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THE EFFECT OF DEFICIENT NUTRIENT
SOLUTIONS AND LONG AND SHORT
LIGHT PERIODS UPON
THE CARBOHYDRATES OF PEAS

THEQIS FOR THE DEGREE OF M. S.

B. H Grigsby
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TABLE V

I Introduction

II Historical Review

III Experimental Procedure

IV Che;ica1 Fethods

V Description of Plants
a. Series I

b. Series II

‘I

VI ‘ perimentel Results
a. Series I
b. Series II

VII Summary

VIII Literature Cited

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Table I

Table II

Table III

Table IV

Table V

Table VI

Table VII

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page

fiumbor of cubic centimeters of single salt stock
solutions to mate twelve liters of each type of
culture solution anu having a total concentration

of one atmosphere.

Dry weights of leaves and stems in three different
types of solution and under three light exposures.
Carbohydrate distribution in pea plants growing in
three types of culture solutions under three light
exposures. Series I

Percentage of sugars and non—sugars in leaves and
stems of plants in Series I. Ratios on basis of
long light complete solution plants.

Dry weights of leaves, stems and roots in three types
of culture solutions and under three light exposures.
Series II

Carbohydrate distribution in pea plants growing in
three types of culture solution and under three light
exposures. Series II

Percentage of sugars and non-sugars in leaves, stems
and roots of plants of Series II. Ratios on basis of

long light complete solution plants.

13

15

17

25

27

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ACIU. "'14ch It pguT

The writer wishes to express his gratitude to
Dr. R. P. Hibbard for helpful advice during the progress
of this work and for his criticism. of the manuscript.
The author is also indebted to Dr. E. A. Bessey an

Dr. R. de Zeeuw for criticism of the manuscript.

IIITRODUC'I‘ION

A study of the literature shows that considerable attention
has been given to an inquiry into the influence of certain chemical
elements on the rate of photosynthesis, and into the influence of the
length of exposure to light on the amount of organic matter produced.
The interaction of these two factors seems not to have received much
serious attention.

The work reported in this paper is an attempt to show some
effects upon photosynthesis and translocation in the garden pea arising
from the deficiency of potassium and calcium in the nutrient solution

and from three different light exposures.

HISTORICAL RdVIEW

A study of photosynthesis can be grouped under two headings:
the first including all work on the relation of mineral elements to photo-
synthesis and the second including all work on the effect of length of
light period on the synthesis of food by plants.

A large part of the work with mineral elements has had to do
with the effect of increasing amounts of the elements on photosynthesis,
but with such work this paper is not concerned.

Nobbe (18), one of the earliest workers to study the effect of
a so-called nutrient solution lacking an element, found that plants manu-
featured less starch when potassium was absent. Stoklasa (30) supported

this view and reported a direct connection between the presence of

potassium and photosynthetic activity. Reed (21), working with algae,
mosses, and ferns, also found that potassium was essential for carbo-
hydrate synthesis and showed that potassium accumulated in those parts
of the plant concerned with carbohydrate transport. The theory that
potassium functions in carbohydrate condensation is supported by Duggar
(5,272), Hartwell (11), Killer (15,347), Russel (24,68), and Yasuda (52).
Hartwell (11) also reported an accumulation of starch in vegetative
parts of the plants growinc in potassium deficient solutions and con-
sidered it due to retarded growth of the plants, due to lack of po-
tassium. Janssen and Bartholomew (13) found that tomato plants deprived
of potassium show an increase in percentage of dry matter.

Smith and Butler (28) found that wheat plants are able to
translocate carbohydrates as readily in the absence of potassium as in
its presence. Nightingale, Schemerhorn, and Robbins (16) found that
tomato plants grown in a solution lacking potassium.are able to trans-
locate carbohydrates as well as plants high in potassium. They also
reported that an accumulation of carbohydrates may occur because of the
retarded nitrogen assimilation by plants in the deficient solution.

much work has been done in regard to the effect of calciwm de-
ficiency in nutrient solutions. Most workers (5, 9, 12, 15, 19, 24,
and 29) seem to agree that this element is used to neutralize certain
acids produced in the growth processes of the plant. They also agree
that calcium forms an intergal part of the cell walls, being laid down
as calcium pectate in the middle lamella. Boehm (2) reported an in-
direct sffect caused by lack of calcium. He found that it stops starch

transfer because of an inactivation of the enzyme diastase. Groom (9)

 

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-3-

also reported an accumulation of starch in calcium deficient plants.

