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STUDIES ON GROWING CERTAIN VEGETABLE
PLANTS IN VARIOUS CONTAINERS

Theeie

Presented to the faculty of the Michigan State
College of Agriculture and Applied Soi-
enoe as partial fulfillment of
the requirements for the
degree of
master of Science

by
Charles Fuller
1950

THESIS

TABLE OF CONTENTS.

Introduction
Review of Literature
Experiment With Lettuce

materials and Methods

Nutrient Solution

Treating Pots

Lime Treatments 1’

Paraffin Treatments

Other Materials Used

Presentation of Results

Discussion

nutrient Treated Containers

Discussion

Effect of Containers on Yield and Cash
value of Produce

Lhme Treated_Containers

Paraffin Treated Containers

Peat Pots Plunged in Sand

Study of Tops and Boots at End of Potting Stage
Pot Extract Experiment

Plan of Treatments

Presentation of Results

Discussion

Effects of Extracts on Plant Growth
Effect of pa. Factor on Plant Growth

EIperiment with Cabbage

materials and Methods

Presentation of Results

Discussion

‘Bulk Peat as a Component of Potting Soil
vs. Potting Soil in Clay Pots

Bulk Peat as a Component of Potting Soil
V's Pant POt'

Effects of Soil velums on Growth of Potted
Plants

Discussion

Effects of Plunging Peat Pots in Sand

Effect of Containers and Treatments on Tops
and Boots

©0334-4050 N l4

General Discussion
Acknowledgements
Conclusions and.Sumnary
Idterature Cited

a1w31~1~

Studies on Growing Certain Vegetable Plants

in Various Containers.

Introduction:

Seventeen major truck crops with a value of more
than $250,000,000.00 were grown in the United States in
1928. Of this lot, a large number are started as seed-
lings in individual containers and later transplanted
in the ereenhouse for forcing or out of doors for field
or garden crops. This method of handling plants is a
common practice with progressive growers. Many types
of plant containers are used for this purpose, and grow-
ers and investigators have observed, under certain con-
ditions, that the containers appear to have a direct
influence on the plants grown in them. For instance,
plants grown in paper containers have a tendency to be—
come yellow, as though suffering from an inadequate
supply of nitrogen,when heavy types of soil are used.
Root injury also has been attributed to the influence of
the container, and peat planting pots have been reported
by some, as having a deleterious effect on plant growth,
while others claim they have unusual merit as containers
in which to start plants.

Review of Literature:

Knott (1) compared the growth of tomatoes started
in certain types of peat pots and in clay pots. In all
cases the more desirable type of growth occurred in the
clay pots. Plunging peat pots in soil or peat moss in-
creased the growth but did not secure satisfactory results.

When peat pots were soaked in liquid manure there was no

marked increase in size of plants. On the other hand,

when an amount of liquid manure equivalent to that taken
up by the peat pots was added to soil in clay pots a 20
per cent increase in size of plants occurred.

Thompson (2), working with peat pots and growing
ten different creps, reports peat pots to be less satis-
factory than clay pots in the same experiment. The
roots failed to penetrate the peat and the high acid con-
tent of these pots was considered as a contributory cause
for the unfavorable results. Other workers, Kbyler (3)
and Edmond (4), obtained somewhat favorable results. In
some cases plants grown in peat pots were earlier and
more vigorous than those grown in other types of plant
containers.

Another investigator, Laurie (5), reports that even
though peat pots were satisfactory from a cultural stand-
point, their use would be neither economical nor practical
for greenhouse floral crops. Better or equivalent results
may be obtained by judicious use of bulk peat either as a
component of the soil or as a mulch on the bench or green-
house beds. Another writer (6) states plants were grown

in two types of peat pots and in fiber and clay pots placai

on open ground in shady places and covered with sand. Roots

grew freely through the peat pots and to some extent through

the fiber pots. More nitrates were needed for the peat pots

than for other types of pots. This additional plant nutri-

ent supply was compensated for by the ease and rapidity with

which the peat pots could be handled when transplanting.

Krebs (7) reports unsatisfactory results with cabbage

and muskmelons when grown in "Growell" peat pots, but
found the\ grew excellent tomato plants. Growell Pot
Company Inc. (8) claim the acid condition in the "Grow-
ell" pots is favorable for horticultural farming; they

are sterile, free of fungus and weed seed; andlfls highly
absorptive, being capable of holding ten or fifteen times
fidflrweight in.moisture. The peat has an affinity for
ammonia or will readily absorb any nutrient solution
desirable for the type of plants to be grown. J. F. M.
(9), a grower, reports satisfactory results growing

tomato plants in plunged"Growell" peat pots. Knott (10)
in discussing paper pots states that a gradual yellowing
of foliage occurs with a subsequent check in plant growth.
This condition is more prevalent when heavy types of soil
are used; moisture is held in contact with the paper and
decay is more rapid than when porous sandy soils are used.
This worker suggests that perhaps bacteria working in the
decaying paper rob the plants of nitrate, thus causing

the yellowing foliage and poor growth. Both growers (ll)
and other investigators have noted conditions similar to
those reported by Knott, and in addition report difficulty
in removing the paper bands or pets when transplanting
and that more careful handling is necessary than for plants
grown in clay pots. Edmond and Lewis (12), after experi-
menting with a nutrient solution on cabbage, show that
growth, time of maturity and quality of plants are direct-
ly influenced by the presence of readily available nutri-

ents. They suggest, from their results, hat gradually

availaile nutrient materials may be applied in combina-
tion early in the season with satisfactory results.
Crist (13) found the variety of lettuce with which he
worked to be more sensitive to alkalinity than to acidi-
ty, and states that any detrimental effe ts of untreated

acid soil seemed to be due more to improper nutrient

conditions than to the acidity itself.

Experiment With Lettuce

Materials and Methods:

Grand Rapids forcing lettuce was grown in flats
from which plants of uniform size and vigor were select-
ed and grown in several types of plant containers, namely:
Clay pots, paper pots, "Neponset" paper pots, "Fertex"
fiber pots, paper bands, wood bands, "Peco" peat pots,
"Growell" peat pots and "Fertex Sparkling Red" pots.

