GROWTH AND CERTAIN ASPECTS OF THE
CHEMICAL COMPOSITlON‘ OF THE ONION.
AS INFLUENCE!) BY NUTRlTION

Thule ﬁn 9h. Dogma of Ph. D.
MICHIGAN STATE COLLEGE
John D. Downers
195$

THE!!!

IIIIIII III III IIIIIII II IIII IIIIIIII

J 321293 00666 1239

This is to certify that the

thesis entitled
Growth and Certain Aspects of the Chem-

ical Composition of the Onion as Inﬂuenced by
Nutrition

presented by

John D . Downes

has been accepted towards fulfillment
of the requirements for

_M_ degree in W e

@i assume

I Major professor

Date March 1, 1955

 

O~169

 

 

 

 

 

GROWTH AND CERTAIN ASPECTS OF THE CHEMICAL COMPOSITION

OF THE ONION AS INFLUENCED BY NUTRITION

By

JOHN D. DOWNES

A THESIS

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

DOCTOR OF PHILOSOPHY

Department of Horticulture

1955

 

 

 

 

till... I}! .0 It

Vi a“;

ACKNOWLEDGMENTS

The author desires to thank Dr. R. L. Carolus for
his active assistance and guidance throughout the conduct of this
work. He wishes also to express his gratitude for the guidance
and general helpfulness of Drs. G. P. Steinbauer, S. H. Wittwer,
L. M. Turk. E. E. Down, and Kirkpatrick Lawton. the other
members of the guidance committee.

Particular thanks are due Dr. E. J. Benne and Ralph
Bacon of Agricultural Chemistry for suggestions. assistance, and
having made available their facilities for the chemical analyses.

He is also indebted to the International Mineral and

Chemical Company for financial assistance.

 

 

 

TABLE OF CONTENTS

 

 

Page
INTRODUCTION ........................ 1
LITERATURE REVIEW .................... 2
Nitrogen ........................ 2
Phosphorus ....... ‘ ............... 4
Pot assium ....................... 5
Sulfur ....................... 6
Manganese ........................ 7 .
Iron ............................ 8 V
Copper .......................... 10
EXPERIMENTATI ON ...................... ll
GROWTH AND COMPOSITION OF THE ONION AS INFLUENCED
BY VARIOUS FERTILIZER NUTRIENTS (1952) ....... 12
Methods and Materials .................. 12
Field Procedures .................. .12
Laboratory Procedures ............... 16
A. Plant Analysis Methods ............ 16
B. Statistical Methods ............... 19
Results ........................... 22
Growth and Yield of Downing Yellow Globe and Ebenezer
Onions as Inﬂuenced by Fertilizer Treatment . . . 22
Composition of Downing Yellow Globe and Ebenezer
Onions as Influenced by Treatment ......... 26
Nitrogen ................... . . . 26
Phosphorus .................... 28
Potassium ..................... 28
Magnesium ..................... 30

Calcium ....................... 33

 

Page

YIELD AND PER CENT DOUBLE BULBS OF EBENEZER ONIONS
FROM SETS GROWN WITH VARIOUS NUTRIENT TREATMENTS 33

Methods and Materials .................... 33
Results ....................... ..... 35

PRODUCTION AND VIABILITY OF SEED BY DOWNING YELLOW
GLOBE MOTHER BULBS GROWN WITH VARIOUS NUTRIENT

TREATMENTS .......................... 36
Methods and Materials .................. . 36
Results ............................ 37

GROWTH, YIELD AND COMPOSITION OF DOWNING YELLOW
GLOBE AND EBENEZER ONIONS AS INFLUENCED BY NUTRIENT

TREATMENT (I953) ....................... 37

Methods and Materials ................... 37

A. Field Procedures .................. 37

B. Laboratory Procedures ............... 38

1. Statistical Methods ............... . 38

II. Chemical Methods ................. 39

Results ........................... . 42
Growth and Yield of Downing Yellow Globe and Ebenezer

Onions as Inﬂuenced by Nutrient Treatment ...... 42

Downing Yellow Globe ................. 42

Ebenezer ........................ 44

Varieties Combined .................. 44

Leaf: Bulb Ratios and Growth ............. 46

Composition ......................... . 48

Nitrogen .......................... 48

Phosphorus ......................... 50

Potassium ........................ . 52

f
A

 

Page

 

Magnesium ........................ 54
Manganese ........................ 57
Calcium .......................... 57
Iron ........................... . 6O
Boron ........................... 62
Sodium .......................... 62
DISCUSSION ............................. 66 ,. J
1 1:.
Yield as Influenced by Nutrition . ' .............. 70 I I
The Inﬂuence of Treatment on Plant Composition ...... 75 ; Ii
Nitrogen ........................ . 75 I
Phosphorus ...................... . 83
Potassium ......................... 84
Magnesium ............... , ......... 89
Sulfur ........................ . . . 91
Manganese . . .................. . . 93
Zinc . . . . . . . . . . . . . . . . . '. ......... .94
SUMMARY AND CONCLUSIONS .................. . 95

 

LITERATURE CITED ......................... 98

 

LIST OF TABLES

TABLE

1. Outline of Nutrient Treatments .............

11. Operating Conditions Employed in the Photometric Deter-
minations ........................

III. The Effects of Various Levels of Potassium on the Photo-
metric Determination of Calcium ...........

IV. The Effects of Calcium. Potassium and Sodium on the
Photometric Determination of Magnesium .......

V. Growth and Yield of Marketable Bulbs of First Crop of
Onions as Inﬂuenced by Treatment ...........

VI. Total Growth and Yield of First CrOp of Onions as Influ-
enced by Treatment ...................

VII. NitrOgen Content of First Crop of Onions as Influenced
by Treatment ......................

VIII . Phosphorus Content of First Crop of Onions as Inﬂuenced
by Treatment ......................

IX. Potassium Content of First Crop of Onions as Inﬂuenced
by Treatment ......................

X. Magnesium Content of First Cr0p of Onions as Influenced
by Treatment ......................

XI . Calcium Content of First Crop of Onions as Inﬂuenced by
Treatment ........................

X18. Inﬂuence of Treatment on pH. Reserve Phosphorus and
Reserve Potassium of the Soil .............

Page

13

I8

20

21

23

25

27

29

31

32'

34

4O

 

 

 

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TABLE

XII.

XIII.

XIV.

XV.

XVI.

XVII .

XVIII .

XIX.

XX.

XXI .

XXII .

XXIII .

XXIV.

 

Foliage Growth and Marketable Bulb Yield of Second Crop
of Onions as Inﬂuenced by Treatment ...........

Foliage Growth and Total Bulb Yield of Second Crop of
Onions as Inﬂuenced by Treatment ...........

Leaszulb Ratios .......................

Nitrogen Content of Second Crop of Onions as Inﬂuenced by
Treatment ........................

Phosphorus Content of Second CrOp of Onions as Inﬂuenced
by Treatment ........................

Potassium Content of Second Crop of Onions as Inﬂuenced
by Treatment ........................

Magnesium Content of Second Crop of Onions as Influenced
by Treatment ........................

Manganese Content of Second Crop of Onions as Inﬂuenced
by Treatment ........................

Calcium Content of Second Crop of Onions as Inﬂuenced by
Treatment ........................

Iron Content of Second Crop of Onions as Inﬂuenced by
Treatment ........................

Boron Content of Second Cr0p of Onions as Inﬂuenced by
Treatment ........................

Sodium Content of Second Crop of Onions as Inﬂuenced by
Treatment ........................

Variability in Composition and Yield of Two Varieties of
Onions ..........................

Page
43

45

47
49 -
51
53
55
58
59
61
63
64

69

 

5;

 

LIST OF FIGURES

FIGURE

1.

3-4-

5-6.

7-8.

9-10.

Sample of Single Plot Showing Row Spacing and Arrange-
ment ...........................

Inﬂuence of Potassium Application on the Potassium and
Magnesium Contents of the Leaves (1953) ........

The Influence of Nitrogen Applications on the Nitrogen,
Manganese and Iron Contents of the Leaves and their
Relation to Yields (I953) .................

Inﬂuence of Phosphorus Application on Phosphorus Con-
tent. Growth and Yield (1953) ...............

Relations of Nitrogen and Potassium Application to Man-
ganese, Iron Accumulation and Yield (1953) .......

Inﬂuence of Magnesium Application on Magnesium Con—
tent and Growth (1953) .................

Pa ge

15

56

76

80

87

92

 

 

INTRODUCTION

Although information from field experiments in which various
quantities of nutrients have been supplied to onions is considerable, the
physiological effects of various nutrients on onion growth and nutrient ac-
cumulation have not been investigated. Studies have also emphasized the
importance of separating plants into various portions for more completely
evaluating physiological relationships and nutrient requirements, but no
complet e separate analyses for tops and bulbs of onions are to be found
in the literature.

Information regarding the importance of the nutrients supplied
to the mother bulb during its formation as reﬂected in its ability to pro-
duce abundant and viable seed under field conditions is lacking. Neither
has the inﬂuence of the mineral content of onion sets on the yields of the
subsequent bulb crop been thoroughly investigated.

In relatively few of the experiments designed to study the
effects on plants of several nutrients simultaneously have single nutrients
been varied alone.

This investigation was undertaken to study the inﬂuence of
the addition of a number of nutrients upon their accumulation in onions,
and to attempt to estimate the direction and magnitude of gross develop-

mental variations associated with any differences in nutrient content .

Liz—...; . -

 

 

 

 

 

LITERATURE REVIEW

Introductory

 

Much of the research done on the responses of onions to
environmental factors has been conducted in the field allowing immediate
application of the information obtained. Pot culture and similar methods
have been used, based upon the idea that control of certain environmental
factors of plant growth should allow more precise study of the effects of
single factors, or the combination effects of a relatively few factors.
Employment of these techniques has contributed information on the
importance and interrelationships of both macro- and micro-nutrients.
On the whole, however, pot and similar cultural techniques have tended

to supplement rather than to supplant field investigation.

Nitro gen

 

Knott (54) concluded that most of the nitrogen required by
onions is needed during the early phases of growth, and its application
may result in early maturity by inducing adequate foliar growth prior
to bulb initiation. Results obtained by Kunkel (58) confirmed the find—
ings of Knott, and showed in addition that supplemental nitrogen was
0f most value in cold springs on wet acid muck soils. In a series of

experiments. Ware and Johnson (94) found that onions gave steadily

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increasing yields with application varying from 0 to 120 pounds of
nitrogen per acre. Results obtained by Wilson (95) indicated that a
shortage of nitrogen is associated with lowered sugar production and
perhaps also with delayed bulb initiation. Sugar was shown to accum-
ulate in all portions of the plant just prior to bulbing. but after bulbing
was initiated the sugar content of the leaves dropped steadily, while
that of the bulbs increased.

In field experiments Lloyd and Lewis (59) found nitrogen
to be especially beneficial in the production of onion sets when the
potassium supplied was adequate, but that nitrogen alone gave only a
slight response. Knott (54) found that on muck soils. which had been
under cultivation less than ten years, a negative response to fertilizer
nitrogen was generally obtained. In sand culture experiments with
Ebenezer sets, Wilson (95) showed that excess soil nitrates reduced
bulb yields. but had no inﬂuence on top growth.

Application of high rates of nitrogen to mother bulbs
CallSed split bulbs and multiple ﬂower scapes, according to Stuart and
Griffin (90), while low nitrogen levels were conducive to single scapes
and uniformity in time of ﬂowering. High soil nitrogen levels may
also induce bulbing instead of ﬂowering.

Stuart and Griffin (90) have described nitrogen deficiency

in Texas 986 Yellow Bermuda onion as being characterized by slow

growth, stiff, upright. light-green leaves, the tips of which showed

a tendency to die.

Pho gphorus

Phosphorus is one of the more important and commonly
limiting elements in onion production. Strong 9} al. (89) reported
that response to phosphorus by onions was more pronounced than re-
sponse to either potassium or nitrogen. Phosphorus deficiency was
marked by pale green foliage, slow growth and poor bulb yields.
Beaumont ﬁt 31: (5) and Hawthorne (48) stated that the most pronounced
response obtained in their experiments was to phosphorus. On newly
cleared muck soils Knott (57) obtained increases in yield with three
consecutive annual applications of 192 pounds per acre of P205. Scale
thickness and color of muck- grown onions was related to phosphorus
application according to Knott (56), who observed that the thickest
scales were found in the plots treated with the largest amount of phos-
PhOI‘Us. Also, it was observed that the effectiveness of copper in im-
proving scale color was associated with adequate phosphorus nutrition.

Bishop (13) found that increasing the quantity of phosphorus

applied in the fertilizer increased the phosphorus content of onions.

Stuart and Griffin (90) found that although plants provided
no phosphorus during the three-month period prior to bulbing, mani-
fested symptoms of phosphorus deficiency for two of the three months,
93 per cent of the seed produced, germinated satisfactorily. At very

low levels of phosphorus. few ﬂower stalks were produced, but seed

production per inﬂorescence was increased.

Potassium

Potassium is frequently low enough in sandy and muck soils
to limit yield. Consequently, it is standard practice to apply potassium
to these soils either alone or in complete fertilizers.

Beaumont _et_al_. (5) found that potassium fertilizer applica-
tion was essential for response to phosphorus additions. On newly
cleared New York muck soils, Knott (57) obtained increased yields of
onions each year with four consecutive annual applications of 195 pounds
0f K20 per acre. Campbell (27) presented data showing that under cer-
tain conditions potassium tends to reduce injury to onions by sodium.
Bremer (20) in Germany found bulb formation in onions to be retarded
by a potassium deficiency.

Hawthorne (48) reported potassium to be the least limiting

of the three major elements supplied in mixed fertilizers, and after the

 

first three years potassium applications frequently depressed yields.
Campbell (27) likewise found that heavy applications of potassium re-
duced onion yields particularly when calcium was deficient . High plant
potassium concentrations are generally associated with lowered contents
of calcium and magnesium (16, 26, 29. 30, 42. 68, 73).

Powers and Wood (70) found a scorching of cane fruit leaves
to be associated with excessive manganese absorption where potassium
supplies were inadequate. Application of lime and potassium resulted
in reduced bronzing of the leaves, increased yields and longer lived

plantings. Loehwing (61) discussed the relation of low plant potassium
contents to the reduction of sap acidity and decreased solubility of iron
in the plant. Nemec (68), Sideris (81) and Sheargt _aI. (79) reported

potassium and manganese concentrations to vary conversely in plants.

Sul fur

 

Sulfur is partly effective through its inﬂuence on soil micro-
organisms according to Boullanger (18). In a series of trials various
Vegetables including onions were grown in both sterilized and unsteri-
lized soils to which 70 grams of sulfur per 30 kg. of soil were added.
In unsterilized soils sulfur increased the yield in every case, while

Very little response was encountered in the sterilized soil.

Sulfur by increasing the acidity of soils, increases the avail-
ability of iron and manganese (46, 57).
Sulfur is required not only for the amino acids essential in
plant metabolism and growth, but, in the onion and similar liliaceous
species, sulfur as allyl propyl disulfide, is contained in the essential

oils which impart the characteristic ﬂavor and odor of this plant group.