In addition, he found that those carbohydrates that had been converted
into starch could not be reconverted into soluble forms. Duggar (5,.180)
and Miller (15, 257) report that calcium plays an important rsle in
carbohydrate translocation.

Hobart (12) affirms that calcium has nothing to do with photo-
synthesis. Schimper (26) found that plants could translocate carbo-
hydrates equally well in the absence of calcium as in its presence.
fiightingale, Addams, Robbins, and Schermerhorn (17) supported this view
and considered that any accumulation of carbohydrates in calcium de-
ficient plants was due to a lack of nitrate absorption and subsequent
protein synthesis.

Gruzit and Hibbard (10) reported that the absence of an element
retarded translocation and impaired photosynthesis.

Tincker (51) found that plants in short light exposures were
able to maintain a high rate of synthesis due to removal of the end-
products of the photosynthetic process. Redington (22) reported that
light exposures up to eighteen hours gave better growth Egg-most plants
and that the poor growth of briefly exposed plants was due to impaired
photosynthesis. Pfeiffer (20) found that with longer light exposures,
tomato plants showed an increase in carbohydrate reserves and total
growth over plants in short light exposures. A30 and Mural (1) reported
that barley and peas exposed to electric light at night made much faster
growth than control plants. Deats (4) found that tomatoes and peppers
exposed to light for varying periods had growth rates proportional to
the length of light exposure. Starch formation was also feund to be

proportional to the length of day.

Garner and Allard (8) reported that the growth of plants was
proportional to the length of eXposure to light and not to the intensity
of the light.

Clements (5), working with water cultures, found that short
exposures to light markedly affected the position of the best cultures

on a twenty-one culture triangle.

ECPER IILmJTJLL PROCL‘DUYE

The plants used in this experiment were grown in the Botany
greenhouse at Michigan State College, East Lansing,.Michigan. The water
culture method was used in preference to sand cultures. One set of plants
was grown in the spring of 1951 and another in the early winter of 1951.
These particular seasons were chosen in order to secure conditions as
favorable as possible for the growth of the plants, since in this locality
plants do not grow well in the greenhouse during summer and early fall.
The garden pea variety, Alaska, was used in both sets, because preliminary
work showed that it grew exceedingly well in water cultures. It was also
easy to secure a large number of seedlings similar as to age, length of
leaf, and general vigor. The seed for both sets came from the same source
and was from the 1950 crop.

Seeds were carefully selected for size, color, and healthy appear-
ance. They were treated with 1 - 100 bichloride of mercury for five
minutes and soaked in water for six hours. After soaking, the seeds were
planted on moist paper toweling in a large galvanized iron germinating
tray which had been cleaned and thoroughly disinfected. The seeds were

kept covered and moist for five days, after which time it was possible to

-5-

select seedlings that were healthy, with two-inch stems, and in
sufficient quantity to fill all culture jars.

The culture solutions were made up in twelve-liter glazed
stoneware Jars. These jars before they were used were thoroughly cleaned,
disinfected with a l - lOO solution of forty per cent formaldehyde and
washed well with distilled water, to remove any formaldehyde that might
have been left in the jars.

In this experiment Shives (27) three-salt nutrient medium
R502 was used as the full or complete solution. The potassium deficient
solutions were made by substituting sodium for the potassium ion in
potassium phOSphate. The calcium deficient solutions were made by re-
placing the calcium ion with sodium in equal proportions. All stock
salt solutions were made up to l - molar concentrations in quantities
sufficient for the entire experimental period. Culture solutions were
then made up from these stock solutions to have a calculated osmotic
concentration of one atmosphere. Table I shows the volume of stock salt
solutions used in each type of cultural solution.

Table I. Number of cubic centimeters of single salt stock
solutions to make twelve liters of each type of culture solution and having

(1)

a total concentration of one atmosphere.

 

 

 

 

 

 

 

 

ture nzgso‘ (halos) KH P0 NaNO N P0
omple to 180 “ 65 21 - .-
‘Einus Potassium 180 65 I“ - J - 1 216 1
‘dinus Calcium 180 - 1 216 T 63 1 1- I
(1) In addition, each culture received 20 Etc. of fifi‘ferric tartrate, V

5 c.c. :54 MnSO4 and 5 c.c. Egg-1151305 solutions.

The plants were grown on galvanized wire screening having
four meshes to the inch. These screens were cut to fit the top of
the Jars, washed, heated, and coated with paraffin before being used.
As the plants grew they were held upright by the aid of short wooden
dowel pins 1/4” in diameter and sufficiently long to serve the purpose.