Twenty pots were included in each treatment. The
potted plants were placed on a greenhouse bench from
March 2 until April 6, a period of 35 days. On April 6,
10 plants from each group, selected as representative,
were cut and weighed. The remaining 10 plants of each
group were transplanted into the cold frame bed, remaining
there from April 6 until hay 5, a period of 29 days.

he peat pots and "Fertex" fiber pots were set into
the cold frame bed with the plants. Other types of con-
tainers were removed from the ball of roots and soil and
no fragments of paper or wood went into the bed with the
plants.

The time plants were in pots (March 2 until April 6)

is designated in tables and discussions as the "potting
stage" and the period they were grown in the cold frame
(April 6 to Key 5) is designated as the "cold frame stage."

The containers with various methods of treating them are

listed in table 1.

-6-

Table l.

Containers and Treatments Included

in the Lettuce EXperiment

Series Containers Treatments

No.

1. Clay pots (4”) ------------ Untreated check.

2. "Neponset" paper pots ----- Untreated.

5. "Growell" peat pots ------- Untreated.

4. Paper bands --------------- Untreated.

5. "Peco" peat pots ---------- Untreated.

6. Paper pots ---------------- Untreated.

7. "Fertex" fiber pots ------- Untreated.

8. Beechwood bands ----------- Untreated.

9. Basswood bands ------------ Untreated.
10. "Fertex Sparkling Red” Pots-Untreated. (Clay pot substitute)
ll. "Neponset" paper pots ----- Paraffin treated.
12. Paper bands --------------- Paraffin treated.
13. Paper pots ---------------- Paraffin treated.
14. Beechwood bands ----------- Paraffin treated.
15. Paper pots -------------- --Lime treated.
16. "Growell" peat pots ------- Lime treated.
17. ”Peco" peat pots ---------- Lime treated.
18. Paper bands --------------- Lime treated.
19. "Neponset" paper pots ----- Lime treated.
20. Beechwood bands ----------- Lime treated.
21. "Peco" eat pots ---------- Soaked in nutrient solution before

using.
22. "Neponset" paper pots ----- Peco nutrient treatment on plants.
23. Paper bands --------------- Peco nutrient treatment on plants.
24. Paper pots ---------------- Peco nutrient treatment on plants.
25. "Fertex" fiber pots ------- Peco nutrient treatment on plants.
26. Clay pots (4”) ------------ Peco nutrient treatment on plants.
27. Beechwood bands ----------- Peco nutrient treatment on plants.
28. ”Growell" peat pots ------- Soaked in nutrient solution before.
'using.
29. "Neponset" paper pots ----- Growell nutrient treatment on plants
30. Paper bands --------------- Growell nutrient treatment on plants
31. Paper pots ---------------- Growell nutrient treatment on plants
52. "Fertex" fiber pots ------- Growell nutrient treatment on plants
53. Clay pots (4”) ------------ Growell nutrient treatment on plants
34. Beechwood bands ----------- Growell nutrient treatment on plants
55. "Peco" peat pots ---------- Plunged in sand.
36. "Growell" peat pots ------- Plunged in sand.
Note: 20 containers were included in each treatment;

4" size being used throughout.

Nutrient Solution.
A nutrient solution which was found satisfactory
by Edmond and Lewis (12) in an earlier experiment with
cabbage, was used in this emperiment. The solution was

made up as follows:

1. Calcium nitrate (Ca(N03)2) ------ 200 grams
Nade up to
Potassium nitrate (KNO3) -------- 50 grams 2 liters.
Potassium.chloride (KC ) -------- 25 grams
2. Monopotassium phosphate (KH2P04)50 grams---made up to
2 liters.
3. magnesium sulphate (M5804) ------- 50 grams--made up to
2 liters.

The above stock solutions were prepared for applica-
tion by placing 100 cc. of each in a 7-liter jar, with
ordinary tap water added to fill jar. Iron was supplied
by adding 14 cc. of a one per cent solution of ferrous

citrate to each 7 liters of solution.

Treating Pots.
Nutrient Treatments.

Ten "Peco" peat pots and lO "Growell" peat pots were
selected at random from the peat pots used in the experi-
ment. These pots were thoroughly saturated with the nu-
trient solution described above. The peat pots were allowed
to dry, drip free, were weighed separately, and the average
weight per pot was calculated and recorded as indicated in

Table 2.

-8-

Table 2. Average Dry heights of Peat Pots and Average

Weights of Peat Pots Saturated with Nutrient Solution.

Average Average Nutrient Percentage
dry weight per solution increase

weight pot after taken up in weight.
per pot nutrient by pots.
treatment
gr. gr. gr.
1. "Peco" peat pots 45.6546 558.6825 295.0279 575.8

2."Growell" peagts 51.2465 164.5579 154.1887 529.4

All peat pots were treated before using. The weight of the
nutrient solution absorbed, as shown in the table, was used
as a basis for making nutrient treatments on other types of
containers. Treatments on other types of containers were
started two weeks after plants were potted.

In one series, each plant was treated with nutrient
solution equivalent to that absorbed by "Peco" peat pots,
applying 50cc. on alternate days until the amount desig-
nated in Table 2 had been applied. (In discussions, and
in tables these treatments are designated as "Peco’ Nutrient
Treatment"). A similar series of treatments were made,
based on the amount of nutrient solution absorbed by "Grow-
ell” peat pots, and are designated in tables and discussions
as "Growell Nutrient Treatment."

Lime Treatments.

Lime treatments were made by thoroughly soaking the

containers in a saturated lime (CaCOS) solution.
Paraffin Treatments.

Paraffin treatments were made by dipping the containers
into a tank of melted paraffin.

Determination of pH. values of Containers and

Other Materials Used.

Seven containers were selected at random from
among each of the various types of containers used.
These containers were even treated at 9530. for a
period of 56 to 48 hours, after which they were fine-
ly pulverized and a sample taken from each and placed
in a closed Specimen bottle to be used in making the
pH. determinations. Three grams of each sample were
placed in separate beakers with 150 cc. of distilled
water. The contents of the_beakers were stirred vig-
orously to moisten thoroughly all particles of the
sample, thus insuring maximum.extraction. After a
period of 24 hours the extracts were filtered off and
used in making the pH. determinations. Other materials
used were treated the same as the containers. Paraffin-
treated containers were excluded from the oven treatment.
The Colorometric Method of determining E. values was used.
An average of the pH values of each type of con-

tainer or material used is shown in Table No. 5.

-10...