Manganese

Bertrand (9) believed manganese and other micronutrients

augmented soil fertility by their catalytic action, and presented data

showing their distribution in plants. He maintained that manganese

was essential to the oxidizing enzymes of plants. Bishop (14) noted

that manganese tended to become localized in regions of active chem-
ical change, and that it is related to chlorophyll formation, and hence

to carbon assimilation. Improvement in plant growth and yield of

crops as a result of manganese application have been reported by many
investigators (35. 39,44, 46. 50. 51,57, 69, 80). Harmer (46) has shown
that soil reaction governs manganese availability through its inﬂuence on
the oxidation status of the nutrient. Manganese in the soil may be of

value to crop plants by increasing ammonification and nitrification (22).

and nitrate assimilation (52).

The relation of manganese to iron in plant metabolism has been
the subject of many papers. Rippel (75), Sideris (84), Erkama (38),
Pugliese (71), Twyman (93), and Somers and Shive (85), produced and
discussed the evidence indicating that an excessive concentration of

manganese in the plant is related to reduced utilization or mobility of

iron and to symptoms of iron deficiency.

Several investigators (4, 60, 66, 67, 83) have shown increased
manganese concentrations in plants as a result of manganese application.
Daniel (36) found manganese concentration in peach leaves to be in-
creased by application of a complete fertilizer, by nitrogen and phos-

phorus, nitrogen and potassium, and to a lesser extent by nitrogen appli-
cations. Hopkins and Gourley (49) obtained the same results with apple
fruits . Muckenhirn (67) found manganese applications increased bulb

yields, manganese contents in the leaves and earlier maturity of onion

bulbs .

Eisenmenger and Holland (37) have stated that there is ample

evidence that manganese applications tend to increase the concentration

0f PhOSphorus in plants.

Iron

 

Boullanger (19) in classifying the catalytic fertilizers for

various crops included iron and sulfur as being especially beneficial to

   

 

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onions. Pugliese (71) noted that in solution cultures of wheat the

plants were damaged by manganese nitrate in the absence of iron, but
that when iron was supplied as the sulfate, a stimulatory action was ob-
served. He concluded that in the presence of adequate iron, plants
could tolerate much higher concentrations of manganese than when it
was absent. The work of Somers, Gilbert and Shive (86) showed that
for normal growth of the soybean in solution culture, the ratio of
available iron to manganese should be about 2 .0. If the ratio was less
than 1 . 5, symptoms of iron deficiency appeared, and when greater

than 2 .0, symptoms of manganese deficiency appeared.

Somers and Shive (85) concluded that iron is functional in the
ferrous state and that manganese in the plant has a greater oxidizing
power than iron. On this basis, ferric iron absorbed by plants is re-
duced to the ferrous state unless the manganese concentration is such
as to prevent the reduction . Since the ferrous iron in any appreciable
concentration is considered to be toxic to plants, a deficiency of man-
ganese results in iron toxicity, and these authors suggest that the
two conditions, iron toxicity and manganese deficiency, are identical

in cause and effect .
Erkama (38) proposed that copper, iron and manganese are

a Physiological unit. and presented a concept wherein ferrous iron

 

10.

enters the root cells, and, the manganese concentration permitting, rises
through the xylem to the leaves where as reduced iron, it is functional and
termed "active iron". This "active iron" becomes incorporated in enzymes
and, through the agency of copper, which promotes protein formation, into
proteins. Some of the iron may also move back down the plant through the
phloem, being incorporated in proteins where copper is functional or de-
posited as insoluble ferric iron where manganese is active. This scheme
allows for the precipitation of iron under conditions of manganese toxicity,

and the utilization of iron in the formation of proteins where copper is adequate.

Copper
Felix (41), investigating possible reasons for the poor growth of
lettuce and onions on certain muck soils in western New York, obtained a

response from both crops by applying 100 to 200 pounds of finely ground

CuSO4 to the soil .

Knott (56) demonstrated that both phosphorus and copper additions
to the soil improved color deveIOpment and increased scale thickness of
Yellow Globe Danvers and Ebenezer onions. Copper, in addition toimproving

the color and scale thickness, gave firmer bulbs.

Muckenhirn (67) applied copper to peat soils in pot experiments

and obtained increased top growth of onions.

Lucas (60) obtained an increase in the concentration of copper in the

Onion as a result of applying copper sulfate to organic soils in which the crop
was grown. Miller and Mitchell (66) reported that copper sulfate applied to

the soil increased the copper contents of lettuce, but not of spinach.

   

 

ll.

EXPERIMENTATION

General Plan

 

The main objectives of this experiment were to study the
influence of eight nutrients (nitrogen, phosphorus. potassium, sulfur.
magnesium, copper. manganese and zinc) at three levels each, on the
growth of onions, and whether the bulbs so produced would vary in
their ability to produce viable seed, or as sets to produce mature market-
able bulbs. Relation of composition to performance and yield was to be
included in the study. These experiments were begun in the spring of
1952, subsequent to some preliminary work done the previous year. and
were to run through the 1953 season when the first portion of the experi-
ment was to be repeated. and the seed and mature bulb crops from the

mother bulbs and sets grown in 1952 would be harvested.

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12.

GROWTH AND COMPOSITION OF THE ONION AS INFLUENCED

BY VARIOUS FERTILIZER NUTRIENTS (1952)

This experiment was set up to study the influence of eight
nutrients (nitrogen, phosphorus, potassium, sulfur, manganese. copper.
magnesium and zinc) at three levels each. on the growth and yield of onions.
Downing Yellow Globe was selected as representative of the type which is

generally grown to maturity from seed, Ebenezer was selected as the

most widely used set onion.

Methods and Materials

 

Field Procedures:

A series of 20 fertilizer treatments involving combinations of
eight nutrients as shown in Table l were employed in a randomized block
arrangement with two replications. In addition to these nutrients and the
calcium appled as Ca(OH)2, iron. as tartrate. and boron, as boric acid,
were applied at the rates of 20 and one pound per acre. respectively to
each plot. Chlorine. at 5.8 pounds per acre. was applied to each plot by
manipulation of the various chemical carriers.

The experimental plots consisted of wooden boxes four feet long,
two feet wide and 14 inches deep, filled to a depth of 12 inches with an unpro-
ductive sand (Plainfield) into which was incorporated to a depth of four inches
one surface inch of screened muck soil, excepting for treatment 20, which

was a 1:1 mixture by volume of screened garden soil and muck soil.

s.

13.

TABLE I

OUTLINE OF NUTRIENT TREATMENTS

 

 

 

 

at
Description

 

 

1/3 X level of all nutrients (1)
X level of all nutrients (2)
3 X level of all nutrients (3)

l/3XN(4) 3XN(5)
l/3XP(6) 3XP(7)
1/3XK(8) 3XK(9)
0 S (10) 3 X S (11)
’ 0 Mg (12) 3 X Mg (13)
0 Cu (14) 3 X Cu (15)
0 Mn (16) 3 X Mn (17)
0 Zn (18) 3 X Zn (19)

X level of all nutrients in soil-muck mixture (20)

 

In treatments 4-19 inclusive all nutrients other than the one listed
were at the medium or X level.

 

Medium (X) Level of Nutrients in Pounds per Acre

 

NitrOgen 150 Magnesium 30

Phosphorus 44 Copper 3
Potas sium 83 Manganese l 0
Sulphur 50 Zinc 3

Nutrient Carriers
The following C . P. grade chemicals were used in preparing the
nutrient treatment solutions.

NH 4No3 H3PO4
(NH4)ZSO4 K2804
NH4CL KCL

KNO3 Mgc12.6H20

Mg(NO3)2 . 6H20
Mn(NO3)2 . 61-120
Cu(NO3)2 . 3H20

 

MgSO4 . 7H20

 

 

*
Numbers in parenthesis following the treatment descriptions
cOrrespond to those used in designating the soil determination

values in Table XIa.

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14.

Prior to seeding an application of 83.4 grams. equivalent to 1.000 pounds
per acre. of chemically pure hydrated lime was incorporated in the surface
four inches of each plot .
The fertilizer application for the entire season was divided into
bi-weekly applications. the aim being to have approximately 70 per cent of
the total fertilizer applied by the time bulbing had begun. Deionized water
was used for irrigation and for bringing the nutrient solutions to equal
volume at time of application.
Two varieties of yellow onions. Downing Yellow Globe and
Ebenezer, were seeded in rows, as shown in Figure l, on May 13. 1952.
Owing to very extensive damage by maggots, all plots were reseeded June 12.
Plants of the Downing variety were thinned to stand approximately two inches
apart in the row, while the Ebenezer was seeded thickly for the production
of sets, and thinned only where necessary to secure a uniform stand.
In this design the control treatment is the X level of all nutrients
(treatment 2), and it also serves as the medium or X level of each nutrient
variable. Thus, comparison of the results of treatments 4. 2 and 5 measures
the effects ofthree levels of nitrogen with a uniform nutrient background. where-
as the effect of change in background. essentially the N x background interaction.
is measured by comparison of treatments 1, 4. 5 and 3. Observation of the

various single nutrient effects suggests which of them may be functioning to

Provide the interaction effects.

15.

 

1'-
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Two rows of Downing
Yellow Globe

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Two rows of Ebenezer

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Figure l. Sample of single‘ plot showing row
spacing and arrangement.

 

 

 

 

 

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16.

The plants were harvested September 5th before the tops had
begun to die, the tops and bulbs being separated at harvest, by cutting
the tops off approximately one inch above the bulb. After being weighed
a brushed 100 grams aliquot was cut into 2-4 inch lengths and dried at
70 degrees Centigrade. After harvesting the bulbs were placed in par-
tial shade for a few days, then moved into a shed where curing was com-
pleted. After curing, the bulbs of each plot were graded into market-
able and unmarketable lots, and the weights of each recorded. Market-
able Downing bulbs were those 1 1/2 inches or greater in least diameter.

Marketable Ebenezer sets were those greater than one-half inch in least

diameter.
Laboratory Procedures:

A. Plant Analysis Methods.

The dried material was ground in a Wiley mill to pass a 20-mesh
screen, again dried at 70 degrees C for 24 hours, and duplicate 0.5 gram
samples were ashed in porcelain crucibles at approximately 550 degrees C.
The ashed samples were wetted with one per cent HClO4, neutralized with
1:3 70 per cent HC104zH20 by volume, and the crucibles filled to within
one-fourth inch of the top with one per cent HCIO4. The crucibles were
then placed on a steam bath until the solution volume was reduced approx-

imately one-half, then filtered while hot through Whatman #40 ashless

paper . The solutions were brought to volume and stored in sample

bottles for analysis .

For calcium, potassium, and magnesium the Beckman model
DU ﬂame photometer was used, following a modification of the procedure
outlined by Brown _et al_. (21) with hydrogen used as fuel . The operating
conditions employed in the photometric determinations are listed in
Table II. The standards for potassium contained potassium alone as the
perchlorate. Preliminary investigations into the subject of the inter-
ferences encountered in ﬂame photometry led to the adoption of the
practice of first determining all the elements listed in all samples using
reference standards containing only the element concerned as perchlorates
in solution. Then, to compensate for the variation introduced into the
determination of any particular element by the presence of all possible
combinations and levels of the other three elements involved, combina-
tion standards were analyzed photometrically and corrections were made
for interfering levels of the other elements as they occurred. The
evidence found in the course of this preliminary work indicates that the
method as outlined by Brown _et_ :1_l_ . may introduce considerable error
into photometric determinations . The method adopted in the work being

reported here is believed to render more accurate determinations for

calcium and especially for magnesium. since the interferences occurring

17.

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19.

under specific operating conditions are evaluated.

No interference of practical importance due to sodium in the
amount 3 found in the plants and under the operating conditions employed
in the spectro-photometric determination of potassium was encountered.
Likewise, in the determination of sodium neither potassium nor calcium
seriously interfered under the operating conditions employed. Neither
sodium nor magnesium interfered appreciably with the determination of
calcium, but potassium did interfere, especially at low concentrations
ofcalcium as shown in Table III. In the photometric determination of

the weak emitter magnesium, potassium, and calcium to a lesser extent,
interfered.

It is clear from the data in Table IV that under the operating
conditions employed as much as 86 per cent of the apparent magnesium
could be attributed to the presence of potassium and calcium in concentra-
tions found to exist in the material being analyzed.

Nitrogen was determined by the Kjeldahl method (2) . Phos-

Phorus was determined by the AD .A.C. (2) colorimetric method involv-

ing the formation of molydenum blue.

B. Statistical Methods.

The experiment was arranged for analysis of the growth and
yield data as a split plot design, the fertilizer treatments serving as the

main P1018. each of which was split for variety, and again for top and

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20.

TABLE III

THE EFFECTS OF VARIOUS LEVELS OF POTASSIUM ON THE
PHOTOMETRIC DETERMINATION OF CALCIUM

(Each Percent T value is the mean of eight readings)

 

 

Concentration of l 2
Elements in Ppm Percent Apparent Difference Percent

 

 

ﬁPerchlorates T Ppm of Ca Error
Ca K

400 500 103.2 415.9 15.9 -- 3.97
200 102.7 413.9 13.9 3.50
50 101.9 407.7 7.7 1.92

0 100.0 400.0 0 O
50 500 14.2 53.0 3.0 6 0
200 13.9 52.0 2.0 4.0
50 13.3 51.0 1.0 2.0

0 13.1 50.0 0 0
10 500 4.0 15.3 5.3 53.0
200 3.5 14.5 4.5 45.0
50 3 5 14.5 4.5 45.0

0 2 5 10.0 0 0

1Pe rcent transmittance

2 .
Ppm as read from curve constructed from transmittance values
using calcium alone in standard solutions.

QJerating conditions:

= 622 mu Phototube - red

= .430 mm Sensitivity - midpoint
H2 =5.86p.s.i. Selector-0.1
02 =10.0p.s.i.

 

 

“no I-

I.» a

 

 

 

 

 

TABLE IV

THE EFFECTS OF CALCIUM. POTASSIUM AND SODIUM IN THE PHOTO-
METRIC DETERMINATION OF MAGNESIUM

 

 

Element Concentrations

 

 

in Ppm as Perchlorates Percentl Apparent Percent
Mg Ca K Na T Mg Ppm Error
100 150 500 0 65.0 123 23.0
100 150 50 0 57.8 117 . . 17.0
100 50 500 0 64.6 122 22 .0
100 50 50 0 56.6 114 14.0
100 O 0 0 54.5 100 0
30 150 500 50 341.6 56 ‘ 86. 6
30 150 500 20 34 .2 55 83 .4
30 150 50 50 26.0 37 ' 23.3
30 150 50 20 25.5 36 - 20.0
30 50 500 50 33 .4 53 76 .6
30 50 500 20 33 .4 53 76 .6
3O 50 50 50 24.5 33 - 10.0
30 50 50 20 24 . 5 33 10 .0
22.8 30 0

3O 50 50 0

 

 

1
Average of two readings - 200 ppm Mg = 100 percent T

Operating conditions:

wave length: 371 mu Sensitivity - max.
slit width = .360 mm Selector - 0.1
Hz = 7.5 p.s.i. Phototube - blue

02 12.0p.s.i.

 

 

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22.

bulb yield in accordance with the methods and reasons given by
Goulden (45) and Cochran and Cox (31). The analysis of variance
including the calculations of least differences required for signifi-
cance at two confidence levels for both single factor effects and all
appropriate interactions as outlined by Cochran and Cox (31) were
completed. The plots were considered as completely randomized
blocks, relative to the composition data.