Fifty seedlings were placed on each of eighteen screens in
such a.manner that all seedlings received as nearly as possible the
same amount of space. All seedlings were started on complete nutrient
solution and given artificial illumination at night. Abration was
provided by forcing air to the bottom of the Jars for a period of one
hour and thirty minutes each day. These conditions were maintained for
a period of two weeks during which time all solutions were renewed once.
The cotyledons were then cut off and the stems supported by a small wad
of non-absorbent cotton placed around the stem and the plants allowed to
grow for another week.

When the plants were three weeks old and well established a
certain number of them.were transferred to solutions deficient in po-
tassium or calcium and placed under varied light conditions. The cultures
were divided into three groups. Six sets of fifty plants each were
placed in solutions as follows:

(1) two Jars of solution R502 complete

(2) two jars of solution B 0 minus potassium

5 2
(5) two Jars of solution R502 minus calcium.
One group was left in the same place in the greenhouse it
occupied in the beginning, but was not given any artificial illumination.

Hereafter plants in this group will be referred to as "intermediate

light" plants. .A second group was placed in a large specially constructed,

-7-

well a’e'ratelbox so that all light could be kept out when that was
necessary. This box was kept cpen for ten hours each day and the
plants in this group will hereafter be referred to as "short light”
plants. A third group was placed on a bench at one end of the green-
house in the light given off by two 1000 watt mazda lamps, provided
with large BenJamin reflectors and suspended three and one-half feet
above the top of the culture Jars. These lights were turned on for
the period of the experiment and the plants grown beneath will here-
after be referred to as ”long light" plants. The temperature of the
air above these plants was kept about equal to that of the air in
other parts of the greenhouse by means of a twelve-inch electric fan
kept running constantly. At night the light from the lamps was kept
from the other plants in the greenhouse by means of a black cambric
curtain.

Plants under all light exposures continued to receive the
daily period of agration and all solutions were renewed twice each
week until the end of the experiment.

The experiment was considered completed when those plants,
in all light exposures, which were in caleium.deficient solutions
showed definite injury and wilting had begun. At this stage obser-
vations on all plants were made and the plants harvested. Stems and
leaves were separated, dried, weighed, ground, and later chemical
analyses were made of all samples .(1)

(1) In the second series roots were also taken for analysis.

-3-

CIET TI CAL I‘ETHODS

All samples for analysis were dried according to the re-
commendations of the Committee on Methods for Chemical Analysis for
the.American Society of Plant Physiologists (23). Two-gram.samples
of the dried material were used for carbohydrate analysis. These
were extracted with eighty per cent ethyl alcohol and filtered.

The alcohol was removed from the filtrate by heating on an electric
hot-plate and supplying a steady blast of air during the heating
process. This method, adapted from the work of Gardner (7), saved
several hours of time, but was wasteful of alcohol. Results obtained
in this way were identical with those of duplicate samples evaporated
by the method outlined by the Committee.

The residue, after evaporation, was taken up in water,
clarified with Home's dry lead, deleaded with disodium phosphate,
following the recommendations of Englis and Tsang (6). It was then
made up to volumeulkraliquots taken for sucrose determinations.

Soluble dextrins, insoluble starches, and hemicellulcses
were extracted by the methodh outlined by the Committee and the re-
ducing power of all fractions determined by the ShafferéHartman (26)
procedure. The results were calculated to grams of cuprous oxide
and the corresponding amounts of glucose obtained from the Munson
and Walker tables and expressed as per cent of dry weight. Tables III
and IV'show the results of the carbohydrate analyses.

For purposes of comparison the percentage of simple sugars
and sucrose were combined and hereafter will be referred to as"sugars".

The percentage of dextrin, insoluble starch and hemicellulose were

combined likewise and will be referred to as "non-sugars". The
values for sugars and non-sugars in plants in long light were taken
as unity and ratios calculated for all other values for both Series I

and II. These values are shown in Tables IV and VII.