Table No. 5. Showing pH. Values of Containers

and haterials Used.

Container
or

Katerial Treatments pH. Reading
1. Clay pots ----------------- New-Unused —————————— 7.8
2. Basswood bands ------------ Untreated ........... 6.6
5. Beechwood bands ----------- Untreated ........... 5,7
4."Neponset" paper pots ------ Untreated ----------- 6.8
5. Paper bands --------------- Untreated ........... 5,9
6. "Fertex" fiber pots ——————— Untreated ___________ 8.4
7. Clay pots ----------------- Old—Used—-e --------- 5.6
8. "Peco" peat pots ---------- Untreated ___________ 4,0
9. "Peco" peat pots ---------- Lime treated -------- 6.9
10. "Peco" peat pots ---------- Nutrient treated----6.0
ll. "Peco" peat pots ---------- Used ................ 4,5
12- "Growell" peat pots ------- Untreated ----------- 4,5
15. "Growell" peat pots ------- Lime treated -------- 6.5
14. "Growell" peat pots ------- Nutrient treated----6.0
l5. Beechwood bands ----------- Paraffin treated----5.6
l6. Beechwood bands ----------- Lime treated ........ 5,5
17. "Neponset" paper pots ----- Paraffin treated-—--6.6
18. "Neponset" paper pots ----- Lime treated -------- 7.8
19. Potting soil -------------- Untreated ——————————— 7,0
20. Potting soil 1/5 lime treated Michigan peat---7.5
21. Hichigan peat ------------- Untreated« __________ 4.8
23. Hichijan peat ~~~~~~~~~~~~~ Lime treated ........ 7,1
33- German peat --------------- Lime treated -------- 7,0
24- German peat --------------- Untreated ----------- 3.7
25. Nutrient Solution ............................. 5,5
26. Paper pots-Used-Decayed ....................... 7,1

27. "Peco" peat pots-Used-Plunged in neutral sand-4.6

 

 

Plate 1. Figs.1-l.- Lettuce plants grown in ordinary
potting soil in (1) untreated clay pots, (2) untreated

"Peco" peat pots, (5) untreated "Growell
untreated "Neponset" paper pots.

pots and (4)

-11..

Presentation of Results.

The results set forth in this paper are based
primarily on: A. The comparative average weight of
plants at the end of the potting stage, or whei re-
moved from the containers and set into the cold frame
bed; B. The comparative weight of plants at the end
of the cold frame stage, or at the time the plants
were harvested; C. The percentage of increase in
weight of plants during the cold frame stage, or the
increase in weight of plants after they were removed
from the direct influence of the containers.
The results with untreated containers are shown
in table 4.
Table 4. Influence of Untreated Containers on
Growth of Lettuce.
Average Average Percentage
weight weight of increase
per plant per plant in weight

at end of at end of during the
potting cold frame cold

stage stage frame stage
gr. gr.

No. Containers Treatments

1. Clay pots (Check)--Untreated~-9.55 215.5 2155.6
2. "Neponset" paper pots-Untreated-5.l5 147.8 4592.0
5. "Growell" peat pots-Untreated-5.61 127.7 5457.5
4. "Fertex Sparkling Red"1Untreated-4.15 155.5 5569.7
5. Paper bands --------- Untreated--6.90 250.0 5255.5
6. "Peco" peat pots--—-Untreated~-8.00 255.9 2848.7
7. Paper pots ---------- Untreated-~5.94 172.5 2040.4
8. ”Fertex" fiber pots-Untreated--12.66 264.5 1908.7
9. Beechwood bands ----- Untreated--20.26 521.9 1488.8
10. Basswood bands ------ Untreated--26.05 568.0 1515.7

1. A pot devised as a substitute for clay pots.

Discussion:

"Fertex" fiber pots (No. 8) and wood bands (No. 9 and

-12-

No. 10) produced markedly heavier plants than clay pots
(No. 1) during the potting stage, while the clay pots
(check) produced heavier plants during this stage than other
types of containers. Plants grown in "Fertex" fiber pots
and in wood bands also produced heavier plants during the
cold frame stage and showed lower percentages of gain
after being removed from the effects of the containers,
than did plants grown in untreated clay pots. In other
words clay pots had a slightly retarding effect on plant
growth when compared with ”Fertex" fiber pots and wood
bands.

The wood bands contained a greater volume of soil
than other containers and it is claimed that nutrients are
contained in the "Fertex" fiber pots. These conditions no
doubt have been responsible for the more vigorous growth
of plants in "Fertex" fiber pots and wood bands. Beechwood
bands decayed to some extent and the soil adhered badly to
the wood resulting in some root pruning when removing this,
container from the ball of soil. Basswood bands remained
free from decay or fungus attack during the potting stage.
The soil did not adhere to the wood, but separated cleanly
and no root injury occurred. The basswood bands were clean,
unharmed, and in excellent condition for further use while
the beechwood bands broke apart readily when removed from
the ball of soil and were useless. The superior results
secured with basswood bands (No. 10) over beechwood bands
(No. 9) may be attributed to the fact that basswood bands
withstood decay, thus reducing bacterial or fungus devel-

opment and the clean separation of soil and wood resulted

-15-

in less disturbance of roots when transplanting.

"Neponset" pots, paper pots, peat pots, and paper
bands show a decidedly retarding effect on growth of
plants during he potting stage, when compared with
plants grown in clay pots. In each case the percentages
of increase in size of plants during the cold frame
stage is markedly greater, indicating that these con-
tainers to have a more deleterious effect on plant
growth than untreated clay pots.

Apparently the greater the retarding effect, that
is, the smaller the plants were in the containers during
the potting stage the greater was the percentage of in—
crease in weight when the plants were removed from the
influence of the container. In other words there was
no long continued residual effect from these containers,
as the plants, when removed from their immediate in-
fluence, at once began to make rapid growth.

These results conclusively indicate that containers
have a direct influence on the plants grown in then.
This influence is deleterious to a marked degree in
certain of the containers. Those containers having the
least retarding effect on the growth of lettuce plants
during the potting stages also produced the heavier more
profitable plants when harvested at the end of the cold
frame stage.

Kutrient Treated Containers.
A series of containers were soaked in nutrient solu-

tion before using and the results compared with nutrient

treated plants grown in similar containers and in un-

treated containers,as shown in Table No. 5.

