treatment initiation in both
cultures in the following chronological order: N, K, S. Ca, B, Mg, P, Fe and
Mn.

However, no chemical analyses were included in this paper to support
the authors' contentions of having developed specific nutrient deficiency symp-
toms.

Fresh weight measurements indicated that only -N treatments resulted
in significantly lower root weights, while -B, —P, -S, as well as -\l treatments,
resulted in a significantly reduced top weight when compared to the check
treatment. The authors were of the opinion that the severe reduction in growth
caused by anion deficiencies reflected a relatively high requirement for anion
nutrients and a low requirement for cation nutrients.

Kramer and Schrader (1945) presented data which showed that the
hydrogen ion concentration of blueberry leaf sap was much greater than in
Other plant species; that young leaves had a lower pH than the more mature
1eaves; and that the isoelectric point of the water soluble proteins in blueberry
leaves was on the basic side of the plant sap pH.

They also found that deficiencies of P, K, Mg, Ca, Fe and B raised

the pH and N deficiency lowered the pH of the leaf sap. These results were

m.-.

 

interpreted to mean that a raise in the pH of leaf sap toward its isoelectric
point was indicative of senescence or the occurrence of disease or injury.
They further postulated that the soluble proteins may act amphoterically as
cations, thus balancing the presence of excessive anions, which could re-

sult from plants growing in soils low in calcium and other exchangeable bases.

Minton, Hagler and Brightwell (1951) grew the rabbiteye blueberry
by sand culture methods and reported that deficiency symptoms of N, P, K,
Mg, Ca and S were similar to those reported by Kramer and Schrader (1942).
Leaf analyses data presented by the authors substantiated the occurrence of
these deficiencies. Significantly higher levels of P, K, Ca, Mg and S over
that of the check nutrient solution were obtained in the leaves when nitrogen
was lacking in the nutrient solution. Nutrient solutions lacking calcium in-
creased significantly the nitrogen and sulfur content of the leaves, while
solutions lacking magnesium decreased the calcium content and increased
the sulfur content of leaves.

The concept that the sensitivity of the highbush blueberry to soil pH
may be correlated with nutrient availability was stimulated by the report of
Bailey (1936). He described a chlorosis of tip leaves which could be corrected
by ammonium sulfate applications. White (1936) had attributed a similar
Chlorosis in gardenias to the use of nitrate nitrogen. He readily corrected
the disorder with ammonium sulfate, and to a lesser degree with iron in-

r1Oculations.

Bailey and Everson (1937) obtained a slight response with iron sul-
fate sprays and iron citrate injections in an attempt to correct the blueberry
leaf chlorosis reported in 1936. Soil tests indicated lower ferrous iron
levels under chlorotic plants than under non-chlorotic plants. Lime appli-
cations were found to induce the chlorosis. These workers concluded that
a lack of soluble iron induced by too high a pH was responsible for the chlorosis.

According to Bailey (1940) the inducement of chlorosis by lime appli- :
cations could be lessened by incorporating peat into the soil.

Stene (1939) found that the effects of pH on highbush blueberry growth
was greatly influenced by rooting medium and by the manner in which nutrients
were added. Plants grown in sand-oak leaf mold where, the pH was maintained
at 3. 5, 5. 2 and 7. 0, showed no significant differences when supplied frequently
with nutrient solution. Plants receiving dry fertilizer grew better at pH 3. 5
and S. 2 than at pH 7. O. The author implied that these results threw doubt on
generally accepted ideas that blueberries require a distinctly acid soil; that
Under certain conditions, where plant nutrients are available in adequate
am Ounts throughout the growing period, the highbush blueberry would tolerate
higher pH ranges than previously conceived.

Merrill (1939) and Harmer (1944) found lime applications beneficial
to grOWth of blueberries in soils of pH 4. 0 or lower. Harmer, in addition,

recOrded considerable decrease in growth if the pH was raised with lime

 

6.

applications to above 5. 2. No mention, however, was made in this report

of inducing leaf chlorosis as was achieved by Bailey and Everson (1937). The
author suggested that poor growth of blueberries in high pH soils may be the
result of decreased manganese and possible boron availability due to large
amounts of availaole calcium and magnesium. He also inferred that nitrates
may exert an inhibiting effect.

Data presented by Cain (1952) indicated that the lack of ammoniacal
nitrogen may be responsible for the appearance of iron deficiency chlorosis
on highbush blueberry plants growing in relatively high pH soils. He was
able to induce this chlorosis on plants grown in sand culture by substituting
equivalent amounts of nitrogen in the form of calcium nitrate for ammonium
nitrate in a complete nutrient solution in which the pH was maintained below
5. 5. The chlorosis appeared only when complete substitution of the ammonium
nitrate was achieved.

Cain maintained that this chlorosis was not necessarily related to soil
PH or to the calcium and iron leaf content. He found that under field condi-
tions blueberry plants grown in soil-sawdust mix at pH 7. 0 made excellent
STOWth and showed little chlorosis, if supplied with ammoniacal nitrogen.
HOWever, plants supplied with nitrate nitrogen developed severe chlorosis
and Suffered from nitrogen deficiency. Leaf analysis of chlorotic leaves
ShoWed, in some cases, lower calcium and a higher iron content than in non-

Chlorotic leaves.

‘1 AM~3

Cain (1954) reported that chlorotic leaves contained a greater total
amount of basic cations (Ca, Mg, K) on a dry weight basis than did non—chlorotic
leaves. Correspondingly, he obtained higher pH values on expressed cell sap
from chlorotic leaves than from non-chlorotic leaves. By injecting various
materials into chlorotic shoots, Cain found that those materials which acidi-
fied the chlorotic tissue also caused a greening of that tissue. Although in-
jections of basic materials did not induce a chlorosis in green tissue, heavy
metal injections did. Cain concluded that the pattern of chlorosis caused by
iron deficiency, nitrate nitrogen, calcareous soils, and heavy metal injections
were visually indistinguishable.

In comparing nitrate nitrogen with ammoniacal nitrogen, Cain indi-
cated that the latter was more readily absorbed and utilized. In addition, he
observed that nitrate nitrogen had a detrimental effect on linear growth even
When equivalent amounts of ammoniacal nitrogen were present in solutions
being compared.

Subsequent work by Cain (1955) indicated that the amino acid content
0f chlorotic leaves was higher than in non-chlorotic leave-s and increased with
the Severity of the chlorosis. This increase could be attributed primarily to
a“ increase in the basic amino acid arginine. Correcting the chlorotic condi-
tion With Fe EDTA resulted in a sharp decrease in the total amino acid con-

tent- Ninety percent of this decrease could be attributed to a disappearance

‘J

of arginine. Cain suggested that some metabolic process, which controlled
the reversible conversion of soluble nitrogen compounds into protein, was
interfered with in chlorotic leaves regardless of the condition inducing the
chlorosis.

The use of leaf analysis as a tool in determining the nutritional status
of field grown highbush blueberries was stimulated by the identification of
magnesium deficiency in Massachusetts (1949) and New Jersey (1950) blue-
berry fields.

Bailey, Smith, and Weatherby (1949) were unable to relate typical
magnesium deficiency symptoms with lower leaf contents of magnesium. They
were unable to increase the leaf content of magnesium with soil applications
of magnesium sulfate applied the previous year. Leaf analyses did indicate
that as the season progressed, calcium increased, phosphorus decreased, and
magnesium and potassium varied inconsistently. Blueberry leaves, in com-
parison to apple leaves, had similar nitrogen levels, but much lower phos-
phorus, potassium, calcium and magnesium levels. They interpreted the low
levels of basic cations as supporting evidence for the theory of Kramer and
SChrader (1942) that the blueberry had low cation requirements. The low
PhOSphorus level was considered to be indicative of a low requirement of this
element, as was suggested by Doehlert and Shive (1936). The authors realized,

hoWever, that the apparent low phosphorus requirement conflicted with the

conception of high anion requirements put forth by Kramer and Schrader (1945).
They inferred that anions, other than phosphorus, may fulfill this requirement.

Mikkelsen and Doehlert (1950) used leaf analyses to substantiate their
diagnosis of magnesium deficiency in New Jersey blueberry fields. Leaf samples
collected from plots treated the previous season with magnesium sulfate or
dolomitic lime had higher levels of magnesium. This increase in magnesium
leaf content corresponded with a disappearance of the magnesium deficiency
symptom. These workers also found that no equivalent reciprocal replacement
of potassium or calcium accompanied the increased magnesium level. On the
contrary, they found that leaves accumulated more potassium, magnesium, and
calcium when magnesium fertilizers were applied. Phosphorus, iron, and
manganese levels in the leaves were unaltered by magnesium applications.
Seasonal influences on leaf composition were apparent in the data presented.
Calcium, magnesium, and potassium levels increased and phosphorus levels
decreased as the season progressed.

Bailey and Drake (1954) continued the study of magnesium deficiency
and found leaf magnesium to increase in both treated and untreated plots as a
result of dry seasons. This increase was sufficient on untreated plots to
greatly reduce the leaf expression of the deficiency. They reported that Epsom
salts raised the leaf magnesium content more rapidly and to a higher level than

dld dolomitic limestone when both materials were applied at rates providing

IO.

equivalent amounts of MgO. This increase in leaf magnesium content reached

its maximum level three years after treatment, and then leveled off. Appli-
cations of magnesium were found to have no effect on potassium, calcium and
nitrogen content of leaves, regardless of the carrier used. Nitrogen, calcium and
potassium were found to increase as the season progressed.

Studies by Popenoe (1952) on seasonal trends of the major nutrient ele-
ment levels in Rancocus highbush blueberry leaves indicated similar responses
as found by Bailey 2:91: (1949) and Mikkelsen and Doehlert (1950). However,
his data showed reversed trends for calcium, phosphorus and magnesium from
one year to the next. He theorized that the ratio of potassium to magnesium
needed to create a deficient magnesium condition in Rancocus was lower than
in other varieties of blueberries. In analyzing mature fruit, he found the potas-
sium content to be higher than the potassium level in leaves sampled at the same
time.

Ballinger (1957) concluded, upon completing a survey on the nutritional
status of Michigan blueberry plantings, that soil moisture was one of the more
important factors influencing growth and production. He found, in addition, that
when calcium occupied more than eight percent of the soil cation exchange capa-
CitY» poor growth could be expected. Leaf analyses indicated that nitrogen was
the most limiting factor on soils having less than eight percent calcium satura-

tion of the exchange capacity. An increase in leaf nitrogen content was corre-

ll.

lated with an increase in yield, up to an apparent optimul level of 2. 10 per-
cent nitrogen. Although few instances of magnesium deficiency were found,
he found some indications that the magnesium content of the leaves was
directly related to yield. He suggested, in conclusion, that soil cation ex-
change determinations be coupled with leaf analyses for determination of

the nutritional status of the highbush blueberry.

12.

EXPERIMENTAL PROCEDURE

The program of experimentation was carried out from September,
1956 to November, 1957 as four separate experiments.

Experiment Iwas conducted primarily to study the influence of high
and low levels of N, P, K, Mg and Ca on growth and leaf composition. It
represented, in addition, an effort to evaluate various means of growing
the highbush blueberry in sand culture for future studies.

Experiment 11 repeated the nutritional study of the initial experiment
under conditions found to be more favorable for growth.

Experiment III was a study of the influence of high and low levels of
B. Mn, Fe, Cu and Zn on growth and leaf composition.

Experiment IV was a study of seasonal changes in leaf and fruit com-
position of field-grown highbush blueberries. In conjunction with this study.

commercial blueberry fields were also surveyed for nutritional disorders.

in“ 1

1.3.

Experiment I

One-year-old rooted cuttings of the highbush blueberry Vaccinium

corymbosum, variety Jersey, were used. These plants were removed from

 

peat-filled propagation frames in late September of 1956. The leaves were
removed, the plants then repacked in moist peat, and held in cold storage at
32 degrees F during October, and at 40 degrees F thereafter. During the
first week of January, the plants were removed from cold storage and the
roots washed free of peat. The plants were then sorted into eight groups on
the basis of uniformity of size and root development. Plants within a group
were designated as a replication. Differences between groups were thereby
confounded into replications.

Seven-inch clay pots, coated interiorly with asphaltum paint, were
used as containers. Drainage, in all cases, was provided by placing a two-
inch watchglass over the drainage opening in the bottom of each pot. Coarse
quartz sand (No. 7 Warsaw quarts) was used as the rooting medium. The
eight replications were arranged on two greenhouse benches, four replications
Per bench. Two finer grades of sand (No. l silica sand and No. 4 Warsaw
quarts) were used as an addition to each replication, so as to observe the
effect of particle size on plant growth.

The nutrient solution designated as the check treatment was derived

from solutions used by Kramer and Schrader (1942), Min’ton St 31; (1951), and

l4.

Cain (1952). Appendix Table 1 shows the modification of this check solution
used to formulate the minus series of treatments initiated at the time of plant-
ing. Plants designated to receive the plus series of treatmeits were supplied
with check solution until February 17. Appendix Table 2 shows the formu-
lation of the plus series of treatments and changes considered necessary in

the check and minus series of treatments. One pint of nutrient solution was
applied every third day. Supplementary watering was used on the intervening
days as necessary. Plants grown in finer grades of sand received the check
solution. As the experiment progressed, additional solution changes (Appendix
Tables 3 and 4) were made to achieve more desirable results. C. P. chemicals
and distilled or de-ionized water were used at all times in the preparation of
the solutions.

To augment the short day lengths existing from January to May, supple-
mentary lighting was used to provide a 16-hour day length. Fluorescent lighting
was placed over one bench, and incandescent lighting over the second bench.
The fluorescent lighting proved inadequate and was replaced by incandescent
1ighting. With the advent of warmer weather, a cheese cloth shade was placed
OVGI‘ both benches during the second week in May. Supplementary lighting was
discontinued at this time.

During the period June 27-28, the plants were transferred to the Horti-

CllltIII'e farm. Nitrogen deficiency symptoms appeared on all plants, except

15.

those receiving the high level of nitrogen. To counteract this, the nitrogen
concentration of the solutions was doubled. The plants were placed in a
newly constructed camouflage net shade house on July 9. At this time the
nitrogen level of the solutions was decreased to the original concentration
used. Also, at this time, de-ionized water was substituted for distilled
water. At certain times, due to inclement weather, nutrient solutions were
not applied. At no time, however, were two consecutive feedings missed.
During the third week of September, all the leaves from each plant
were collected and total shoot length measurements recorded. The shoots
and the original cutting stem were then removed and the roots separated
from the sand by utilizing a forty mesh screen. After being oven-dried at
150 degrees F, dry weight measurements were recorded for all plant parts.
Because of a depressing growth interaction effect between fluorescent
lighting and certain treatments, the leaves, after grinding, were composited
by Combining a replication originally under fluorescent lighting with one orig-
inally under incandescent lighting. When at all possible, equivalent propor-
tions of each replication were used. This procedure provided four leaf samples
per treatment, each having sufficient tissue for analyses of ten elements.
The leaf samples were analyzed in the Agricultural Chemistry labora-
tories. Total nitrogen was determined by use of the standard Kjeldahl method

and potassium by use of the flame photometer. Magnesium, calcium, boron,

l6.

phosphorus, manganese, iron, copper and zinc were determined spectro-

graphically.
Experiment Il

Two-year-old Jersey highbush blueberry plants, grown one season in
the cutting bed and one season in the nursery row, were used. The plants
were pruned back to one or two vigorous shoots. The roots were washed
free of soil and organic matter. The plants were then weighed and sorted
into five groups on the basis of root development and shoot number. Four
of the groups were used as replications in a sand culture experiment. The
remaining group was planted in vermiculite".

The plants were planted in 12—inch clay pots coated on the interior
with asphaltum paint. A four-inch watchglass was placed over the drainage
Opening, the lower third of each pot filled with coarse quartz sand (No. 7
Warsaw quartz) prior to planting in a semi-fine sand (No. 4 Warsaw quartz).
The two grades of sand were used, because semi-fine sand, although superior
‘0 COarser sand, retained excessive moisture at the bottom of the pot.

To avoid having the fibrous roots fold into a compact mass during

planting, the roots were first dispersed in distilled water previously added

"‘ ‘
~
. - — - — — — — _ _ — -

IMeffium textured agricultural vermiculite distributed by the Zonolite Company,
Chlcago, Illinois, under the trade name of Terra-lite.

semi-fine sand to cover the roots. The pot was then drained and filled to
capacity with additional semi—fine sand.

This planting procedure was used, also, in planting the plants in ver-
miculite. Due to the coarseness of the vermiculite, these plants were planted
at a much deeper level than those planted in sand. This provided additional
plant support and prevented dessication of the unestablished roots.

The plants, after planting, were placed on four greenhouse benches
shaded with cheesecloth. Within each replication, treatments were assigned
at random. The treatments, shown in Table II, were initiated one day after
planting. One quart of nutrient solution was added every third day, and sup-
plementary watering was provided on the intervening days as necessary.

During the first week of June, the vermiculite group was moved from
the greenhouse to a site sheltered from the wind but not from other environ-
mental influences. Due to the change of environmental conditions, apparent
nitrogen deficiency symptoms appeared on all plants, except those receiving
the high level of nitrogen. Late 1', these plants were transferred to the
Horticulture farm with plants of Experiments 1 and 11.

Until the third week of September, Experiment II was conducted simul-
taneously with, and in similar manner as Experiment I.

ExPeriment 11 plants, including the vermiculite group, were returned

to the greenhouse during the third week of September, to obtain greater growth

18.

differences between treatments and more distinct foliage disorders. The
experiment was terminated on November 1. The procedure of termination

was identical with that for Experiment 1.

Experiment III

One-year-old rooted Jersey highbush blueberry cuttings, similar to
those utilized in Experiment I, were used. . These plants, however, were left
in the cutting frame and transferred into the greenhouse during the third week
of September to prevent the plants from going into dormancy.

During the third week of December, the plants were removed from the
cutting frame, the roots washed free of peat, and each plant weighed and label-
ed accordingly. The plants were then sorted into three groups on a basis of
t0p growth and root development. These three groups were then divided into
six replications. The differences between groups were confounded with repli-
cation.

The plants were planted in the same manner as described for Experi-
ment 1. For the first two weeks after planting, the plants received only 3 nitro-
gen solution. By the end of this period the plants showed leaf colorations indi-
cative of plants going into dormancy. During the first week of January the
leaves were stripped off, the plants removed from pots and placed into poly-

ethylene bags. These plants were then kept in cold storage at 40 degrees F

until the last week of June.

19.

Upon removal from cold storage, the plants were replanted in two-
gallon glazed porcelain crocks. The interior of these crocks had been pre-
viously coated with silicone spray to seal off existing cracks. The drainage
opening was covered with a two-inch watchglass. The planting procedure was
identical to that used in Experiment 11. Four of the replications were planted
in sand; the remaining two replications were planted in vermiculite. Within
each of the six replications, treatments were denoted at random. After plant-
ing, the plants were transferred to the shade house at the Horticulture Farm.

To provide high and low treatment levels of boron, manganese, iron,
copper and zinc, modifications of the minor element solution, originated by
Hoagland, were added to the check solution used in Experiments I and II.

The plants were returned to the greenhouse during the third week of
September. Day lengths of 16 hours were imposed by supplementary incan-
descent lighting. The experiment was terminated on November 16 and 17, and
the leaves, shoots, and original cutting pieces were removed for dry weight
measurements. During the period November 18 to 28, the roots — one repli-
cation at a time - were washed free of sand and vermiculite for dry weight
measurements.

The leaves were analyzed as in Experiments 1 and II.
Sand and vermiculite replications were treated separately in the statis-

tical evaluation of the data.

20.

Experiment IV

Leaf samples were collected biweekly in 1957 from June 15 to September
5 from nine field plots considered to be free of any nutrient disorder. From
adjacent plots fruit samples were also taken at the same time.

Each plot was composed of five to ten bushes. Five plots were of the
Rubel variety, the remaining four were of the Jersey variety. The location
of these plots provided excellent representation of the more important blue-
berry production areas in western Michigan.

Each leaf sample consisted of leaves taken from all sides of the parti-
cular plot sampled. Only those leaves from the middle of terminal and strong
growing lateral shoots, which were expected to become fruitful the following
year, were used. A survey of the fruitfulness of these shoots, as shown by
the presence of fruit buds in September, indicated all to be fruitful. Yield
records were also obtained from these plots.

Until the first picking by the grower, fruit samples were obtained by
removing the berries from the apical portion of fruit clusters terminating.
Preferably vigorous shoots of the previous season. No cluster was sampled
twice. After the first picking an attempt was made to collect a representative

sample of the berries left on the bush.