DESCRIPTION OF PLAN 3 IN SERIES I.AT HARVEST TIME

The plants in all cultures and under all light exposures
appeared to grow normally for one week after being changed to the
deficient solutions. After that time the minus calcium plants seemed
to grow none at all and characteristic red patches began to appear
on the leaves in all light exposures, the degree of injury being pro-
portional to the length of exposure. These patches first appeared
near the midrib and at the ends of small veins, but as the inJury in-
creased its spread outward toward the leaf.margins until finally the
entire leaf became dried and brown. Before the leaves became dry
all tendrils on the plants had wilted and become dry. The potassium
deficient plants also showed indications of leaf injury but of a
different kind and to a lesser extent. In these plants grayish white
patches appeared on the margins of the older leaves and gradually
spread to the inner portions of the leaf. These patches seemed to be
dry immediately after appearing, spread very slowly,.and never appeared
on young leaves. Plants in complete solutions showed no injury in any
case. A detailed description of the plants under each light exposure

follows.

-10-

Series I
Long Light.

1. Complete:
plants healthy, 36 inches tall and growing
vigorously, light green in color, many blossoms
and pods.

2. Minus Potassium:
plants of same height as those in complete solu-
tion, color similar, but many leaves showing the
type of inury Just described, fewer blossoms and
pods than in the complete solution.

25. Minus Calcium:
plants 24 inches tall, many of the leaves dying
but still light green in color and showing the
dark red patches already described, no blossoms or
pods present.

Intermediate Light.

1. Complete:
plants 32 inches tall, dark green leaves, none of
which were dead, several blossoms and pods present.

2. Minus Potassium:
plants 30 inches tall, leaves green but showing grayish
patches described above, some blossoms and half grown

pods present.

-11-

3 . iii nus Calcium:
plants 22 inches tall, leaves similar to those
described under long light minus calcium, but
more of them still green, no blossoms or pods
present.

Short Light.

1. Complete:
plants 56 inches tall, as healthy as the "complete"
plants in long and intermediate light, fewer blossoms
and pods present than in other plants in complete
solution.

2. Kinus Potassium:
plants 34 inches tall, leaves green, but showing
some grayish patches, few blossoms and pods present.

3. Minus Calcium:
plants 22 inches tall, leaves wilted but not dry,

red patches present, few blossoms and no pods present.

EKPZSRDLSI‘ETAL RESULTS

The dry weights of stems and leaves of plants in Series I
were taken and ratios calculated as percentages of dry weight of long
light complete plants. These values are shown in Table II.

In Series Ilplants in complete solution show a decrease in
weight as the light exposure is shortened. Leaves in short light
show an increase of six per cent in weight over the intermediate light

plants and stems show an increase of one per cent, hit these differ-

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ences are not significant.

Leaves of minus potassium plants show a slight increase in
weight in long light, but in all other light exnosures there is a
noticeable decrease. Minus potassium stems are lighter in dry weight
than the complete stems. Short light minus potassium stems, however,
show a five per cent increase over minus potassium plants in inter-
mediate light, both show less increase than minus potassium long light
plants.

Leaves of minus Calcium plants show a decrease as the light
period is shortened and the decrease is greater than in.minus potassium
or complete plants. The stems show practically the same weight in
both short and intermediate light, but long light causes a nine per cent
increase. .All values for.minus calcium stems are lower than the corres-
ponding parts in other solutions.

These results are in accord with the generally observed fact
that the length of light eXposure directly influences the growth of
plants and that growth generally decreases as the light is reduced.

It is also observed, with one exception, that when an element is lacking
a decrease in weight occurrs. Long light.minus potassium leaves are

the only exception. Minus calcium plants show the greatest decrease of
all plants.

Thus, for plants growing in deficient solutions for the length
of time they were in this experiment, and, for seedling plants of the
garden pea, a deficient solution usually results in a low dry weight
while a short light exposure produces the same effect but to a greater

degree.

-13-

Table II - Dry weights of leaves and stems in three different types

of solutions and under three light exposures.

 

 

 

 

 

 

 

 

 

 

 

Leaves Stems
ulture .Light Dry wt. Ratio Dry wt. Ratio
olution _ treatment ,grams ,_grams

Long 18.0876 100.0 24.9693 100.0
pomplete Inter- 14.2092 78.0 18.0241 72.1

mediate

Short 15.1986 84.0 18.2653 73.1

Long, 19.3430 106.7 18.4954 74.0
iwinus Inter- 10.5518 58.3 11.1094 45.5
Potassium mediate __

Short 9.2298 51.0 12.6393 50.6
lhinus Inter- 10.2780 56.8 12.0752 49.2
paloium mediate

Short 7.8848 43.5 12.4518 49.?

 

 

 

 

 

 

 

 

-14-

The increases that did appear, as in the case of short light
plants when compared with intermediate light plants, are so slight
that no significance can be assigned to the results.