Table No. 5. Comparing the Growth of Lettuce Plants
in Nutrient-Treated Containers with Nutrient-treated
Plants and Untreated Containers.

Average Average Percentage
weight weight increase
per plant per in weight
at end of plant during
potting at end cold frmne
stage of cold stage
frame
stage
No. Containers Treatments gr. gr.
1. Clay pots Untreated (Chock)9.55 213.5 2135.6
2. Clay pots-with "Peco" nutrient
treatment on plants --------- 18.11 299.7 1554.5
3. Clay pots—with "Growell" nutri-
ent treatment on plants ----- 11.60 259.4 2136.2
4. "Peco" peat pots untreated ----- 8.00 235.9 2848.7
5. "Peco" peat pots soaked in nu~
trient solution before using-16.66 351.0 2006.8
6. "Growell" peat pots untreated-- 3.61 127.7 3437.7
7. "Growell" peat pots soaked in
nutrient solution before using-13.20 230.7 1647.7
8. Beechwood bands untreated ------ 20.26 321.9 1438.8
9. Beechwood bands with "Peco" nu-
trient treatment on plants-~-30.26 415.0 1271.4
10. Beechwood bands with "Growell
nutrient treatment on p1ants-—22.90 325.6 1321.8.
11. Paper bands-~untreated --------- 6.90 230.0 3233.3
12. Paper bands-with "Peco" nutrient
treatments on plants ---------- 20.63 375.8 1721.6
13. Paper bands—pith "Growell" nutri-
ent treatments on plants ------ 20.12 358.8 1683.3
14. Paper pots-untreated --------- -- 5.94 172.5 2040.4
15. Paper pots-with "Peco" nutrient
treatments on plants ---------- 19.80 366.2 1749.4
16. Paper pots-with "Growell" nutri-
ent treatments on plants ------ 19.02 291.3 1431.5
17. "Neponset" paper pots--untreat-
ed 3.15 147.8 4592.0
18. "Neponset" paper pots-with "Peco"
nutrient treatments on plants-~5.l4 208.2 3989.5
19. ”Neponset" paper pots with'Grow~
ell" nutrient treatnents on plants 4.03 185.3 4495.5
20. "Fertex" fiber pots-untreated---l2.66 264.3 1908.7
21. "Fertex" fiber pots-with "Peco"
nutrient treatments on plants-18.00 304.0 1588.8
22. "Fertex" fiber pots~with "Grow-
ell" nutrient treatments on
plants -------------------------- 17.32 276.0 1493.5

 

Illa

 

Plate :1. Figs. 5-8.- Lettuce plants grown in
ordinary potting soil in (5) untreated clay pots,
(6) untreated paper bands, (7) untreated paper pots

and (8) untreated beeohwood bands.

Discussion:

Nutrient treatments have resulted in marked in-
creases in weight of plants during the po ting stage,
when compared with plants grown in untreated containers,
in every case, excepting with "Neponset” paper pots.
These gains are most pronounced on peat and paper con-
tainers. "Neponset" paper pots gave very unsatisfac—
tory results untreated, or with nutrients applied on
plants (No. 17, No. 18 and No. 19), yet marked increases
in percentages of gain occurred durin? the cold frame
stage, after removal from the influence of the pot.

The heaviest plants grown during the potting stage
and during the cold frame stage and the lowest percent-
age of gain in weight after removing the influence of
the containers is shown for wood bands (No. 8, No. 9,
and No. 10), indicating these containers to have less
influence on plant growth, under conditions of this ex-
periment, than other containers used.

The percentage of increases is much less pronounced
when nutrients were used than for untreated containers
and it appears that any deleterious effect on plant
growth that may be due to the containers themselves may
be overcome, to a considerable degree, by the use of
nutrients. In other words the materials of Which the
containers are made may, through absorption, deprive the
plants of the necessary nutrients, thus causing the plants
to appear subnormal in size. Soil organisms active in
breaking down the materials of which the containers are

made may utilize the nutrient materials to such an ex-

-16..

tent as to retard plant growth. It appears to be a

definite nutrient problem for when nutrients are provi-

ded, plant develOpment proceeds in a normal manner.
E“fect of Containers on Yield and Cash

Value of Produce.

 

Calculations were made from.the data in Table54
and 5 to show the comparative value of untreated con-
tainers and nutrient-treated containers, based on yield
and cash returns from.each. Nutrient treatments were
made as described on page 7. The plants were all grown
in containers for an equal length of time and in the
cold frame for an equal period. When harvested at the
end of the cold frame stage the lettuce was sold for
.075 cents per pound. Comparative yields in pounds and
cash returns for lettuce from untreated and treated con-

tainers are shown in table 5-n.

[La

 

 

Plate ::1. Figs. 9-12.- Lettuce plants grown in
ordinary potting soil in (9) untreated clay pots,
(10) untreated "Fertex" fiber pots, (ll) Untreated
"Fertex Sparkling Red" pots and (12) untreated
basswood bands.

-17...

Table 5-A. Comparative Yields and Cash Returns
from Lettuce Plants Grown in Untreated Containers and
in Nutrient Treated Containers; with Percentage of
Increase in Cash Value of Produce Due to the Nutrient
Treatments.

Percent of
increase in

Yield Cash re-Yield Cash
10 turns 10 returns

plants 10 plants 10 cash returns
lbs. plants lbs.p1ants due to nu-
trient treat—
No. Containers. . ments.
l.Beechwood bands ----- 7.08 $0.551 8.14 0.609 12.80
2.Basswoos bands ------ 8.09 .607 8.09 .607 Untreated
5.Paper bands --------- 5.06 .579 8.09 .607 57.56
4."Peco" peat pots----5.l9 .589 7.72 .580 52.95
5.Paper pots ---------- 5.97 .284 7.25 .542 47.60
6.”Fertex" Fiber pots-5.81 .455 6.58 .518 16.02
7.Clay pots(Check)---—4.70 .555 6.15 .416 25.59
89Growell" peat pots--2.81 .210 5.07 .580 44.77
9."Neponset" paper pots5.25 .245 4.55 .525 25.25
10."Fertex Sparkling Red"
pots-5.571 .245 3.57 .245 Untreated

1 Clay pot substitute

There is no doubt but that under conditions of this

experiment, untreated wood bands have produced outstandingly

better lettuce plants than other untreated containers used;

with basswood bands producing remarkably heavier

the beechwood bands.

satisfactory gains from nutrient treatments.

plants than
Plants grown in beechwood bands show

The remarkable

response of plants, grown in paper and peat containers, to

nutrient treatments seems to indicate that these types of

containers must have a constant supply of readily available

nutrients present if profitable plants
grown in untreated basswood bands show

a yield and cash return as those grown

ments in beechwood bands.

wifli

are produced.