Commercial fields, in addition, were surveyed for apparent nutrient

disorders. Representative samples of leaves showing these disorders were

collected,

21.

All leaves were washed in a distilled water solution of Dreft“ and
rinsed with distilled water. They were then oven-dried at 150 degrees F.

The fruit samples were not washed. The procedure for analysis of
both fruit and leaf samples followed that described for Experiment I.

The calcium level in the blueberry fruit was below that which could
be determined accurately on the spectrograph. Because of this, the calcium
content of the fruit was determined by using a Versenate method, as pre-

sented in the Appendix.

‘
~
.-
—
——-—_
——————

Trade name for a mild detergent.

22.

RESULTS

Experiments I and 11: Influence of N, P, K, Mg and Ca Levels in Solution

 

Growth in Experiment I, at least initially, occurred in a series of
distinct flushes- -each flush being terminated by a phenomenon in which the
terminal bud aborted. This appeared to be the same "periodic bud abortion"
reported by Kramer and Schrader (1942). As the experiment continued, the
interval of time between flushes became progressively less. In addition,
by late May, the tip bud aborting phenomenon ceased to occur.

In May and June shoot growth, arising from the basal portions of exist-
ing shoots and from the original stem, developed under most treatments. The
vigor of these shoots was dependent upon the particular treatment imposed.

Growth response to treatment, particularly to that of the low and high
Potassium treatments, differed according to the environment. Early in the
exPerirnent under low light intensity, 0 ppm potassium in solution was not
ehOUgh to sustain blueberry plant life, so small amounts of potassium (24 ppm)
were added. At the same time an additional 58 ppm potassium was added
to all but the low and high potassium treatment solutions. This is shown
in Appendix Table 2. The 292 ppm potassium in solution, initially used as
the high potassium treatment, appeared as the optimum treatment by the end

0f February. By the middle of April, however, the reverse was true. Ad-

23.

justments as indicated in Appendix Table 3 were then made.

About the first of May it became readily noticeable that half strength
solutions resulted in more growth. Subsequently, additional changes in solu-
tions were made, as depicted in Appendix Table 4.

Plants used in Experiment 11 grew vigorously after planting and did
not show the distinct flush pattern of growth observed in Experiment I. No
permanent solution changes had to be made in the course of this experiment.

Leaf analyses of the two experiments indicated that a considerably
lower leaf content of all nutrient-elements, except iron, was present in

Experiment I than in Experiment II.

LEAF NUTRIENT ELEMENT COMPOSITION A8 INFLUENCE!) BY
THE NITROGEN LEVEL IN SOLUTION

 

EXPERIMENT I
PERCENT DRY WEIG'IT PPM DRY WEIGHT
IO 30 50 .70 90 HO I30,£>O 250 20 60 100 A I25 225 3
v 4P7r I IV I v I

 

    
 
    
  
       
 
  

  

  
   

 

E z
a ............. 9
2 I:
‘ §
8 a
0
§ ‘ °
W NITROGEN LEVEL 3
V* 2' PPM x\\\\\V 4
0,. .3255 :5. 1......
;.;:;.;.; ,-:-:- " M

Significantly amount:
mmumsss "rot I35

”0'“th WeatS'loAaotIV.

PERCENT DRY WEIGHT

.IO .30 .50 7O .90 HO

     

 

\\\\\\\_\_\\\\\M

Sanieronfly different:
from chock"! 5% Hiatl'l.
from high N mm A of 5%AA otl'k

EXPERIMENT]!
PP U DRY WEIGHT

l 30 150 2.50

     
    

   
 

u .
s
E ................. 5
§ I:
i
.3. .
O
a :x~ Q
In . -------------
4 I“ ._ _ NITROGEN LEVEL 3 c“ 5,5,," NITROGEN LEVEL
g V 2| PPM 4 2| PPM
c. W .05 pp" -(checl) 2,, ;.; I05 PPM -(choell
:,...;.;. 525 PPM m =25 525 PPM fl
Slonlflcontiy different: Significantly different:
mmuasasnmm tromchecktots‘l. non-a
mmNmtIMMAotSV.Aaotl'/. fmhithmtmntsotsxanutl’I-s
Figure 1

 

24.

Leaf Nutrient-Element Composition

Influence of the Nitrogen Level in Solution (See Figure 1)

Experiment I

 

When the nitrogen level in solution was raised from 21 ppm to 525 ppm
the leaf content of nitrogen increased from 1. 83 to 2. 80 percent, and phosphorus
from . 20 to . 24 percent. Subsequently, magnesium decreased from . 38 to . 29
percent, calcium from . 60 to . 51 percent, boron from 275 to 182 ppm, and man-
ganese from 118 to 45 ppm. Iron, copper, and zinc leaf contents also decreased,
but not significantly.

Plants receiving 105 ppm and 525 ppm nitrogen in solution were signifi-
cantly lower in potassium content (. 654 and . 770 percent) than those receiving
21 ppm nitrogen (. 865 percent K).

Experiment II

 

As the nitrogen supply (21-105-525 ppm) increased, significant increases
in leaf content of nitrogen (l. 71 to 2. 60 percent) were obtained. Potassium, how-
ever, decreased from 1. 022 to . 826 percent. The manganese leaf level (339 ppm)
induced by the high nitrogen treatment, was significantly higher than that occur-
ring under the check treatment (159 ppm) and low nitrogen treatment (205 ppm).
Both the high and low nitrogen treatments resulted in significantly lower
leaf Phosphorus (. 24 percent) than did the check treatment (. 29 percent). \

Magnesium, calcium, copper and zinc decreased, but not significantly, as

“ltrogen supply increased. Boron and iron levels showed non-significant variations.

LEAF COMPOSITION

LEAF COMPOSITION

LEAF NUTRIENT ELEMENT COMPOSITION AS INFLUENCED BY
THE PHOSPHORUS LEVEL IN SOLUTION

EXPERIMENT I

 

      
   

  
      

   

 

PERCENT DRY WEIGHT PPM DRY WEIGHT
IO 30 SO 7'0 90 IJO ISO/L60 250 2\:0\\ 60 100 A I25 225 325
a“ l i a I .
2 Mn 1
Q :
:7; s\\\\\\\\.\\_\\\\\\\\\\\*
8 F0:
3
O
0
Mg Cu -
PHOSPHORUS LEVEL 5 mm LEVEL
In
0 ....... PPM- .. o.......m
Co 30 ...... PPM -(cneck) 2" ~:- 30 ...... PPM -(enocl)
‘ ‘ l50 ...... PPM m 35: 150.. .PPM m
SugnIlIcontly different Significantly diffnnnlt
from checkalrat5°k u at W. from cMcitotS'I. ##OII'I.
from mng P lrootmntaol5°k AA otl'l. from high P mm.us%..mm
EXPERIMENT]!
PERCENT DRY WEIGHT PPM DRY WEIGHT
IO 30 50 7O 90 I I0 I 30 AI 50 2 50 20 60 IOO I25 225 325
I V I v v v v v v v ‘lh—y—y—r—

 

PHOSPHORUS LEVEL

PHOSPHORUS LEVEL

...... PPM O . .PP I
so ...... PPM [meme 2,, 30. PPM -(cnockl
I50 ...... PPM 11:3 I50 ......
SanIlIcanIIy dillevenl San-liconlly different:
from check * at 5% *all 01 |'/. Item check It of 5% it of l‘l.
lvom mm P treatment A at 5% AA at W. from high P motmnt A at 5% AA otlfib

Figure 2

Influence of the Phosphorus Level in Solution (See Figure 2)

Experiment I

When the phosphorus level in solution was increased (0-30-150 ppm).
the phosphorus level in the leaf increased from . 15 percent to . 22 percent to
. 28 percent. High and low phosphorus levels resulted in larger amounts of
potassium (. 728 and . 703 percent) than found for the check (. 654 percent).
Conversely, these same treatments resulted in lower amounts of nitrogen
(2. 11 and 2. 06 percent) than that induced by the check (2. 30 percent).

0 ppm phosphorus in solution significantly increased the manganese
level (103 ppm) in the leaf over that level (55 and 62 ppm) found in plants re-
ceiving 30 and 150 ppm phosphorus.

The iron level (350 ppm) in the leaves of plants under the high phos—
phorus treatment was the highest obtained in this experiment under any treat-
ment.

The magnesium, calcium, boron, copper and zinc levels in the leaf

were not appreciably altered by changes in concentration of phosphorus in

solution.

Experiment 11

Raising the content of phosphorus in solution (0-30-150 ppm) increased
the leaf content of phosphorus (. 13 to . 41 percent), calcium (. 56 to . 65 per-

cent), and boron (150 to 310 ppm), but lowered the manganese content (230 to

127 ppm).

26.

Nitrogen leaf contents were decreased from 2. 46 percent in the check
to 2. 28 percent by the low phosphorus treatment, and 2. 19 percent by the high
phosphorus treatment. These results were in accord with that found in Experi-
ment I, however, the differences were not significant in Experiment II.

Contrary to results obtained in Experiment I, 30 ppm phosphorus re—
sulted in a higher potassium leaf content (. 956 percent) than did 0 ppm or
150 ppm phosphorus (. 783 and . 769 percent K, respectively). Magnesium
leaf levels were influenced in similar fashion, but differences were not sig-

nificant.

Varying the phosphorus level in solution had little influence on iron,

copper and zinc leaf levels.

LEAF WTRIENT ELEMENT COMPOSITDN AS INFLUE'KID BY
THE POTASSIUM LEVEL IN SOLUTION

EXPERIKNT I
PERCENT DRY WEIGIT

  
   

3:2:szs:s:;:;:::s:2: POTASSIUM LEVEL
0 . . . . . . PPM

LEAF COMPOSITION

       
 

c. 30 ..... PPM -(chock)
4'12; PPM E
SW” mm: W m:
MMPQSSS InoH'b Mendtmsx ttotlfi
homhIVIKWAMS'kAAoII‘YA MWKWACS'LAAOII'L
WHEN”!
PERCENT DRY WEIGHT PPM DRY WEIGHT
.Io 30 .50 ,70 90 ”,0 tag/[50 250

 

         

-I "°_ POTASSIUM LEVEL
0 ...... PPM
30 ..... PPM -(cmu)
, I50 ..... PPM m
SWIcoMIy different: Significantly dflfomt:
"unmitasxnoim fromchcktotfflb ttd
MIMI-K WAatSfiSAAmI'l. fmhighKMoImtAotlrbAAmW.

Figure 3

Influence of the Potassium Level in Solution (See Figure 3)

Experiment I

 

By increasing the potassium level in solution (0—30-150 ppm), an in—
crease of potassium (. 481 to I. 11 percent) coupled with decreases of magnesium
(. 41 to . 31 percent), calcium (. 47 to .42 percent), and manganese (71 to 51 ppm)
_ was obtained in the leaf.

Boron and copper levels in the leaf were lower under the check treat-
ment than under the high and low potassium treatments.

Nitrogen, phosphorus, iron and zinc levels in the leaf showed little
change under varying levels of potassium in solution.

Experiment II

 

Potassium, magnesium and manganese leaf levels responded in similar
fashion to Experiment I under the same treatment. As the potassium concen-
tration in solution increased, the leaf content of potassium was raised signi-
ficantly from . 576 to l. 335 percent, while magnesium dropped from . 49 to . 42
percent, and manganese from 205 to 156 ppm. However, the influence upon
magnesium and manganese was not significant.

Nitrogen leaf content showed a decreasing, but not significant, trend
(2. 65 to 2. 46 to 2. 39) as the potassium supply was increased.

The remaining nutrient-elements showed erratic or slight changes

under the three levels of potassium in solution.

LEAF COMPOSITION

LEAF COMPOSITION

LEAF NUTRIENT ELEMENT COMPOSITION AS INFLUENCED BY
THE MAGNESIUM LEVEL IN SOLUTION

EXPERIAQ'NT I
PERCENT DRY WEIGHT PPM DRY WEIGHT
IO 30 ,50 7O 90 MO \2\§0 20 63 I00 n," I25 2% 325

 

     
 

    

   

u. a \\\\\\\\\\ \\\\\\‘\\\\\\\\\\\‘.\‘§\_\\\\\\\\NA
2
E
In
i
O
o
w '- MAGNESIUM LEVEL 3
0 PPM 4 \ m
c, -. 24 PPM -(choctl) .;.; PPM munch)
................ I22 PPM fl 31 -
Significantly dittoranti Significantly dIffanntt
Ivomchcclitmws tit-otl'lA Imehaattats'b ##atI'b
fromhithgtnatmaMaotS'IAAAatl'I. fmhithoMMadSfiAActli
EXPERIMENT]!
PERCENT DRY WEIGHT PPM DRY WEIGHT
IO 30 50 TO 90 HO ISO I50 250

 

T I TH
\\\\\\.\\\\\\\\\X\\\ \\\\\\\\\\.\\\\\\\\\\\\\\\\\\\\\\x\\:

 

     
 
   

 

   

2
Q
’:
§
....... x
O
U
MAGNESIUM LEVEL ‘3 MAGNESIUM LEVEL
0 PPM ~‘ \ 0 PPM
24 PPM -(check) Zn .;. 24 PPM .(choct)
I22 PPM m 5:123 * '22 PP“ -
Significantly different. SanIflcanIIy different:
IvomchecktotbfiLMtotIfib framchecktatb‘l. Mtotl'l.
mmhiqhwlmIMMA015./0AAOII% from higthmatmantAotbfib AAatl‘VA

Figure 4

28.

Influence of the Magnesium Level in Solution (See Figure 4)

Experiment I

 

An increase in the concentration of magnesium (0-24-122 ppm) in solu-
tion increased magnesium (. 25 to . 42 percent) and decreased phosphorus (. 23
to . 20 percent), potassium (. 776 to . 663 percent), and boron (282 to 196 ppm)
levels in the leaf.

The high magnesium treatment promoted a non-significant increase in
the copper level (48 ppm) in the leaf over that of the check (34 ppm).

Differences in leaf contents of nitrogen, calcium, manganese, iron and
zinc were variable and not significant.

Experiment II

 

With an increase in the magnesium content (0-24-122 ppm) in solution,
magnesium proportionately increased from . 36 to . 59 percent in the leaf. Sub-
sequently, decreases of potassium (1. 054 to . 802), boron (382 to 211 ppm), man-
ganese (232 to 134 ppm), and iron (238 to 178) also occurred. The reduction in
leaf boron, however, was not significant.

Phosphorus and zinc levels in the leaf were lowest with the check treat—
ment and increased with either increasing or decreasing levels of magnesium in

solution.

The copper level in the leaf was increased from 32 ppm in the check to 42 ppm
in the high magnesium treatment. This response was similar to that obtained in
Experiment I, however, it still was not a significant response.

Nitrogen and calcium leaf levels were influenced only slightly by varying

the magnesium concentration in solution.

 

LEAF NUTRIENT ELEMENT COMPOSITION AS INFLUENOED BY
THE CALOIW LEVEL IN SOLUTION

    
        
       
 
  

 

 

 

EXPERIKNTI
PERCENT DRY WEIG‘IT PPM DRY WEIGHT
.IO .30 .50 .70 90 I10 I30.l.50 250 20 60 I00 ,. IZS 225 325

 

\\\:¥:

. : CALCIUM LEVEL
\\\\\\ chum

   

CALCIUM LEVEL

\ 0....PPM
CO ;.-.:.; ................ . -.; 40..PPM -(cnect) 2032' 40... PPM -(dt0ctl
. ..PPM a 3:3. 200..PPM fl
Siqifloontly diftennti SIonIerantty difhrent:
MMIUSVA itatlfi frunchecttatS’l. tint”.
MWCOWAUD%AAOH%

from NgtiCotnottnentAOIS'kAA otl’l.

PPM DRY WEIGHT

     
 
      

   
 

"a:
2
g P?- , . .
§ ,, ....... , .. .....‘ WWW \\\\\\\\s:
“I “q
4 2; CALCIUM LEVEL 5 LEVEL
0....PPM 4 ~ ..PPM
40. . . PPM -(ctiecII) 2.. ;.;. co. . .PPM -Imt
. .. 200..PPM 53 200..PPM -
SIonificantIy different: Significantly different:
Mctueckeatsx an aim Iromchecltats‘l. "ems
from tIIinCatreatmentA at5%AAatI'l.

tram nigh Ca treatment A at 5% AA atlfib

Figure 5

29.

Influence of the Calcium Level in Solution (See Figure 5)

Experiment I

 

The influence of the calcium level in solution on leaf composition was
negligible with all nutrient elements, except potassium and iron. The 0 ppm
calcium treatment resulted in a potassium level (. 775 percent) significantly
above that induced by the check treatment (. 654 percent). As the calcium
content increased in solution from 0 to 200 ppm, the iron content of the leaf
decreased from 295 ppm to 248 ppm. This decrease was not significant.

Experiment II

 

Increasing the calcium concentration in solution from 0 ppm to 200
ppm decreased potassium (. 992 to . 931 percent), magnesium (. 59 to . 48
percent), manganese (391 to 202 ppm), iron (263 to 153 ppm), copper (53 to
31 ppm), and zinc (13 to lOlppm), in the leaf. Of these elements, only potas-
sium was not significantly lowered.

The calcium leaf content showed some indication of increasing with

an increase in the calcium supply. This increase, however, was not significant.

30.

Foliar Symptoms

The expression and rapidity of appearance of foliar symptoms depended

to a large extent on solar radiation. Figure 6 shows the biweekly average solar

radiation for the experimental period. Characteristic leaf pegrnentation due

to nitrogen, phosphorus, and magnesium deficiencies appeared sooner and

were more conspicuous under high solar radiation. Under low solar radiation

as encountered in late winter, under shading, or in the fall months, these same

symptoms faded or developed completely different characteristics, as was the

case with magnesium deficiency.

Descriptions of the various symptoms induced by the ten treatments

used, are as follows:

Nitrogen deficiency: Under the prevailing low solar radiation avail-
able in the initial stages of Experiment I, the low nitrogen treatment, which
Originally contained 56 ppm nitrogen, provided sufficient nitrogen to maintain
0Ptirnum growth. To induce foliar symptoms of nitrogen deficiency, the nitrogen

leVel in solution was reduced to 21 ppm. With the advent of increased solar

radiation, coupled with the use of only 21 ppm nitrogen in solution, deficiency

Symptoms rapidly developed.
In Experiment II, nitrogen deficiency symptoms appeared within two

Weeks after treatment initiation. The symptoms were further intensified when

the plants were moved out of doors into full sunlight. The symptoms of nitrogen

 

Figure 6
Solar radiation available to blueberry plants used in the pot
culture studies conducted in 1957.

The shading imposed by the shade house decreased the

available solar radiation by 67 percent.

Data used to compile this chart are presented in Appendix

Table 18’“.

*Solar radiation data received through the courtesy of Mrs. Cottom.
Hydrologic Research Project, U. S. D. A. , Soil Conservation

Service.

 

 

 

     

 

 

v.
o
u N
w i
m
u a
.w o
n E
U s
o .
H G".
O
U
u in
a .m
mm
4w
em 6
NW N
NE m...
u . P i
1. F
n Am
. u Mm
. a .m
M mm
m... A
Nd. .
.mm .
«L M
R" M
To
me .
0' 8.
50 E
F
. . . . . . . mu m . . c
0 0 0 O 0 0
5 5 5 o 5 n
w 5 m 4 W 3 3 2 2 m m v

~20 tum mmE04<uitcfie 3 20:3ka

31.

deficiency, existing in both Experiments I and II, faded considerably when the
plants were moved into the shade house.

Nitrogen deficiency became apparent when the leaves turned progres-
sively more yellowish-green basipetally. With increased severity of the defi-
ciency, the basal leaves exhibited minute reddish necrotic spots (Figure 7)
over the entire leaf surface. Young shoots arising from the base of nitrogen
deficient plants, were tinted a distinct pink. This coloration changed rapidly
to a pale green upon cessation of growth.

In Experiment 1, leaves deficient in nitrogen contained 1. 83 percent
nitrogen, as compared to 2. 30 percent in check leaves. Wider differences
between nitrogen deficient and check leaves (I. 71 and 2. 46 percent) were ob-
tained in Experiment II.