The effect produced by lack of potassium, however, is of a
different nature and probably due to some interference with normal
activity of the plant. This will be taken up later in the discussion
when the results of chemical analyses are presented.

Table III shows the distribution of the various carbohydrate
fractions in all solutions in Series I. The simple sugars in the leaves
for the three light conditions in the complete solution do not vary much.
Long light plants, however, show highest values while intermediate and
short light plants are about the same. The values for sucrose in the
leaves of these plants are much higher than the simple sugar values and
show considerable variation. Soluble dextrins and insoluble starches
in these plants are low but show rather wide variations as a result of
the three light conditions. Hemicellulose in plants grown in this solu-
tion is quite high except for short light which indicates that there
may be a utilization of this material by the plants for cell wall con-
struction. The values for'a11.these fractions in the stems correspond
to those in the leaves, but are usually lower than the leaf values.

The simple sugars and soluble dextrins, however, are exceptions.

In the case of leaves of minus potassium plants there is a
great difference in simple sugars, depending upon the light exposure;
while sucrose values show much similarity to sucrose values in plants
grown in the complete solution and under corresponding light exposures.

For this solution high soluble dextrin and insoluble starch values are

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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-15-

found as compared with these values in complete solution plants.
Hamicellulose values, while they show the same reduction in short light,
do not show such marked changes as they do in plants grown in complete
solution. Stems in this solution show the same trend as the leaves.

The calcium deficient plants,show in both stems and leaves,
much reduced values for simple sugars as compared to the values for
complete solution plants. High values for insoluble starch are found in
these plants as well as in the potassium deficient plants.

The use of a table of ratios will facilitate a comparison of
the various culture solutions as influenced by light exposures. In
Table IV the various carbohydrate fractions have been combined as sugars
and non-sugars and ratios computed, based on the values for plants
in the complete solution growing in long light.

A study of Table IV shows that the production of sugars and
non-sugars,in both leaves and stems of plants grown in the complete solu-
tion,is always decreased as the light period is shortened.

The potassium deficient plants, with one exception, show de-
creases in sugars and non-sugars in shortened light exposures to a
greater extent than the complete plants. The leaves in long light do not
show a decrease in the amount of non-sugars produced.

Calcium deficient plants show the same response to shortened
light exposures as the other two types of cultures, and the values are
lower than the corresponding ones in minus potassium plants.

The results for deficient solutions in this Series indicate
that the absence of either potassium or calcium interferes with photo-

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the findings of Gruzit and Hibbard (10). The nature of this inter-

ference will be discussed after the results of Series II are reported.

SERIES II

On November 17, 1931, a second Series of cultures were placed
in the same type of culture solutions and under similar light conditions
as Series I. These plants were Just three weeks old at the time of
change and had received the same treatment as those in Series I before
being placed in the deficient solutions. Thus, there was a difference
of one week in the age of the plants in the two Series at the time they
were introduced to deficient solutions and changed light conditions.

With the exception of long light, which was the same in both
Series of cultures, here was a difference in the amount of light
naturally occurring. This was due to the season of the year and could
not be avoided. The plants grown in the spring probably receive more
sunlight than the fall grown plants, especially in the case of inter-
mediate light plants.

Due to these differences in the age of plants and light condi-
tions, the two Series of cultures are not duplicates and one can not
be considered as a check on the results of the other. The plants of
Series I were somewhat older than those of Series II and had produced
a considerable number of blossoms and pods. Thus, some of the carbo-
hydrates had gone into pod construction and are not shown in the analyses
reported. However, the results are of value in that they exhibit similar
effects and certain trends are established that make it possible to draw

certain conclusions.

319-

ESCRIPTTON OF PLAHTS IN SERIES II

Long Light.

1. Complete:
plants 34 inches tall, leaves dark green, few
blossoms, but no pods present, roots long and
apparently healthy.

2. Minus Potassium:
plants 34 inches tall, color similar to complete
plants, but lower leaves showed gray patches on
the margins, few shoots at base of the plants, fewer
blossoms than complete plants, no pods present, roots
shorter than those of plants in complete solution,
but healthy in appearance.

3. Minus Calcium:
plants 20 inches high, but all dried, red patches
very apparent in leaves and a few patches were present
on the stems, no blossoms or pods present, roots short
and very much branched, several shoots, two to four
inches long, at the base of the plants.

Intermediate Light.