Results:

Growth and Yield 9_f_ Downing Yellow Globe and Ebenezer

 

 

 

Onions _e_t_s Inﬂuenced by Fertilizer Treatment
The inﬂuence of phosphorus on leaf and marketable bulb pro-
duction, Table V, was the most outstanding result of this test. In both
varieties the medium and high levels of phosphorus applied resulted in
significant increases in marketable bulb yields. However, phosphorus
did not significantly increase the leaf growth. In fact, with the Ebenezer
variety leaf growth was significantly reduced at the high phosphorus
level compared to the low level (Table V).
The leaf growth was significantly increased with both the
medium and high levels of the complete nutrient treatment . This effect
was not entirely due to nitrogen, apparently. since the leaf growth re-

sulting from the medium and high levels of the complete nutrient

 

 

 

 

 

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GROWTH AND YIELD OF MARKETABLE BULBS OF FIRST CROP OF

TABLE V

ONIONS AS INFLUENCED BY TREATMENT
(Grams of fresh weight per 4 square feet)

 

 

 

 

 

wTreatment“ Downing Yellow Globe Ebenezer“
Low Medium High Low Medium High
Complete Leaf 229 446 735 193 455 1 108
Bulb 131 391 341 58 223 553
Total 360 837 1076 251 678 1661
Nitrogen Leaf 165 446 611 598 455 741
Bulb 150 391 391 149 223 337
Total 315 837 1002 747 678 1078
Phosphorus Leaf 381 446 403 671 455 427
Bulb 170 391 670 115 223 516
Total 551 837 1073 786 678 943
Potassium Leaf 294 446 538 604 455 680
Bulb 191 391 377 104 223 471
Total 485 837 915 708 678 1151
Sulphur Leaf 332 446 412 652 455 793
Bulb 216 391 323 121 223 222
Total 548 837 735 772 678 1015
Magnesium Leaf 389 446 502 592 455 655
Bulb 267 391 448 168 223 385
Total 656 837 950 760 678 1040
Copper Leaf 421 446 334 696 455 689
Bulb 335 391 255 482 223 300
Total 756 837 589 1178 678 989
Manganese Leaf 353 446 391 652 455 634
Bulb 220 391 311 169 223 245
Total 573 837 702 821 678 879
Zinc Leaf 618 446 363 542 455 678
Bulb 461 391 276 243 223 215
Total 1079 837 639 785 678 893
Complete Leaf 960 701
soil Bulb 607 706
Total 1567 1407
’A11 except listed nutrients at medium level
#
*Ebenezer bulbs greater than 1/2 inch in diameter
Leaves L .S .D .05 264 301
L .S . D .01 361 411
Bulbs L .S . D .05 251 94
L.S.D .01 N.S. 128
Totals L.S.D .05 334 210
L . S.D .01 456 287

23.

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24.

treatment were disproportionately greater than the increases resulting
from the application of additional nitrogen alone. This indicates that
although phosphorus was most outstanding in affecting bulb yields, other
nutrients than nitrogen also were responsible for increasing the leaf
growth. All the nutrients applied except zinc and copper increased bulb
yields .

Although nitrogen increased bulb yields in both varieties, its
affect on leaf growth was most pronounced in Downing Yellow Globe.
Both nitrogen and potassium appeared to be effective in increasing bulb

production at the high level with Ebenezer, but phosphorus was more

effective with the Downing Yellow Globe.

The effects of pctassium were similar to those of nitrogen,
although it appeared to be more effective in increasing leaf growth in

Downng Yellow Globe than in the Ebenezer variety.

The high manganese as contrasted to the low manganese treat-
ment increased bulb growth, but had no appreciable effect on leaf growth.
The addition of either copper or zinc resulted in decreased bulb yields
and foliage growth, indicating that with the sandy soil used in this experi-

ment, both were toxic at the high level of application.

Differences shown by the two varieties in leaf and bulb growth

might have been due in part to spacing. In Table VI the total growth

 

 

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TABLE VI

TOTAL GROWTH AND YIELD OF FIRST CROP OF ONIONS AS INFLUENCED
BY TREATMENT
(Grams per 4 square feet - varieties combined)

 

Approximate per-

 

Treatment Low Medium High
cent change
in yield

Complete Leaf 211 451 92 l 336

Bulb 1 90 398 487 156

Total 401 849 1048 250

Nit rogen Leaf 381 451 676 77

Bulb 168 398 439 161

Total 549 849 1 l 15 103

Pho sphorus Leaf 526 451 41 5 -21

Bulb 257 398 724 182

Total 783 849 l 1 39 46

Potassium Leaf 449 451 609 36

Bulb 223 398 458 105

Total 672 849 1067 59

Sulphur Leaf 492 451 602 22

Bulb 282 398 347 23

Total 774 849 949 23

Magnesium Leaf 491 451 578 18

Bulb 361 398 541 50

Total 852 849 1 1 1 9 32

Copper Leaf 558 451 512 - 8

Bulb 493 398 397 - 20

Total 1015 849 909 - 14

Manganese Leaf 502 451 513 2

Bulb 288 398 355 23

Total 790 849 868 10

Zinc Leaf 580 451 521 - 10

Bulb 421 . 398 413 - 2

Total 1001 849 934 - 7
Complete Leaf 830
soil Bulb 694
Total 1524

t
From low to high level of nutrient applied

L.S.D. .05 L.S.D. .01
Treatments (within apart) 122 166
Parts (within a treatment) 39 52
Treatments (total) 168 230

 

 

 

 

26.

(includes both marketable and unmarketable bulb yields) of the two
varieties was averaged. Leaf growth was sigmificantly reduced by
the medium and high zinc, copper, and phosphorus treatments, and
increased by high nitrogen, potassium, sulfur. magnesium, and the

complete treatments at the high level of application.

Composition o_f_Downing Yellow Glove an_d_ Ebenezer Onions

 

as Influenced by Ersatment

Nitrogen:- In most instances the increase in nitrogen contents
may be attributed to reduced growth and incomplete utilization of absorbed
nitrogen. Reduced nitrogen concentration as shown in Table VII in most
cases was probably a result of increased growth and carbon assimilation.
The increase in nitrogen content of the leaves and bulbs of the plants
grown with the high nitrogen and high complete treatments suggests that
nitrogen absorption and accumulation in these treatments more nearly
kept pace with requirements for nitrogen than was true of most of the
other treatments. It is obvious that nitrogen was one of the limiting

nutritional factors in the growth of the plants. Since there was insuffi-
cient plant material for nitrogen determinations for both replications,
no estimate of the probability that the values given represent the treat-
ment were possible. The nitrogen content of the bulbs of the Downing

variety were roughly half that of leaves, while in the Ebenezer variety

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27.

TABLE VII

NITROGEN CONTENT OF FIRST CROP OF ONIONS AS INFLUENCED BY
TREATMENT
(Nitrogen in per cent of the oven dry weight)

 

 

 

 

Treatment* Downing Yellow Globe Ebenezer
Low Medium High Low Medium High
Complete Leaf 1.53 l .78 2.02 1 .98 2.19 2. 91
Bulb .84 .80 1.54 1.56 1.92 2.36
Nitrogen Leaf 1.52 1.78 1.90 1.70 2.19 2.75
Bulb .81 .80 1.11 .91 1.92 2.51
Phosphorus Leaf 1 .78 1 .78 1.53 2.49 2.19 2.26
Bulb 1.04 .80 .80 2.44 1.92 2.25
Potassium Leaf 1.77 l. 78 1.49 2.39 2.19 2.25
Bulb .96 .80 .78 1.76 1.92 2.60
Sulphur Leaf 1.81 1.78 1.73 2.35 2.19 2.47
Bulb .96 .80 .90 1.62 1.92 1.24
Magnesium Leaf 1 .63 1.78 l .74 2.26 2.19 2.23
Bulb .84 .80 .94 2.08 1.92 2.15
Copper Leaf 1.63 1.78 1.66 2 .44 2 . 19 2.25
Bulb .91 .80 .91 1.63 1.92 1.98
Zinc Leaf 1.84 1.78 1.70 2.36 2.19 2.25
Bulb 1.15 .80 .97 2.12 1.92 2.85
Complete Leaf 3 . O6 2 . 04
soil ' Bulb 2.20 2.51

 

28.

the nitrogen content of tops and bulbs were almost equal .

Phosphorus:- Phosphorus fertilization increased the phosphorus
contents of the leaves and bulbs of the Downing variety and the bulbs of the
Ebenezer variety, but had little inﬂuence on the concentration of phosphorus
in the leaves of the latter variety. Increasing the application of nitrogen.
as shown in Table VIII, reduced the phosphorus contents of the leaves
and bulbs of Downing, possibly as a result of, increased growth. With

the Ebenezer variety, nitrogen had no effect on leaf contents of phosphorus,
but resulted in increasing the phosphorus content of the bulbs.

Potassium, sulfur, and magnesium fertilization had no distinct
inﬂuence on the phosphorus contents of the leaves or the bulbs of either
variety. The addition of copper reduced the leaf content of phosphorus
slightly, but had no effect on the bulb content . Manganese showed atendency
to reduce the phosphorus contents of Downing bulbs and Ebenezer leaves,
to increase the content of Ebenezer sets, and to have no effect on Downing
leaves. Zinc additions, possibly as a result of reducing growth, showed

a tendency to increase phosphorus contents of the bulbs of both varieties

and the leaves of Ebenezer. As with the nitrogen values, however, statis-

tical analysis could not be applied to this data due to lack of material.
Potassium:- The potassium contents of the leaves of both

varieties were increased to a greater extent than were the contents of the

 

 

 

 

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TABLE VIII

PHOSPHORUS CONTENTS OF FIRST CROP OF ONIONS AS INFLUENCED BY
TREATMENT
(Phosphorus in percent on the oven dry basis)

 

 

 

Treatment,“ Downing Yellow Globe Ebenezer

Low Medium High Low Medium High
Complete Leaf .259 .217 .185 .380 . 274 . 254
Bulb .244 .195 .289 .300 .313 .348
Nitrogen _ Leaf .255 .217 .179 .292 , .274 .290
Bulb .265 .195 . 169 . 165 .313 .280
Pho sphorus Leaf .205 . 217 .256 .290 .274 .270
Bulb .200 . 1 95 .220 .240 . 313 .325
Potassium Leaf .228 . 217 . 242 .282 .274 .226
Bulb .195 .195 .216 .266 .313 .154
Sulphur Leaf . 256 . 217 . 240 .216 .274 .258
Bulb .224 .195 .207 .267 .313 .214
Magnesium Leaf . 205 . 217 .225 .276 .274 .292
Bulb .206 .195 .180 .253 .313 .290
Copper Leaf .260 . 217 . 205 .294 .274 .288
Bulb .188 .195 .179 .310 .313 .280
Manganese Leaf .190 .217 . 217 .270 . 274 .222
Bulb .229 .195 .174 .230 .313 .280
Zinc Leaf .170 . 217 .210 .284 .274 .284
Bulb . 190 . 195 .200 .280 .313 .250

Complete Leaf .132 .258

soil Bulb . 379 .500

 

*
All except listed nutrients at medium level

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30.

bulbs, as a result of potassium application. as shown in Table IX. The
reduction in potassium in the Downing variety as a result of increased
nitrogen application, was probably the result of dilution by grthh. Sulfur
showed a tendency to reduce potassium contents in the Downing variety,
while magnesium increased it in the leaves of Ebenezer. Copper, man-
ganese, and zinc had no distinct effect on potassium contents. The rela-
tively high potassium content with the low level complete nutrient treat-
ment may be explained by the limited grovvth resulting from the lack of
adequate nitrogen, while the increased contents at the high level com-

plete treatment may be explained as a function of the increase in potassium

supplied. The soil plot evidently supplied sufficient potassium, for the

levels in leaves and bulbs of both varieties were almost twice those found

in the plants from any other plot in spite of high yields and maximum

growth .

Magnesium:- The application of magnesium increased the
magnesium content of Ebenezer leaves, but had no consistent effect in the
other variety, as shown in Table X. Nitrogen applications increased the
leaf content of magnesium in both varieties. Phosphorus, sulphur, man-

ganese, c0pper, and zinc had no consistent inﬂuence on the magnesium
content of the plants, and potassium reduced it only slightly. The increase

in magnesium contents with the high levels of the complete nut rient treat-

POTASSIUM CONTENT OF FIRST CROP OF ONIONS AS INF LUENCED BY

TABLE 1X

 

 

 

 

 

TREATMENT
(Potassium in percent on the oven dry basis)

“ﬂ * Downing Yellow Globe Ebenezer
Treatment Low Medium High Low Medium High
Complete Leaf 1.46 *. 1.05 1.58 1.74 1.07 1.87

Bulb 1.36 1.11 1.49 1.34 1.48 1.84
Nitrogen Leaf l .59 1 .05 .90 1 .17 1.07 .98
Bulb 1.86 1.11 1.05 1.13 1.48 1.33
Phosphorus Leaf 1.40 1.05 1.16 1.07 1.07 1.31
Bulb 1.49 1.11 1.39 1.31 1.48 1.29
Potassium Leaf .65 1.05 1.18 .65 1.07 1.70
Bulb 1.19 1.11 1.36 1.10 1.48 1.69
Sulphur Leaf 1 .27 1.05 .76 .96 1.07 1.12
Bulb 1.33 1.11 .83 1.12 1.48 .91
Magnesium Leaf 1.15 1.05 1 . 19 1.01 1.07 1.24
Bulb 1.19 1.11 1.29 1.30 1.48 1.47
Copper Leaf 1.20 '1 .05 1 .11 .85 1 .07 1.08
Bulb 1.37 1.11 1.05 1.26 1.48 1.48
Manganese Leaf 1.13 1.05 1.14 1.15 1 .07 1.17
Bulb 1.11 1.11 1.07 1.07 1.48 1.27
Zinc Leaf 1.11 1.05 1.23 1.26 1.07 1.25
Bulb 1.12 1.11 1.29 1.31 1.48 1.48
Complete Leaf 2. 74 2 . 77
soil Bulb 2.17 2.06
*
All except listed nutrients at medium level

Leaves L.S.D. .05 .40 .48

L.S.D. .01 .54 .66

Bulbs L.S.D. .05 .43 .32

L.S.D .01 .59 .44

31.

TABLE X

MAGNESIUM CONTENT OF FIRST CROP OF ONIONS AS INF LUENCED BY
TREATMENT
(Magnesium in percent on the oven dry basis)

 

 

 

 

* Downing Yellow Globe Ebenezer
t
Treatmen Low Medium High Low Medium High
Complete Leaf .086 .100 .111 .123 .088 .135
Bulb .050 .056 .047 . 047 . 058 .070
Nitrogen Leaf .093 . 100 . 123 .084 .088 .148
Bulb . 050 .056 .061 .058 .058 .058
Pho sphorus Leaf .085 . 100 . 090 . 084 . 088 . .078
Bulb .053 .056 .038 . 056 .058 .062
Potassium Leaf .1 15 . 100 .090 .138 .088 . 123
Bulb .073 .056 .054 . 065 . 058 .060
Sulphur Leaf . 115 . 100 .090 . 133 .088 .133
Bulb .059 .056 .056 .048 .058 .038
Magnesium Leaf . 084 . 100 .092 . 084 . 088 .1 20
Bulb .055 .056 .041 .065 . 058 .070
COpper Leaf .109 . .100 .088 .084 .088 .101
Bulb .051 .056 .060 .047 .058 .070
Manganese Leaf .110 .100 .084 .133 .088 .099
Bulb .068 .056 .039 .048 .058 . 070
Zinc Leaf . 086 . 100 .072 . 138 .088 . 100
Bulb . 068 .056 .039 .047 .058 .074
Complete Leaf . 206 .107
soil Bulb . 066 .068

 

 

* .
All except listed nutrients at medium level

 

 

 

33.