Plants

practically as great

nutrient treat-

From these results,

it appears,

the plants grown in the wood bands were making nearly maxi-

mum growth, therefore, they show less response to the nutri-

~18-

ent application than plants retarded or set back because
of the influence of the containers in which they were
grown. "Fertex" fiber pots, "Peco" peat pots and paper
bands show yields above the average of the untreated
containers. Plants grown in the "Fertex" fiber pots made
comparatively small response to nutrient treatments and
have yielded above the average in the nutrient-treated
series. Clay pots have yielded below the average in
both the untreated series and the nutrient-treated series.

From the results of this eXperiment lettuce plants
were most satisfactory when started in wood bands and
paper bands indicating, perhaps, that band types of con-
tainers are more satisfactory for certain plants than
pots.

Lime—Treated Containers.

a series of containers were soaked in a solution of

lime (CaCOB) until thoroughly saturated and the results

compared with untreated containers.

 

 

Plate 7. Fig 20.- Showing characteristic top and
root growth of lettuce plants grown in "Growell"
peat pots, plunged in sand during the potting stage.

-19-

Table 6.- Effect on Growth of Lettuce of Treating Various
Plant Containers with Lime

-~~4a¥erage*<nverage Percentage pH.
weight weight of increase Reading
per plantper plantin weight
at endcf at and during cold
potting of cold frame stage

 

stage frame
stage
No. Containers Treatments gr. gr.
‘I.Paper pots—Lime treatedf 4.61 274.4 5852.2 6.6
2. Paper pots—Untreated 5.94 172.5 2040.4 5.9
5.Paper bands-Lime treated 5.55 205.5 5750.4 6.6
4.Paper bands-Untreated 6.90 250.0 5255.5 5.9
5."Neponset"
paper pots--Lime treated 5.48 76.6 2101.1 7.6
6."Neponset" '
paper pots--Untreated 5.15 147.8 4592.0 6.8
7.Beechwood
bands ------ Lime treated16.55 541.4 1990.6 6.5
8. Beechwood
bands-----§Untreated 20.26 521.9 1488.8 5.7
9."Peco" peat
pots ------ Lime treated 5.62 212.0 5824.4 6.9
lO."Peco" peat
pots ------ Untreated 8.00 255.9 2848.7 4.0
ll."Growe11"
peat pots—Lime treated 5.55 181.1 5558.4 6.6
12."Growell"
peat pots—-Untreated 5.61 127.7 5457.5 4.5
Discussion:

Treating plant containers with lime water before using
has in nearly every case raised the pH. value of the con-
tainers near to that commonly considered the optimum (slight-
ly acid) for growth of lettuce; yet in general a retarding
influence on plant growth has been evident during the pot-
ting stage, when compared with untreated containers. Cor-
respondingly greater percentages of increase in weight of
plants occurred during the cold frmne stage after removal
of the effects of the containers.

From.these results it is evident that lettuce may be
grown in relatively low acid media under certain conditions,
such, for instance, as the untreated peat planting pots

(No. 10 and No. 12).

-20-

The’Peco" peat pots in this instance had a pH. value of
4.0, yet when plunged in neutral sand and used to grow
lettuce during the potting stage the pH. value was raised
from 4.0 to 4.6 (No. 27-Tab1e #2). It appears that the
acidity of the containers was not greatly changed during
the potting stage and probably would not be changed to
any extent during the cold frame period; therefore, the
low pH. valueshad a less deleterious effect on plant
growth than those just below the neutral point as in
treatment No. 9 and No.11.

Lime treatments in themselves probably have created
a more nearly optimum condition in the containers for
the activity of soil organisms. Consequently, they have
consumed correspondingly greater amounts of available
nutrients in the lime-treated pots, thus retarding plant
growth during the potting stage. When, however, the
plants were all placed in the cold frames under conditions
in which plant nutrients were abundant plants grown in
lime-treated containers or in lime-treated planting pots,
in general, show remarkably greater percentages of increase
in weight than plants grown in untreated containers. It,
therefore, appears that the pH. factor of a container may
be only indirectly responsible for poor plant growth and
in any case the condition may be readily overcome by the
presence of nutrient materials. This is indicated by re-
sults with nutrient-treated containers (treatments 5 and
7, table 5) wherein it is shown that any detrimental ef-
fect that may be due to the low acid reaction of the peat

pots is overcome to a marked degree by nutrients.

-21...

On the other hand, "Fertex" fiber pots (treatments 21 and
22, table 5) with alkaline reaction show also an increase

in weight of plants when nutrients are applied.

 

Zia,

 

 

Plate V. Fig 21.- Showing characteristic top and
root growth of lettuce plants grown in "Peco" peat
pots plunged in sand, during the potting stage.

Paraffin-Treated Containers.

Certain investigators have suggested that yellowing

foliage and poor growth of plants in paper containers as

possibly being due to the consumption of nutrients by the

bacteria in the decaying paper.

To prevent the decay of

containers and possibly eliminate yellowing foliage and

poor plant growth, several types of containers were dipped

in melted paraffin before using and the effect on plant

growth compared with untreated containers (Table 7).

Table 7.- Comparative Results Obtained with Lettuce Using

Paraffin-Treated and Untreated Containers.

 

Average Average Peroentage
weight weight of increas
per plant per in weight
atendof lflantat (hrnugafld
cold frame and of frame
, stage cold frame stage
No . Containers Treatments . gms . stagggns.
1. "Neponset" paper pots-—paraffin treated 3.61 173.3 4700.6
2. "Neponset" paper pots-~untreated 3.15 147.8 4592.0
3. Paper bands paraffin treated 6.36 214.6 3274.2
4. Paper bands untreated 6.90 230.0 3233.3
5. Paper pots paraffin treated 6.28 184.0 2256.6
6. Paper pots untreated ' 5.94 172.5 2040.4
7. Beechwood bands paraffin treated 15.91 325.7 1947.1
8. Beechwood bands untreated 20.26 321.9 1488.8

-33-

The paraffin-treated containers remained clean and free
from.decay or discoloration throughout the potting stage.