1. Complete:
plants 30 inches tall, small leaves, light green in
color especially at the t0p of the plants, few
blossoms and no pods present, roots long and healthy,

no shoots at base of the plants.

2. Minus Potassium:
plants 30 inches tall, leaves light green in color
and showing dried margins, few blossoms and no pods
present, roots shorter than those in complete solu-
tion, intermediate light.

3. Minus Calcium:
plants 22 inches tall, but leaves wilted and showing
red patches already described, no blossoms or pods
present, roots short and yellow, many shoots at base,
four to six inches long, and these also showing red
patches.

Short Light.

1. Complete:
plants 30 inches tall, healthy but leaves light green
in color, no blossoms or pods present, roots healthy
and no shoots at base of the plants.

2. Minus Potassium:
plants 28 inches tall, leaves small and very light
green in color, margins show grayish patches, no
blossoms or pods present, roots short and a few shoots
four inches long at base of the plants.

3. Minus Calcium:
plants 20 inches tall, but all of them dried, leaves
show abundance of red patches, no blossoms or pods

present, roots short and branched, no shoots at base.

-21-

EXPERIMEETAL RESULTS

The plants of Series II were harvested, the leaves and stems
were separated and dried in exactly the same manner of those of Series I.
In addition, the roots of these plants were also taken. The dry
weights of all parts of the plants in the different types of solutions
and under different light exposures were obtained, and ratios calculated
based on long light complete solution plants. These values are recorded
in Table V.

From.this Table it is seen that in the complete solution there
is a decrease in weight in all parts of the plant as the light exposure
is decreased, thus agreeing with the results of the first Series.

The leaves of minus potassium plants in this Series again show
an increase in weight in long light as compared with the leaves in the
complete solution. In intermediate light plants, however, there is a
decrease in weight in:stems and roots as well as in leaves when compared
with the plants in complete solution. All parts of the plants under
short light show a slight increase in weight over those in complete
solution under similar light conditions. The difference is considered
too small to be significant.

Calcium deficient plants show a decrease in weight in all light
exposures as compared to plants in complete solution,but the most sig-
nificant decrease occurs in the case of long light. The differences

between.minus potassium and minus calcium.plants are in no case

significant.

Table V’- Dry weights of leaves, stems and roots in three types

of culture solutions and under three light exposures.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Series II
Leaves I’Stems Roots
lture Light Dry wt. natio ry wt. atio ry wt. atio

solution treatment ggrams erams grams

_gngf 14.1815 109.0 4.7975 100.0 7.1582g,lO0.0
Complete Inter. 11.6406 82.0 7.4528, 50.2 5.7454 ' 79.7

Short 6.7895 47.8 5.2974 55.8 5.5154 46.0
_..__....1 _1 __ ..
hinus Inter. 10.0427 70.7 7.1690 48.4 4.2191 58.6
Potassium

Short 7.5650 52.2 5.5282 56.0 5.4574 48.8

Long 11.5154 81.0 9.7987 68.9 5.9295 54.6
hinus Inter. 10.8754 76.5 7.0518 47.5 5.4520 47.9
Calcium

Short 6.7585 47.4 4.8546 52.7 2.8975 40.5

 

 

 

 

 

 

 

 

 

 

 

~23-

In plants in deficient solutians under all light exposures
the greatest variations in dry weight occur in the stems which indi-
cates that translocation of materials has been influenced in some
manner by the treatments given.

In the case of short eXposures to light, the light and not the
nutrient solution is clearly the limiting factor. The plants are not
receiving enough light to enable them to function in a normal manner,
therefore under these conditions, variations in weight due to culture
solutions are not apparent. Under other light exposures, however, the
effects of nutrient conditions can be readily seen.

The distribution of the carbohydrate fractions in the plants
of Series II is shown in Table VI. The results obtained for plants
in complete solution and under long light again may be considered as a
control and compared to those values obtained from plants growing in
deficient solution. Here, as in Series I, we find that all fractions
are decreased in value as the light exposure is shortened and that the
greatest variations are found in the amount of sucrose produced. The
amounts of all fractions, except dextrin and hemicellulose,are usually
greater in the leaves than in the stems. This is especially true in the
case of short light plants. In long light the stems may show slightly
higher values than the leaves and this is probably due to a greater
abundance of material available for translocation under this condition.
In other light conditions the plants probably are not able to manufacture
a supply of food much in excess of their immediate needs, and conse-
quently there is a smaller supply available for translocation and storage,

thus giving low values for carbohydrates in the stems.