I

ment may have been a function of the nitrogen applied. These results
were not treated statistically and no estimate of error is given.
Calcium:- Compared to the medium level of application, nitrogen
at the high level increased the calcium contents in the bulbs of Downing
Yellow Globe and in the leaves of Ebenezer as shown in Table XI. Phos-
phorus applications progressively decreased the calcium content of the
bulbs, possibly as a result of increased growth. Increasing the quantities
of potassium applied resulted in reduced calcium contents in both varie-
ties . It appeared that magnesium application tended to increase calcium
content in the leaves of both varieties. Sulfur, copper and manganese
manifested no significant effects with respect to calcium content of the
plants, but zinc at the high rate of application showed a tendency to re-

duce calcium contents in both leaves and bulbs.

YIELD AND PER CENT DOUBLE BULBS OF EBENEZER ONIONS FROM

SETS GROWN WITH VARIOUS NUTRIENT TREATMENTS

Methods and Materials

Sets of the Ebenezer variety produced in 1952 in the plots
receiving the various nutrient treatments described in the first experi-

ment were stored at 32 degrees F arenheit, and planted the following

 

IV

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TABLE XI

CALCIUM CONTENT OF FIRST CROP OF ONIONS AS INFLUENCED BY
TREATMENT
(Calcium in percent on the oven dry basis)

 

 

 

 

Treatment” Downing Yellow Globe Ebenezer

Low Medium High Low Medium High
Complete Leaf . 37 .49 .38 . 70 . 54 1 .00
Bulb .43 .41 .42 .20 .17 .18
Nitrogen Leaf .61 .49 .55 . 52 .54 . 78
Bulb .34 .41 .52 .25 .17 .16
Phosphorus Leaf . 38 .49 .45 .49 .54 . 52
Bulb .49 .41 .33 .19 .17 .15
Potassium Leaf . 53 .49 .37 . 64 .54 .57
Bulb .50 .41 .37 . .19 .17 .19
Sulphur Leaf .48 .49 . 50 .68 .54 . 63
Bulb .48 .41 .47 .21 .17 .19
Magnesium Leaf . 37 .49 .45 .53 . 54 . 65
Bulb .42 .41 .37 .16 .17 .14
C0pper Leaf . 44 .49 . 48 . 66 .54 .56
Bulb .43 .41 .47 .17 .17 .13
Manganese Leaf .46 .49 . 43 .62 .54 .56
Bulb .45 .41 .32 .16 .17 .18
Zinc Leaf . 47 .49 .36 .64 .54 .48
‘ Bulb .42 .41 .34 .15 .17 .16

Complete Leaf 1 . 05 . 75

soil , Bulb .44 .12

 

 

 

 

*_ .
All except listed nutrients at medium level

Leaves L.S.D. .05 .19 .05
L.S.D. .01 .25 .08

Bulbs L.S.D. .05 .08 N.S.
L.S.D. .01 .11 N.S.

35.

spring in a muck soil which had been uniformly fertilized with 1, 000
pounds per acre of a 3-12-12 mixture applied broadcast . The sets were
planted April 8, 1953 three inches apart in rows 16 inches apart . Two
sizes of sets, 1/2 to 3/4 inches and 3/4 to 1 inch in least diameter
were employed.

A split plot design in which the block (replication) was split
for size of set, the subplots being the various nutrient treatments, was
used. Three blocks were used, giving three replications for size of set
and six replications for nutrient treatment. The subplots consisted of
ten plants each, and appropriate border rows were provided.

In September the bulbs were harvested. A record of individual
bulb weights, doubleness, and ﬂowering tendency was made.

Results:

The yields of bulbs from sets grown with the high sulfur and
the high manganese treatments were reduced 13 .2 and 13.7 per cent
respectively from the yields obtained from sets grown with the medium
level complete nutrient treatment. No difference in effects due to other
nutrient treatments were obtained, nor was there any difference in
yield due to size of sets employed. No difference in tendency to bolt

was observed.

Possibly as a result of reduced average bulb size, the sets

36.

from the high sulfur and the high manganese treatments produced 33 .4

and 39.7 per cent fewer double bulbs respectively than did the sets from
the medium complete nutrient, treatment . The sets produced with the soil-
muck mixture (Treatment 20) gave the highest yield and the greatest per
cent of doubles, only 54 per cent of the bulbs on the average in six repli-
cations being free of this undesirable feature. The small sets produced

24 per cent doubles, compared to 40 per cent for the large sets.

PRODUCTION AND VIABILITY OF SEED BY DOWNING YELLOW GLOBE

MOTHER BULBS GROWN WITH VARIOUS NUTRIENT TREATMENTS

 

Methods and Materials

Four bulbs of Downing Yellow Globe of approximately equal
size from each of the nutrient treatments described in the first experi-
ment were planted in fertile soil in 10-inch pots plunged in greenhouse
ground beds. The bulbs were planted in February, and watered with
tap water as needed. No fertilizer was applied, since the soil had been
fertilized and manured the previous fall. Records were kept of ﬂower-
ing dates, and the yield and germination of the seed produced in each
inflorescence. The seeds were threshed by hand and cleaned with a

Clipper fanning mill equipped with pans for catching the light seed, which

were counted for each inﬂorescence.

37.

Results:

The data relative to seed production were so inconsistent that
no reliable inferences could be drawn from them, but it appeared that any
nutrient treatment capable of producing a bulb of adequate size should also
be capable of producing a bulb which would produce. viable seed if planted
in a soil and under conditions which would be employed in practical seed
production.

The mean seed weight for all treatments was 4.24 milligrams,
and the coefficient of variation was 37 .5 per cent . The seed weight means
ranged from 3.58 to 5.09 milligrams, the lightest seed being found in the
treatment without zinc, and the heaviest seed being produced by the bulbs
grown the previous year with the soil-muck mixture (Treatment 20)..

Germination percentage varied from 73 .2 for the minus sulfur
treatment to 100 for four treatments; low level complete, low potassium,

high copper, and high manganese.

GROWTH, YIELD AND COMPOSITION OF DOWNING YELLOW GLOBE AND

EBENEZER ONIONS AS INFLUENCED BY NUTRIENT TREATMENT (1953)

Methods and Materials

 

A. Field Procedures .

 

With modiﬁcations, this experiment was a repetition of the

38.

first experiment. The same field plot was used both years for each of
the various nutrient treatments.

To provide for a uniform stand of evenly spaced plants, a
spacing board was used in sowing the Ebenezer seed, andin transplanting
the plants of the Downing variety, which had been seeded in vermiculite
in the greenhouse and fertilized with a solution of 10-52-17 fertilizer in
distilled water. Planting was done in mid-April.

Iron and boron were applied at the rates of four and .20 pounds
per .acre respectively, instead of the 20 pounds and 1 pound per acre
rates used in the first year. Deionized and distilled water were again
employed for irrigation and in preparing the nutrient solutions for appli-
cation.

The plants were harvested the last week in September, and
handled as described in the first experiment .

B. Laboratory Procedures.

 

1. Statistical Methods: - The design employed was a split

 

plot, as described in the first experiment, and the growth and yield data
were analyzed in accordance with the design. As before, the grth was
measured by the fresh weight of the tops, and the yield was measured

by the weight of the cured bulbs.

The composition data were analyzed statistically as completely

39.

randomized blocks, the plants from both replications having been

available to permit statistical treatment .

11. Chemical Methods: - In order to learn of the residual

 

effects of the first year's fertilizer applications, prior to planting a '
soil sample composed of three sub-samples of the complete profile

of each plot was collected. The pH of a 1:2 soilzwater mixture was
determined, using a Beckman pH meter . A five-gram aliquot of soil
from each plot was extracted with .135 HCl and the phosphorus and
potassium contents of the extract determined. The Beclonan model

D .U . Flame Photometer was used for the potassium determinations,
and the phosphorus was determined by the A.O .A.C. colorimetric
method employing hydroquinone and sodium sulfite as reducing agents
in complexing ammonium phosphomolybdate (2). The results of these
tests are given in Table XIa.

Play} Analyses:

 

The dried plant material was ground in a Wiley mill to pass
a 20-mesh screen, dried again for 24 hours at 70 degrees C, and cooled
in a desiccator prior to weighing out samples for analysis. .
Nitrogen, potassium, and calcium contents were determined
for all plant samples, as described in the first experiment. Sodium

was determined by use of the ﬂame photometer following the method pre-

TABLE XIa

INFLUENCE OF TREATMENT ON pH. RESERVE PHOSPHORUS AND

RESERVE POTASSIUM OF THE SOIL"
(All values means of the two replications)

 

- Treatment

 

pH Reserve P Reserve K
Lbs. per A. Lbs. per A.

1 1/3 X all 7.56 62 50
2 X all 7.12 81 80
3 3 X all 6.76 117 110
4 1/3 xN 7.52 87 68
5 3 X N 7.09 77 44
6 1/3 XP 7.21 74 64
7 3 X P 7.34 102 63
8 1/3 X K 7.27 75 45
9 3 X K 7.50 89 88
10 O S 7.47 62 57
11 3 XS 6.97 96 6O
12 0 Mg 7.32 83 81
13 3 X Mg 6.79 97 75
14 0 Cu 7.35 60 68
15 3 X Cu 7.19 74 60
16 0 Mn 7.40 66 83
17 3 X Mn 7.25 60 71
18 0 Zn 7.31 73 66
19 3 X Zn 7.40 67 64
20 X all 7.02 117 401

*
Samples taken at the beginning of the second crop season.

40.

1".“ 4

 

 

41.

viously described for potassium and calcium. Phosphorus, magnesium,
manganese, copper, iron and boron were determined spectrometrically
with a prism type instrument.

In the spectrometric analyses two- gram samples of oven-
dried plant material were ashed at 550 degrees C. The ash was dis-‘
solved in 50 per cent (by volume) HCl, LiCl2 was added as an internal
standard, and the solution was brought to a volume of ten milliliters with
50 per cent HCl. A volume of 0.25 milliliters of this solution was applied
to each member of three regular carbon electrode pairs. The solution
thus applied was rapidly dried under a heat lamp to reduce absorption
by the electrode, and the determinations made immediately in a Jarrell-
Ash spectrometer. The photographic plates produced were evaluated using
a microphotometer, and the logarithm of the relative intensity (relative to
the intensity of the lithium line) was plotted against element concentration.
The values of four reference samples serving as standards were included

on every plate. With few exceptions, the values used in plotting the
curves were arithmatical averages of the element concentrations corres-

ponding to the various logarithm of relative intensity values.

42.

Results:

Growth and Yield g Downing Yellow Globe and Ebenezer

 

 

 

Onions as Inﬂuenced by Nutrient Treatment

 

Downing Yellow Globe:- The depression of leaf growth and bulb
yields with the high nitrogen treatment was the most pronounced effect
obtained in this experiment . As shown in Table X11 leaf growth and
marketable bulb yield were reduced 44 and 24 per cent respectively
in the Downing variety by the high nitrogen compared to the medium
nitrogen treatment . This effect of nitrogen was again expressed in the
reduction in leaf growth and bulb yield obtained with the high complete
compared to the medium complete treatment .

Compared to the low level, application of the high level of
either phosphorus or potassium showed a tendency to increase bulb yield,
with phosphorus decreasing, and potassium increasing the leaf growth.
The high level of magnesium and copper also had a tendency to increase
the leaf growth and bulb yield compared to the low level treatments.

Sulfur at the high, compared with the medium level of application, re-
sulted in significantly reduced leaf growth, but had no affect on bulb.
Yield. Manganese showed a tendency to increase leaf growth and depress
bulb yields at the high level of application, while zinc significantly re-

duced bulb yields at the high rate of application without affecting leaf

growth .

TABLE XII

FOLIAGE GROWTH AND MARKETABLE BULB YIELD OF SECOND CROP OF
ONIONS AS INFLUENCED BY TREATMENT
(Grams of fresh weight per 4 square feet)

 

l

 

 

 

Treatments; Downing Yellow Globe Ebenezer
Low Medium High Low Medium High
Complete Leaf 235 398 ‘ 204 156 292 212
Bulb . 1097 1195 979 513 682 807
Total 1332 1593 1183 669 974 1019
Nitrogen Leaf 322 398 222 220 292 164
Bulb 1208 1195 911 661 682 567
Total 1530 1593 1133 881 974 731
Phosphorus Leaf 317 398 288 244 292 248
Bulb 1070 1195 1272 611 682 818
Total 1387 1593 1560 855 974 1066
Potassium Leaf 230 398 404 202 292 278
Bulb 1152 1195 1246 787 682 683
Total 1382 1593 1650 989 974 961
Sulphur Leaf 315 398 267 231 292 271 '
Bulb 1140 1195 1189 621 682 763
Total 1455 1593 1456 852 974 1 034
Magnesium Leaf . 260 398 394 254 292 241
Bulb 1108 1195 1215 642 682 710
Total 1368 1593 1609 896 974 951
Copper Leaf 276 398 398 223 292 295
Bulb 1 195 1195 1294 666 682 78 1
Total 1471 1593 1692 889 974 1076
Manganese Leaf 262 398 339 302 292 342
Bulb 111 1 1 1 95 1077 843 682 806
Total 1373 1593 1416 1145 974 1148
Zinc Leaf 309 398 293 221 292 236
Bulb 1366 1195 1090 809 682 756
Total 1675 1593 1383 1030 974 992
Complete Leaf 278 198
soil Bulb 1238 903
E Total' 1416 1101
*All except listed nutrients at medium level
Leaves L. S. D. .05 109 57
L .S.D. .01 149 78
Bulbs L. S. D. .05 208 179
L. S. D. .01 285 N.S.
Totals L. S. D. .05 193 152
L. S. D. .01 264 207

In terms of total growth, nitrogen and zinc were significantly
detrimental at the high level, while potassium, magnesium and copper
were significantly beneficial at the medium level compared to the low
level of application as shown in Table XIII.

Ebenezerz- Although, as in the Downing Yellow Globe, nitro-
gen first increased then reduced leaf growth with increased applications.
bulb yields were not significantly reduced (Table XII). The detrimental
effect of nitrogen relative to leaf growth was reﬂected again in the com-

plete treatment. Phosphorus at the high level resulted in increased bulb
yield compared to the low level with no effect on leaf growth. It is quite
probable that the increased bulb yield obtained with the application of
the high level complete treatment was due in part to the added phosphorus
applied.

Potassium resulted in a significant increase in leaf growth,
perhaps at the expense of set production. when applied at the medium
level compared to the low. Copper did not reduce set yields in the

second experiment as it did in the first experiment and increase leaf
growths.