Nitrogen excess: When the nitrogen concentration in solution was in-

 

CreaSEd from 420 ppm to 525 ppm (Appendix Tables 3 and 4), tip leaves on
high nitrogen treated plants developed an interveinal chlorosis followed by a
rapid abscission. acropetally, of basal leaves (Figure 11). No foliar dis-
orders' Were noted on the basal leaves prior to abscission. Upon moving the
plants into shade and lowering the nitrogen content to 262 ppm in solution tem-
porarily, the phenomenon ceased, shoot growth was renewed. Reverting back

to 5 . . .
25 ppm nitrogen, however, dld not result in a re-occurrence of the phen-

 

 

Figure 7

Upper left - Nitrogen deficiency. Note pale greenish yellow
basal leaves covered with minute red spots.

Upper right - Potassium deficiency. Note necrotic areas
along margin of leaves.

Lower left - Phosphorus deficiency. Note purpling of basal leaves.

Lower right - Acute petiole angle, associated with phosphorus
deficiency.

 

 

 

 

32.

Leaf analyses showed 2. 80 percent and 2. 60 percent nitrogen, respec-
tively, for the high nitrogen treated plants in Experiments I and II.

Phosphorus deficiency; In Experiment Ithe basal leaves of plants re-

 

ceiving 0 ppm phosphorus in solution became coriaceous in texture and turned
a dark purple (Figure 7). Tip leaves exhibited, at the same time, a greenish-
purple coloration. The greater the light intensity, the more intense the purple
coloration. Decreasing the light intensity by shading rapidly eliminated the
purplish coloration, but not the coriaceous leaf condition on basal leaves.

Only in direct sunlight did plants in Experiment II show purple pig-
mentation. This purple coloration disappeared rapidly after placing the plants
in the shade house. No further foliar pigmentations developed on these plants
for the duration of Experiment II.

In some instances the petiole angle of leaves on fast growing shoots
in Experiment II became extremely acute. This condition resulted in the leaf
being Pressed against the stem (Figure 7).

Leaf analyses of the 0 ppm phosphorus treated plants indicated a phos-
phorus Content of . 15 percent and . 13 percent, as opposed to . 22 percent and
‘ 29 Percent in the check leaves, respectively, for Experiments 1 and II.

Phosphorus excess: In Experiment 11 plants receiving 150 ppm phos-

 

phorus showed apparent nitrogen deficiency on basal leaves (Figure 8). Analy-

Ses . . .
of leaves taken from these plants indicated a nitrogen content of 2. 19 per-

Figure 8

Marginal scorch of basal leaves due to excess potassium.
Symptoms undistinguishable from that resulting from
magnesium and calcium excess.

Top - Apparent nitrogen deficiency due to high
phosphorus treatment.

Bottom - Potassium toxicity on basal leaves, in-
distinguishable from magnesium toxicity.

 

33.

cent, while leaves taken from check plants contained 2. 46 percent nitrogen.

Although 150 ppm phosphorus in solution depressed the nitrogen content
below that found in check leaves in the first experiment, no distinguishable
Symptoms were present.

Potassium deficiency: Only in Experiment I did foliar symptoms of
POtassium deficiency become visible. Approximately six months after treat-
ment initiation, small necrotic spots appeared on basal leaves just inside the
leaf periphery (Figure 7). With increased severity of the condition, the
ueCrotic spots coalesced into a necrotic area. which extended to the leaf
margin.

Earlier in Experiment I, 26 ppm potassium had to be added to keep
the minus potassium treated plants alive (Appendix Table 2). At this time,
hOWever, no foliar disorders were apparent. Analyses of leaves from these
Plants indicated the potassium content to be . 48 percent; the check leaves
in Experiment I had a potassium content of . 65 percent.

Potassium excess: The foliar expression of potassium toxicity became
eVident only in Experiment II and only in the late stages of the experiment.
ShOrtly after returning the plants to the greenhouse in September of 1957, a
dark grayish-brown marginal burn developed on basal leaves of high potassium
treated plants. Analyses of leaves from these plants showed the potassium

level to be 1. 3 percent.

 

 

 

34.

Magnesium deficiency: The expression of magnesium deficiency was

 

found to vary according to the amount of solar radiation the plant received.
This is shown in Figure 9.

In February under low solar radiation (biweekly average of 250 gram-
calories per cmz), magnesium deficiency appeared as an arc of necrotic
oval areas close to the midrib on basal leaves. Abscission of these leaves
occurred within three weeks after the initial appearance of the symptom.
When the solar radiation increased to a biweekly average of 350 gram-calories
per cm2 in March, necrotic oval areas began appearing along the leaf mar-
gin. By May, with solar radiation reaching a biweekly average of 450 gram-

2, necrotic areas ceased to form.

calories per cm

The symptoms now appeared as a mottled yellowish-red submarginal
1'Tlterveinal chlorosis. Associated with the cessation of necrotic area develop—
ment was a decrease in leaf abscission of afflicted leaves. By the end of
June, under strong solar radiation (biweekly average of 550 gram-calories
Per cmz), the expression of magnesium deficiency changed to a bright red
sllbrtnarginal interveinal chlorosis. Accompanying the development of red
Pigrnentation was a tendency of the leaf margin to curl abaxially.

In July, by moving the plants from the greenhouse to an outdoor shade

hOUSe, the average biweekly solar radiation was reduced to 100 to 200 gram-

CalOI‘ies per cm2. Consequently, the bright red coloration of magnesium

 

 

deficiency achieved under strong solar radiation faded to a dull red. Newly

afflicted basal leaves began showing necrotic areas close to the midrib at

the base of the leaf blade. Abscission of such leaves occurred very rapidly.

Transferring Experiment II back into the greenhouse did not result

in the formation of pigments. Chemical analyses showed the level of mag-

nesium to be . 25 percent and . 36 percent in leaves from deficient plants,

and . 34 percent and . 44 percent in leaves from check plants for Experiments

I and II, respectively.

Magnessium excess: Apparent toxicity symptoms from the 122 ppm

magnesium treatment were present only in Experiment II. These symptoms

appeared on basal leaves, and were indistinguishable from those described

for potassium toxicity. Leaves from plants in Experiment II under high

magnesium treatment had a . 58 percent magnesium content, as compared to

~ 45 percent in check leaves. It was interesting to note that under 0 ppm cal-

Cium treatment, plants also accumulated . 58 percent magnesium.

Calcium deficiency: The appearance of foliar disorders that could

be attributed to a deficient level of available calcium did not manifest them-
selves until de-ionized water was substituted for distilled water. In Experi-
ment I. terminal leaves of plants receiving 0 ppm calcium showed a slight

yelloWish-green blotchiness. Plants in Experiment II, under the same treat-

ment» developed a marginal chlorosis on tip leaves, and a tendency toward

36.

rosetting. Basal leaves, in addition, developed tip and marginal scorching.

These basal leaves later abscissed. Chemical analyses of the calcium con-

tent in these leaves did not indicate what could be considered a deficient

level of calcium in comparison to other treatments. It did indicate in

Experiment H leaves an extremely high level of magnesium, comparable

to that resulting from the high magnesium treatment.

Calcium excess: In Experiment 11 basal leaves on plants supplied

 

with 200 ppm calcium developed tip and marginal burning, identical to that

found on plants receiving high levels of potassium and magnesium.

Plant Growth

Considerable differences in growth response between Experiments I
and II were obtained, using the same treatment. These differences may re-
flect an. interaction between environmental conditions existing during the
CCurse of each experiment and the nutrient treatment.

Much of the growth in Experiment Iwas made during periods of low
solar radiation; whereas, in Experiment II the initial flush and part of the
second flush growth were made under relatively high solar radiation. Figures
10 and 11 show representative plants from Experiment II for the different

treatm ents.

The growth responses encountered in Experiments 1 and II are recorded

Figure 10

Influence of low levels of N, P, K, Mg and Ca in solution on
top growth as compared to check in Experiment 11.

Top left - check

Top right - 21 ppm nitrogen
Middle left - 0 ppm phosphorus
Middle right - 0 ppm potassium
Bottom left - 0 ppm magnesium
Bottom right - 0 ppm calcium

 

 

 

   

Figure 10

Figure 11

Influence of high levels of N, P, K, Mg and Ca in solution on
top growth as compared to check in Experiment 11.

Top left - check

Top right - 525 ppm nitrogen
Middle left - 150 ppm phosphorus
Middle right - 150 ppm potassium
Bottom left - 121 ppm magnesium
Bottom right - 200 ppm calcium

 

 

 

m “Er ‘
r

TREATMENT

Growth as influenced by the N, P, K, Mg and Ca level in solution

EXPERIMENT I

 

 

 

LEAF DRY WEIGHT - GMS. SHOOT DRY WEIGHT-6M5.
°!????§H 0'23“
WI
N\\\\\\\\\s

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KW
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COW

 

 

 

I l I l I i I ‘ . V
TREAT. LEVEL hi: §§§ TREAT. LEVEL 3;: §
L.s.o.[ 5%? L m fl L.S.D. [31‘] E

 

ORIGINAL STEM DRY WEIGHT - GMS.
O I 2 3 4

 

V
TREAT: LEVEL L0" x\\\
”'6“ m

L.s.o. @

Figure 12

in Appendix Tables 7 and 9. Graphic illustrations of these data are presented
in the following dissertation:

Experiment I

 

 

Leaf dry weight (See Figure 12): A decrease in leaf dry weight below
that of the check occurred when 21 ppm or 525 ppm nitrogen, 0 ppm phosphorus.
and 0 ppm calcium treatments were employed. The effect of the low calcium
treatment, however, was slight and not significant.

Increases in leaf dry weight over that obtained with the check resulted
with the O or 150 ppm potassium and the 0 ppm magnesium treatment. These

increases, however, were not significant. The 150 ppm potassium treatment
resulted in the highest leaf dry weight.

Shoot dry weight (See Figure 12): Only those plants receiving 150 ppm

 

Potassium made significantly more shoot dry weight than the check. Substan-
tial but non-significant increase over that of the check did occur with solutions
devoid of magnesium and potassium.
Significant decreases in shoot dry weight below that of the check re-
sulted only Under 525 ppm nitrogen and 0 ppm phosphorus treatments.
Although the 21 ppm nitrogen treatment was not significantly lower in
shoot dry weight than the check, the resulting decrease induced by it was con-

siderable.

The remaining treatments resulted in shoot dry weight approximating

that of the check.

38.

Original stem dry weight (See Figure 12): The original stem refers
primarily to the cutting piece and subsequent shoot growth existing at the end
of the first season in the cutting bed.

The only significant increase over the check treatment was induced
by the 0 ppm potassium treatment. The 150 ppm potassium treatment also
showed an increase which approached significance.

The 525 ppm nitrogen in solution depressed the dry weight of the
original stem, but not significantly.

Top dry weight (See Figure 13): Treatments fell into three groups

 

on a basis of plant response in the form of top growth -- those treatments
that severely reduced top growth, those that had little effect on it, and those
that substantially increased top growth over that of the check.

The 0 and 525 ppm nitrogen and 0 ppm phosphorus treatments comprise
the first group. The second group of treatments consisted of the 150 ppm
phoSphorus, 122 ppm magnesium, and both the 0 and 200 ppm calcium treat-
meflts. The last group, which increased top growth, consisted of the O and
150 ppm potassium and 0 ppm magnesium treatments.

Root dry weight (See Figure 13): Substantial decreases in root dry

 

weight below that of the check were induced by the 525 ppm nitrogen and 0 ppm
phQSIEmorus in solution. Only the former treatment, however, resulted in a

Slgnificant decrease.

 

Figure 13

Top dry weight, root dry weight, total dry weight and total
shoot length in Experiment I, as influenced by the N, P,

K, Mg and Ca level in solution.

 

 

TREA TMENT

TREA TMEN T

 

Growth as influenced by the N. P. K. Mg,and Ca level in solution

EXPERIMENT I

TOP DRY WEIGHT ' GMS. TOTAL DRY WEIGHT'GMS.
4 6 8 IO 12 I4 I6 0 4 8 I2 16 20 24
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ROOT DRY WEIGHT-GMS. TOTAL SHOOT LENGTH - MM.
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REAT LEVEL HIGH m TREAT. LEVEL HIGH m
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Figure 13

39.

Highly significant increases in root dry weight were achieved by 0 and
150 ppm potassium in solution.

Noticeable, but non-significant, increases were obtained when using
the 0 ppm nitrogen, 150 ppm phosphorus, 0 and 122 ppm magnesium, and 0
ppm calcium treatments.

Total dry weight (See Figure 13): Significant differences from the
check were recorded only for the decrease induced by the 525 ppm nitrogen
treatment and the increase induced by the 150 ppm potassium treatment. In
addition, however, non-significant decreases resulted from the 0 ppm nitro—
gen and phosphorus treatments, and increases from the 0 ppm potassium and
magnesium treatments.

Total shoot length (See Figure 13): Greatest total shoot length was
achieved with 0 ppm magnesium in solution with 150 ppm potassium in solu-
tion resulting in the next greatest shoot length. Both treatments induced highly
Significant increases in shoot growth over that of the check. A similar but
non—significant increase was induced also by the 150 ppm phosphorus treat-
ment.

A severe depression of total shoot length occurred with the 0 and 525
ppm nitrogen and the 0 ppm phosphorus treatments.
The response to the remaining treatments paralleled that of the check

01‘ were slightly higher in shoot length.

40.

Egperiment 11
Leaf dgy weigfi (See Figure 14): Only the 150 ppm phosphorus treat-
ment resulted in significantly greater leaf weight than the check.

Similar responses to that of the check were obtained by using the O and

150 ppm potassium and 0 and 122 ppm magnesium treatments.

Leaf dry weight was depressed by solutions containing 21 ppm and 525
PPm nitrogen, 0 ppm phosphorus, and 0 and 200 ppm calcium. A significant

dapression below the check, however, was only obtained with the high nitrogen

and low phosphorus and calcium treatments.

Shoot dry weight (See Figure 14): There were no significant differ-

ences in shoot dry weight between treatments. A positive, but non~significant,
réi‘Sponse was evident when plants were given solutions containing 150 ppm

Phosphorus. Negative non-significant responses were achieved with the 525

me nitrogen and 0 ppm phosphorus and calcium treatments.

Total shoot leggth (See Figure 14): Severe reductions in shoot length

were caused by the 21 ppm nitrogen, 525 ppm nitrogen, 0 ppm phosphorus,

and 0 ppm calcium treatments. Only the decrease due to the low nitrogen

treatment was not significant.

The 150 ppm phosphorus treatment increased shoot growth over that

Of the check, but not significantly.

Little difference in total shoot length was recorded between the check

a . .
nd remaining treatments.

Figure 14
Leaf dry weight, total shoot length, shoot dry weight and orig-
inal stem dry weight in Experiment II, as influenced by

N, P, K, Mg and Ca level in solution.

L
E
E
.3
E

TREATMENT

 

Growth as influenced by the N, P, K, Mg and Ca level in solution

EXPERIMENT II

LEAF DRY WEIGHT- GMS.

0 2 4 6 8 I0 12 I4 16
I I T I I I I n

 

CHECK j

NW
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KW
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Low m
TREAT. LEVEL m6” m
L.s.o. IE] IE

TOTAL SHOOT LENGTH - MM.

 

600 I400 2200 3000
I I I H r T
CH ECK |

 

l

l l l l J
LOW w
TREAT. LEVEL HIGH m
L. s. o. E

Figure 14

SHOOT DRY WEIGHT - GMS.
O 2 4 6 8 IO

TREATMENT

 

Low m
TREAT LEVEL ”is” m

NO SIGNIFICANT DIFFERENCE

ORIGINAL STEM DRY WEIGHT— GMS.
i! 4 6 8 l0

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Low m
TREAT. LEVEL HIGH m

NO SIGNIFICANT DIFFERENCE

    
  
 

 

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TREATMENT
/

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M9

  

Ca

v...-

 

41.

Original stem dry wehghyt (See Figure 14): No significant differences
existed between treatments. The high phosphorus treatment, however, did
increase and the high nitrogen decrease stem weight.

Top dry weight (See Figgre 15): Plant top growth response to treat-
ment, as indicated by top dry weight, reflected three categories of treatment
influence.

Detrimental influences were exerted by the high nitrogen and low
PhOSphorus, magnesium and calcium treatments.

Slight influences on top growth were registered by the low nitrogen
and potassium treatments, and by high potassium, magnesium and calcium

treatm ents.

A beneficial influence on top growth was achieved only with the high
phosphorus treatment.

Root dry weight (See Figure 15):. Only the low nitrogen treatment
resUlted in a significantly greater root dry weight than the check. All other
treattIITents reduced root growth, with the exception of the 150 ppm phosphorus
treatrrient. Significant reduction in root growth below that of the check, how-
EVer, were induced only by the low calcium and high nitrogen treatments.

Total dryweight (See Figure 15): Total dry weight was significantly
reduced by high nitrogen and low calcium treatments, and increased by the

hlgh phosphorus treatment. A non-significant reduction trend was noted also

 

Figure 15
Top dry weight, root dry weight, total dry weight, and dry
weight accumulation in Experiment H as influenced by

the N, P, K, Mg and Ca level in solution.

 

Growth as influenced by the N, P, K, Mg and Co level in solution

EXPERIMENT 11'

TOP DRY WEIGHT - (ms.
5 I0 Is 20 25 so 35
I I I I I fl

 

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TREATMENT

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TREAT. LEVEL kg: §

ROOT onv WEIGHT- (ms.
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42.

with the low magnesium, low phosphorus, and high calcium treatments.
Remaining treatments showed only slight variations from that of the
check.
Dry weight accumulation (See Figure 15): Only those plants re-
ceiving 150 ppm phosphorus in solution accumulated significantly more dry

weight than the check.

Dry weight accumulation was severely reduced by solutions contain-

ing 525 ppm nitrogen and 0 ppm calcium.
The remaining treatments, except 21 ppm nitrogen and the 122 ppm
magnesium, induced the accumulation of lower dry weights in varying de-

grees than check. The two exceptions produced slightly more dry weight

than the check.

'rre'é-r: 1

43.

Root Systems

Root systems were found to reflect a deficiency or toxicity level
of the nutrients studied in Experiment 11. Although similar differences
were observed in Experiment I, they were not as outstanding.

Figure 16 illustrates the typical color associated with certain
root systems. The influence of the various nutrient levels on the root

systems of plants grown in sand culture is shown in Figures 17 to 21.

 

 

Figure 16

Typical color of root systems under various treatments.

 

| IIIIIII'III I I!

 

Figure 17

Low nitrogen level - Root growth was stimulated by the low
nitrogen treatment. The lateral roots, however, were
considerably coarser in texture and fewer in number than
those induced by the check treatment. These roots had a
blackish-brown coloration as compared to the reddish-

brown check roots.

High nitrogen level - Lateral root development was inhibited
severely by solution levels of 525 ppm N. Correspondingly,
the entire root system was stunted. A considerable number
of dead roots were present, and the remaining roots were
dark brown to black in coloration.

 

Figure 17

Figure 18

Low phosphorus level - The 0 ppm phosphorus level stunted
root growth considerably. The fibrous root system was
characterized by being dark in color and having very
fine lateral roots.

High phosphorus level - Plants receiving 150 ppm phosphorus
developed a root system comparable on a dry weight
basis to that of the check. This root system, however,
was considerably lighter in color and finer in texture.

Lateral roots under high phosphorus treatment were
abundant from the base of the stem to the periphery of
the root system; whereas, the majority of lateral roots
of the check occurred close to the periphery of the root
system.

 

Figure 18

Figure 19

Low potassium level - Plants given a solution devoid of potas-
sium developed a considerably smaller root system than
the check. The fibrous roots were characterized by be
ing coarse textured and dark brown. The few lateral
roots present showed considerable dieback.

High potassium level - Maintaining 150 ppm potassium in solu-
tion resulted in a root system about the size developed
under the low potassium treatment. Root texture, color,
and lateral root growth, however, approximated that ob-
tained with the check solution.

 

Figure 19

P wl‘Pile I...I I I

Figure 20

Low magnesium level - Leaving magnesium out of the nutrient
solution resulted in a coarse fibrous root system having
only a few lateral roots near the periphery of the root
system. The color of these roots tended to be dark brown.
The lateral roots may have developed as a result of using
impure de-ionized water in late August.

High magnesium level - Increasing the magnesium level in
solution to 122 ppm caused the development of a dark
brown, very coarse, brittle root system. Lateral root
growth was definitely less than the check.

 

Figure 20

Figure 21

Low calcium level - The fibrous root system of plants re-
ceiving a solution devoid of calcium, although severely
stunted, showed considerable root development at the
terminal ends. This root growth presumably occurred
after contamination with impure de-ionized water in
August, 1957. The remaining portion of the root system
was dark in color, very coarse, and showed little lateral
branching.