~24-

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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In the plants growing in minus potassium solution there is a
marked falling off in the amounts of simple sugars and sucrose formed
and the decline is more pronounced as the light period is shortened.
After exposure to long light, however, it is shown that insoluble starch
and hemicellulose accumulate in the leaves. Evidently these plants are
able to produce a certain amount of material that is chanfed into in-
soluble forms and then are unable to reconvert them into materials that
can be moved. The stems of these plants show a decrease in these two
fractions, especially in the case of insoluble starch.

Plants in minus calcium solutions show a great reduction in all
fractions under all light conditions, with the exception of hemicellulose
in the leaves of short light plants. This value for hemicellulose, how-
ever, is below the corresponding one in complete solution plants.

Reed (21), killer (15) Bugger (5), and others have ascribed to calcium

a £810 in translocation of carbohydrates and have not considered it as
important in the synthesis of these products. It should be borne in
mind, however, that because of the difficulty in separating the two
processes, a statement that calcium functions in one process and does not
function in the other, can hardly be made. The results, reported here,
indicate that calcium is important in the process of translocation and
that it also has a very vital function in the synthesis of carbohydrates.
When calcium is lacking very low values are obtained for simple sugars,
sucrose, and hemicellulose in the leaves. 'The stems also show correspond-
ing decreases. It seems likely that these plants have not been able

to produce any appreciable quantities of food and have been forced to call

upon the materials already made and stored before the period of deficiency

a lack of calcium. Thus, destructive or katabolic processes are
taking place. That this may ave happened is indicated by the
fact that the amount of szgars is somewhat reduced and the amount
of non-sugars is greatly reduced. The fact that the plants were
gradually dying nd the manner of the dying process also lends
support to this view. Reserve material probably could not be
broken down rapidly enough to supply the needs of the plant, there-
fore, death from starvation occurs in those parts more remote from
the food supply. This was s own by the death of tendrils and young
leaves and also by the ailure of plants to produce blossoms.

The results of the analyses of the roots of plants in this
Series are shown in Table VII. The values for sugars are quite
low, but non-sugars, the bulk of which is hemicellulose, are quite
high, regardless of the culture solution and light exposure.
The re ults have little value other than to point out the small
amounts of sugars and the abundance of non-sugars present in all

types of eglture solution and under all light exposures.

.27-

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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728-

Most workers agree in assigning to potassium the £316
of aiding in the condensation processes rather than in modifying
translocation. It is not intended that this work should be taken
as a direct contradiction of that idea. The plants in these experi-
ments probably had stored enough potassium to enable them to carry
on condensation processes for the leng h of time they were in de-
ficient solutions, but the supply may not have been in excess of such
needs. Plants are known to have the ability to transport potassium
to those points where it is needed most, therefore the potassium in
these plants may have been concentrated in synthesizing regions and
none of it left for translocation purposes. It is merely suggested
here that potassium may also play an important part in translocation
as well as in condensation processes.

Plants in the minus calcium solution show a decrease in the
production of sugars and non-sugars in both leaves and stems as com-
pared to the values of corresponding light conditions in complete solu-
tion plants. The values are also lower than those in potassium.de-
ficient plants. Variations between long and intermediate light plants
are not significant, but the fractions in short light are probably
significantly lower than those in the other solutions. The stems of
all calcium.deficient plants show variations that follow the same
general order as those in complete and minus potassium stems. The
values for long and intermediate light plants are again approximately
the same, but short light plants show quite a large decrease from the
corresponding values in the other two types of solutions.

The good growth and the apparently healthy condition of the

plants before they were placed in deficient solutions indicated that

9299

the supply of calcium was adequate gsrell growth processes. It is
generally observed that calcium is not easily moved in plants after
it has once been laid down. This being the case, the plants would
not be able to use the calcium in translocation of materials and a
deficiency of calcium in the nutrient solution would likely be mani-
fested in the amount of reserve materials in the stems of the de-
ficient plants. The results give support to this view in every case.
In addition, there is also a considerable decrease in the amount of
sugars formed which indicates that the plants have had difficulty

in synthesizing the more soluble carbohydrates.

The general appearance of the plants indicated that little
if any growth had taken place while in the deficient solution. The
height of the plants, as compared with those in complete and minus
potassium solutions, suggested also that little if any growth had
occurred.