(See #47 Plate—II, #52 Plate m and #37 Plate 172:). In no
instance noteddid roots penetrate the paraffin-treated
materials. These treatments, however, had a slightly retard-
ing effect on plant growth during the potting stage, when
compared with untreated containers. In every case plants
grown in paraffin-treated containers show a greater percentage
of increase in weight during the cold frame stage or after
removal from the direet influence of the containers than is
shown for plants grown in untreated containers.

Slight discoloration of roots occurred in paraffin-treated
"Neponset" pots and in paper pots,due, no doubt, to the fact
that drainage vents were not made in these containers after
dipping in paraffin. Further, it is probable the paraffin
treatments reduced aeration of soil and roots which together
with the lack of drainage have been factors causing the

unsatisfactory results with paraffin-treated containers.

APeat Pots Plunged in Sand.

Knott”)

concludes plunging peat pots in soil or peat moss
did not give satisfactory results. In this eXperiment peat pots
were plunged in neutral sand and compared with untreated peat

pets. The results are shown in Table 8.

-24-

Table 8.- Comparative Results with Lettuce Grown in Plunged
Peat Pots and Untreated Peat Pots.

Average Average Percentage
weightpi‘ weightper of increase
plant at plant at in weight

end of end of during cold
potting cold fiane frame stage
No. Container Treatments stage,gms. stagegs.

 

1. ”Peco" peat pots,p1unged in sand 4.00 177.0 4325.0
2. "Peco" peat pots,untreated 8.00 235.9 2848.7
3. "Growell" peat pots,plunged in sand 4.83 185.4 3738.5
4. "Crowell" peat pots,untreated 3.61 127.7 3437.3

 

Seven-inch clay pots were used for this experiment. The
peat pots were soaked in tap water, allowed to dry until they
could be handled without crushing, at which time the plants
were set into them. Moistened sand was placed in the bottom
of the clay pots. The peat pots with plants were placed in the
clay pots and more moistened sand filled in around and Just
covering the peat pots (Figs. 60 and 62, plate E).

Untreated "Peco" peat pots (No.2) grew better plants than
when plunged in sand, as in No.2, during the potting stage. A
reverse condition occurred with "Growell“ peat pots (to. 3 and
No. 4), in which case the plunged pots produced better plants
during the potting stage. It is evident, however, that plung-
ing peat pots in this experiment had a greater retarding effect
on plant growth, as in both cases the plants grown in plunged
pots during the potting stage show greater percentages of increase
in weight during the cold frame stage when all were under

similar conditions.

 

145g

 

Plate VI. Figs 45-49.- A series of lettuce plants
grown in ‘Neponset" pots. Number 45 was treated with
lime before using; number 46 was untreated; number
47 was paraffined before using; the plants in number
48 received the "Growell" nutrient treatment; the
plants in number 49 received the "Peco" nutrient
treatment. Note the relatively small differences
between the plants.

-25..

Boots grew freely through the "Peco" peat pots (Fig.21,
Plate E), but did not spread into the sand. The roots coming
through the peat were coarse with few fibrous or hairy roots
present. A few coarse rhizome-like roots penetrated through
the "Growell" peat pots. (Fig. 20, Plate:§). These too,
clung around the pot and did not spread into the sand. It
often appeared that roots only penetrated the "Peco" peat
pots through thin or porous spots as in Figure 21, plate 11:.
In this particular case the only roots appearing on the outer
surface of the pot dame through the fissdé-like crevice Just
above the pointer.

The fact that the sand used in thhs experiment was
slightly alkaline may have been a factor in preventing more
of a root distribution outside the peat pots. These results
may indicate that lettuce has a marked sensitiveness to

alkalinity, as has been shown by Crist.(13)

Study of Tops and Roots at End of Potting Stage.

TOps of plants grown in wood bands, clay pots and "Fertex"
fiber pots were normal in color and texture. Those grown in
containers receiving nutrients were noticeably darker green
than normal—plants grown in nutrient treated "Neponset" con-
tainers being excepted. The tops of plants grown in other
types of containers were light in color with thin opaque-like
texture, with a decided yellowing of plants grown in "Neponset"

paper pots.

-26-

A study of the roots of plants cut for weighing at the
end of the potting stage showed a yellowing or brownish
discoloration of roots when in contact with decaying paper
material. This condition was reduced remarkably on nutrient
treated plants. The roots penetrated the paper materials freely
and discoloration was most pronounced where fungus growth was
most abundant, indicating, possibly, a relation between the
fungus development and the discblored roots. It was further
noted that marked discoloration of roots occurred when the
growing points of roots came into contact with the red coloring
matter in the "Neponset" paper pots. Observations made in this
case showed that roots penetrating these pots would, upon
reaching the colored material, turn at right angles, pushing
between the layers of paper rather than penetrating through
the colored outer layer. As the plants grown in the "Neponset"
containers were generally poor, regardless of treatments, it is
possible the coloring material may have had a toxic effect on
plants that even nutrients were unable to overcome.

No root injury was noted in wood bands.

Roots ramified throughout the peat pots freely but did not
come through to the outer surface to any considerable extent,
except at the bottoms of the pots where moisture was retained
by the boards upon which the pots were placed. Discolored roots
noted in the "Peco" peat pots were more pronounced at the point
where roots passed from the ball of soil into the peat material
than after penetrating the peat. In this case discoloration
of roots may have been due to chemical reactions between the

acid peat and neutral soil.

-37-

No root injury or discoloration was noted in "Growell"
peat pots, yet root ramification was free in the peat material.
The character of the root development within the peat material
and the fact that no root injury or discoloration was noted
in the "Growell" peat would seem to indicate that acidity,
within certain limits at least, may have had only an indirect
effect on plant growth.

In brief, it has been shown (Table 5) that peat containers
having relatively low pH. values and "Fertex" fiber pots with
alkaline reaction both give rise to marked increases in per-
centages of weight of plants produced, when nutrients were
used. Therefore, when nutrients are available in sufficient
quantities to promote optimum plant growth the pH. value of a
container within certain limits is not a factor limiting the
growth of lettuce plants.