High calcium level - Root growth was reduced below that of
the check by using 200 ppm calcium in solution. Also
lateral branching was reduced, and the root system was
considerably coarser in texture. In both Experiments
I and II root color under this treatment was considerably
lighter than the check.

 

Figure 21

Vermiculite as a Growing Media

Blueberry plants were found to grow extremely well in vermiculite
if supplied with sufficient nitrogen and phosphorus. Plants not receiving
nitrogen or phosphorus made very little growth in comparison to plants under
the remaining treatments (Figure 22). The plants, however, still had a
greater dry weight accumulation than plants grown in sand under all treat-
ments, except the 0 ppm nitrogen and 150 ppm phosphorus (Appendix Table 11).
Greatest growth response was achieved when the plants received solutions
devoid of potassium (Appendix Table 11 and Figure 22).

Although only one replication of plants growing in vermiculite was
used for comparison with sand grown plants, there were obvious indications
that leaf composition was influenced by treatment (Appendix Table 10). By
increasing the nitrogen supply from 21 ppm to 525 ppm in solution, the leaf
content of potassium was raised from . 778 percent to 1. 11 percent and boron
lowered from 241 ppm to 51 ppm. Increasing the nitrogen supply from 105
to 525 13pm did not alter the leaf content of nitrogen appreciably.

Raising the phosphorus concentration in solution did not increase the
phosI31'101':us content of the leaf, but high levels did result in the lowest iron
leaf content under any treatment.

Increasing potassium from 0 ppm to 150 ppm did increase the leaf

44.

Figure 22

Growth response of plants growing in vermiculite as influ-
enced by -N, -P, +K and check treatments”.

Top: 21 ppm nitrogen treatment in comparison to
Check treatment.

Middle: 0 ppm phosphorus treatment in comparison
to check treatment.

Bottom: 0 ppm potassium treatment in comparison
to check treatment.

*NOTE: Plants under the remaining treatments in Experiment 11
responded in similar fashion to that of the check.

 

Figure 22

content of potassium from . 819 percent to 1. 13 percent and the manganese
leaf content from 164 ppm to 226 ppm.

When the concentration of magnesium in solution was raised from 0 ppm
to 121 ppm, nitrogen was decreased from 2. 52 percent to 2. 31 percent and
boron from 280 ppm to 81 ppm. Magnesium, however, only showed a slight
raise.

By increasing the calcium content in solution the leaf content of nitro—
gen was reduced from 2. 53 percent to 2. 28 percent, magnesium from . 36 per-
cent to . 30 percent, and potassium from 1. 09 percent to . 894 percent. Iron,
on the other hand, increased from 357 ppm to 511 ppm. No appreciable in-
Crease in the calcium content of the leaf resulted when the calcium supply
was increased.

The only foliar symptoms indicative of a deficency to appear were

those of nitrogen and phOSphorus. These were observed shortly after initia-

tion of the low level treatments of these respective elements. No foliar

tOXicity symptoms resulted from the high levels of the nutrients studied.

46.

Experiment lll: Influence of the B, Mn, Fe, Cu and Zn Levels in Solution

The growth of plants in sand in Experiment III was not sufficient to ob—

tain significant differences between treatments. Definite trends, however.

in growth response to treatment did exist. This lack of growth of these

plants may have been due to the depletion of carbohydrate reserves during

the forced growth period in the fall of 1957. This apparent lack of reserve

carbohydrates was further intensified by initiating Experiment III in the

shade house.

The use of vermiculite as a rooting media resulted in greater growth
than that achieved in sand. The use of only two replications of these media.
however, proved inadequate to overcome experimental error. Consequently.
stati stical evaluations of growth response to treatment showed no signifi-

cant differences, even though distinct trends were apparent.

 

LEAF COMPOSITION

LEAF COMPOSITION

   

Significantly different:

LEAF NUTRIENT ELEMENT COMPOSITION AS INFLUENOED BY
THE BORON LEVEL IN SOLUTION

PERCENT DRY WEIGHT
IOO 4O

   

0.00 ..... PPM
0.50 ..... PPM
7.50 PPM

from cucumsx Psall'b
fmmhigha treottnentAatS'IAAAatl‘l-

 

GORON LEVEL

EXPERIMENT m — SAND

 

     

250 o
a
2 Mn
9
I:
§ r.
a
a
U .
a CU
3
-tcrnci)

  

PPM DRY WEIGHT

20 50 ISO 250 350 450

 

frotncheotitats‘b etatl$
fromhlgnS WAGS$AAOII$

EXPERIMENT m — VERMICULITE

PERCENT DRY WEIGHT
20 4O 60 80 I00 240

 

BORON L
0.00 ..... PPM
0.50 ..... PPM
7 50 . .. PPM

Significantly different:
from checkout 5% int: at PA
from high 8 treatment A at 5% AA at l'/.

280 320

    

EVEL

N
-(check)

LEAF COMPOSITION

 

PPM DRY WEIGHT

 

Significantly differutt:

Figure 23

frornchecktotS'b entrain.
from high 8 treatment Aat5% AAatIV.

   

47.

Leaf Nutrient Element Composition

Influence of the Boron Level in Solution (See Figure 23)

Sand Medium
By increasing the boron supply (0 to 7. 5 ppm) significant increases in

leaf content were obtained for boron (54 to 500 ppm), magnesium (. 35 to . 42
percent), and potassium (. 619 to . 906 percent).

Under the high boron treatment, notable but nonsignificant, decreases
below that found in check leaves were obtained for nitrogen (2. 78 to 2. 47 per-

cent) and copper (24 to 19 ppm).

Iron leaf levels increased nonsignificantly with either increasing or

decreasing boron supply. Only slight changes were noted in the leaf content

of manganese, phosphorus, and calcium.

Vermiculite Medium

With increased boron supply significant increases in leaf content of
boron (52 to 500 ppm) and potassium (. 688 to . 911 percent), similar to that
Observed in the sand medium, were obtained. Subsequently the calcium leaf

level, in contrast to sand medium, increased (. 54 to . 61 percent) and man-

ganese decreased (236 to 170 ppm). These changes, however, were not

Sign ificant.

Leaf levels of iron and nitrogen were in accord with that obtained

 

LEAF NUTRIENT ELEMENT COMPOSITION AS INFLUENCED BY
THE MANGANESE LEVELIN SOLUTION

EXPERIMENT m —$AND

PERCENT DRY WEIGHT

LEAF COMPOSITION
x

MANGANESE LEVEL

Significantly different-
from chechtot5% "I at I56
from high Mttreattnent A at 5% AA atl%

     

PPM DRY WEIGHT
I50

250 350 450

      
   

  
 

B

2M0

9 :

t .

In .

8 F°.

3

O

o ,

IL CU '

" MANGANESE LEVEL

In

“ o.oo ..... PPM
0,50 ..... -(m)
7.50 ..... m

Significantly different:
from check 1II at 5% H! at l‘/.
from high Mntreatment A at 5% AA at 1'1.

EXPERIMENT III — VERM/CUL/TE

PERCENT DRY WEIGHT
.80

E .

E P

o

3

3w
MANGANESE LEVEL
0.00 ..... PPM

Co 0.50 ..... -(chectI)

7.50 ..... P m

Significantly different:
from checksot5’l. we at l’/.
from high Mn treatment A at 5% AA at 1%

Figure 24

 
   

PPM DRY WEIGHT
0.. 42er [sag/enema“

       
 

e
z
9
':
II)
2 Fe
5
0
EC" ,,,,, MANGANESE LEVEL
T‘ 000 ..... PPM .

Significantly different
from check It! at 5% In: at W.
from high Mn treatment A at 5% A A at IV.

in the sand medium under the same treatment.

Copper phosphorus and magnesium leaf levels were not appreciably

influenced by varying the boron supply.

Influence of the Manganese Level in Solution (See Figure 24)

Sand Medium

As the manganese level in solution increased (0 ppm to . 5 ppm to 7. 5

ppm), the leaf content of manganese increased significantly from 65 ppm to

182 ppm.

A sharp decrease in the leaf content of magnesium (. 40 to . 30 percent)

was induced by 7. 5 ppm manganese in comparison with . 5 ppm manganese in

solution.

The remaining elements changed only slightly under the various levels

of manganese in solution.

Vermiculite Medium

Phosphorus and iron significantly increased when the solution content of
manganese was raised or lowered.

By increasing the manganese level in solution, nonsignificant decreas—
ing tI‘ends existed for nitrogen, potassium, boron and copper; while an increas-
ing trend existed for manganese. Magnesium and calcium leaf levels showed

1' .
mle Change as the solution content of manganese was altered.

48.

LEAF NUTRIENT ELEMENT COMPOSITION AS INFLUENCED BY
THE IRON LEVEL IN SOLUTION
EXPERIMENT m — SAND
PERCENT DRY WEIGHT PPM DRY WEIGHT
20 40 60 80 logggo 2'80 320 0 20 50 I50 250 350 450

 
  
  

   
  

   
   

         

2 i
2
a 3 Mn:
2 t
3 § r
0 .
3
a u
M : GU .
~' ° neon LEVEL 3 -,: mom LEVEL
o....m - o....PPii
5....PPM -iciiocii) 5....m I-checll
75...PPM - 75...?” B
Significantly dittetent' SIgnIflaantty diffetent:
tvomchecktot5‘l. tioll$ frotnchecttat5‘l. Otml‘
framhighFetreattnentAotfi‘l-AAatIV. froinhigtiFetieatMAat5'lAAAatl'k
EXPERIMENT m — VERMICULIYE
PERCENT DRY WEIGHT PPM DRY WEIGHT
20 497 so g 60 IOO .249 280 7 320 o
3
t 2 Mn
i 3 '
III
I 2 Fe
8 z
0
fi 0
In Cu
4 u : IRON LEVEL '5 :
0.. . .PPM [:3 4
5. . . . PPM -(checl)
75. . . PPM m
significantly different Significantly different
from check # at 5% IN: at I96 ftom check It at 5% e. at
inin high Fe treatment A at 5% AA at W. from high Fe tnotment A at 5']. AA of”.

Figure 25

49.

Influence of the Iron Level in Solution (See Figure 25)

Sand Medium

With increasing iron content in solution (0 - 5 - 75 ppm), nitrogen de-
creased progressively from 3. 02 to 2. 62 percent, while phosphorus increased
from . 29 to . 32 percent. Neither element, however, changed significantly.

The 75 ppm iron treatment, in contrast to check, depressed signifi-
cantly the leaf content of potassium (. 710 to . 622 percent) and magnesium
(92 to 43 ppm). The iron leaf level was not decreased with 0 ppm, but sub-
sequently increased from 160 to 227 ppm when 75 ppm iron was used. This
increase was not significant.

Boron levels were significantly higher in leaves under the 0 ppm than
under 5 or 75 ppm iron treatment.

Vermiculite Medium

The depressing effect of increasing iron availability on leaf manganese
(274 to 67 ppm) was more pronounced in vermiculite than in sand. As in
sand medium, nitrogen leaf content was higher (3. 02 percent) with 0 ppm iron
than with 5 ppm (2. 76 percent) or 75 ppm iron (2. 82 percent).

The 75 ppm iron content in solution, as compared to the 5 ppm iron
SOlIIti0n content, lowered the leaf content of magnesium (. 30 to . 25 percent)
and Calcium (. 57 to . 50 percent), but raised the iron (147 to 291 ppm) and

phosphorus (. 23 to . 30 percent), as well as potassium (. 780 to . 803 percent)

 

 

 

LEAF WTRIENT ELEMENT COMPOSITDN AS mrLueuch BY
THE COPPER LEVEL IN SOLUTION
EXPERMIENT m —$AND
PERCENT DRYWEIOIT PPM DRY WED"
.29 4O .69 .89 IOO £40 2 80 3.20 O

   
 
  

  

:- ':-:-:-:-:-:-:-:-:-:-:-...,._ -:

  

 
  

 

. Caz-:-
"""" .. COPPER LEVEL ':;:;:;
. moo ..... PPM
. W 0.02 ..... PPM -icn.cio
.5-531'3-00 ..... PM -
Siwlftcontty diffennt= w afferent:
Imm¢¢D$ OOMI% MMtd5$ .‘dl‘
fnmhtfiCumA¢5%AAotl% MWCMWA¢5SAAMWA
EXPERIMENT m— VERMICILITE
PERCENT DRY WEIGHT PPM DRY WEIGHT

.20 .40 .60 .80 IOO .240 2.90 320
i i i r 4-rv f Vi r

     

COPPER LEVEL

“W 832:3:533 ma...)
3.00 ..... PPM m

   
    
  

SWIcantIy different: Significantly altfennt:
frotndiecktd5‘b t. otl$ tmnchectitatfls ttdl‘l
fioinhighCutieotmemAatMSAAatl‘l. fmnhighCiitveatmentAatS'LAAotIV.

Figure 26

mum S
is

ti”

Content. The influence upon phosphorus and iron were significant.
Boron increased nonsignificantly, with either increasing or decreasing

iron supply.

Influence of the Copper Level in Solution (See Figure 26)

Sand Medium

Varying the copper content in solution resulted in no significant
changes in leaf composition. There was, however, some indications that
nitrogen and calcium decreased and copper increased with increasing levels
of Copper in solution.

Vermiculite Medium

Increasing the copper level in solution resulted in an increase in the
leaf content of nitrogen (2. 70 to 2. 99 percent), copper (16 to 19 ppm), and
boron (119 to 241 ppm), and decrease of calcium (. 60 to . 50 percent), and
manganese (265 to 182 ppm). Only boron, however, changed significantly.

The leaf level of iron increased as the solution content of copper in-
Cl‘eased or decreased. The increase of iron that occurred when the copper

Supply decreased from . 02 ppm to 0 ppm was significant.

 

 

LEAF NUTRIENT ELEMENT COMPOSITION A5 INFLUENCED BY
THE ZINC LEVEL IN SOLUTION

EXPERIMENT III —$AND
PERCENT DRY WEIGHT PPM DRY WEIGHT

29 49 so 39 todgao 2'80 320 o 20 so I50 250 340 450

      

 

 

 

            
   
 

N .
S .
P P -:-:.:-:-;-:-:-;-: 2
S :3:1:1:1:1:1:3:?:3:3 Q
3 K ‘ I'I'I'Z'I'I'l'Z'I'I‘i'I'I'I'I'Z'I':PI’I‘I'I’I‘I‘I‘I’ gt“
0 313:1:313:3:1133323:1:3:3:?:3:?:3:3:3:3:3:3:-:1:1:3:3:i; 3
3 . .. u
4 Mg -:-:-:-:-::-:-:-:;:;:;:;:
12313125133511: ZINC LEVEL 3 2m LEVEL
g mm ..... an an a rw
c0 .;.;.;.;:;.;I;.;.;.;.-I;.;:;.;.;.;.;: 005.. .PPM =(Cm, O 06 .PPM -(MI
'1:35353:3:323:3:1:?33§3:3:1:323:1:5.513: 075- PPM 0.75.. .PPM -
Significantly different: Significant” gum:
fromctiecliittot5'lc ttotl'b touchedtot5% itatl'b
fromhiwtlntnottnentAOtS'IoAAotIVA fmhlghlllWAd5%AAotl%
EXPERIMENT m - VERMICILITE
PERCENT DRY WEIGHT PPM DRY WEIGHT
.29 40 60 80 IOOVQQO 2 80 320 0 £2,413 I50 250 359 450

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LEAF COMPOSITION

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:::_:_:-:_:::_; I'm LEVEL
0.75....PPM -

 

Significantly different significantty different:
fromcheclutrat5'lctitiotl‘h TMCDOCR*OIS% titiotl'b
from high In treatment A at 5% AA at I‘/. from high In treatment A of 5% AA ofl'lo

Figure 27

Influence of the Zinc Level in Solution (See Figure 27)

Sand Medium

 

A significant increase in the leaf content of boron (181 to 248 ppm)
resulted when the zinc level in solution was increased. The increase in
leaf nitrogen (2. 67 to 2. 83 percent) that occurred with increased zinc levels
in the solution was not significant.

Magnesium leaf levels were lowered significantly by increasing or
deCreasing the zinc supply.

Only slight variations in leaf concentrates were exhibited by the re-

rhaiming elements that were analyzed.

Vermiculite Medium

 

Nitrogen increased, but not significantly, when the zinc content in

SOlution was increased from . 05 ppm to 7. 5 ppm. Phosphorus, however.

Ht

nCI‘eased significantly with increasing or decreasing zinc supply.
Other nutrients showed nonsignificant variations. However, leaf
1eVels of boron and manganese were lowered and iron raised by the addition

of Zinc to the nutrient solution.

Foliar Symptoms

Plants growing in sand developed a considerable number of foliar dis—
orders of a chlorotic nature that were not confined to any one treatment. They
were also not apparent in the vermiculite medium or in preceding experiments.
Characteristic foliar disorders were induced by the 0 ppm boron, 7. 5 ppm
manganese, and the 7. 5 ppm zinc treatments.

Plants growing in vermiculite developed only boron toxicity symptoms,
although they were considerably more vigorous and contained less boron and
more manganese in their leaves than similarly treated plants in sand.

Descriptions of the treatment induced are as follows:

Boron Deficiency (See Figure 28): Tip leaves of actively growing

 

shoots suddenly ceased to enlarge. This cessation of leaf expansion was fol-
lowed by a slight interveinal chlorosis localized along the leaf margin. Accom—
panying the leaf disorder was a dying of the terminal growing point.

The boron level in leaves of plants exhibiting these symptoms was 54
ppm. Check leaves, in comparison, registered a boron content of 199 ppm.

Although plants growing in vermiculite under the 0 ppm boron treat-
ment did not show foliar symptoms, their leaf content of boron was 52 ppm.
Check plants in vermiculite had a leaf content of 170 ppm boron.

Boron Toxicity (See Figure 28): Boron toxicity appeared initially on

 

basal leaves and developed acropetally. The disorder appeared as a mottled

Figure 28

Top - Boron deficiency
Bottom left - Boron toxicity

Bottom right - Boron toxicity

 

53.

interveinal chlorosis followed by a light brown marginal scorch. This
scorch proceeded to envelop the entire leaf blade with increased severity
of the toxicity. Leaf drop did not occur until the entire leaf was scorched.

Leaves from affected plants contained 500 ppm boron regardless of
rooting medium.

Copper Toxicity (See Figure 29): Tip leaves of plants which were
receiving 3 ppm copper in solution developed a blanched appearance. This
chlorotic condition extended from the leaf margin to the midrib. The basal
portions of the primary lateral veins and the midrib, however, remained
green. At the time the experiment was terminated, the leaves of these plants
were exceptionally easy to detach.

Chemical analyses of leaves from these plants indicated a copper
content of 25 ppm as opposed to 24 ppm in the check, and 20 ppm in the leaves
Of plants receiving solutions devoid of copper.

Manganese and Zinc Toxicity (See Figure 29): The interveinal chlorosis
resulting from high levels of these two elements were indistinguishable. The
disorder only appeared on those plants growing in sand. Terminal leaves
Were affected initially, and the condition progressed basipetally. The mid-
rib and, contrary to copper toxicity, nearly the entire length of the lateral
Veins remained green. As the condition increased in severity, a few small

red necrotic spots appeared. A faint marginal reddening accompanied the

development of these spots.

Figure 29

Top - Copper toxicity
Bottom left - Manganese toxicity

Bottom right - Zinc toxicity

 

A manganese leaf content of 182 ppm was associated with the chlorotic

leaf condition induced by the high manganese treatment. Check leaves con-

tained 92 ppm manganese.

Although higher manganese leaf levels were obtained in Experiment II,
only a manganese leaf content of 339 ppm induced a chlorotic leaf condition.

Plants in Experiment III growing in vermiculite also did not develop
fol iar symptoms of manganese toxicity, even though their leaf content of
manganese was considerably higher than that found in sand. Those plants
receiving the high manganese treatment had a leaf content of 280 ppm man-

ganese, in contrast to check leaves containing 210 ppm manganese.

No zinc analyses were performed.

 

Plant Growth

Rooting medium did not appreciably influence growth responses to

treatment. Greater growth of the plants in vermiculite, however, resulted

in a considerable increase in magnitude of response. Growth data are pre-

sented in Figures 30 and 33, and in Appendix Tables 13 and 15.

fluid Medium
Top dry weight (See Figure 30): Moderate to severe retardation of
tOp growth resulted when boron was left out of the nutrient solution, or when

excessive amounts of manganese, iron and zinc were added to it. Response

to the remaining treatments was not appreciably different from the check.