Varieties Combinedz- No pronounced difference in leaf color

 

due to treatment was observed. but in both years the plants grown in
the soil-muck plot (Treatment 20) were darker green in color than those

in any other plot . The fresh weight data express the size of the

44.

r mar—3m

 

FOLIAGE GROWTH AND TOTAL BULB YIELD OF SECOND CROP OF
ONIONS AS INFLUENCED BY TREATMENT
(Mean yields in grams per 4 square feet - varieties combined)

 

——7

TABLE XIII

 

 

——

 

 

 

u , Approximate
Treatment Low Medium H1 gh Percent Change,“
_— in Yield
Complete Leaf 1 96 345 208 6
Bulb 8-72 1 009 940 8
Total 1068 1 354 1 148 8
Nitrogen Leaf 271 345 193 - 29
Bulb 966 1009 777 -20
Total 1238 1354 970 - 22
Phosphorus Leaf 281 345 268 5
Bulb 921 1009 1093 14
Total 1202 1 354 1361 1 3
Potassium Leaf 216 345 340 57
Bulb 978 1009 994 2
Total 1194 1 354 1334 1 2
Sulphur Leaf 273 345 269 - 2
Bulb 934 1009 1029 10
Total 1207 1 354 1298 8
Magnesium Leaf 257 345 318 24
Bulb 919 1 009 1026 l 2
Total 1176 1 354 1 344 14
Copper Leaf 249 345 322 29
Bulb 1000 1 009 1 098 10
Total 1249 l 354 1420 14
Manganese Leaf 282 345 341 21
Bulb 1037 1009 997 -4
Total 1319 1354 1338 2
Zinc Leaf 266 345 265 0
Bulb 1142 1009 990 - 13
Total 1408 1354 1255 - 11
Complete Leaf 21 3
soil Bulb 1 1 00
Total 1313
.:* .
From low to high level Of nutrient applied
#*
All except listed nut rient s at medium level
L.S.D. .05 L.S.D. .01
Leaves 120 N .S .
Bulbs N . S . N . S .
Totals 72 99

45.‘

46.

foliage better than any other measure. No blast occurred, or was there
any difference in leaf tip die-back among the treatments.
Averaging the combined growth and yield of the two varieties

in 1953 (Table XIII) showed the general tendency of nitrogen and the com-
plete treatment at the high levels of application to reduce leaf and total
growth compared with medium level. Phosphorus, potassium, sulfur, mag-
nesium and copper increased the total growth at the medium and high levels
of application compared to the low level“. Manganese had no significant effect,
but zinc at the high level of application reduced total growth.

Leaf:Bulb Ratios and Growth:- The relation of top growth to bulb

 

 

yield for the two years is shown in Table XIV. The effectiveness of the
high level of phosphorus, for example, in increasing the bulb yield rela-
tive to the tOp growth was manifested in the smallest ratios, 0.60 for
Downing Yellow Globe, and 0.83 for Ebenezer in the first crop. The aver-
ages for the two varieties were 1 .43 for Downing Yellow Glove and 2.90
for Ebenezer in 1952, and 0.27 and 0.31 for these varieties in the follow-
ing year.
Compared to 1952. when they resulted in increased growth, the
high levels of nitrogen and potassium were detrimental to growth in 1953.
Zinc reduced growth and yield both years. Copper reduced yields the
ﬁrs‘ Year, but not the second, while phosphorus and magnesium were bene-

ficial both years. Sulfur has no pronounced detrimental or beneficial

TABLE XIV

LEAF : BULB RATIOS

 

 

 

 

Treatment First Crop Second Crop

Low Medium High Low Medium ,High
Complete Downing 1.75 1 . 14 2 . 15 .23 .33 .21
Ebenezer 3.33 2.04 2 . 01 .25 .36 .24
Nitrogen Downing 1.10 1.14 1 .56 .27 .33 .24
Ebenezer 4.01 2 .04 2 .20 .31 .36 .26
Phosphorus Downing 2.24 1.14 0 .60 .30 .33 .23
Ebenezer 5.83 2.04 0 .83 .32 .36 .31
Potassium Downing 1.54 1 .14 l .43 .22 .33 .33
Ebenezer 5.80 2.04 1 .44 .28 .36 .40
Sulphur Downing 1 .54 1 .314 1 .31 .28 .33 .23
Ebenezer 5.38 2.04 3 . 57 .38 . 36 .32
Magnesium Downing 1 .46 1 .14 1 .12 .23 .33 .33
Ebenezer 3.46 2.04 1 .70 .35 .36 .28
Copper Downing 1 .26 1 .14 l .31 .24 .33 .30
Ebenezer 1 .44 2.04 2 .29 .28 .36 .33
Manganese Downing ' 1.60 1 .14 1 .26 .24 .33 .32
Ebenezer 2.04 2.59 . 32 .36 . 37
Zinc Downing 1.34 1 .14 1.31 .23 .33 .27
Ebenezer 2 .23 2.04 3.15 .25 .36 .27

Complete Downing 1 .58 .19

SOil Ebenezer 0 .99 . 22

r—

h

47.

 

 

 

all
I

48.

effect either year, but appeared to influence leaf growth more than it

did bulb yield.

Composition

 

Nitrogen:- The nitrogen contents of the leaves and bulbs of
both varieties were found to be significantly increased by the high rate
of nitrogen application. The nitrogen contents of the leaves and the
bulbs of the Downing variety were increased 28 and 30 per cent respect-
ively as a result of high level nitrogen application, compared to the low.
In the Ebenezer variety application of the high level of nitrogen com-
pared to the low increased the nitrogen contents of‘the leaves 44 per
cent, and of the bulbs 32 per cent. The high level complete nutrient
treatment also resulted in significantly increased nitrogen contents in
both leaves and bulbs of both varieties, which was due chieﬂy to the
nitrogen supplied, since no other nutrient consistently increased the
nitrogen contents of the plant (Table XV). With few exceptions the low-
est nitrogen content found in either variety was in those plants grown
with the low level complete nutrient treatment. In the soil plot a .

Slight increase in the nitrogen content of the bulb and slightly reduced
COntent s in the leaves were found.
The tendency of the high nitrogen and high complete treat-

ments to promote increased leaf and bulb nitrogen contents was

 

TABLE XV

NITROGEN CONTENT OF SECOND CROP OF ONIONS AS INF LUENCED BY
TREATMENT
(Nitrogen in percent on the oven dry basis)

 

 

 

 

 

Treatment” Downing Yellow Globe Ebenezer
Low Medium High Low Medium High
Complete Leaf 2 . 76 2 .97 3.62 3 .03 3 . 31 3.76
Bulb 1.99 2.40 3.15 2.17 2.63 2.93
Nitrogen Leaf 2 .86 2 . 97 3.65 2.77 3 . 31 4.00
Bulb 2.11 2.40 2.75 2.16 2.63 2.85
Phosphorus Leaf 3 . 14 2 .97 2 .95 3.09 3 .31 3.23
Bulb 2.52 2.40 2.43 2.84 2.63 2.59
Potassium Leaf 3.10 2 .97 3.11 3.40 3.31 3.28
Bulb 2.72 2.40 2.47 2.85 2.63 2.64
Sulphur Leaf 2.96 2 . 97 2 .92 3.23 3 . 31 3.22
Bulb 2.44 2.40 2.45 2.67 2.63 2.43
Magnesium Leaf 3 .03' 2 . 97 3.05 3 .28 3 .31 3.34
Bulb 2.50 2.40, 2.69 2.73 2.63 2.91
Cepper Leaf 3.14 2 .97 2.92 3.14 3.31 3.19
Bulb 2.41 2.40 2.49 2.71 2.63 2.81
Manganese Leaf 2 .71 2 .97 3.09 3.33 3 . 31‘ 3.33
Bulb 2.54 2.40 2.37 2.84 2.63 2.64
Zinc Leaf 2.85 2.97 2.99. 3.25 3.31 3.36
Bulb 2.41 2.40 2.54 2.64 2.63 2.76
Complete Leaf 2 . 94 3.04
3011 Bulb 2 .73 2.79

 

 

 

 

*
All except listed nutrients at medium level

Leaves L.S.D. .05 .34 .26
L.S.D. .01 .46 .36
Bulbs L.S.D. .05 .44 .30
L.S.D. .01 .60 .40

50

observed both years, though the nitrogen contents found in the 1953
crops were about 50 per cent greater than those found in the 1952
crops. This may have been due in part, at least, to the fact that
about 15 per cent of the annual nitrogen allotment had been applied
to the crop destroyed by maggots in 1952, and may not have been
completely available to the replants.

On the average, Ebenezer contained approximately eight
per cent more nitrogen in the leaves and bulbs than did the Downing

Yellow Globe variety.

Phosphorusz- The phosphorus content of the onion bulb

 

was two to eight times greater than that in the leaf, and in this respect
differed distinctly from the other nutrients studied. The inﬂuence of
treatment on the content of phosphorus in the bulb was striking; a
difference of 294 per cent being found between the highest and lowest
PhOSphorus contents of the bulbs (Table XVI).

The application of phosphorus resulted in increased phosphorus
Content of the bulbs of both varieties.

The data for the two years were quite different. the

phosphorus content of the 1952 crops being essentially the same for

leaf and bulb (Table VIII). The 1953 crops were found to

 

1...

 

my.

14 .11

 

 

TABLE XVI

PHOSPHORUS CONTENT OF SECOND CROP OF ONIONS AS INF LUENCED ‘

 

 

 

BY TREATMENT
(Phosphorus in percent on the oven dry basis)

Treatment“ Downing Yellow Globe Ebenezer
Low . Medium High Low Medium High
Complete Leaf .17 .15 .19 .14 .13 .17
Bulb .34 .60 1.24 .59 .75 1.34
Nitrogen Leaf .12 .15 .16 .14 .13 .15
Bulb .43 . 60 .42 .68 . 75 . 63
Phosphorus Leaf . 14 . 15 . 14 . 14 .13 . 15
Bulb .36 .60 .83 .54 .75 1 .03
Potassium Leaf .14 .15 .14 .18 .13 .14
Bulb . 42 . 60 .53 . 63 . 75 . 77
Sulphur Leaf .15 .15 .13 .14 .13 .16
Bulb .35 .60 .40 .60 .75 .75
Magnesium ‘ Leaf .13 .15 .14 .12 .13 .15
Bulb .44 .60 .74 .76 .75 .77
Comer Leaf .15 .15 .13 .13 .13 .15
Bulb .51 .60 .54 .73 .75 .70
Manganese Leaf .13 .15 .12 ‘ .15 .13 .15
Bulb .40 .60 .43 .64 .75 .72
Zinc ~ Leaf .16 .15 .14 .15 .13 .14
Bulb .37 .60 .56 .60 .75 .62

Complete Leaf . 12 . 13

3°11 ‘ Bulb .53 .89

‘

 

*
All except listed nutrients at medium level

Leaves L.S.D. .05 .03
L.S.D. .01 .04

.22
(DC/J

Bulbs .S.D. .05 N.S. .06
S.D.

L
L. .01 N.S. .09

51.

contain about 27 per cent less phosphorus in the leaves and 185 more
phosphorus in the bulbs than the 1952 cr0ps in the case of the Downing
Yellow Globe variety. However, the content of phosphorus in the bulbs
was found to be much more variable than the leaf content in both years.
Potassiumz- Potassium inﬂuenced its own absorption or accu-

mulation in the plant to a greater extent than was found with any other
nutrient, with the exception of the effect of phosphorus on the bulb con-
tent . The effect was found in both bulb and leaf potassium contents,
but in contrast to phosphorus this response was more pronounced in the
leaves . Compared to the low level, the high level of potassium applied
increased the leaf content of potassium 181 per cent in Downing leaves.
On the same basis nitrogen increased the potassium concentration in
the leaves approximately 24 per cent . The potassium contents of the
Ebenezer variety were also increased by application of both nitrogen
and potassium. None of the other nutrients appeared to have an indepen-
dent effect on potassium absorption in either variety (Table XVII).

However, in combination the other elements apparently inﬂuenced potas-

Sillm accumulation, as evidenced by the high concentrations in both leaf "

and bulb with the high level complete nutrient treatment . On the aver-
age, Ebenezer containly slightly more potassium in both. leaves and

bulbs than did Downing Yellow Globe. In the 1952 crop (Table IX) the

52.

_ --'_——.~_' A1"! I.

 

 

TABLE XVII

POTASSIUM CONTENT OF SECOND CROP OF ONIONS AS INF LUENCED

 

 

 

 

 

BY TREATMENT
(Potassium .in percent on the oven dry basis)

Treatmerita‘ Downing Yellow Globe Ebenezer
Low Medium High Low Medium High
Complete Leaf 1.38 2.84 5.21 1.90 3.32 4.89
Bulb 1.10 1.49 2.12 1.22 1.63 2.11
Nitrogen Leaf 3.27 2 .84 4.04 3.26 3 .32 4.05
Bulb 1.66 1.49 1.30 1.62 1.63 1.60
Phosphorus Leaf 3.18 2.84 3.11 3.54 3.32 3.59
Bulb 1.57 1.49 1.59 1.68 1.63 1.65
Potassium Leaf 1.54 2 .84 4 .33‘ 2 .06 3.32 4.25
Bulb 1.00 1.49 1.90 ' 1.20 1.63 1.97
Sulphur Leaf 3.00 2 .84 2 .86 2.96 3.32 3.24
Bulb 1.44 1.49 1.54 1.67 1.63 1.55
Magnesium Leaf 3 .34 2 .84 3.07 3.46 3 .32 3.38
Bulb 1.51 1.49 1.66 1.64 1.63 1.68
Copper Leaf 3.13 2 .84 3.03 3 .28 3.32 3.30
Bulb 1.56 1.49 1.62 1.70 1.63 1.52
Manganese Leaf 3.25 2 .84 2.87 3.21 3.32 3.21
Bulb 1.49 1.49 1.48 1.69 1.63 1.59
Zinc Leaf 3.28 2.84 2.84 3.17 3.32 3.39
Bulb 1.40 1.49 1.60 1.60 1.63 1.60

Complete Leaf 3 .46 4.75

so“ Bulb 2.00 1.93

 

 

 

 

*
All except listed nutrients at medium level

Leaves L.S.D. .05 .55 .71
L.S.D. .01 .75 .97
Bulbs .05 .33 .21

L.S.D.
L.S.D. .01 .45 .28

Final- H --. ,I.r_

 

 

 

54.

bulbs generally contained more potassium than the leaves, but the reverse
was found to be true in 1953.

Magnesium:- Potassium application had significantly morezin-
ﬂuence on the magnesium content of the leaves than did the quantity of
magnesium applied (Table XVIII). In both varieties an increase in the
quantity of potassium applied resulted in a 50 per cent reduction in the
magnesium content of the leaves, which was associated with an increase
in leaf potassium content, as shown in Figure 2.

This effect of potassium probably also accounts for the de-
pression in leaf magnesium content with the high level complete nutrient
treatment (Table XVIII) and Figure 2. There was an indication that
zinc. copper and sulfur reduced leaf magnesium contents. Manganese
and magnesium had no effect on the magnesium content in the Downing
Yellow Globe variety, but increasing the quantity of magnesium applied
significantly increased the magnesium content of the leaves of Ebenezer.

The bulb content of magnesium in both varieties, on the aver-,

I .
age, was about half that of the leaf. Although the leaf content of magnes-
ium was adversely affected by potassium applications, potassium had

relatively little inﬂuence on the magnesium content of the bulb. The

magnesium contents of leaves and bulbs of both varieties were found to be

markedly lower in 1952 than in 1953 (Table X) .