Photographic comparisons of lettuce plants grown in
different containers and with different treatments are shown

in Plates I to Z, inclusive.

 

 

Plate 2:1. Figs. 50-54.- A series of lettuce plants
grown in paper bands. Number 50 was treated with
lime before using; number 51 was untreated; number
52 was paraffined before using; the plants in number
53 were given the "Peco" nutrient treatment; the
plants in number 54 were given the "Growell" nutrient
treatment. Note the well preserved condition of
the paraffined pot and also the very much larger
size of the nutrient-treated plants.

270a

~28-
Pot Extract Experiment.

Materials and Methods:

This experiment was conducted to determine, if possible,
the reason why containers seem to have a direct influence on
the growth of the plants they support. Extracts were made of
several types of containers and other materials and applied
on growing plants. The plants used in this experiment, Grand
Rapids forcing lettuce, were started in prOpagating sand.
Seedlings of uniform size were selected and transplanted in
propagating sand in 4" new clay pots.

Two hundred twenty plants were potted and divided into
22 lots of 10 each for subjection to treatments, as shown in
table 9. Each treatment included 10 plants; therefore, 10
containers of each kind were coargly ground, and divided into
10 equal portions by weight, from which fresh extracts were
made to be available for alternate daily treatments over a
period of 20 days. Kichigan peat and German peat were used
in weights equivalent to the weight of 10 "Peco" peat pots.
The media used in making the soil extract and soil plus one-
fifth Michigan peat were used in weights equivalent to the
weight of new clay pots.

The extracts were made by placing a one-tenth portion of
each material into separate porcelain containers and adding to
each a liter of distilled water. The materials were agitated

frequently to bring about the greatest possible extraction;

When needed for treatments the extracts were drained off
through a wire screen (16 to l" mesh) and distilled water
added to bring the volume up to 1000 c.c., or enough to

make one treatment of 100 c.c. on each of the 10 plants.

Plan of Treatments.

Plants were potted March 24, 1929, and nutrient solution
such as used in the experiment with containers was applied,
100 c.c. per plant, on alternate days on all plants until
10 treatments had been given. On April 15, 1929, extract
treatments were started, applying 100 c.c. per plant on
alternate days until 10 treatments had been made. Nutrient
treatments were continued over this period on 3 sets of 10
pots each. Each pot was placed in a separate tray to prevent
loss of nutrients and extracts. From May 5 to may 26 tap
water only was applied to all containers. The pots were
shifted about at intervals to elimdnate or equalize any

possible advantage due to location.

Presentation of Results.
The different extracts, nutrient solution and water only
were compared as to their effects on height and weight of
lettuce plants at the end of a given period. The results are

shown in Table 9.

-30-

Table 9- Growth of Lettuce Plants an Influenced by Various
Pot Extracts.

End of End of Am pH. Rex-caning

extract 5131) water weight value of increase
treatmaits treatments parplant of in heighth
Average Average when extents of plants

 

 

height height harvested during the
per plant per plant and of tap water
in centi- in centi- tap Inter treatment
meters meters treatment
No. Extracts. gms.
1. Natrient Solution 17.93 23.95 127.5 6.6 4»33.51
2. ”Peco" peat pots 13.15 10.94 30.8 4.0 -20.20
3. Michigan peat. 13.63 11.43 30.8 4.8 —-19.23
4. "Growell" peat pots 12.06 9.52 25.4 4.5 -26.68
5. German peat. 11.73 9.52 25.4 3.7 -22.16
6. Tap Water 1 12.06 10.16 25.4 --- -1e.70
7. Soil Solution 11.73 10.78 134.0 7.0 - 8.81
8. Nutrient solution 17.60 23195 124.? 6.6 +36.06
9. "Fertex" fiber pots 11.25 8.30 10.5 8.4 -35.54
10. Clay pots (11811?) 10.46 7.62 3.9.6 7.8 ~37.27
11. Clay POtS (used) 14060 13.15 .202 606 ’11002
12. "Neponset" paper pots 10.91 9.52 32.3 6.8 —14.60
13. Paper pots (new) 10.94 8.07 19.5 5.9 -'34.32
14. Beechwood bands 11.73 8.40 13.8 5.7 (39.64
15. Basswood bands 11.73 7.62 L1§.8 6.6 .—53.93
16. Nutrient solution 17.78 24.58 138.9 6.6 .138.24
17. Distilled water 1 11.88 11.09 25.4 -s- — 7.12
18. Paper pots (used-decayed)]1$ 9.19 2.9.5 7.1 - 29.26
19. "Peco" pots (used) 10.94 9.67 22.7 4.5 -13.13
20. Michigan peat . '
(1Dme treated) 12.52 9.52 25.4 7.1 -'31.51
21. "Peco" peat pots
(lime treated) 11.10 7.62 19.5 6.9 ‘45.66
22. Potting soil and 2
1/5 Mich. peat. 10.95 8.89 21.6 7.5 -—11.92

 

1 pH. determinations were not made on tap water or distilled water.
2 Extract No.22, was taken from pots in which cabbage had been
grown; the soil having been mixed with 1/5 its volume of lime-
treated Michigan peat when prepared for the cabbage.

A11 plants averaged 8.86 centimeters in height when extract
treatments were begun.

309.

 

 

Plate WIT. Figs.55-59.- A series of lettuce plants
grown in Beechwood bands. Number 55 was treated with
lime before using; number 56 was untreated; number
57 was paraffined before using; the plants in number
58 were given the "Growell" nutrient treatment; the
plants in number 59 were given the "Peco" nutrient
treatment.

-31-

Discussion.

Growth of plants was uniform during the period nutrient
treatments were made; it slowed up perceptibly during the
period extract treatments were made, and the plants actually
shrunk in size during the following period in which only tap
water applications were made. In several cases shrinkagewas
so great that plants were smaller than at the end of the
period of nutrient treatments, or had shrunk below the average
of 8.86 centimeters.

The decrease in size of plants was due to an actual
shrinkage of the leaves. A yellow cast appeared on the
foliage soon after starting the extract treatments. In
those cases showing plants smaller at the end of the extract
experiment than at the close of the nutrient applications
shrinkage was in evidence before completing the series of

extract treatments.