Root dry weight (See Figure 30): All treatments resulted in a lower

root dry weight than the check. The 0 ppm iron and 3 ppm copper treat-
ments exerted the least inhibiting effect, while 0 ppm boron and 7. 5 ppm
zinc resulted in the greatest decrease in root dry weight.

Treatment influence on root dry weight did not coincide exactly,

however, with its influence on root texture. As shown in Figure 31, few

differences can be observed between the minus treatments and the check.

In Figure 32, the coarse root texture induced by high levels of iron, man-

ganeSe and zinc is readily discernible.

 

Figure 30

Growth of plants in sand as influenced by the 3. Mn, Fe,

Cu and Zn level in solution.

TREATMENT

TREA Tiff IV 7

Growth as influenced by the 8, Mn, Fe, Cu and Zn level in solution

EXPERIMENT m SAND

TOP DRY WEIGHT - GMS.
6 7 8 9 IO

 

 

CHECK J

W

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Mn

        
       

0

Cu

Zn

LOW &\\\\\\\

HIGH M
NO SIGNIFICANT DIFFERENCE

TREAT. LEVEL

ROOT DRY WEIGHT - GMS.
0.5 I!) 2.5

I I

 

CHECK J

W

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M,

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Low k\\\\\V

TREAT. LEVEL HIGH m
NO SIGNIFICANT DIFFERENCE

TREATMENT

T

TRE A TME N

Figure 30

TOTAL DRY WEIGHT-GMS.
8 9 IO II I2 l3

 

 

CHECK J

 

 

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LOW \\\\\\§

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NO SIGNIFICANT DIFFERENCE

TREAT. LEVEL

DRY WEIGHT ACCUMULATION-GMS
3 4 5 6 7

T I I I I

m
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Mn
Fe
Cu

Zn

00000000
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LOW m
HIGH m

NO SIGNIFICANT DIFFERENCE

TREAT. LEVEL

 

Figure 31

Influence of the low B, Mn, Fe, Cu, Zn and check treat—

ments on root development in sand culture.

 

 

   

din

Figure 31

F" I.

Figure 32

Influence of the high B, Mn, Fe, Cu, Zn and check treat-
ments on root development in sand culture.
Note coarse texture of the high Fe, Mn and Zn treat-

ments in comparison to the check treatments.

 

*Zn

”In

Figure 32

56.

Total dry weight (See Figure 30): All treatments, except 3 ppm
copper, reduced total dry weight noticeably below the check. The low boron
and high manganese, iron, and zinc treatments resulted in the most severe
reduction of weight.

Dereight accumulation (See Figure 30): Plants receiving solutions
devoid of iron or zinc, or high in copper, accumulated appreciably more dry
matter than the check; while those plants receiving no boron or excessive

manganese accumulated less dry matter than the check.

Vermiculite Rootig Medium

The growth response to treatment of plants growing in vermiculite
was of the same magnitude for all growth measurements (Figure 33).
Severe reductions in growth were induced by high levels of manganese,

iron and zinc. Less severe reductions resulted from the high and low boron

and the low manganese, copper and zinc treatments.

Similar growth responses to that of the check were obtained with
solutions high in copper. Only plants receiving the 0 ppm iron solution

made greater growth than the check.

Figure 33

Growth of plants in vermiculite as influenced by the B, Mn,

Fe, Cu and Zn level in solution.

TREATMENT

TREATMENT

Growth as influenced by the B, Mn,Fe,Cu and Zn level in solution

EXPERIMENT III VERMICULITE

TOP DRY WEIGHT - GMS.
O 5 IO IS
I I I

 

 

CHECK j

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Cu

 

 

Zn§§§§§§§§§§§§

I J

LOVI §§§§
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NO SIGNIFICANT DIFFERENCE

l l L

TREAT. LEVEL

ROOT DRY WEIGHT- GMS.

 

 

 

 

012:???
CHECK 1
a

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LOW’ §§§§
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NO SIGNIFICANT DIFFERENCE

TREAT. LEVEL

ffigun333

20 25 30
I I I

TRE ATME N T

TREATMENT

IWn

Fe

Cu

Zn

5 I0 I5
I 1

TOTAL DRY WEIGHT-GMS.
20 25 30 35
T I I I

 

 

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§§§§§§§§§§§

 

l I l L l 1
LOW' §§§§
TREAT. LEVEL H'GH m

NO SIGNIFICANT DIFFERENCE

DRY WEIGHT ACCUMULATION-GMS.

 

 

 

 

<3 s l0 n: In) 2? no
CHECK ]
3..

0000000000000000
00000000000000000

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Fe

Cu

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No SIGNIFICANT DIFFERENCE

TREAT. LEVEL

57.

Experiment IV: Seasonal and Field Nutrient Disorder Studies

 

General Observations

During the late spring and early summer portion of the 1957 grow-
ing season considerable rainfall occurred in the blueberry producing areas
of Michigan. As a result, excellent growth was made in the majority of
the blueberry fields.

Consequently,the vigorous growth and the accompanying high soil
moisture aggrevated a potential, but at the time unknown, shortage of mag-
nesium in all but a few blueberry fields. Subsequently, foliar expression
of magnesium deficency occurred in two Rubel plots (plots 35 and 49) pre-
viously considered free of nutrient disorders.

The Rubel bushes constituting plot 35, in addition, were of lower
vigor and had considerably smaller leaves than other Rubel plots in the
seasonal survey. The keeping quality of fruit harvested from this plot was
extremely poor?

Seasonal Influence on Leaf Composition

Definite seasonal trends existed for all nutrient elements in blueberry
leaves, except boron. The data pertaining to these results are presented in
Figures 34 and 35, and in Table I. Additional information is presented in

Appendix Table 16.

*Evaluation of fruit from this plot was made by Richard Woodruff during a
cooperative shelf life experiment.

Nitrogen decreased in the leaf as the season progressed from 2. 86
percent to l. 96 percent. The greatest decrease (2. 86 to 2. 17) occurred
from June 15 to July 12. From July 12 to August 9 little change in leaf
nitrogen occurred. - During the period August 9 to September 5, nitrogen
decreased from 2. 21 percent to l. 96 percent.

Phosphorus decreased in the leaf from . 21 percent on June 15 to . 16
percent on July 12. No further significant changes occurred during the re-
maining portion of the season.

Potassium in the leaf showed a significant biweekly decrease (. 712
to . 507 percent) from June 15 to July 27. Thereafter, only small nonsignifi-
cant decreases occurred until September 5, at which time potassium in-
creased to a level significantly above that of the previous sampling date,
August 22.

Magnesium increased in the leaf from . 19 percent to . 33 percent
during the period June 15 to August 22. The largest increase (. 24 to . 33 per-
cent) occurred during, and immediately following, the harvest period (July 27
to August 22).

The leaf content of calcium remained at about . 38 percent from June 15
t0 July 12. Subsequently, it increased biweekly to a high of . 60 percent on

September 5.

Although manganese tended to increase as the season progressed. it

Figure 34

Seasonal influence on leaf content of N, P, K, Mg and

Ca (percent dry weight).

PERCENT DRY WEIGHT

2.“)

2.60

2.40

2.20

2.00

.40 _ (Calcium f:

  
  

Seasonal influence on leaf content of
N, P,K,Mg, ond Co —- percent dry
weight

L.S.O. forN ‘

 

5% l%
D U L.S.D. forK

Potassium

5 '5
U D L.s.o. forCo

 

 

 

 

 

 

h Magnesium: / T
.20 >¢Z 50]. Pl.
[:1 D L.S.D. for M9
. Phosphorus }
.00 ’3‘, Blue 0. forl P l . l J
I5 29 I2 26 9 22 5
JUNE JULY AUGUST SEPT.

LEAF SAMPLING DATE

Figure 34

Figure 35

Seasonal influence on leaf content of Mn, Fe, 3. Cu and

Zn (parts per million of dry weight).

 

PARTS PER MILLION

 

 

 

 

 

 

 

 

 

 

 

 

 

 

340" Seasonol influence on leaf content of
.. Mn.Fe,B,0u, and Zn-ports per million
of dry weight
300
1%
260
220
I80 - L
_ / ' ‘
sss
”o" use. for Fe
_ Iron
I00 [
Tol- J
- PI.
50 .. Boron a
' L.S.D. for a [J
30%
20]-
Copper
use for Cu ’3 '3
/ T“—
IO " \
.. Zinc/ 9% |
L.s.o for Zn [1
o l l l l l LJ
I5 29 I2 26 9 22 5
JUNE JULY AUGUST SEPT.

LEAF SAMPLING DATE

Figure 35

appeared that leaf levels of this element were affected more by soil mois‘
ture than by seasonal effects. During dry periods manganese decreased to
as low as 207 ppm, and increased to as high as 341 ppm in wet periods.
This was particularly true with the Jersey variety of blueberry, which ac-
cumulated far greater amounts of manganese in the leaf than did the Rubel
variety. A comparison between the manganese leaf content of these two
varieties is presented in Table I.

The leaf content of iron, with the exception of the June 30 sampling,
increased gradually from 1.28 ppm on June 15 to 177 ppm on August 22.

Boron leaf levels varied significantly during the season, bUt showed
no explainable trends. The leaf content of boron was considerably higher,
regardless of date or variety, than that found in previous years on the same
plots (Appendix Table 23).

Copper levels in the leaf decreased slightly as the season progressed.
A high of 15 ppm copper was obtained in leaves sampled June 15 and a low of
12 ppm was obtained on September 5. The decrease, although small, was
significant.

The zinc content of blueberry leaves increased from 9 ppm on June 15
to 13 ppm on July 26. Subsequently, it decreased to a final level of 7 ppm

on September 5.

TABLE I

60.

Nutrient Element Composition of Blueberry Leaves as Influenced by Variety -

Percent Dry Weight

 

 

I
r‘fi

Leaf Composition

 

 

Variety
N P K Mg Ca B Mn Fe Cu Zn
Rubel 2. 30 .17 . 546 . 25 . 45 . 0064 . 0210 . 0152 . 0014 . 0010
Jersey 2. 23 . 18 . 562 . 26 . 49 . 0053 . 0342 . 0153 . 0014 . 0010
N. S. N. S. N. S. N. S. N. S. N. S. *"‘ N. S. N. S. N. S.

 

 

WJersey significantly higher at the 1 percent level of significance.

61.

Seasonal Influence on Fruit Composition

Although the concentrations of all nutrient elements declined as the
fruit matured, considerable differences in the magnitude of decline existed
between elements. Data pertaining to this survey are present in Figures
36 and 37, Table II, and Appendix Table 17.

Greatest decline of all elements occurred from June 15 to July 26
(Figures 36 and 37). July 26 marked the beginning of the harvest period,
after which fruit composition showed only slight changes in composition.

The most rapid decline during this period was registered by the
manganese level which decreased 73 percent. Slightly less rapid declines
prevailed for boron (61 percent), calcium (59 percent), phosphorus (55 per-
cent) and nitrogen (54 percent). Magnesium decreased moderately, while
slow declines were evident for iron (29 percent), copper (24 percent), and
potassium (20 percent). These decreases were all significant.

From July 26 to August 22, slow declines were apparent for all ele-
ments, except iron and copper. During this period, iron levels showed
significant, but unexplainable fluctuation, whereas copper levels remained
steady.

Samples collected on August 22 and September 5 consisted only of
mature fruit and showed no change in nutrient composition except for potas-
sium. Potassium showed a definite, but nonsignificant, increase from August

22 to September 5.

Figure 36

Seasonal influence on fruit content of N, P, K, Mg and

Ca (percent of dry weight).

ligand

PERCENT DRY WEIGHT

2.20

200 P
l.80 -
1.60 -
L40 -
I20—
LOC-

.60 -

.30

.20 -

  
  

Seosonol influence on fruit content
of N, P, K, Mg, 0nd Co — percent of
dry weight

°/.
5%
L.S.D. for N H

 

Potassium/ ‘

   
   
    

 

5% m
L.S.D for K D
57. '7'
PhO’phOfus LS.D. TOT co D U 50,.
LSD. for P U
.IO ’MOQDOSIUIII

 

 

.00

 

 

L.S.D. for Mg 5.3% '3
l

I I

l

 

JUNE JULY AUGUST SEPT,

FRUIT SAMPLING DATE

Figure 36

Figure 37

Seasonal influence on fruit content of Mn, Cu, Fe and B

(parts per million of dry weight).

PARTS PER MILLION

   

 

 

 

 

 

 

 

 

 

 

I30 -
l20
Seosonol influence on fruit content of %
Mn,Cu,Fe, and B — ports per million '
no _ of dry weight PI
5% l
0 :
IOO r Mongonese g
90 -
LS D for Mn
80 l-
L L
70 -
60 -
its
595
5° " [l L.S.D. for Fe
Iron
40 r
30
20 I'L
sss
L.S.D. for B
'0 /Copper *
sss ~—
U L.S.D. for Cu
O l 1 1 l 1 4
I5 29 I2 26 9 22 5
JUNE JULY AUGUST SEPT.

FRUIT SAMPLING DATE

Figure 37

 

 

 

62.

Variety, in addition to date of sampling, exerted considerable influ-
ence on fruit composition. There were higher levels of potassium and nitrOc
gen and lower levels of calcium, magnesium, and manganese in Rubel fruit

than in Jersey fruit. This is shown in Table 11.

Nutritional Disorder Survey

The environmental conditions that promoted the vigorous growth of
blueberry plantings in 1957 may have stimulated the occurrence of nutrient
disorders other than magnesium deficiency. Foliar symptoms ascertained
to be the result of nutrient disorders are illustrated in Figures 38 to 42.
Chemical analyses of leaf and fruit samples associated with the particular
nutritional are presented in Appendix Table 20.

Magnesium deficieng: This disorder was the most prevalent

 

nutrient disorder observed in 1957. Noticeable differences in the foliar ex-
pressions of the deficiency existed between varieties Rancocus, Rubel and
Jersey. These differences are illustrated in Figure 38.

(Coupled with these foliar differences were noticeable distinctions in
the degree of susceptibility of these varieties to magensium deficiency.

In plantings known to be low in magnesium, Rancocus was found to
be most severely affected, Rubel less so, and only in a few cases did Jersey

exhibit foliar symptom s.

63.

TABLE II

Nutrient Element Composition of Blueberry Fruit as Influenced by Variety —
Percent Dry Weight

 

1 ‘-
4

Nutrient Element Composition

 

 

Variety N P K Mg Ca B Mn Fe Cu

Rubel l. 36 .14 . 731 . 061 .123 . 0021 . 0036 . 0038 . 0007

Jersey 1. 29 . 14 . 664 . 069 . 174 . 0021 . 0075 . 0039 . 0008
N. S. N. S. *"‘ N. S. "‘ N. S. ”“3 N. S. N. S.

 

“Jersey variety significantly different in fruit composition from Rubel
variety.

Figure 38

Top left - Magnesium deficency symptoms on the Rubel
variety of blueberry. Chemical analyses of the normal
medial leaves (BL 54) and basal leaves (BL 56) exhibit-
ing symptoms of the same shoots are presented in
Appendix Table 20.

Top right — Magnesium deficiency on partially shaded leaves
of the Jersey variety of blueberry. Chemical analyses
of these leaves (BL 132) are given in Appendix Table
20.

Bottom left — Magnesium deficiency symptoms on blueberry
bushes of the Rancocus variety that were interplanted
with the Rubel bushes described above.

Bottom right - Extreme case of magnesium deficiency on
Pemberton blueberry bushes.

 

 

 

64.

The expression of magnesium deficiency on the Jersey variety also
differed according to shoot vigor. These differences are presented in
Figure 39.

As previously noted in greenhouse studies, the foliar expression of
magnesium was altered by the amount of solar radiation received by the leaf
prior to the appearance of the symptom. As shown in Figure 39, the change
from red to yellow to necrotic areas correspond to the amount of shade im-
posed on these leaves by their position on the shoot which arose from the
center of the bush. Figure 39 illustrates the effect of extreme shade.

Chemical analyses of green leaves (BL 130). red leaves (BL 131) and
yellow and necrotic leaves (BL 132) are presented in Appendix Table 20.

With leaves low in phosphorus (. 12 percent) and low in magnesium
(. 07 percent), the expression of magnesium deficiency was considerably
different but still recognizable as such. Figure 39 shows this complex con-
dition.

Temporary flooding effects: In fields flooded more than five to seven

 

days by late spring and early summer rains, foliar patterns, illustrated in
Figure 40, were observed. Leaf analyses of these leaves indicated extremely
low nitrogen and phosphorus (BL 55).

Manganese toxicity: Jersey plants grown in excessively wet areas

 

developed foliar symptoms which, on the basis of leaf analyses (BL 153),

 

 

Figure 39

Top left - Magnesium deficiency on leaves taken from a
slow growing shoot arising from within the bush.

Top right - Magnesium deficiency on leaves taken from a
rapidly growing sucker shoot arising from the base
of the plant.

Bottom left - Magnesium deficiency on shaded basal leaves
of shoots arising from within the bush.

Bottom right - Magnesium deficiency symptoms complicated
by phosphorus deficiency.

 

 

 

appeared to be the result of excessive accumulations of manganese. Figure
41 shows this phenomenon.

Phosphorus deficiency: Symptoms closely resembling phosphorus

 

deficiency as developed in pot culture were observed in a four-year-old
planting on virgin ground in the Fruitport area (Figure 40). Leaf analyses
(BL 58) of these leaves indicated a phosphorus content of . 12 percent.

General fertilizer toxicity on light soils: In one field the apical por-

 

tion of the leaf blade showed an interveinal chlorosis (Figure 41). As the
condition increased in severity, dark brown necrosis developed on the leaf
margin. The symptom appeared initially on basal leaves and progressed
acropetally. Toxicity symptoms of the basic cations developed in pot culture
bore a resemblance to these field symptoms. Chemical analyses of these
leaves (BL 61) registered a nitrogen content of 3. 62 percent and a potassium
content of l. 79 percent, which was much above the average values.

Potassium accumulation in tip leaves: The accumulation of potassium

 

in tip leaves resulted in an interveinal chlorosis. This accumulation appar—
ently can be stimulated by more than one factor.

In several fields, terminal leaves of shoots growing under dense
shade exhibited the chlorosis illustrated in Figure 41. The potassium content
of these leaves (BL 82) registered 1. 28 percent, while exposed tip leaves (BL 81)
on the same plants registered . 313 percent.

Potassium accumulation in tip leaves also was found to take place when

an apparent shortage of calcium existed. An illustration is presented in Figure 42.

Figure 40

Top left - Leaf showing phosphorus deficiency.

Top right - Young plant exhibiting phosphorus deficiency
symptoms. Leaf analyses presented in Appendix
Table 20 as sample BL 80-57.

Bottom left - Note acute petiole angle that was apparently
associated with phosphorus deficiency.

Bottom right - Leaf symptoms induced by temporary flood-
ing. Leaf analyses indicate low nitrogen and phos-
phorus. Leaf analyses presented in Appendix
Table 20 as sample BL 55-57.

 

Figure 41

Top left - Apparent manganese toxicity resulting from
prolonged exposure to excess soil moisture. Leaf
composition presented as sample BL 50 in Appendix
Table 20.

Top right - Apparent toxicity resulting from over fertili-
zation on a dry sandy planting site. Leaf composition
given as sample Bl 61-57 in Appendix Table 20.

Bottom - Interveinal net chlorosis apparently resulting
from the accumulation of basic cations in tip leaves
subjected to extreme shade. Chemical composition
given in Appendix Table 20. See sample BL 82-57.

 

Figure 42

Sensitivity of the Rubel Highbush Blueberry to Apparent Excessive
Fertilization when grown in a soil of low pH.

Top left - Bushes appeared excessively vigorous. Analyses

of medial leaves from these bushes are presented as
sample Bl 58 of Appendix Table 20. Soil tests indicated
a ph of 3. 5 (Ballinger 1957, personal correspondence).

Top right - Considerable tip dieback or previous season‘s

Middle

Middle

Bottom

terminal shoot growth was apparent.

left - Excessive lateral shoot growth was stimulated
by dieback of the previous season’s shoot tips.

right - Light yellowish-green tip leaves showed a faint
net chlorosis. Scorching of the apical portion of the
leaf blade was evident in many cases. Leaf analyses
of these tip leaves are given as BL 84 in Appendix
Table 20.