If these plants have not had enough calcium to provide for
growth there probably was less to provide for translocation, there-
fore, it seems logical to conclude that a disturbance in translocation
would take place. The results seem to show that this is the correct
conclusion. The data do not permit any positive statement in regard
to the function of calcium in the synthesis of carbohydrates, but a
relationship is seemingly indicated. Further work toward this and
would probably yield valuable information.

The low values for short light plants can probably be best
eXplained by the fact that plants are synthesizing very little be-

cause of the reduced light supply and in addition are suffering from

450-

a lack of calcium. Thus, destructive or katabolic processes are
taking place. That this may have happened is indicated by the
fact that the must of sugars is szmewhat reduced and the amount
of non-sugars is greatly reduced. The fact that the plants were
gradually dying and the manner of the dying process also lends
support to this view. Reserve materiel probably could not be
broken down rapidly enough to supply the needs of the plant, there-
fore, death from starvation occurs in those parts more remote from
the food supply. This was shown by the death. of tendrile and young
leaves and also by the failure of plants to produce blossoms.

The results cf the arelyses of the roots of plants in this
Series are shown in Table VI. The values for sugars are quite
low, but non-eumrs, the bulk of which is hemicellulose, are quite
high, regardless of t‘:.e culture solution and. light exposure.
The results hcve I.i.ttle vane other than to point out the small
amounts of sugars and the abundance of non-sugars present in all

types of c lture solution and under all light expemree.

1. Two series of pea plants were grown in three types of nutrient
solutions and in three lengths of light exposure. Series I was
grown in the spring of 1931 and Series II was grown in the early
winter of 1931.

2. The data show that length of liglt exposure directly influences
the amount of dry matter produced by the plants.

3. A deficiency of potassium may cause an increase in the weight of
leaves produced by plants eXposcd to light for long periods but not
in weight of stems.

4. Short and intermediate light exposures coupled with the lack of
potassium produce a much reduced dry weight as compared with that of
plants in a complete solution.

5. A deficiency of calcium.produces a reduction in dry weight under
all light conditions.

6. The production of carbohydrates is influenced by the length of
light exposure .

7. Translocation of carbohydrates may be influenced by lack of po-
tassium in plants growing in long light. Such plants show an increase
of hemicellulose and insoluble starch in the leaves when compared
with plants in complete solution.

8. Production of carbohydrates in all other light exposures is de-
creased by lack of potassium.

9. Lack of calcium.tends to produce a reduction in the amount of
carbohydrates formed and transported under all light conditions.

10. It is suggested that plants in calcium deficient solutions and
under short light exposures break down products elaborated before the
period of deficiency began, to supply the necessary energy to maintain

life until death sets in.

LITEPinnE CITED

1. Aso, Keijino and umejira‘Murai. An experiment on the promotion
of plant growth by the influence of electric light. (ibst. Jap.)
Jour. Sci. Agric. Soc. fiQg; 31-36. 1924.

2. Boehm, J. Uber den vegetabeleschen nfihrwerth. der Kalksalze.
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3. Clements, Harry F. Plant nutrition studies in relation to the
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4. Deats, Harlan E. The effect on plants of the increase and de-
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5. Bugger, Benjamin, M. Plant physiology xv-+ 516. Illus.
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6. Englis, D. T., and C. Y. Tsang. The clarification of solutions
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7. Gardner, F. 3., Useful device for evaporating alcohol from plant
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8. Garner, W. W., and H. A. Allard. Further studies in photOperi-
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9. Groom, P., Preliminary note on the relation between calcium and

the conduction of carbohydrates in plants. Ann. Bot.‘125 91-96.

1896.

10. Gruzit, 0. M., and R. P. Hibbard. The influence of an incomplete
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11. Hartwell, B. L. Starch congestion accompanying certain factors
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12. Hobart, F. 0., Calcium in plant metabolism. Pharm. Jour.'11§;
500. Bot. absts.‘14; 569. 1924.

13. Janssen, G., and R. P. Bartholomew. The translocation of potassium
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14. Loew, 0., The physiological rale of mineral elements in plants.

U. S. D. A. Bureau Plant Ind. Bul. 45. 28-46, 54-56. 1903.

15. miller, Edwin 3., Plant physiology. xxiv 4-900. Illus.
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170 ___, R. :50 Adams, and o

 

 

ffects of calcium deficiency on nitrate absorption and on metabolism

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18. Hobbs, F., J. Schroeder and R. Erdman. Uber die organische Leistung
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24. Russel, Edward I., Soil conditions and plant growth. 4th ed.
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(Biol. abate. 4(2) Feb. 1930.)

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