MAGNESIUM CONTENT OF SECOND CROP OF ONIONS AS INF LUENCED

TABLE

XVIII

 

 

 

 

 

 

BY TREATMENT
(Magnesium in percent on the oven dry basis)
Treatment* Downing Yellow Globe Ebenezer
Low Medium High Low Medium Higi
Complete Leaf . 53 . 38 . 33 . 65 . 49 . 45
Bulb .17 .20 .20 .20 .23 .22
Nitrogen Leaf . 37 . 38 .39 . 45 .49 .53
Bulb .18 .20 .16 .23 .23 .23
Phosphorus Leaf . 39 . 38 . 42 .50 . 49 .55
Bulb .16 .20 .21 .21 .23 .25
Potassium Leaf .56 .38 .27 .89 .49 .41
Bulb .18 .20 .16 .21 .23 .24
Sulphur Leaf . 51 . 38 . 36 . 51 . 49 .57
Bulb .16 .20 .18 .24 .23 .27
Magnesium Leaf . 36 . 38 . 32 . 46 . 49 . 63
Bulb .16 .20 .22 .22 .23 .25
Copper Leaf . 41 . 38 . 29 .54 .49 .55
Bulb . 20 . 20 . 22 .25 .23 .23
Manganese Leaf . 39 . 38 . 36 .54 .49 .54
Bulb .18 .20 .20 .21 .23 .19
Zinc Leaf . 46 . 38 . 39 . 51 .49 .46
Bulb .15 .20 .22 .23 .23 .18
Complete Leaf .31 , .39
soil Bulb .16 .20
*
All except listed nutrients at medium level
Leaves L.S.D. .05 .09 .14
L.S.D. .01 .13 20
Bulbs L.S.D. .05 N.S. N.S.
L.S.D. .01 N.S. N.S.

55.

 

 

 

OH

(J‘.

56.

% K .......... Downing Yellow Globe ‘70 M 9
--.... Ebenezer
5.. o a . ...O‘Qe. K
I 0‘...’#~..’e~‘.
e I e
/ .... {-3 l .00
4‘0 dt- ’ .0.. ‘- ...:
cos .3 t:
’I’ ‘\ ’I’f K e ‘
3.0 __ 'I "’ ...: T 0.75
O I ‘ :4’
........ v.“’ 0"\
2.0 g t "2:: a g a. 0.50
*- 0“.” -‘. '. ‘s pd“-~~
«I. '9'. ~ '00- - v
o‘eeoO‘... ..e'e. . ...-00".".M..'O
LO 4. "on" 9 4)- 0.25
O

 

 

 

 

Figure 2. Influence of Potassium Application on
the Potassium and Magnesium Contents
of the Leaves.

a.

‘n

at!

‘v

...vn

. ,b.

;b\-

1..

57.

Manganesez- The quantity of nitrogen supplied in the nutrient
treatment resulted in a phenomenal increase in the contents of manganese
found in the leaves and bulbs of both varieties. However, manganese did
not appear to inﬂuence its own absorption. Although no other nutrient,
with the exception of sulfur, was found to significantly increase manganese
accumulation in either leaf or bulb, in combination they appeared to in-
crease the effectiveness of nitrogen in increasing manganese accumu-
lation (Table XIX). On the average, the leaf content of manganese was
about twice that of the bulb content in the Downng Yellow Globe variety,
and more than twice the bulb content in the Ebenezer variety.

Calcium: - In Downing Yellow Globe high leaf calcium concen-
trations were associated with the high level sulfur, the low level potas-
sium and the low level zinc treatments. High nitrogen applications
Significantly increased and high potassium treatment significantly de-
creased the calcium content in the leaves (Table XX). In Ebenezer
the high levels of applied manganese, copper, sulfur and nitrogen
Significantly increased the calcium contents of the leaves. The calcium
content of the bulbs of Downing Yellow Globe was found to be about 10
Per cent of that of the leaves, and in Ebenezer the sets contained only
abOUt 6.5 per cent as much calcium as the leaves. On the average,

Ebenezer contained more calcium in the leaves and less in the bulbs

 

TABLE XIX

MANGANESE CONTENT OF SECOND CROP OF ONIONS AS INF LUENCED
BY TREATMENT
(Manganese in ppm on the oven dry basis)

 

 

 

———

 

 

 

 

 

 

 

 

Treatment,’ Downing Yellow Globe Ebenezer
Low Medium High Low Medium High
Complete Leaf 24 55 261 39 69 298
Bulb 17 25 86 19 28 80
Nitrogen Leaf 29 55 . 168 49 69 206
Bulb 18 25 56 25 28 62
Phosphorus Leaf 49 . 55 53 48 69 63
Bulb 26 25 34 26 28 30
Potassium - Leaf 44 55 30 95 69 40
Bulb 24 25 19 31 28 25
Sulphur Leaf 44 55 56 ' 43 69 64
' Bulb 22 25 32 24 28 36
Magnesium Leaf 41 55 26 57 69 50
Bulb 27 25 25 30 28 25
Comer Leaf 75 55 42 54 69 63
Bulb 41 25 35 27 28 29
Manganese Leaf 51 55 34 64 69 59
Bulb 30 25 30 27 28 26
Zinc Leaf 56 55 39 53 69 68
Bulb 28 25 30 26 28 25
Complete Leaf 31 44
soil Bulb 19 21
*
All except listed nutrients at medium level
Leaves L.S.D. .05 47 43
L.S.D. 64 58
Bulbs L.S.D. . 11 - 8
L.S.D. 15 11

59.

TABLE XX

CALCIUM CONTENT OF SECOND CROP OF ONIONS AS INFLUENCED
BY TREATMENT
(Calcium in percent on the oven dry basis)

 

 

_—

 

 

Treatment. Downing Yellow Globe Ebenezer
Low Medium High Low Medium High
Complete Leaf 1.48 1.42 1.59 1.85 2.09 2.18
Bulb .18 .15 .15 .13 .12 .13
Nitrogen Leaf 1.30 1.42 1.74 1.35 2.09 2.50
Bulb .16 .15 .18 .13 .12 .17
Phosphorus Leaf 1.48 1.42 1.79 1.79 2.09 2.03
Bulb .20 .15 .16 .14 .12 .11
Potassium Leaf 2.32 1.42 1.39 2.84 2.09 2.61
Bulb .19 .15 .17 .14 .12 .13
Sulphur Leaf 1 .75 1.42 1.91 2 .10 2.09 2.72
Bulb .21 .15 .14 .13 .12 .14
Magnesium Leaf 1.69 1 .42 1.50 2.04 2.09 2.02
Bulb .16 .15 .16 .12 .12 .12
Copper Leaf 1.68 1.42 1.60 2.09 2.09 2.94
Bulb .18 .15 .17 .14 .12 .12
Manganese Leaf 1 .70 l .42 l .64 l .90 2. 09 2.95
Bulb .16 .15 .16 .14 .12 .13
Zinc Leaf 1.81 1.42 1.55 1.96 2.09 2.13
Bulb .15 .15 .16 .13 .12 .14
Complete Leaf 1 . 61 2 . 00
soil Bulb .14 .13

 

 

 

 

* -
All except listed nutrients at medium level

Leaves L.S.D. .05 .37 .28

L.S.D. .01 .50 .38

Bulbs L.S.D. .05 N.

L.S.D .01 N.

.22
5950

S.
S.

60.

than did Downing Yellow Globe. In the 1952 crop calcium was almost
equally distributed in the leaves and bulbs of Downing Yellow Globe,
although the variation in content was greater in the leaves than in the
bulbs, while in Ebenezer the leaves contained three times as much
calcium as the bulbs (Table XI). The leaf content of calcium in both
varieties in 1953 was approximately three times the leaf contents
found in 1952.

1591: - In Downing Yellow Globe the high potassium treatment
resulted in an increase in the iron contents of the leaves. Nitrogen,
also, manifested a tendency to increase iron contents in the leaves,
and the high level of the complete nutrient treatment increased the
iron contents of the leaves approximately 20 per cent over those found
in the high potassium treatment, indicating that some of the other
nutrients involved tended to inﬂuence iron accumulation, or to increase
the effectiveness of potassium in this role (Table XXI). No difference
in bulb contents of iron were found which did not fall within the limits
0f exPerimental error.

In Ebenezer the highest iron concentration was obtained with
the high level of complete nutrient treatment, and the second highest

level was obtained with the low potassium treatment, completely re-

versing the condition encountered with Downing Yellow Globe. However,

I [I‘vlilll

'5

TABLE

XXI

IRON CONTENT OF SECOND CROP OF ONIONS AS INF LUENCED BY
TREATMENT
(Iron in ppm on the oven dry basis)

 

 

 

 

 

 

 

* Downing Yellow Globe Ebenezer
Treatm ent Low Medium High Low Medium Hi gh
Complete Leaf 43 53 106 91 83 109
Bulb 39 52 63 69 72 76
Nitrogen Leaf 43 53 74 90 83 105
Bulb 54 52 57 65 72 80
Phosphorus Leaf 53 53 53 87 83 95
Bulb 57 52 50 72 72 68
Potassium Leaf 43 53 88 104 83 82
' Bulb 51 52 68 73 72 74
Sulphur Leaf 53 53 48 96 83 98
Bulb 48 52 51 68 72 72
Magnesium Leaf 52 53 47 91 83 91
Bulb 57 52 55 65 72 75
Copper Leaf 46 53 41 93 83 97
Bulb 54 52 55 70 72 73
Manganese Leaf 54 53 46 89 83 90
Bulb 55 52 54 70 72 73
Zinc Leaf 64 53 51 89 83 76
Bulb 50 52 61 69 72 66
Complete Leaf 136 136
‘3011 Bulb 56 81
*
All except listed nutrients at medium level
Leaves L.S.D. 33 N.S
L.S.D. 45 N.S
Bulbs L.S.D. N.S N.S.
L.S.D. N.S N.S.

 

 

l ..10. ..n'l’l! ...: - 41.”.
4.,

neither of these differences were statistically significant.
In general, the quantities of iron found in Ebenezer were
somewhat higher than those found in the Downing variety.

Boron:- No difference between the boron contents of the

 

bulbs of Downing Yellow Globe due to the various treatments was found.
Nitrogen gave a significant increase in the boron content of the leaves
when applied alone at the high rate, or in the high level of the complete
nutrient treatment (Table XXII). There was a suggestion that zinc and
potassium were inimical to increased boron concentrations in the leaves
of Downing Yellow Globe.

With Ebenezer no significant differences between either bulb
or leaf boron contents due to treatment was found.

With the Downing variety the average bulb content of boron
was approximately 71 per cent of the leaf content, but in Ebenezer the
bulb content was only 50 per cent of the leaf content .

Sodiumz-No consistent difference in the sodium content of the

 

bulbs was found in either Downing Yellow Globe or Ebenezer. In the
Downing Yellow Globe variety the sodium contents of the leaves was
increased with the low levels of the complete nutrient treatment, the
low level of potassium and the low level of nitrogen (Table XXIII). In

the Ebenezer variety phosphorus and zinc showed a tendency to lower.

TABLE XXII

BORON CONTENT OF SECOND CROP OF ONIONS AS INFLUENCED BY
TREATMENT
(Boron in ppm on the oven dry basis)

 

 

 

 

 

Treatment,“ Downing Yellow Globe Ebenezer .
Low Medium High Low Medium H1gh
Complete Leaf 25 27 36 42 40 51
Bulb 17 21 21 21 22 25
Nitrogen Leaf 28 27 38 39 40 45
Bulb 21 21 18 23 22 21
Phosphorus Leaf 32 27 29 40 40 41
Bulb 23 21 23 21 22 _ 20
Potassium Leaf 32 27 26 48 40 40
Bulb 20 21 20 19 22 21
Sulphur Leaf 31 27 27 46 40 44
Bulb 18 21 20 20 22 20
Magnesium Leaf 27 27 26 41 40 45
Bulb 21 21 22 20 22 21
Copper Leaf _ 27 27 25 45 40 49
Bulb 20 21 20 22 22 20
Manganese Leaf 27 27 24 48 40 42
Bulb 20 21 22 21 22 20
Zinc Leaf 33 27 24 45 40 43
Bulb 19 21 21 20 22 18
Complete Leaf 20 32
soil Bulb 16 - 18

 

 

*
All except listed nutrients at medium level

Leaves L.S.D. .05 7 N.S
L.S.D. .01 9 N.S
Bulbs L.S.D. .05 N.S. N.S
L.S.D. .01 N.S N.S

TABLE XXIII

SODIUM CONTENT OF SECOND CROP OF ONIONS AS INFLUENCED BY
TREATMENT
(Sodium in percent on the oven dry basis)

 

 

 

 

 

- a:
Treatment Downing Yellow Globe Ebenezer
- Low Medium High Low Medium High
Complete Leaf . 116 .069 .078 . 169 .098 .088
Bulb .067 .063 . 085 .066 .048 .057
Nitrogen Leaf .109 .069 .061 .096 .098 .095
Bulb .045 .063 .065 .052 .048 . 053
Phosphorus Leaf .073 .069 . 066 . 123 .098 .088
Bulb .081 . 063 .062 . 057 .048 . 055
Potassium Leaf .136 .069 .034 .126 .098 .074
Bulb .081 :063 .056 .058 .048 . 055
Sulphur Leaf .086 .069 . 085 .075 .098 . 108
Bulb . 060 .063 .047 .067 .048 .063
Magnesium Leaf .081 .069 .072 .091 .098 .106
Bulb .069 .063 .117 g .067 . .048 .058
COpper Leaf .096 .069 . 057 .071 .098 .095
Bulb . 054 . 063 .070 .055 .048 .062
Manganese Leaf .080 .069 .079 . 085 .098 .086
Bulb . 070 .063 .066 .055 .048 .054 '
Zinc Leaf .081 .069 .056 .130 .098 . 088
Bulb .065 .063 . 057 .056 .048 . 053
Complete Leaf .096 .106
soil Bulb . 080 . 059

_

 

 

*
All except listed nutrients at medium level

Leaves L.S.D. .05 .044 .054
L.S.D. .01 .060 .074
Bulbs L.S.D. .05 N.S. N.S
L.S.D. .01 N.S. N.S

Ill-I‘ll..l

and potassium and the high level of the complete nutrient treatment
significantly lowered the sodium contents of the leaves.

'Although their bulb sodium contents were about the same,
the varieties differed in their average leaf contents. the leaves of
Ebenezer Containing 20 per cent more sodium than the leaves of Downing

Yellow Globe .

6o.

66.

DISCUSSION

In repeated experiments Downing Yellow Globe and Ebenezer
onions were grown in a modified sand culture designed to study the inﬂu-
ence of nitrogen, phosphorus, potassium, sulfur, magnesium, copper,
manganese, and zinc, at three levels each, on their growth and chemical
composition. The relation of these treatments to the production of Downing
bulbs and their subsequent performance in the production of viable seed
was also studied. The relation of these treatments to the production of
Ebenezer sets and their subsequent performance in producing a cr0p of
mature bulbs under field conditions was inclucbd in the investigation.

A modified culture of Plainfield sand was employed as a
means of obtaining greater precision in the measurement of the effects
of the various nutrients, particularly manganese, copper and zinc.