~ Poor keeping quality fruit on right taken from bushes
described above. Illustration represents state of fruit
72 hours after harvest. Chemical analyses of poor
keeping quality fruit (BF 64) and good keeping quality
of fruit (BF 70) are presented in Appendix Table 20.
Good keeping quality fruit taken from bushes growing
in soil of pH 4. 7 (Ballinger 1957, personal corres-
pondence).

 

 

66.

DISCUSSION

Only small differences in leaf composition of N, P, K, Mg, Ca, Cu,
and Zn, under a given set of environmental conditions, may separate that
level which can be considered deficient from that which is in excess. This
narrow range appears to reflect the stringent nutritional requirements char-

acteristic of the blueberry.

The leaf content of manganese, boron and iron, however, does not
fall into a narrow concentration range. The leaf levels of these elements
appeared to be proportional to the external supply. This was clearly illus-
trated for manganese and boron in Experiment III. Plants deficient in boron
registered 54 ppm boron in the leaf. In the same experiment, a six fold
increase in leaf content of boron induced no apparent toxicity symptoms,
while a ten fold increase proved toxic. Manganese appeared toxic when leaf
concentrations were double that found in check leaves. Whereas, an iron
Content of 162 ppm in leaves was associated with excellent growth, plants
having an iron leaf content of 227 ppm were stunted. As to how low an iron
leaf content may be before a shortage of iron exists was indicated by Cain
(1954). He associated iron deficiency with a leaf content of 60 ppm iron or
less with the Jersey variety in sand culture.

Although foliar analyses may be used successfully as a measure of

determining the nutritional status of the highbush blueberry, the existence of

only a narrow nutrient composition range between that which would be con-
sidered normal and that indicative of a shortage or excess necessitates a
high degree of care in the collection and analyses of leaf samples.

Differences of intensity and balance in leaf composition and growth
due to treatment between Experiments I and II may reflect the cumulative
effects of difference in age of plant, influence of sand medium on vigor, and
the environmental conditions associated with each experiment. Of all these
influences, however, light may have exerted the greatest effect. This asser-
tion is based on the apparent sensitivity of the blueberry to light as indicated
by its response to quality of light and amount of solar radiation in these studies,
and by the definite day length required by the blueberry, as shown by Perlmutter
and Darrow (1942).

The sensitivity of the blueberry to light was apparent in the concurrent
studies in several ways. Early in Experiment I, under the same fluorescent
lighting, which was adequate for good strawberry growth, blueberry plants
failed to grow. A change to incandescent lighting resulted in a marked growth
response. The occurrence of foliar deficiency symptoms of nitrogen and phos-
phorus and the characteristic expression of magnesium deficiency also showed
marked dependence on the amount of solar radiation received. Growth response
to varied levels of potassium, in addition, were apparently altered by the pre-

vailing amount of solar radiation. These particular plant responses to light

may indicate that there is an increased requirement for most nutrient ele-
ments, except potassium, as the amount of solar radiation increases. Corres-
pondingly, there is an increased requirement for potassium when the amount
of solar radiation decreases. The need of changing the nutrient-element bal-
ance in solution with changes in solar radiation to maintain a suitable nutrient—
element balance in the plant was over emphasized by Proebsting and Kenworthy
(1954). These workers inferred that the plant's requirement for nitrogen de-
creased with decrease in solar radiation.

The light conditions that existed during the period in which Experi-
ments I and II were conducted differed widely. In Experiment I, in contrast to
Experiment 11, most of the growth occurred under low light periods. In addi-
tion, extreme shade prevailed for an extended period of time prior to leaf
sampling. Therefore, the results obtained in Experiment I may reflect the
nutritional requirements of the blueberry under low light intensity, such as
would be found in propagating beds and houses, while Experiment [I probably
reflects the nutritional requirements of field grown plants.

In sand culture the leaf content of all nutrient elements, except iron
and copper, increased as the supply of the element increased. Iron and copper
only increased when the external concentration was extremely high.

With the vermiculite medium only potassium and boron increased in
the leaf as the external concentration of these elements increased. Substan-

tial increases over that found in check leaves were achieved also for manganese.

69.

iron, and copper when solutions containing the high level of these elements was
used.

The lower intensity of nutrient elements in leaves from plants growing
in vermiculite and the greater disruption in these leaves of the nutrient~element
balance due to treatment in Experiment III probably was due to dilution because
of the increased growth of plants in this medium as compared to those plants
in sand.

The influence of the nitrogen level in solution on leaf composition, as
determined in Experiments I and 11 suggests that if a lower than optimum level
of another nutrient-element is available to the blueberry plant, the addition of
nitrogen may induce a deficiency of that nutrient-element. Reuther, Embleton
and Jones (1958) in reviewing the literature, found this to be generally true in
most fruit crops, particularly in regard to phosphorus, potassium, boron, zinc
and copper.

Phosphorus shortage, as well as phosphorus excess, decreased the
nitrogen level in the leaf. The influence of excess phosphorus on reducing the
nitrogen level in the leaf has been reported by Brown (1945) on peach. Most
reports on fruit crops, however, either indicate no effect on nitrogen or an
increase in nitrogen in the leaf when phosphorus is in excess supply.

When the supply of potassium or magnesium was increased from 0

ppm to 30 ppm or 24 ppm, respectively, the antagonistic influence of potassium

70.

on the uptake of magnesium was equal in severity to the reciprocal antagonism
exerted by magnesium on potassium uptake.

A further increase in supply of these two elements, however, indi—
cated that the antagonistic influence of potassium on magnesium uptake was
less severe than the reciprocal antagonism of magnesium on potassium uptake.
These results were only achieved in Experiment 11. In Experiment 1 high
levels of magnesium showed no antagonism toward the leaf content of potas-
sium. In the same experiment, high levels of potassium induced only a 10
percent decrease of magnesium in the leaf below that found in the check leaves.

These findings are contrary to what has been found in other fruit
crops. Cain (1951), Shear, Crane and Meyers (1951), Lagasse and Drosdoff
(1948) and others have all stressed the marked antagonism of potassium on
reducing the leaf content of magnesium.

Foliar symptoms of magnesium deficiency were not induced by the
150 ppm potassium treatment. This prevailed even though the leaf content of
potassium in these leaves was considerably higher than in the leaves of the
0 ppm magnesium treated plants, and sufficiently high enough to cause mar-
ginal scorching of the basal leaves. This indicated that the critical level of
magnesium in blueberry leaves below which foliar expressions of magnesium
deficiency will develop may be independent of the potassium concentration in

the leaf. Thus, a blueberry plant provided with sufficient magnesium to

maintain the leaf content of magnesium above this critical level may not exhibit
symptoms when supplied with an excess of potassium.

These findings are not in accord with the conception put forth by
Shear, Crane and Meyers (1946) that magnesium deficiency may be the re-
sult of potassium excess. Granted that high levels of potassium are associated
with magnesium deficiency, the content of magnesium, however, must be
below a critical level for the expression of magnesium deficiency to appear.

The 0 ppm calcium treatment in Experiments I and II promoted the
accumulation of heavy metals, magnesium, and potassium in the leaf. A sim-
ilar balance of nutrient elements occurred in leaves taken from field plants
growing in soil of pH 3. 5 and thought to be calcium deficient (BL58 - Appendix
Table

The reduction in growth, development of foliar patterns on both basal
and tip leaves, and the tendency toward rosetting that characterized these
plants receiving 0 ppm calcium may not have been due entirely to an actual
calcium shortage. It is conceivable that these responses of the plant resulted
from the toxic accumulation and subsequent antagonisms of those elements
that were accumulated readily in the leaf as a result of the low calcium treat-
ment. The influence of the low pH of the 0 ppm calcium can not be segregated
from that of the 0 ppm level of calcium in this study. In the field, however,

low calcium is associated generally with soils having a pH below 4. 0.

The potassium-boron relationship observed in Experiment III does not
reflect the findings of other investigators with other plants. Reeve and Shive
(1944) demonstrated that when the boron supply was increased from a deficient
level of . 001 ppm up to . 1 ppm, there was an increase in potassium in tomato
leaves. An additional increase, however, up to 5 ppm boron resulted in a
definite decrease in leaf content of potassium. The depression of potassium
leaf levels by excess boron supply has also been found by Hernandez and
Childers (1956) on peach and by Bergman (1957) on grape.

It is theoretically conceivable that at the pH of 4. 0 to 4. 2 maintained
in Experiment III, a disruption of the potassium-boron relationship as found
in leaves of plants adapted to a higher pH could occur. This disruption may
further be intensified by the ease in which the blueberry apparently absorbed
monovalent cations, such as potassium.

The difference in the leaf levels of manganese between Experiment I
and 11 may be attributed to differences in light intensity that prevailed during
each experiment. This contention is supported by the investigations of McCool
(1935), which indicated that manganese toxicity and corresponding leaf levels
of manganese decreased with decreasing light intensity. Morris and Pierre
(1947) implied that this interaction of light and manganese leaf concentration
may have influenced in similar fashion their results on the effects of manganese

toxicity on Lespedeza.

 

These workers also observed that manganese toxicity symptoms were

73.

less pronounced at a high iron level than at lower iron levels. Subsequently,
they found that this was due to an antagonistic relationship of iron on the up-
take of manganese. This same antagonism of iron on the uptake of manganese
was found in Experiment [[1, particularly in plants grown in vermiculite.

The reverse relationship of manganese impeding the uptake of iron
was not apparent in Experiment III. In Experiment 11, however, the general
increase in leaf content of manganese was accompanied by a decrease in the
leaf content of iron below that found in Experiment I. This implies that the
possibility of manganese impeding the uptake of iron as proposed by Somers
and Shive (1942) may occur, depending upon environmental conditions.

It is also noteworthy that a high manganese leaf content was associated
with a deficient level of every major nutrient element. The significance of this
phenomenon cannot be explained at present.

The high copper level in solution did not inhibit root or top growth in
Experiment 111, although copper is usually more available at a low pH. This
lack of toxicity may be explained by the fact that copper did not increase appre-
ciably in the leaves with increased copper supply. Smith and Specht (1953).
however, demonstrated with orange trees that lethal quantities of copper will
be absorbed by the roots, but will not be transported to the leaf.

Smith (1956) reported that in addition to copper, high levels of man-

ganese and zinc in solution also supressed root development without appreciably

 

74.

altering the above ground portions of orange trees. In this present study on
blueberry plants, however, solutions high in manganese, zinc and iron de-
pressed both top and root growth to a considerable extent.

Magnesium levels in the blueberry leaf decreased with increasing or
decreasing supply of the heavy metal nutrient elements studied. Similar de-
creases in the magnesium level of orange trees was achieved by Smith (1956)
using high levels of copper, zinc and manganese. The antagonistic effects of
high iron on the accumulation of magnesium in the leaf has not been reported
for other crops.

A reciprocal antagonistic relationship of magnesium on the leaf content
of boron, iron and manganese was apparent in Experiment 11.

The seasonal leaf sampling survey showed that the greatest consistency
in the leaf content of all nutrient elements occurred during the three week period
prior to and including the first week in which 35 percent of the crop could be
harvested. This period of the season, therefore, may be considered as the
optimum time to collect blueberry leaf samples, if an accurate diagnosis of
the nutritional status of a blueberry plant is to be made.

Variety differences, in respect to leaf composition and nutrient re-
quirement of manganese and magnesium should be taken into consideration
when evaluating the nutritional status of the blueberry by foliar analyses.

As indicated in the results, considerably more manganese may be

found in the leaves of the Jersey variety than in the Rubel variety. This same

‘J

CJl

phenomenon was evident upon re-evaluation of data collected by Ballinger
(1957, unpublished data) in 1955 and 1956. This is presented in Table III.

The inability of the Rubel variety to accumulate as much manganese
as the Jersey variety on a given site may explain why Rubel is more adapted
to fertile soils of greater moisture content than is Jersey. Blueberry bushes
of the Jersey variety planted in the wetter portions of blueberry fields showed
foliar disorders and shoot dieback in 1957 that were later associated with high
manganese leaf levels. Correspondingly, no Rubel bushes were found that
showed evidence of manganese toxicity even though planted in close proximity
to the Jersey variety. '

Although manganese toxicity has not been previously reported affect-
ing blueberries, it has been shown by many workers as a limiting factor in the
production of such crops as potatoes (Berger and Gerloff, 1948), tobacco
(Bortner, 1935), Lespedeza (Morris and Pierre, 1948) on acid soils.

Field leaf samples of 1957 also indicated that with the Rubel variety
magnesium deficiency may be associated with a much higher leaf level of mag-
nesium than with the Jersey variety. Hence, it may be assumed that the Rubel
variety has a greater requirement for magnesium. Similar differences in
magnesium requirements between varieties have also been found in celery

(Pope and Munger, 1951).

Chemical analyses of blueberry leaves, sampled as described in the

 

 
 

 

 

 

methods of Experiment IV, can be expected to indicate low or high levels of a
particular nutrient, if a shortage or excess exists for that nutrient. It will
not, however, show these conditions in the same magnitude nor will it show
associated nutrient interrelationships to the same extent as would analyses of
the tip or basal leaves that are exhibiting the particular symptom.

Medial leaves, for example, on a shoot whose basal leaves are exhib-
iting magnesium deficiency symptoms, will indicate upon analyses a shortage
of magnesium. The potassium content of these medial leaves, however, will
not be abnormally high. Yet, analyses of the basal leaves will show an extreme
shortage of magnesium accompanied by a definite excess of potassium.

Hence, the identification of questionable nutrient disorders may be
enhanced greatly if analyses of affected leaves could be compared to a corres-
ponding tip or basal leaf standard composition range. Further research along
these lines should provide valuable information.

Tentative standard leaf composition values, as established by a survey
reported by Ballinger (1957) do not reflect necessarily optimum levels of nutri-
ents. They represent the average nutrient-element composition of leaves col-
lected from bushes in plots of high productivity. The fact that two of nine plots.
which were designated as free of nutrient disorders, exhibiting magnesium
deficiency symptoms in 1957, illustrate the fallacy of considering leaf composi-

tion values obtained by survey methods as the optimum.

‘1
‘J

Based upon the occurrence of magnesium deficiency in the field and
results of this study, the suggested standard values have been reassigned. A
tentative standard range for the nutrient-elements in the leaf is proposed.

This range is presented in Table IV.

Plants, whose leaf composition compares favorably to this range of
nutrients, may be expected to be of good vigor and to be productive, providing,
however, that proper climatic conditions and cultural practices prevail.

The magnesium deficiency condition that existed in many blueberry
plantings in 1957 probably was the cumulative effect of a number of influential
factors, such as greater soil moisture, generally low magnesium supply, and
an increased availability of nitrogen as manifested by higher nitrogen leaf
levels.

The antagonistic influence of potassium, which would ordinarily be
suspected as a causative agent in magnesium deficiency conditions, probably
exerted only a minor influence in 1957. This assertion is made on the basis
that the leaf level of potassium was lower in seven of nine standard plots in
1957 than in the two years previous (see Appendix Table 19).

This decrease in leaf potassium levels appeared even in plots showing
magnesium deficiency. The two plots in which potassium did increase showed

also the highest nitrogen levels. A relationship similar to that found in Ex-

periments I and II.

 

 

 

 

 

 

 

TABLE IV

Tentative Standard Range for Optimum Blueberry Leaf Composition (Per-
cent Dry Weight) as Compared to the Tentative Standards Established
by Ballinger (1957)

 

 

Percent Composition

 

 

Nutrient
Standard Range Standard Established by Ballinger

Nitrogen 1. 95 - 2.15 l. 98
Phosphorus . 15 - ? 0.16
Potassium . 450 - . 550 0. 527
Magnesium 25 - . 30 0. 28
Calcium . 50 - 80 0. 74
Boron . 0050 - . 0150 0. 0049
Manganese . 0050 - . 0350 0. 0168
Iron . 0070 - . 0200 0. 0150
Copper . 0010 - . 0020 0. 0015
Zinc . 0008 - . 0020 0. 0020

 

The antagonistic relationship between an increasing nitrogen
supply and leaf content of magnesium was illustrated in Experiments I and II.
This same relationship appeared in the field. A planting showing mild to
moderate magnesium deficiency, was given supplemental ammonium sulfate
(one-quarter pound per bush) during the early part of July 1957. Within two
to three weeks most of the planting appeared as illustrated by Figure 38.

Although the foliar expressions of magnesium deficiency have been

previously described by Bailey etal: (1947) and Miklzelson and Doehlert (1947),
and Kramer and Schrader (1942) for the highbush blueberry, the relationship
between light and the development of these symptoms as observed in the
present studies has not been reported.

The differences between varieties in nutrient-element composition

of fruit (Table 11) may be related to the generally observed differences between

varieties in keeping quality. The Rubel fruit, which accumulated more nitrogen

and potassium and less calcium, magnesium and manganese than the Jersey

fruit, often has poorer keeping quality. The keeping quality of Rubel appeared

to be reduced if nitrogen and potassium were higher and calcium lower than

average.

In re-evaluating the data collected by Ballinger in 1956, similar

varietal differences in fruit composition were noted. This is presented in

Table III.

TABLE III

Nutrient Element Composition of Blueberry Leaves and Fruit as Influenced
by Variety - Percent Dry Weight (Re-evaluation of Unpublished Data
Collected by W. E. Ballinger in 1956)

 

 

Nutrient Element Composition

 

 

 

Variety
N P K Mg Ca B Mn Fe Cu Zn
Leaf
Rubel 1.73 .14 .480 .22 . 62 . 0037 .0102 .0127 .0018 .0017
Jersey 1.71 .14 .479 .23 .72 .0034 .0195 .0152 .0017 .0021
N. S N. S. N. S. N. S N. S. N. S N. S N. S
Em
Rubel 613 074 531 . 037 . 32 . 0070 . 0011 . 0023 . 0005
Jersey . 532 062 445 . 037 . 31 . 0069 . 0019 . 0025 . 0005
‘ N. S ‘ N. S. N. S. N. S. " N. S. N. S.

 

or ““‘Jersey variety significantly different in fruit composition from

Rubel variety.

81.

Leaf composition did not reflect the significant varietal difference
found in fruit composition in respect to potassium and calcium. It did, how-
ever, reflect the greater manganese content of the Jersey fruit. Consequently,
leaf analyses should be accompanied by fruit analyses if nutrient disorders
involving fruit are to be accurately diagnosed.

The foliar symptoms associated with shortages of particular nutrient
elements in the current study differed in several respects to that reported by
Minton, Hagler and Brightwell (1951) for the rabbiteye blueberry, and by
Kramer and Schrader (1942) for the highbush blueberry. In both of these re-
ports potassium deficiency developed as an interveinal chlorosis on young
leaves and was accompanied by a severe necrosis of older leaves. In the
current study, foliar symptoms of potassium deficiency were confined to a
slight submarginal necrosis on older leaves. These symptoms did not appear
until five months after treatment initiation, and then only in Experiment I.
These workers also reported that foliar symptoms of phosphorus deficiency
were slow to appear. The time of appearance of foliar symptoms of phos—
phorus shortage in the current study depended on the amount of solar radiation
received. This probably was an indirect relationship with carbohydrate accum-
ulation in these leaves. This relationship was not considered in the previous
studies.

Kramer and Schrader (1942) observed that terminal leaves of boron

82.

deficient plants were misshapen. This condition was not observed in Experi-
ment III. The lack of misshapen leaves, however, may represent a difference
in severity of boron deficiency.

A shortage of any one of the nutrient elements, except nitrogen and
phosphorus, and an excess of any one of the nutrient elements, except phos-
phorus, in the current pot and field studies was associated with the occurrence
of a chlorosis or a necrosis, or both. In light of the reports of Kramer and
Schrader (1945) and Cain (1952, 1954, 1955), these results suggest that any
disturbance of the metabolic processes within the blueberry leaf that causes
the cell sap to have a higher pH value will be manifested by the appearance
of a chlorosis or necrosis. The patterns of this chlorosis or necrosis will
depend on the particular element or elements that cause the nutrient disorder.

Excess potassium accumulations may occur in both tip and basal
leaves. Potassium appeared to accumulate in tip leaves when these leaves
were subjected to extreme shade, or when calcium was in short supply. The
accumulation of potassium in basal leaves occurred when magnesium was in
short supply, or when excessive N-P-K fertilizers were applied. These ac-
cumulations may be explained on the basis that a shortage of an antagonizer
exists at the time of accumulation of potassium in these leaves. Based on the
appearance of deficiency symptoms, calcium may assume this role in tip leaves

while magnesium may assume it in basal leaves. A shortage of either one of

 

 

 

 

 

83.

these elements may result in an accumulation of potassium in those leaves
affected most severely by the shortage. It appears, however, that calcium
cannot substitute for magnesium and vice versa in this antagonistic function
in the blueberry plant.

This explanation is in accord with some of the ideas expressed by
Cain (1951) to the effect. that the accumulation of basic cations in the leaves
of such plants as the apple are the result of a shortage of an antagonizer.
Cain, however, contended that basic cations could substitute for each other

in this function.

84.

SUMMARY

One- and two-year-old rooted cuttings of the highbush blueberry Vac-

cinium corymbosum L. were grown in quartz sand and in vermiculite under

 

varied levels of ten nutrient elements. Leaf analysis and plant response to
treatment in terms of foliar expressions, root development and growth were re-
corded and discussed. In addition, leaf and fruit samples were collected
biweekly in the summer of 1957 to ascertain seasonal influences on leaf and
fruit composition. Commercial blueberry fields were also surveyed for
nutritional disorders. Leaf analyses, photographic and descriptive records
were collected of the nutritional disorders observed.

In sand culture the leaf content of N, P, K, Mg, Ca, B and Mn in-
creased as the supply of the element increased. Iron and copper increased
in the leaf only when a high external supply existed. With the vermiculite
rooting media only potassium and boron increased in the leaf as the supply
of the element increased. Manganese, iron and copper leaf levels increased
substantially only when solutions containing high levels of these elements
were used.

In varying the concentration of particular nutrient elements in solu-
tion, numerous nutrient interrelations became apparent. Some of these re-
lationships are as follows:

1. As the supply of nitrogen increased, all elements except phosphorus

decreased in the leaf.

2. A shortage or excess of phosphorus decreased the nitrogen level
in the leaf.

3. As the supply of potassium or magnesium increased from 0 ppm
to 30 ppm or 24 ppm, respectively, the antagonistic influence of potassium
on the uptake of magnesium was equal in severity to the reciprocal antagonism
exerted by magnesium on potassium uptake. With further increases in the
supply of these two elements, the antagonistic influence of potassium on mag-
nesium uptake was less severe than the reciprocal antagonism of magnesium
on potassium uptake.

4. Iron showed a strong antagonistic influence on the uptake of man-
ganese. Manganese did not exhibit a reciprocal relationship on iron.

5. A low level of any one of the major elements in solution resulted
in a high manganese leaf level.

6. A low level of calcium in solution promoted the accumulation of
the heavy metal nutrient-elements, magnesium and potassium in the leaf.

7. The potassium level in the leaf increased wit11 increased supply
of boron.

The expression and rapidity of appearance of foliar symptoms depended
to a large extent on solar radiation. Characteristic leaf pigmentation of N, P and
Mg deficiencies appeared sooner and were more conspicuous under high amounts
of solar radiation. Under low amounts, these same symptoms faded, or in the

case of magnesium deficiency, developed completely different characteristics.

86.

A shortage of any one of the nutrient elements, except nitrogen and
phosphorus, and an excess of all nutrient elements, except phosphorus, were
associated with the occurrence of a chlorosis or necrosis, or both. It was sug-
gested that any disturbance of the metabolic processes within the blueberry
leaf that increases the cell sap pH value will be manifested by the appearance
of a chlorosis or necrosis.

Growth response to treatment differed according to available solar
radiation. There appeared to be an increased requirement for most major
nutrient elements, except potassium, as the amount of solar radiation increased.
Correspondingly, there was an increased requirement for potassium when the
amount of solar radiation decreased. Under low solar radiation the high potas-
sium treatment induced the greatest amount of growth, while under high solar
radiation the high phosphorus treatment stimulated the greatest amount of
growth.

Root systems were found to be more indicative of a deficiency or
toxicity than were foliar symptoms in sand culture. Low nitrogen levels in
solution stimulated root growth, while high N, B, Mn, Fe and Zn and low Ca,
B, Mn solution levels noticeably reduced root development. The high phos-
phorus treatment induced the most desirable root system.

Blueberry plants were found to grow extremely well in vermiculite if

supplied with nitrogen and phosphorus. Plants growing in vermiculite showed

87.

noticeable reductions in growth when supplied with potassium or iron.

Definite seasonal trends existed for all nutrient elements in the leaves
except boron. Nitrogen, potassium, phosphorus and copper decreased, while
magnesium, calcium, iron, manganese and zinc increased in varying degrees
as the season progressed. Late in the season potassium increased and zinc
decreased in the leaf.

. -

The biweekly leaf sampling study indicated that the greatest consist-
ency in the leaf content of all nutrient elements occurred during the three
week period prior to, and including, the first week in which 35 percent of the
crop could be harvested.

Marked varietal differences were apparent in respect to leaf and fruit
composition and nutrient requirements. Considerably more manganese was
generally found in the leaves of theJersey variety than in leaves of the Rubel
variety. Subsequently, the Jersey variety was found to accumulate toxic amounts
of manganese, while the Rubel variety did not, even though both were grown on
the same or on similar excessive wet sites. Foliar symptoms of magnesium

\
deficiency were associated with a much higher medial leaf content of magnes-
ium with Rubel than with Jersey. This was interpreted to mean that Rubel
has a higher requirement for magnesium than Jersey. Rubel fruit usually con-

tained higher levels of potassium and lower levels of calcium than did Jersey

fruit. These differences in fruit composition were associated with differences

 

 

 

I. llin.fl v .
l t 1 lflfitvyl 1 il’l:
I O.‘ 1‘

I ‘Vxll: l

in keeping quality. Rubel fruit showed lower keeping quality than Jersey
when nitrogen and potassium were higher and calcium lower than average.
Although the concentration of all nutrient elements in the fruit de-
clined with increased maturity, considerable differences in the magnitude
of decline existed between elements. The percent decrease of these elements
during the six week period prior to harvest was as follows: manganese - 73
percent; boron - 61 percent; calcium - 59 percent; phosphorus - 55 percent;
nitrogen - 54 percent; magnesium - 41 percent; iron — 29 percent; copper -
24 percent; and potassium - 20 percent. Slow declines of all nutrient elements
except iron and copper occurred during the harvest period. ‘
The nutritional disorder survey indicated the existence in 1957 of
shortages of nitrogen, phosphorus, magnesium and calcium, excesses of

nitrogen, potassium and manganese in commercial blueberry fields.

89.

LITERATURE CITED

Bailey, J. S. 1936. A chlorosis of cultivated blueberries. Proc. Amer. Soc.
Hort. Sci. 34: 395-396.

Bailey, J. S., and J. N. Everson. 1937. Further observations ona chlorosis:
of the cultivated blueberry. Proc. Amer. Soc. Hort. Sci. 35: 495-496.

Bailey, J. S. 1941. The effect of lime applications on the growth of cultivated
blueberry plants. Proc. Amer. Soc. Hort. Sci. 38: 465-467.

Bailey, J. S., C. T. Smith, and R. T. Weatherby. 1949. The nutritional
status of the cultivated blueberry as revealed by leaf analysis. Proc.
Amer. Soc. Hort. Sci. 54:205-208.

Bailey, J. S., and M. Drake. 1934. Correcting magnesium deficiency on
cultivated blueberries and its effect on leaf potassium, calcium and
nitrogen. Proc. Amer. Soc. Hort. Sci. 63: 95-100.

Ballinger, W. E. 1957. Nutritional conditions of Michigan blueberry planta-
tions. Thesis, Ph. D. degree, Michigan State University.

Ballinger, W. E. 1957. Unpublished data.

Berger, K. C., and G. C. Gerloff. 1947. Manganese toxicity of potatoes
in relation to strong soil acidity. Proc. Soil Sci. Soc. Amer. 12:
310-314.

Bergman, E. L. 1958. Response of Concord grape vines (Vitis Labrusca L.)
to various levels of essential nutrient elements. Thesis, Ph. D.

degree, Michigan State University.

Bortner, E. E. 1935. Toxicity of manganese to Turkish tobacco in acid
Kentucky soils. Soil Sci. 39: 15-24.

Brown, D. S. 1945. The growth and composition of the tops of peach trees
in sand culture in relation to nutrient-element balance. W. Va. Agr.

Exp. Sta. Bul. 322: 1-72.

Cain, J. C. 1948. Some interrelationships between calcium, magnesium and
potassium in one-year-old McIntosh apple trees grown in sand culture.
Proc. Amer. Soc. Hort. Sci. 51: 1-12.

 

 

 

 

9 0 .

Cain, J. C. 1952. A comparison of ammonium and nitrate nitrogen for
blueberries. Proc. Amer. Soc. Hort. Sci. 59: 161-166.

Cain, J. C. 1954. Blueberry chlorosis in relation to leaf pH and mineral
composition. Proc. Amer. Soc. Hort. Sci. 64: 61-70.

Cain, J. C., and R. W. Holly. 1955. A comparison of chlorotic and green
blueberry leaf tissue with respect to free amino acid and basic
cation contents. Proc. Amer. Soc. Hort. Sci. 65: 49-53.

Doehlert, C. A., and J. W. Shive. 1936. Nutrition of blueberry (Vaccinum
corymbosium L.) in sand cultures. Soil Sci. 41: 341-350.

 

Harmer, P. M. 1944. The effect of varying the reaction of organic soil on
the growth and production of the domesticated blueberry. Proc.
Soil Sci. Amer. 9: 133-141.

Hernandez, E., and Childers, N. F. 1956. Boron toxicity induced in a
New Jersey peach orchard, Part II. Proc. Amer. Soc. Hort.
Sci. 67: 121-129.

Kramer, A., and A. L. Schrader. 1942. Effect of nutrients, media and
growth substances on the growth of the Cabot variety of Vaccinum
corymbosium. Jour. Agr. Res. 65: 313-327.

 

 

Kramer, A., and A. L. Schrader. 1945. Significance of the pH of blueberry
leaves. Plant Phys. 20: 30-36.

Lagasse, F. S., and M. Drosdoff. 1948. The nutrition of tung trees. Proc.
Amer. Soc. Hort. Sci. 52: 11-17.

McCool, M. M. 1935. Effect of light on the manganese content of plants.
Contrib. Boyce Thompson Inst. for Plant Res. 7: 427—437.

Merrill, T. A. 1939. Acid tolerance of the highbush Blueberry. Mich.
Quart. Bul., \lov. 1939:112-116.

Mikkelsen, D. S., and C. A. Doehlert. 1950. Magnesium deficiency in
blueberries. Proc. Amer. Soc. Hort. Sci. 55: 289-292.

Minton, N. A., T. B. Hagler, and W. T. Brightwell. 1951. Nutrient-ele-
ment deficiency symptoms of the rabbiteye blueberry. Proc. Amer.
Soc. Hort. Sci. 58: 115—119.

bu»-

 

 

 

91.

Morris, H. D., and W. H. Pierre. 1947. The effect of calcium, phosphorus
and iron on the tolerance of lespedeza to manganese toxicity in cul-
ture solutions. Proc. Soil Sci. Soc. Amer. 12: 382-386.

Perlmutter, F., and G. M. Darrow. 1942. Effect of soil media, photo-
period and nitrogenous fertilizer on the growth of blueberry seedlings.
Proc. Amer. Soc. Hort. Sci. 40: 341-346.

Pope, D. T., and H. M. Munger. 1953. Heredity and nutrition in relation
to magnesium deficiency chlorosis in celery. Proc. Amer. Soc.
Hort. Sci. 61: 472-480.

Popenoe, J. 1952. Mineral nutrition of the blueberry as indicated by leaf
analyses. Thesis for M. S. Degree, University of Maryland, College
Park.

Proebsting, E. L. Jr., and A. L. Kenworthy. 1954. Growth and Leaf Analysis
of Montmorency cherry trees as influenced by solar radiation and inten-
sity of nutrition. Proc. Amer. Soc. Hort. Sci. 63:41-48.

Reeve, E., and J. W. Shive. 1944. Potassium-boron and calcium-boron re-
lationships in plant nutrition. Proc. Soil Sci. Soc. 47: 1-14.

Reuther, W., T. W. Embleton, and W. W. Jones. 1958. Mineral nutrition
of tree crops. Ann. Rev. Plant Phys. 9: 175-206.

Shear, C. B., H. L. Crane, and A. T. Meyers. 1946. Nutrient-element
balance: A fundamental concept in plant nutrition. Proc. Amer. Soc.
Hort. Sci. 47: 239-248.

Smith, P. F., and A. W. Specht. 1953. Heavy-metal nutrition and iron
chlorosis of citrus seedlings. Plant Phys. 28: 371-382.

Smith, P. F. 1956. Effects of high levels of copper, zinc and manganese on
tree growth and fruiting of Valencia orange in sand culture. Proc.
Amer. Soc. Hort. Sci. 67: 202-209.

Somers, I. I., and J. W. Shive. 1942. The iron-manganese relationship in
plant metabolism. Plant Phys. 17: 582-602.

Stene, A. E. 1939. Some observations on blueberry nutrition based on
greenhouse culture. Proc. Amer. Soc. Hort. Sci. 36: 620-622.

APPENDIX

92.

 

 

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Appendix Table 6

Leaf Composition of Blueberry Plants in Experiment I as Influenced by
Various Levels of N, P, K, Mg and Ca

 

 

 

 

 

Treat- Nutrient Content - Percent Dry Weight
m nt

e N P K Mg Ca B Mn Fe Cu Zn
CK 2. 30 . 22 . 654 . 35 . 46 . 0207 . 0055 . 0281 . 0034 . 0012
-N l. 83 . 20 . 866 . 38 . 60 . 0275 . 01.18 . 0289 . 0053 . 0014
+N 2. 80 . 24 . 770 . 29 . 51 . 0182 . 0045 . 0229 . 0036 . 0008
-P 2.11 .15 . 728 . 34 . 49 . 0187 . 0103 . 0293 . 0039 . 0009
+P 2. 06 . 28 . 703 . 32 . 51 . 0174 . 0062 . 0356 . 0035 . 0011
-K 2. 29 .21 .481 .41 .47 .0284 .0072 . 0289 .0049 . 0010
+K 2.23 .23 1.110 . 31 .42 .0293 .0051 . 0291 .0053 .0012
-Mg 2. 39 . 23 . 776 . 25 . 43 . 0282 . 0059 . 0305 . 0039 . 0010
+Mg 2. 31 . 20 . 663 . 42 . 44 . 0196 . 0058 . 0307 . 0048 . 0009
-Ca 2. 20 . 21 . 775 . 33 . 45 . 0236 . 0053 . 0295 . 0040 . 0009
+Ca 2. 28 . 20 . 673 . 32 . 45 . 0221 . 0055 . 0248 . 0037 . 0011

L. S. D. 5% . 20 . 03 . 065 . 05 . 09 . 0082 . 0013 N. S. N. S. N. S.

1% .27 .04 .088 .06 N.S. N.S. .0017 N.S. N.S. N.S.

 

 

Appendix Table 7

Growth Measurements of Blueberry Plants in Experiment I as Influenced by
Various Levels of N, P, K, Mg and Ca

 

 

 

Treat- Dry Weight (gm 8) 3:310': h
ment Leaf Shoot Stem Top Root Total gt

(mm)
CK 5. 34 2. 60 2. 47 10. 41 3. 51 13.91 1136
-N 1. 97 1. 55 2.37 5. 89 4. 01 9. 90 640
+N 1. 83 .91 2. 04 4. 77 1. 22 6. 00 838
-P 2. 64 1. 10 2. 64 6. 37 2. 92 9. 29 622
+P 5. 35 2. 83 2. 53 10. 71 3. 98 14. 69 1406
-1< 6.19 3. 34 3. 31 12. 84 4. 76 17. 60 1315
+1< 7. 72 4. 15 3. 08 14. 94 5. 36 20. 31 1539
-Mg 7. 38 3. 41 2. 78 13. 57 4. 37 17.93 1714
+Mg 5. 94 2. 84 2. 54 11.32 4. 00 15. 32 1331
-Ca 4.53 2. 87 2. 81 10. 20 3. 97 14.17 1118
+Ca 5. 27 2. 65 2. 88 10. 80 3. 75 14.54 1299
1.. s. D. 5%2. 40 1.18 .66 3. 62 1. 41 4. 95 285
1% 3.18 1.55 NS 4.80 1.86 6.56 377

 

 

 

 

 

 

Appendix Table 8

Leaf Composition of Blueberry Plants in Experiment II as Influenced by
Various Levels of N, P, K, Mg and Ca

 

 

 

 

Treat- Nutrient Content - Percent Dry Weight
ment N P K Mg Ca B Mn Fe Cu Zn
CK 2. 46 . 29 . 956 . 45 . 58 . 0274 . 0159 . 0179 . 0032 . 0009
-N 1.71 .24 1.022 .45 .75 .0241 .0205 .0225 .0031 .0013
+N 2. 60 . 24 . 826 . 38 . 55 . 0238 . 0339 . 0196 . 0023 . 0009
-P 2. 28 .13 . 783 . 39 . 56 . 0150 . 0230 . 0193 . 0026 . 0011
+P 2.19 .41 .769 .37 .65 .0310 .0127 .0218 .0028 .0009
-K 2. 65 . 28 . 576 . 49 . 63 . 0250 . 0205 . 0185 . 0030 . 0012
+K 2. 39 . 27 1. 335 . 42 . 63 . 0244 . 0156 . 0212 . 0042 . 0010
-Mg 2. 57 . 42 l. 054 . 36 . 62 . 0382 . 0232 . 0238 . 0032 . 0011
+Mg 2.64 .23 . 802 . 59 . 68 .0211 . 0134 .0178 .0041 .0012
~Ca 2. 53 . 30 . 992 . 59 . 55 . 0328 . 0391 . 0263 . 0053 . 0013
+Ca 2. 47 . 29 . 931 . 48 . 73 . 0296 . 0202 . 0153 . 0031 . 0010

L. S. D. 5% . 31 . 04 .142 . O9 .10 N. S. . 0092 . 0055 . 0015 . 0003

1% .41 .05 .191 .12 .14 N.S. .0124 N.S. N.S. N.S.