A small quantity of organic soil was added to each plot for the purpose

of providing a more suitable medium for plant growth, and to obtain

the other benefits attending the presence of organic colloids in the cultural
media. The spacing of the plants, and the rates of nutrients applied

were comparable to those employed in field practice, with the exception
0f the rate of copper applied, which was reduced because of the pH value

0f the soil and the lack of any appreciable amount of organic materials

~ «--.... ‘I

 

 

 

.,|.

(at.

67.

in the medium. In order to measure single nutrient effects independ-
ently, the carrier chemicals were selected to provide variation only
in the nutrient being considered as a variable, all others being equal
in concentration. This was done because the interpretation of the re-
sults of many nutrition experiments have been partially obscured by
variation in the nature and concentration of the ions. associated with
the nutrient variables.

The onion plants were divided into leaf and bulb portions
at harvest to facilitate determining the nutrient distribution in the
plants . Practically all the onion analysis found in the literature relating
to composition have been restricted to the bulb, or to samples of the
entire plant included in the sample. The leaf bases of the onion may
more nearly correspond to the petioles of dicot leaves which serve as
the portion of the plant commonly employed in tissue analysis. Leaf
analysis has been suggested as possibly the best index of the nutrient
condition of woody dicots (79, 91) . The studies reported herein empha-
size the difference in the contents of the various nutrients found in both
leaves and bulbs . Onion bulbs, though foliar in origin, have been found
t0 behave quite differently than photosynthetically-active portions of the
leaves with respect to salt accumulation (8).

The phosphorus content of the onion plant is more equally

68 .-

distributed between leaves and bulbs when phosphorus is deficient and
four to five times more concentrated in the bulb than in the leaf when
supplies are adequate, as shown in Table XXIV. Variations in phosphorus
content are generally greater in bulbs than in leaves . The nitrogen con-
tent of onion bulbs is generally higher, relative to the leaves than the
storage organs of beets (6). The relatively high concentration of nitrogen,
potassium, calcium, magnesium, and manganese in the leaves compared
to the bulbs of onions (Table XXIV) suggests that care be exercised in
the selection of the tissue employed in analysis for diagnostic purposes.
Bulb initiation is conditioned by long days and high temperatures,
the minimum length of day required to initiate bulbing varying with the
variety (62). These factors have been found to modity the response to
nutrients . Once the conditions become favorable and bulbing begins,
further foliage development becomes much retarded (89); and, since the
volume of foliage developed prior to the onset of bulbing is generally
related to the size of the bulb subsequently developed, the practice is to
fertilize for early leaf growth prior to bulb enlargement. Hawthorne (48)
has shown that an excess of nitrogen after bulb development is initiated
contributes to thickened necks and poor storage. Excessive nitrogen
fertilization also results in an increased number of double and triple -

growing points and multiple ﬂower scapes. A deficiency of nitrogen

 

 

69.

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70.

results in rigidly erect, stiff-necked plants whose tops fail to fall

over normally. Phosphorus promotes thickened and dark-colored

bulb scales, and is necessary for favorable inﬂuence of copper (55).
The development of full color in pigmented onion's is enhanced by copper,
and on acid muck soils additions of copper have been beneficial parti-
cularly in conjunction with increased phosphorus fertilization. A
marked potassium deficiency results in retarded bulb formation, and

in light soils produces thin bulb scales. Excess potash delays maturity
of onions grown in muck soils (54). A deficiency of manganese often
results in reduced yields and retarded bulb development on organic
soils which are alkaline in reaction. The application of sulfur, by
increasing soil acidity, increases the availability of manganese, but
must be carefully controlled to avoid reduction in the availability of

copper, nitrogen and phosphorus (46).

_Yiel_da_s_lnfluenced byNthrition

In this study neither the shape nor the color of the bulbs was
influenced by the treatments employed. Phosphorus exerted the most
Pronounced effects of any nutrient the first year, and gave by far the
Smallest leafzbulb ratio and highest bulb yield. Comparing the low level

with the high level phosphorus treatment, bulb yields were increased

III." It. .

 

71.

294 and 348 per cent respectively for Downing and Ebenezer. Although
the leaf growth of Downing was slightly increased by added phosphorus
the leaf growth of Ebenezer was decreased almost 40 per cent. The
following year added phosphorus had very little effect on the leaf growth
of either variety, but again increased bulb yields. The bulb yield of '
Ebenezer as a result of the high phosphorus treatment, was increased
relatively more than was the bulb yield of Downing.

The favorable effect of added nitrogen the first year may have
been due to the extreme deficiency of this element in the sand employed.
High levels of the other nutrients, including phosphorus and potassium,
as indicated in the yields obtained with the high level complete treat-
ment, failed to offset or counter the effects of high nitrogen in 1953.
The high nitrOgen application reduced the growth of Downing more than
it did the growth of Ebenezer. It appeared that Ebenezer, either as a

result of its genetic constitution or closer spacing, was less sensitive
to changes in the quantities of nitrogen and phosphorus available than
the Downing Yellow Globe.

Potassium applied at the high rate compared with the low in the

first crop increased the leaf growth of Downing Yellow Globe 83 per cent
and of Ebenezer 13 per cent, with corresponding bulb yield increases of

97 and 352 per cent. The following sea son the high level of potassium

:1...) ’1. n

-‘-——-—-—-—-~-~—-—-.-—-——..
.. __— -..... ..--

4f

 

72.

a gain increased the leaf and bulb growth of the Downing variety 76
and 8 per cent respectively, and while decreasing set production in
Ebenezer 13 per cent increased the leaf growth 38 per cent. Potassium,
then, seemed to promote both leaf and bulb growth, as did nitrogen.
while phosphorus promoted bulb growth at the expense of foliage de-
velopment. These differences probably account for the delay in maturity
accompanying the use of high rates of nitrogen and potassium, and the
increase in earliness resulting from increased rates of phosphorus
application. These results are in accord with the findings of Strong (89),
Beaumont gt ill. (5), Knott (54), and Hawthorne (48), with the onion, and
with the results of Amin (1) relative to the effects of phosphorus on the
hyacinth. The results suggest that onions grown for sets, as they tend
to be more foliar in development, might be benefitted by a reduced
1(20:P205 ratio than appears to be optimum for the production of mature
bulbs. Many of the results of investigations of the effects of phosphorus
upon the growth of bulbs have shown reduced top and bulb growth due to
high phosphorus levels, but in most of the solution cultures used it was
found that the phosphate precipitated certain of the micronutrients, and
it is possible that some of the supposedly detrimental effects of phosphorus
were indirect and the result of decreased availability of these micro-

nutrients (23) . The data of Amin (1) in this connection show almost no

73.

change in phosphorus concentration in the hyacinth bulbs which suffered
reduced foliar and bulb growth as a result of high phosphorus concen-
trations in the nutrient solutions employed.

Increased leaf and bulb growth in both varieties resulted from
the high level of magnesium applied in both seasons. Magnesium tended
to promote leaf and bulb growth more equally than did some of the other
nutrients.

Sulfur at the high rate of application compared with none in-
creased the yield and growth of both varieties both seasons with the
exception that the leaf growth of Downing was reduced the second season.
Supplied in the sulfate form, sulfur increased the soil acidity from pH 7.49
to pH 6.79. I

Adding manganese increased the leaf growth of Downing and
decreased the leaf growth of Ebenezer in both seasons The bulb yield
of both varieties were increased the first and slightly decreased the

second seasons

In the first crop both copper and zinc reduced leaf and bulb
growth, but in the second year copper applications resulted in slightly
increased growth, while zinc at the high level of application reduced bulb
yield and total growth 13 and 11 per cent respectively on the basis of an

average of both varieties.

This suggests that where nitrogen, phosphorus and potassium
are adequate, or in excess, a favorable response to copper may be anti-
Cipated. The detrimental effect of zinc was more pronounced on the
Downing than on the Ebenezer variety, but it was not possible to ascertain

Whether this was a differential varietal response, or whether it was
associated with bulb enlargement.

The data relative to seed production by Downing mother bulbs

PrOduced the previous season with the various nutrient treatments was
incomplete, since many of the bulbs failed to produce flowers. It is
C101.1btful if the nutrients provided the mother bulb during its formation
have any great effect on the resulting seed crop, providing the mother
bUIb is of normal size and is planted in adequately fertilized soil. How-
ever, high nitrogen applications have been shown to induce multiple
irlflorescences which frequently increased seed yield. Stuart and Griffin (90)
have shown that even where no phosphorus was applied to the mother bulb
for three months prior to flowering, germinability of the seed produced
Was not affected.
No differential effect on the keeping quality or tendency to
SD rout in storage due to treatment was found in either variety, or in the
bUIbs of Ebenezer grown from sets that were produced under the various

trG—‘atments. Sixty Ebenezer sets produced in 1952 with 15 of the 20

75.

nutrient combinations employed were planted in a replicated experi-

ment on muck soil. Although the Ebenezer sets grown with the high sulfur and
the high manganese treatments resulted in reduced yields in the crop grown
from them the following year, possibly owing to smaller average bulb size.
significantly fewer double bulbs were obtained. tending to offset the im-
portance of the reduction in yield. It appeared that planted in the same

soil and provided normal fertilization, sets of the same size have equal

productive capacity.

The Inﬂuence 3f Treatment 92 Plant Composition

 

 

Nitrogenze The high rate of applied nitrogen increased the
nitrogen contents of the bulbs and leaves despite greatly increased yields
the first season resulting in a 214 per cent increase in the nitrogen re-
moved by the bulbs of Downing. and a 484 per cent increase in the nitrogen
removed by the sets of Ebenezer. In the next year in spite of higher yields
with the low nitrogen treatment. the nitrogen removed in the bulbs with the
high nitrogen treatment was increased over the preceding year. with the
high application, due to an increased nit rOgen content of the crop, indi-
cating luxury comsumption. Thus, with a 25 per cent decrease in yield.
the removal of nitrogen in the bulbs of Downing was slightly increased.

Alteration of the quantity of applied nitrogen influenced the

 

 

76.

concentration of the other nutrients in the tissues. The potassium con-
centration of the leaves of both varieties was increased about 25 per cent.
and the calcium concentration increased approximately 34 per cent in
Downing, and 85 per cent in Ebenezer leaves, by the high as compared
with the low level of applied nitrogen. In the bulb of the Downing variety,
potassium content was reduced by the high nitrogen treatment. No
pronounced inﬂuence of nitrogen application on the calcium content of

the bulbs of either variety was found. No significant change in the bulb
or leaf content of magnesium, sodium, phosphorus, or copper was

found to be associated with increasing rates of nitrogen application.

However, a phenomenal increase in the concentration of
manganese and an increase in the concentration of iron in the leaves and
bulbs of both varieties resultedfrom increasing the level of nitrogen
applied from the low to the high level.

It is improbable that the increased soil acidity resulting
from the high nitrogen treatment was responsible for the increased
manganese concentration in the plants, because the high sulfur treat-
ment reduced the soil pH more than did the high nitrogen treatment,
but the plants contained less than one-third as much manganese.

Although the high sulfate sulfur treatment increased

the manganese content of the leaves 40. per cent over the low treatment.

77.

the high nitrogen treatment. as compared to the low, increased the
manganese contents of Downing and Ebenezer leaves 480 and 320 per
cent respectively. The bulb contents were also increased as shown
in Table XIX, and were about equal to the manganese contents found
in cherry and peach leaves as reported by Kenworthy (53), while the
levels found in the onion leaves were more than twice as great. Of
several plants studied, True (92) found spinach to be the only plant
with a higher manganese content in the root than in the leaf. Though
none of the other nutrients individually showed any tendency to increase
the manganese contents of the leaves or bulbs at high rates of application.
when their application was associated with the high application of nitrogen
in the high complete treatment, the leaves accumulated approximately
an additional 100 ppm of manganese. On the basis of this evidence. it
appears that it is quite possible that the extremely high manganese con-
tents in the leaves and bulbs of the 1953 crop were toxic to the extent
of being responsible for the reduced yields obtained with the high rates
of nitrogen applied.

The relation of nitrogen application to nitrogen, manganese
and iron concentrations in theleaves and the yields of Downing and
Ebenezer bulbs are shown graphically in Figures 3 and 4. These dia-

grams illustrate the slight change in nitrogen and iron content accom-

Mn (ppm) and Fe (ppm)

Leaf Content of "(9611041,

Figure 3. Downing Yellow Globe

 

 

 

 

 

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Figure 4. Ebenezer 3'":
”600
"600
«400
4-300
--200
«100
O

 

 

 

78.

Figures 3.4. The Influence of Nitrogen Application on the Nitrogen,
Manganese and iron Contents at the Leaves and their

Relation to Yield. I953 .

79.

panying a rather marked increase in manganese content 0f the leaves

and their relation to the yield of bulbs, emphasizing that apparently

small changes in the nitrogen content of a crop may be associated with

important changes in the yield of the crop. It is probable that the in—
creased nitrogen content. of the leaves is the result rat her than the
cause of growth reduction, due to the toxic concentration of manganese
in the tissues. It may be noticed that although resulting in an increase
in leaf manganese content, the high levels of the nutrients other than
nitrOgen (supplied in the high complete mixture) appeared to ameliorate
the toxic effects of manganese with the result that yields were slightly
increased. This effect was much more pronounced with Ebenezer than
with the Downing variety. One of the reasons why Ebenezer was less
susceptible to the maleffects of high nitrogen application may have been
due to the fact that Ebenezer consistently contained about twice the con-
centration of iron found in Downing, and despite higher average contents
of manganese. was able to respond to applied phosphorus to a greater
degree than was the Downing variety, as shown in Figures 5 and_6.
While the Downing Yellow Globe variety was increased in yield. from
574 to 611 bags per acre, an increase of 6.4 per cent, the Ebenezer
variety was increased from 322 bags to 393 bags per acre. an increase
of 22 per cent. when thetphosphorus was increased from the medium to

the high level of application.

80.

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81.

The yield data in Table XII suggest that for the Downing variety
nitrogen even at the low level was detrimental to bulb growth, except when
used in connection with the medium levels of the other nutrients, as shown
by comparison of the bulb yields for the low complete and low nitrogen
treatments, and since the high level of phosphorus was one of the most
beneficial treatments, a nitrogen phosphorus relationship is suggested.

Iron contents of the leaves and bulbs was found to have been in-
creased with increasing rates of nitrogen application, but to a lesser extent
than manganese, indicating that the high levels of manganese found in the
plant did not interfere with iron absorption, though possibly with its avail-
ability (84). The leaves of the plants grown in the high nitrogen treatment
were slightly pale compared to those in soil plots. The greenest leaves
in both years were found in the soil plots, and the plants from these plots
were found to have the highest iron contents, “and a relatively lower man-
ganese content. This is additional evidence that the high manganese contents
of the plants grown with high nitrogen levels exhibited manganese toxicity
which resulted from interference with iron absorption or utilization. It
appears that Ebenezer was considerably more tolerant to high nitrogen
applications than was Downing, and that increasing the quantity of other ~
nutrients applied resulted in a pronounced increase in bulb yields, even

with increased manganese concentrations in the leaves (Figures 3 and 4).

82.

From this it would appear that on sandy soils with little
buffering capacity, applications of large amounts of nitrogen may re-
sult in a high absorption of manganese which may be toxic to onions.
It is possible that nitrogen might be of some uselin facilitating the ab-
sorption of manganese by other crops on sandy soils, and might aid the
plant in acquiring adequate manganese on overlimed sandy soils. Per-
haps this effect of hit rogen would not be found on muck soils due to
their high buffer capacity.

Manganese was the only nutrient other than nitrogen which
was found to increase the nitrogen content of the leaves, and this effect
was noted only in the Downing variety, and agrees with the results of other
workers on peach (36), on grasses (l4), and with oats (32). The nitrogen
contents of the crops grown in 1952 were much lower in both leaf and bulb than
those grown in the same plots the following season. Downing showing a larger
increase in nitrogen than Ebenezer. The variation in nitrogen content as
a per cent of the mean for all treatments was greater the first than in the
second season. and was found in every case to be approximately 50 per
cent greater in the bulbs than in the leaves. One of the possible explanations
for the lack of injury from nitrogen in the 1952 crop may be due to the fact
that iron was supplied at the rate of 20 pounds per acre in 1952, and at the

rate of four pounds per acre in 1953.

83.

Phosphorus:- The high phosphorus treatment resulted in a 134

 

per cent increase in the phosphorus contents of the bulbs of Downing and
a 92 per cent increase in the phosphorus contents of the bulbs of the
Ebenezer, but had no appreciable effect on the phosphorus contents of
the leaves of either variety, in the second crop. Neither nitrogen nor
potassium contents of the plants were significantly altered as a result
of increased phosphorus applications, but the calcium contents were
increased 21 per cent in the leaves of the Downing variety and 13 per
cent in the leaves of Ebenezer, with the high phosphorus treatment .
The calcium contents of the bulbs of both varieties were reduced,
possibly as a result of growth dilution. The boron, manganese, iron.
and sodium contents were little affected by variation in the quantity

of applied phosphorus, although Biddulph has attributed iron deficiency
to high phOSphorus contents in the plant (12) and in the growing medium
(1 l) .

The high complete treatment resulted in the highest phosphorus
contents of the bulbs, followed by the high levels of phosphorus. potassium.
sulfur and manganese in both varieties, and by zinc in the Downing variety.
The bulbs of both varieties from the soil plots were relatively high in
phosphorus content. The increase in phosphorus content resulting from.

the application of the high levels of nitrogen. manganese. zinc, and the

84.

complete treatments were likely due to reduced growth, but the other
instances of increased bulb phosphorus were accompanied by increased
bulb yields.

In Figure 5 is shown the relationship between phosphorus appli-
cation, growth and yield. and phosphorus contents of leaves and bulbs in
the Downing variety. Leaf growth was not affected in the same manner
as bulb yield with increasing applications of phosphorus. As shown in
Figure 6, a more nearly linear relationship between bulb phosphorus
content and yield was encountered in the Ebenezer than in the Downing
variety.

Potassium:- Although phosphorus application resulted in an
increase phosphorus content only in the bulbs, high potassium applications
doubled the potassium content of both leaves and bulbs in both varieties.
Potassium inﬂuenced its own absorption more than it was influenced by
any other nutrient . Potassium had no inﬂuence on the nitrogen content
except to reduce it slightly where potassium additions increased yields.
Compared to the low level of application, the high level of potassium
increased the phosphorus contents of Downing leaves and bulbs despite
significantly increased growth.

Added potassium significantly reduced the calcium, and to a

greater extent. the magnesium contents of the leaves. but had little

85.

effect on the bulb contents of these two nutrients. Although the amount

by which magnesium was reduced by the high potassium treatments was
small per unit of potassium concentration increase, as shown in Figure 2,
the trend was, nevertheless, definite and was not affected by the increased
nutrient content in the high complete treatment. Even when the leaf growth
was depressed by the high complete treatment, potassium contents were
highest in bOth varieties and the magnesium content was lowered. This
problem of reduced magnesium contents as, a result of potassium appli-
cation is of importance with crops other than onions, and has been re-
ported by other investigators (16, 17, 25, 26, 27, 29, 30, 34, 42, 68).

A reduction in the sodium contents in the plants of both-
varieties was found as a result of high potassium application. Boron
contents were reduced about one-fifth in the leaves of both varieties,
while manganese was reduced 32 per cent in the leaves, 81d 21 per cent
in the bulbs of the Downing variety, and 50 and 19 per cent in leaves and
bulbs respectively in the Ebenezer variety. Daniel (36) found that a mix-
ture of nitrogen and potassium increased the manganese contents of peach
leaves to a greater extent than nitrogen alone, and that a complete mix-
ture containing nitrogen, potassium and phosphorus resulted in a 90 per
cent increase in manganese concentration over a mixture of any two of

the nutrient s.

 

 

Iron was increased almost 50 per cent in the leaves and 33 per
cent in the bulbs of the Downing variety, and 21 per cent in Ebenezer
leaves with the high potassium treatment. The tendency of potassium to
be associated with increased iron contents of plants has been reported
by other workers (49. 61, 68, 81). _.The increase in iron contents with
increased application of potassium might be interpreted as a function of
a reduction of manganese contents due to the relatively large K:N ratio
in the fertilizer treatment. In this connection it might be pointed out
that each increment of applied nitrogen reSulted in significantly increased
manganese accumulations. If it may be assumed that nitrogen directly
increased nitrogen accumulation, it is probable that it also served in-
directly to favor manganese absorption by countering the depressive
effects of potassium upon manganese.

In Figures 7 and 8 are shown data which serve to substantiate .
the suggestion that nitrogen and potassium acted oppositely with respect
to manganese and iron accumulation and hence upon yield. These figures
show in addition that although the degree of response with the two varie-
ties was different, the directions of the responses were similar. These
figures show that nitrogen increased both iron and manganese accumu-
lation in the leaves of both varieties. the manganese accumulation pre-

sumably resulting in decreased usefulness of the iron contained with a

86.

 

 

 

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resultant yield depression. In Ebenezer potassium additions depressed
both manganese and iron, but the manganese was depressed relatively
more than the iron with the result that potassium resulted in increased
yields, whereas nitrogen additions increased the accumulation of man—
ganese to a much greater extent than they did the accumulation of iron,
with resulting low yields. In Downing, however, potassium additions.
in addition to depressing manganese accumulation, increased the ab-
sorption of iron with the result that yields were increased to a greater
extent than they were in Ebenezer.

Nevertheless, Ebenezer appeared to be affected relatively
less by the high nitrogen applications than was Downing, and it is sug-
gested that this is the result of the failure of the high potassium appli-
cation to as effectively promote an increased iron uptake in Ebenezer
as it did in Downing. Loehwing (61) has pointed out that sap acidity and
iron solubility is increased with plant potassium content, while Sideris
found both iron and potassium contents to be increased with high potas-
sium application (81), and found that high plant pH values associated
with high nitrate absorption to be as effective as high manganese in the
culture solution in precipitating iron in pineapple roots (82).

The effect of nitrogen in increasing iron and the effect of

potassium in depressing manganese accumulation was more pronounced

88.

 

 

 

89.

in the Ebenezer than it was in the Downing variety. High nitrogen
treatment reduced the yields of Downing more than it did the yield
of Ebenezer, apparently because iron was increased to a greater ex-
tent in Ebenezer than it was in Downing Yellow Globe.

From these relationshps the interactive inﬂuence of nitrogen
and potassium on the accumulation of the catalytic fertilizers manganese
and iron is quite apparent. It indicates an additional need for care in
balancing these nutrients in fertilizer practice for. sensitive crops.
These relationships apparently vary depending on either the variety
or the stage at which the crop is harvested. In addition, the evidence
on the effect of potassium on magnesium absorption indicates a
possibility that on soils that are initially low in magnesium, application
of magnesium should be adjusted to compensate for the increased
potassium application.

Magnesium:- Magnesium applications had no significant

 

effect on the contents of nitrogen, copper, calcium, iron, boron or
sodium. Despite an increase in yield of Downing bulbs, as a result
of applying magnesium, the phosphorus concentration of the bulbs was
increased by 68 per cent with the high rates of application. There has
been some suggestion of a relationship between magnesium and phytin

in the mineralization of soil phosphorus (35). It is recognized, of

 

 

 

90.

course, that phytin is the principal form of stored phosphorus in
many, if not all, seeds, usually in the form of salts with metals
such as calcium or magnesium (40), and it is possible that some

phosphorus is stored in bulbs in this form. The calcium and mag-

 

nesium salts of phytic acid are sparingly soluble, and are concentrated

_l‘.‘ I

\

I.

_ ..r.

,-——-—.-4
.

in the outer coats of cereals and other seeds, providing a reserve of

these nutrients for the growing plant (88).

 

The decrease in the potassium contents of Downing leaves

 

as a result of high magnesium applications may be, in part at least,
due to increased growth. No effect of magnesium application on the
potassium content of Ebenezer leaves or bulbs was found. The fact
that the magnesium concentration in Downing leaves was maintained
with increased growth, suggests that high magnesium applications
favored growth. The increased contents of magnesium in the leaves
of the Ebenezer variety may have been due to an increase in concentra-
tion with a decreased growth. There was a tendency for magnesium
applications to result in decreased manganese accumulations in the
leaves of Downing as a result of increased growth, but in Ebenezer.
despite decreased leaf growth, there was no change in the manganese.
Other than the significant increase in magnesiumcontent in

Ebenezer leaves with a high magnesium application, no nutrient was

91.

found to increase the plant magnesium contents. All the nutrients

at the high level, with the exception of manganese and zinc, resulted
in decreased magnesium concentration in the leaves, presumably as

a result of increased growth. Potassium caused a significant reduction

in magnesium content that could be only partially accounted for in in-

creased growth._ The high magnesium application slightly reduced the

‘7

iron content, and resulted in a 40 per cent reduction of the manganese

 

D -. ‘:’

concentration in Downing leaves. No effects of magnesium additions

 

”2;...

on the iron or manganese concentrations in the bulbs were found.

The magnesium contents found in the leaves and bulbs of the
crop grown in 1953 were almost twice those found in the crop the previous
year, in spite of an almost three-fold increase in bulb yield. In both

years increased yields and plant contents of magnesium resulted from

 

the high rates of magnesium application. These relationships are shown
graphically in Figures 9 and 10 for the second crop.

Sulfur:- Sulfur had no significant effect when applied at various

 

rates, as sulfate, on the nitrogen, potassium, c0pper, iron, boron or
sodium contents of the leaves or bulbs of either variety. However, the
application of sulfur resulted in increased phosphorus contents of the

bulbs of both varieties. The magnesium contents of the leaves of the

Downing variety were significantly reduced and the calcium contents

92.

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93.

i
were increased by sulfur application, while in Ebenezer leaves, the

sulfur treatment significantly increased the calcium concentration, but
had no effect on magnesium. No change in the bulb contents of either
magnesium or calcium as a result of sulfur application was obtained.
In Ebenezer the calcium content was increased, despite increased leaf
and bulb growth. Although the increase in bulb contents of manganese
was statistically significant in both varieties as a result of increased
sulfur application, probably the difference was too small to be of
physiological importance. The leaf contents of manganese were not
significantly increased by applied sulfur.

Manganese:- The high manganese treatment resulted in in-

 

creased nitrogen contents of Downing leaves and calcium contents of
Ebenezer leaves, with increased leaf growth in both varieties. No
other significant inﬂuence of manganese on plant composition was found.
Applied manganese did not significantly inﬂuence its own absorption, or
that of iron.

Depressions in manganese content resulted from the appli-
cation of high levels of potassium, magnesium, copper and manganese
in both varieties, and by zinc in the Downing variety. The contents of
manganese in the plants grown in the soil plots were low. Dilution by

increased growth may have been responsible for a part of the reduction

94.

in manganese concentration due to applications of phosphorus, potas-
sium and copper, but manganese concentration was decreased in the
face of reduced growth as a result of the application of manganese and
zinc at the high rate.

zmé:— Zinc at the high rate of application resultedin in-

 

creased concentrations in the plant of nitrogen, phosphorus and potassium
in both varieties, and of calcium and manganese in Ebenezer probably
chieﬂy through a yield reduction. Magnesium, sodium and boron contents
were slightly reduced in both varieties, and calcium and manganese in
the Downing variety, by added zinc. The application of zinc at the high
rate reduced yields both seasons, indicating that in sandy, poorly buffered
soils the quantities of zinc which may safely be applied to onions is much
less than that frequently applied to the same type of soils supporting

citrus, for the control of white bud of corn (77), or for correcting zinc

“ (deficiency in onion on muck soils (69).

 

 

 

 

SUMMARY AND CONGLUSI ONS

A modified sand culture experiment involving the inﬂuence
of three levels of application of nitrogen, phosphorus, potassium, sulfur,
magnesium, copper, manganese and zinc, upon the growth and composition
of two varieties of onions was conducted for two growing seasons. The
nutrient carriers were selected to provide variation only in the nutrient
being considered as a variable, all others being equal in concentration.

The leaves and bulbs, separated at harvest, were separately analyzed for

their contents of total ash, and nitrogen, phosphorus, potassium, magnesium.

copper, manganese, calcium, iron, boron and sodium.

Bulbs of Downing Yellow Globe grown with the 20 different
nutrient combinations were planted the following season for seed production.
Sets of Ebenezer onions grown with the same 20 nutrient combinations
were planted the following season in a muck soil for the production of a
mature bulb crop.

No significant nutrient inﬂuence on the production or viability
of seed was found. Sets of Ebenezer produced with the high sulphur and
with the high manganese treatments resulted in reduced bulb yields and
fewer double bulbs when grown to maturity in a muck soil.

In the course of the analytical work a procedure was developed

for evaluating specific interferences by potassium, calcium, magnesium and

>95 .

 

 

96.

sodium in various combinations of concentration in the photometric
determination of these elements.

Growth and composition of onions in a modified soil
culture medium were found to be associated with treatment and related
to each other. There were significant differences due to variety.

1. Nitrogen was found to increase growth and yield
when it was limiting and the plants were able to absorb sufficient iron
to balance an enormous increase in accumulated manganese associated
with a high nitrogen application. Where yield was reduced by high nitro-
gen applications. a five- to ten-fold increase in the manganese contents
were found, though definite toxicity symptoms did not appear.

2. Phosphorus was found to be very beneficial to bulb
yield while at the same time reducing top growth, which indicated that
this nutrient probably contributed to early bulbing.

3. Potassium increased both leaf growth and bulb yields,
and tended to counteract the detrimental effect of high nitrogen by de-
pressing manganese and increasing iron absorption and utilization.
Potassium inﬂuenced its own absorption more than any other nutrient,
and was the most significant nutrient in altering the magnesium content
of the plant. Potassium application at the high level reduced both the

magnesium and sodium contents of the foliage.

97.

4. Magnesium applications increased both leaf and bulb
yield, and the magnesium contents of the leaves.

5. Application of sulfur increased yields, and phosphorus
and calcium contents of leaves, and manganese contents of the bulbs.

6. Copper applications affected yields erratically and
had no significant influence on the copper content of the plant.

7. Manganese increased yields the first year, but decreased
them the second, which may have been related to a reduced iron application
the second season. Possibly as a result of reduced growth, the nitrogen,
phosphorus and calcium contents were increased in the plants the second
year. Manganese treatment was without significant effect on manganese
composition.

8. Zinc depressed yields both years, and possibly as a re-
sult increased contents of phosphorus were found in the bulbs. but it
caused a decrease in the boron content of one-variety.

9. Zinc applications resulted in the depression of the
potassium contents of the leaves of the Downing Yellow Globe variety, and

increased the calcium content in the Ebenezer variety.

‘51,:

10.

ll.

98.

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