 

 

Appendix Table 9

Growth Measurements of Blueberry Plants in Experiment 11 as Influenced by
Various Levels of N, P, K, Mg and Ca

 

 

 

 

 

 

 

Treat- Dry Weight (gms) Shoot
ment Leaf Shoot Stem Top Root Total Accumu- Length
lation (mm)
CK 10.44 5.50 7.48 23.42 13.11 36. 53 16.13 2111
-N 7. 55 4. 84 8. 12 20. 51 16. 35 36. 86 19. 56 1420
+N 3.11 1. 30 5. 99 10. 64 5. 99 15. 46 . 48 1271
-P 6. 21 3.17 7. 21 16. 59 10. 40 26. 99 9. 92 1293
+P 15. 22 9. 41 9. 19 33. 64 ' 13. 46 47. 28 30. 69 2795
-I( 9. 90 4. 29 7. 81 22. 00 9. 95 31. 95 14. 37 2137
+K 9. 84 4. 51 7. 08 21. 43 10. 76 32. 20 I4. 62 1997
-Mg 8.83 4.77 7.61 18.70 10.26 28.81 11.29 2061
+Mg 11. 23 5. 37 7. 40 24. 00 10. 93 34. 93 17. 78 2307
-Ca 3. 77 2. 01 6. 48 12. 26 7. 99 20. 25 3. 40 805
+Ca 8. 06 4. 08 7. 81 19. 95 10. 01 29. 96 12. 46 1880
L. .S. D. 5% 3, 77 N. S N. S. 6. 94 3. 86 10. 17 9. 72 808
1% 5, 08 N. S. N. S. 9. 36 5. 20 13. 70 13. 10 1089

 

 

Appendix Table 10

Leaf Composition of Blueberry Plants in Experiment 11 Grown in Vermiculite
and Subjected to Various Levels of N, P, K, Mg and Ca

 

 

Nutrient Content - Percent Dry Weight

 

 

Treat-

ment N P K Mg Ca B Mn Fe Cu zn
-N 1.59 .17 .778 .37 .70 .0241 .0229 .0222 .0021 .0007
CK 2.44 .20 .881 .33 .55 .0155 .0172 .0393 .0017 .0011
+N 2.41 .21 .11 .23 .37* .0051 .0352 .0231 .0013 .0008
-1> 2.36 .16 .860 .30 .54 .0212 .0235 .0314 .0019 .0012
CK 2.44 .20 .881 .33 .55 .0155 .0172 .0393 .0017 .0011
+P 2.25 .20 .955 .28 .59 .0314 .0203 .0139 .0028 .0011
-1< 2.46 .19 .819 .33 .61 .0202 .0164 .0347 .0017 .0013
CK 2.44 .20 .881 .33 .55 .0155 .0172 .0393 .0017 .0011
+1< 2.41 .18 .13 .26 .54 .0200 .0226 .0250 .0021 .0006
~Mg 2.52 .19 .851 .31 .473 .0286 .0219 .0282 .0016 .0007
CK 2.44 .20 .881 .33 .55 .0155 .0172 .0393 .0017 .0011
+Mg 2.31 .17 .885 .34 .72 .0081 .0175 .0195 .0016 .0014
C4 2.53 .19 .09 .36 .46"‘ .0257 .0223 .0357 .0015 .0009
CK 2.44 .20 .881 .33 .55 .0155 .0172 .0393 .0017 .0011
+Ca 2.28 .20 .894 .30 .56 .0150 .0231 .0511 .0019 .0012

 

"Obtained by extending the standard curve: hence, the values should be re-
garded as relative rather than absolute. ‘

 

 

Appendix Table 1 1

Growth of Blueberry Plants In Experiment 11 Grown in Vermiculite when
Subjected to Various Levels of N, P, K, Mg and Ca

 

Growth Measurements

 

 

Treat-
m ents Top Growth Root Growth Dry Weight Ac— Shoot Growth
(gms) (gm 3) cumulation (gm s) (mm)
—N 22. 95 10. 91 19. 08 2005
CK 70. 19 17. 44 70. 16 4592
+N 52. 22 16. 64 54. 68 3014
-P 23. 45 8. 50 21. 74 1650
CK 70.19 17. 44 70.16 4592
+P 48. 49 14. 58 50. 60 3058
-K 85. 08 21. 65 95. 39 5054
CK 70. 19 17. 44 70. 16 4592
+K 71. 00 16. 03 74. 56 3049
-Mg 66. 07 14. 55 68.15 4967
CK 70. 19 17. 44 70. 16 4592
+Mg 59. 57 12. 18 60. 41 3008
-Ca 66. 70 19. 89 72. 41 281.8
CK 70. 19 17. 44 70. 16 ' 4592

+Ca 68. 57 I7. 78 73. 88 5424

 

Appendix Table 12

Leaf Composition of Blueberry Plants in Experiment III Grown in Sand
and Subjected to Various Levels of B, Mn, Fe, Cu and Zn

__-— i r
:- I 4

Nutrient Content - Percent Dry Weight

 

 

Treat-
ment N P K Mg Ca B Mn Fe Cu
CK 2. 78 . 31 .710 .40 .52 .0199 .0092 .0160 .0024
-B 2. 77 . 30 .619 .35 .51 .0054 .0082 .0216 .0022
+B 2. 47 .32 .906 . 42 .53 .0500 .0100 . 0195 .0019
-Mn 2. 60 . 31 . 710 .38 .50 .0208 .0065 .0193 .0021
+Mn 2. 73 . 32 .662 . 30 .50 . 0225 .0182 .0167 . 0022
-Fe 3. 02 .29 .693 . 36 . 53 .0271 .0070 .0162 .0023
+Fe 2. 62 . 32 . 622 . 28 . 50 .0215 .0043 .0227 .0026
—Cu 2. 85 . 30 .688 . 36 .54 .0224 .0084 .0183 .0020
+Cu 2. 64 . 29 .675 . 35 .50 .0239 .0097 .0214 .0025
~Zn 2. 67 . 30 .671 . 33 . 52 .0181 .0070 .0158 .0020
+zn 2. 83 . 31 . 656 . 30 . 50 .0248 .0068 . 0158 . 0022
L. s. D. 5% N. s. N. s. .082 .07 N. s. .0051 .0042 .0056 N. s.
1% N. s. N. s. .110 N. s. N. s. .0068 .0056 N. s. N. s.

 

 

Appendix Table 13

Growth Measurements of Blueberry Plants in Experiment III Grown in Sand
and Subjected to Various Levels of B, Mn, Fe, Cu and Zn

 

 

Dry Weight (gm s)

 

 

Treatment
Top Root Total Accumulation

CK 9.18 2. 98 12.15 4. 78
-B 7 49 1. 71 9 19 4 09
+8 8 87 l 99 10 86 4 48
-Mn 8 82 1.86 10 68 4 58
+Mn 7. 03 l. 77 8. 80 4. 05
-Fe 8. 39 2. 40 10. 79 5. 55
+Fe 7. 97 2. 02 9. 99 4. 60
-Cu 8.68 2.17 10.85 5.18
+Cu 9.30 2. 59 11.89 6.50
-Zn 8. 93 2. 23 11.16 6. 20
+Zn 8.19 I. 59 9. 78 4. 53

L. S. D. N. S. N. S. N. S. N. S.

 

Appendix Table 14

Leaf Composition of Blueberry Plants in Experiment III Grown in Vermiculite
and Subjected to Various Levels of B, Mn, Fe, Cu and Zn

 

 

L

Nutrient Content - Percent Dry Weight

 

 

Treat-
ment N P K Mg Ca B Mn Fe Cu
CK 2. 76 . 23 .780 .30 .57 .0170 .0209 .0147 . 0016
-B 2. 79 .25 .688 . 32 . 54 .0052 .0236 .0190 .0014
+8 2. 33 . 23 .911 . 32 . 61 . 0500 . 0170 .0192 . 0016
-Mn 3.07 .25 .813 .29 .56 .0200 .0210 .0199 .0018
+Mn 2. 78 . 25 .768 . 31 .50 . 0162 . 0280 .0200 .0015
-Fe 3. 02 .24 .800 . 31 . 53 .0306 .0274 . 0162 . 0017
+Fe 2. 82 . 30 .803 . 25 .50 . 0235 .0067 .0291 . 0017
-Cu 2.70 .24 I .714 .35 .60 .0119 .0265 .0202 .0016
+Cu 2. 99 .24 .734 . 31 .50 . 0241 .0182 .0190 .0019
-Zn 2. 83 . 25 .830 . 32 52 . 0257 .0343 .0184 . 0017
+Zn 3. 29 . 25 . 768 . 31 . 50 .0189 .0254 . 0183 . 0018
L. s. D. 5% N.S .02 .109 N.S NS .0108 .0138 .0045 N.S
1% N. s. .03 N.S N.S N.S .0153 N.S. .0065 N.S.

 

Appendix Table 15

Growth Measurements of Blueberry Plants in Experiment III Grown in
Vermiculite and Subjected to Various Levels of B, Mn, Fe, Cu and Zn

 

 

Dry Weight (gm s)

 

 

Treatment
Top Root Total Accumulation

CK 20. 61 3. 31 23. 92 21. 08
-B 1.6. 01 2.14 18.16 14. 82
+3 17.59 2.16 19.75 16.41
-Mn 14. 77 1. 79 16. 75 13. 73
+Mn 8. 00 1. 01 9. 00 6.16
-Fe 26. 72 4. 39 31.10 28. 26
+Fe 6. 94 . 78 7. 72 4. 88
-Cu 15.82 2. 44 18.25 15.41
+Cu 20. 82 3. 33 24.15 21. 31
-Zn 16. 90 2. 92 I9. 82 16. 98
+Zn 8. 66 1. 35 10. 01 7.17
L. S. D. N. S. N. S. N. S N. S.

 

 

Appendix Table 16

Nutrient-Element Composition of Blueberry Leaves Collected Biweekly from
june 15 to September 5 - Percent Dry Weight“

 

 

 

 

Sampling Date L. S. D.

Element June June July July Aug. Aug. Sept. 5% 1%
‘ 15 30 12 26 9 22 5

N 2.86 2.47 2.17 2. 20 2.21 2.02 .96 .11 .14

P .21 .20 .16 .16 .16 .17 .17 .01 .02

K .712 .626 . 546 . 507 .486 .476 . 514 . 037 .048

Mg . 19 .21 .22 .24 .27 .33 .31 .02 .03

Ca .39 .38 .39 .47 .49 .53 .60 .06 .08

B . 0065 . 0056 . 0046 . 0062 . 0053 . 0067 . 0063 . 0015 . 0019

Mn . 0208 . 0341 . 0211 . 0257 . 0271 . 0253 . 0341 . 0072 . 0095

Fe .0128 .0168 .0126 .0147 .0154 . 0177 .0168 .0026 . 0035

Cu . 0015 . 0014 . 0013 . 0014 . 0014 . 0013 . 0012 . 0001 . 0002

Zn . 0009 . 0009 . 0011 . 0013 . 0013 . 0008 . 0007 . 0003 . 0004

 

 

*Each value represents the mean of nine plots, four of which were of the

jersey variety and five of the Rubel variety.

Appendix Table 17

Nutrient-Element Composition of Blueberry Fruit Sampled Biweekly Through-
out the Growing Season - Percent Dry Weight“

 

 

 

 

Element Sampling Date - L. S. D.
June June July July Aug. Aug. Sept. 5% 1%
15 30 12 26 9 22 5
N 2.27 1.76 1.55 1.06 1.03 .78' .78 .17 .22
P .25 .18 .15 .11 .11 .09 .08 .06 N.S.
K . 873 . 776 . 734 . 690 . 665 . 561 . 609 . 049 . 005
Mg . 096 . 085 . 074 . 057 . 057 . 041 . 040 . 007 . 010
Ca .295 .216 .187 .123 .107 .045 .046 .046 .061
B . 0039 . 0030 . 0023 . 0016 . 0016 . 0010 . 0010 . 0004 . 0005
Mn . 0125 . 0081 . 0061 . 0034 . 0030 . 0022 . 0022 . 0029 . 0039
Fe . 0040 . 0043 . 0037 . 0029 . 0046 . 0034 . 0038 . 0008 . 0011
Cu . 0009 . 0009 . 0007 . 0007 . 0007 . 0007 . 0006 . 0002 N. S.

 

 

*Each value represents the mean of nine plots, four of which were of the

Jersey variety and five of the Rubel variety.

Appendix Table 18

Weekly Average of Phyrheliometer Readings of Solar and Sky Radiation in
1957 (Radiation in Gr. -Cal. per cm2 of Horizontal Surface)

 

 

 

Week Ending Radiation Week Ending Radiation
February 4 182. 3 July 1 493. l
11 167. 0 8 509. 8
18 258. 2 15 558. 9
25 218. 6 22 625. 0
March 4 318. 6 29 625. 0
11 319. 5 Aug. 5 598. 0
18 382. 9 12 594. 0
25 368. 0 19 520. 0
April 1 326. 3 26 463. 8
8 187. 6 . Sept. 2 266. 0
15 417. 9 9 335. 8
22 306. 8 16 296. 0
29 392. 9 23 ' 319. 0
May 6 643. 2 30 475. 2
13 384. 2 Oct. 7 412. 2
20 271. 2 14 314. 0
27 422. 1 21 206. 0
June 3 620. 8 28 147. 6
10 593. 7 Nov. 4 146. 7
17 553. 2 11 170. 0

24 607. 1 18 89. 0

 

Appendix Table 19

Comparison of the Nutrient-Element Content of Blueberry Leaves Sampled Three
Years in Succession from Nine Field Plots During the Same Physiological Growth
Period (Date Pertaining to the Years 1955 and 1956 Reported by Ballinger, 1957).

 

 

Nutrient Content - Percent Dry Weight

 

 

Plot Year
N P K Mg Ca B Mn Fe Cu Zn
14 1955 2.11 .17 . 558 . 33 . 77 121 186 190 20 27
1956 1.85 .10 .539 . 17 .59 64 172 130 18 17
1957 2. 27 .16 . 532 . 23 . 44 80 452 209 16 15
17 1955 2. 20 .15 . 520 . 30 . 69 46 88 180 10 22
1956 1.97 .13 .440 .23 .57 31 143 140 18 15
1957 2.30 .15 .544 .26 .65 55 153 143 17 15
18 1955 1. 98 .19 . 636 . 39 . 59 69 139 140 11 29
1956 1. 81 . 14 . 590 . 26 . 57 42 120 130 18 12
1957 2.26 .17 .520 .28 .42 93 153 130 14 15
19 1955 1. 94 . 20 . 559 . 46 . 78 44 176 200 8 21
1956 1.68 .14 .552 .25 .50 27 180 120 16 14
1957 2.12 .16 .518 .27 .44 63 211 157 16 10
35 1955 2. 25 .19 . 522 . 28 . 74 38 117 200 11 22
1956 1.85 .14 560 . 18 .65 22 8O 90 12 21
1957 2.04 .15 .518 .19 .44 36 107 141 12 13
41 1955 2.18 . 15 .511 .27 .65 45 245 160 9 22
1956 1.91 .15 .551 .19 .95 32 167 110 6 19
1957 1. 97 .15 .511 .20 .51 41 174 128 12 14
44 1955 2.19 .16 . 491 . 30 . 70 68 275 180 11 20
1956 1. 81 .13 504 . 25 l. 29 43 305 150 20 28
1957 2.14 .18 .416 .25 .61 60 478 141 15 15
49 1955 2.16 . 15 . 467 . 27 . 55 46 133 150 13 20
1956 1. 92 . 17 . 494 . 27 . 94 45 116 160 28 8
1957 2.27 . 16 .460 .25 .40 62 152 139 16 9
51 1955 2.16 . 20 . 528 . 33 . 57 6.1 206 180 12 15
1956 1.74 .13 .458 .25 1.13 41 169 130 23 20
1957 2. 47 . 18 . 547 . 25 . 35 64 430 135 12 11

 

Appendix Table 20

Nutrient~Element Composition of Leaves and Fruit Collected from Commercial
Blueberry Plantings Surveyed for Nutritional Disorders in 1957

 

 

Sample Date of Nutrient Content - Percent DrLWeight
NO- Sampling N P K Mg Ca B Mn Fe Cu Zn

 

BL24 Julyll 1.99 17 .544 .19 .38 .0038 .0183 .0115 .0011.0006
BL53 Julyll 2.61 .21 -866 .19 .38 .0048 .0411 .0191 .0013 .0012
81.54 July11 2.15 .16 .636 .18 .36 .0046 .0137 .0116 .0014 .0009
BL 55 Julyll 1.04 .14 .514 .16 .37 .0046 .0167 .0175 .0012 .0006
BL 56 July11 2.21 .16 .766 .11 .36 .0068 .0553 .0200 .0015 .0011
BL 58 Aug. 9 2.04 .17 .558 .35 .33 .0052 .0210 .0195 .0026 .0012
81. 61 Aug. 9 3.62 .15 1.79 .13 .62 .0036 .0920 .0420 .0040 .0011
BL 80 Aug. 21 2.03 .12 .669 .16 .59 .0021 .0249 .0352 .0016 .0013
81. 83 Aug.21 2.62 .12 1.76 .07 .53 .0018 .0299 .0178 .0016 .0006
BL 84 Aug. 18 2.08 .22 .872 .20 .38 .0017 .0030 .0124 .0015 .0005
BL130 Aug. 23 2.02 .15 .538 .13 .47 .0021 .0146 .0177 .0017 .0007
BL131 Aug. 23 1.77 .14 1.11 .06 .47 .0016 .0083 .0166 .0019 .0008

BL132 Aug. 23 2.22 .17 1.32 .06 .56 .0016 .0126 .0219 .0019 .0009

BF 64 Aug. 18 .969.09 .750 .043 .052 .0008 .0025 .0034 .0004
BF 70 July 29 .681.07 .478 .039 .105 .0008 .0015 .0019 .0007
81. 81 Aug. 21 1.64 .16 .313 .28 .55 .0030 .0069 .0277 .0015 .0009

BL 82 Aug. 21 2.32.18 1.280 .30 .52 .0074 .0243 .0294 .0032 .0011

 

The determination of calcium in fruit by a combination of the EDTA ("Versenate")
method and spectrographic determination of magnesium.

Information collected and written up by Gerhard Bunemann, M. S. U. , March 1958.
modified by the present author for blueberry fruit.

Introduction

 

The complexometric titration is based upon the property of EDTA (Ethy-
lene diamine tetraacetic acid) to complex selectively the ions of Calcium and
Magnesium.

The amount of divalent ions present in one gram of dry matter is found by
dissolving the ash in acid solution and subsequently titrating at a buffered pH of
10. 0 to 10. 5. At first the EDTA complexes all the calcium ions present, and
then all the magnesium ions, and finally the magnesium which is part of the in-
dicator. This exchange of the Mg from the indicator for Na from the EDTA
causes the color change of the indicator from pink or purple to pure blue.

The titration must be carried to an endpoint which does not retain the
slightest purple tinge. Practice on both standards and fruit samples may be
necessary. The calcium value is obtained by subtracting the meq MgH from
the total meq cations.

Method

Materials: 1. EDTA ("Versenate" or "Versene") = Ethylene diamine
tetraacetic acid (disodium-dihydrogen salt): 2 g in 1 liter H 0 (approx. ).
2. Indicator: Mix 0. 5 g. Eriochrome Black T (Ba er, F. 241)
with 4. 5 g. Hydroxylamine - HCl (NI-120R. HCl) and dissolve in 120 m1
ethanol. Make up new solution at least every four weeks.
3. Calcium oxalate standard. Dry 1 g of Ca-ox overnight at
80’C, and then store in a desiccator. Dissolve in H 0, with the addi-
tion of approx. 10 ml HCl (1:1) and approx. 5 ml HN 3 (conc.) and make
up to 500 ml in volumetric flask. This standard contains 3. 12 mg or
. 1557 meq Ca in 5 ml solution.

 

At the time of titration for standardization of the EDTA add 1 mg
(= . 0822 meq) of Mg” to the 5 ml aliquot of the Ca solution, giving

. 1557 meq Ca
+. 0822 meg of Mg
. 2379 meq of Ca + Mg in Standard

 

* (as MgClz solution, calculate amount according to normality of solution).

Calculate the equivalence of the EDTA solution from the number of mi

EDTA used to titrate the above mixture as a pH of 10. 0 - 10. S; e. g.

ave. 21. 94 ml EDTA used: . 2379
W

Diehl _e_t 31; suggest adding the Mg to the standard EDTA solution. In
work with fruit samples, which always contain some Mg, the method des-
cribed above seems simpler and therefore more adequate.

meq = . 0109 meq cations per ml of EDTA.

Note: Always add water to make a total volume of approx. 125 m1 before
adding the buffer. Indicator degenerates in water, titrate quickly.

4. Buffer: Dissolve 135 g of C. P. Ammonium Chloride in 1140 ml
conc. NH4OH and dilute to 2000 ml with distilled and de-ionized water.
This buffer solution can be expected to give a pH of 10. 5 or higher.

5. Magnetic stirring equipment.
Let the stirrer run fast enough to produce a whirlpool of 1-2

inch depth. This will ease the accurate observation of the color change.

6. Fluorescent light and background against which the color change
can be observed conveniently.

Procedure

 

Ash 1 g of carefully dried and ground fruit sample in a small porcelain
crucible at 550° overnight. Transfer the ash into a 250 ml beaker. Rinse
crucible quantitatively with 0. 5 m1 1:1 HCl into the beaker and wash quantitatively
with distilled and deionized water. Add about 100-125 ml distilled and deionized
water. Then add sufficient ammonium buffer solution to bring the pH up to 10. 0-
10. l (10 ml buffer should do). Make sure the water is added before the buffer
to avoid undesirable precipitations. Use about 6 drops of Eriochrome Black T
indicator and titrate quickly, to reach clear blue endpoint exactly like the one
achieved on the standard solution. Run two parallel samples and check agree-
ment. The detection of the endpoint is difficult and one should practice on the
standard solutions before attempting to run any actual fruit samples.

Calculation examples:

 

. 0109 (meq/ml) x 6. 6 (ml used) = . 0719 meq Mg + Ca
. 0719 - . 0452 (meq Mg, spectrograph determination) = . 0267 meq Ca
. 0267 meq Ca x 20. 04 = . 5150 mg Ca in l g dry wt.

2 . 052% Ca in fruit sample.

Modification by present author: To obtain meq of Ca + Mg, the number of
ml of EDTA used was plotted graphically against a standard concentra-
tion gradient.

Special considerations:

 

Interferences may be expected from any divalent ions; therefore, the
quality of the distilled water is of utmost importance. The metal ions which
might interfere with the endpoint, are present in the fruit in such small amounts
that they may be neglected in the calculation.

This method is also suitable to determine the Ca + Mg in immature fruit
samples. Because of the higher concentration of these elements as well as of
interfering substances, and because of the possibility of precipitations it is
advisable to reduce the weighed amount to . 250 g in order to work with the
same concentration of EDTA as in the determination of mature fruit contents.

ifr..':' :04.“'n;..~q

ml 4.! ‘21s. (I—

11.81....1 41.1.1; 01.4.1