Effects of Extracts on Plant Growth

As would be expected, the extracts from various
materials showed different results. With pklnts uniform in
size when extract treatments were started, nutrient treatments
Nos. 1, 8 and 16 stimulated the plants that they showed marked
gains during the period tap water was used. Plants treated
with extracts from used ckly pots, No. 11, showed greater
gains in height during the period of extract treatments

than plants treated with other extracts. The plants were also

\Jvn

-32..

heavier when harvested at the end of the tap water treat-

ment. A 11.02 per cent loss in height of plants occurred

with plants treated with extracts from used clay pots during the
period tap water treatments only were made. Clay pots having
been used several times will have absorbed quantities of plant
nutrients. These nutrients presumably were directly
responsible for the small shrinkage of plants treated with

this extract.

Plants treated with an extract of potting soil (No. 7)
show the smallest percentage of loss following the period of
extract treatments and ranked second in average weight per
plant.

Wodfibands and "Fertex" fiber pots, all showing out-
standingly good results in the untreated series of the
pot experiment (Table 4), have shown a remarkably high
percentage of shrinkage during the period of tap water
treatments. The nutrient materials capable of extraction
from the wood bands is so small as to have had no stimulat-
ing effect on plant growth. A deleterious result. occurred
which may have been due to a small amount of toxic material
in the extract. Under conditions of the containers experi-
ment this toxic material was absorbed by the soil, con-
sequently very little checking in plant growth occurred.

Untreated "Fertex" pots (No. 8, table 4) produced
excellent plants. The "Fertex" pots extracts had a decidedly

retarding effect; plants were smaller at the end of the tap

-33-

water treatment than at time of completing the nutrient
treatment. A shrinkage of 35.54% in height occurred during
the tap water treatments. There appeared to be a glue or
sizing filler in these containers which may have acted as

a factor retarding growth of plants treated with this
extract. Extracts No. 12 from."Neponset" paper pots which gave
very unsatisfactory results in the containers experiment
show results in the extract experiment very similar to
those secured with water only (No. 6 and 17). These pots
appear as though treated With a light oil or paraffin.

The material floated freely during the short periods

given to making the extracts; the water was not discolored,
and as a result, any toxic substances present may have not
been made available.

Distilled water treatment (No.17) following the period
of nutrient treatments, show a remarkably small disturbing
effect on the growth of plants. The percentage of decrease'
(7.12%) in height of plants is smaller than for any of the
extracts.

Plants treated with extracts of "Peco" peat pots (No.2)
and extracts of Michigan peat (No.3) made greater gains
during the period of extract treatments and were heavier
when harvested than plants treated with other extracts
(used clay pots extracts being excluded). Extracts from

lime treated "Peco" peat pots (No.21) and extracts from

lime-treated Michigan peat (No.20) have given less satis-
factory results than extracts from the same materials
untreated. Plants treated with extracts of "Growell" peat
pots (No.4) and bulk German peat (No.5) showed a greater
percentage of shrinkage and were lighter in weight when
harvested than plants treated with extracts from."Peco"
peat pots (No.2) and bulk Michigan peat (No.3).

Extract No.22, from used soil (potting soil containing
1/5 lime treated Michigan peat in which cabbage had been
grown) showed a comparatively small percentage of decrease
(11.92%) in height of plants. The only plant lost in the
entire experiment was carried under this treatmento-the
loss was due apparently to a fungus attack on roots at
surface of soil.

Extracts from used "Peco" peat pots (No.19) resulted in
but small shrinkage in height of plants when compared with
plants treated with extracts fromznew "Peco" peat pots (No.2)
indicating perhaps that the readily available nutrients had
been washed out during the period of use.

Plants treated with extracts of used paper pots (No.18)
fiecayed paper pots removed from plants when setting in cold
frames) showed greater gain during the period of extract
treatments and were heavier when harvested than were plants

treated with extracts from new paper pots (No.13).

'-

(No.10) made less growth than plants treated with other
extracts during the period extract applications were made

and a shrinkage of 37.27% in heighth of plants occurred

-35-

Plants treated with extracts from new clay pots

during the tap water treatments.

Effect ofppH. Factor on Plant Growth

To what extent the pH. of the extracts used has in-

fluenced plant growth is doubtful; however, Table 10

presents some interesting data on this question.

Table 10.- Some Effects ofng. on Growth of Lettuce Seedlings.

 

Percentage Average pH.
ofdnnnkage weight value
in height per plant of
of plants when extracts
during the harvested
tap water and of
treatments tap vata'
treatments,
No. Extracts of: 3mm.
1. Basswood bands 53.93 16.8 6.6
2. Lime-treated "Peco" peat pots 45.66 19.5 6.9
3. Beechwood bands 39.64 19.5 5.7
4. New Clay pots 37.27 19.5 7.8
5. Clay pots (used) 11.02 47.2 6.6
6. Tap water 18.70 25.4 ---
7. ”Fertex" fiber pots 35.54 19.5 8.4
8. New paper pots 34.32 19.5 5.9
9. Lime-treated Michigan peat 31.51 25.4 7.1
10. Decayed paper pots used 29.26 19.5 7.1
11. Potting soil 1/5 lime-treated 11.92 21.6 7.5
Michigan peat (used)
12. Distilled water 7.12 88.4 ---

 

A...

 

 

Iflate :2. Figs. 60-64.- Lettuce plants grown in (60)
"Growell" peat pots plunged in sand in large clay pots,
(61) untreated "Growell" peat pots, (62) "Peco" peat
pots plunged in sand in large clay pots, (63) untreated
"Peco" peat pots and (64) ordinary clay pots.

-35-

It was assumed when starting these studies that,
perhaps, the acidity of certain containers may have been
a factor retarding growth of plants. In the above table
high percentage of decrease in height of plants, and
light weight of plants seem to be more or less closely
related to neutral or slightly alkaline pH. values.
Exceptions occur; for instance, extracts from.beechwood
bands (No.3) and from new paper pots (No.8) have a rather
low acid reaction yet plants produced show high percentages
of decrease in height and light weights when harvested.

New and used clay pots present a further exception. .During
their period of use the used clay pots (No.5) have absorbed
quantities of nutrients. These nutrients given up in the ex-
tracts have stimulated plant growth, producing heavy plants
and reducing the percentage of decrease in height of plants
to a remarkable degree. 'The new clay pot material (No.4)
having no nutrients produced plants of light weight with a
high percentage of shrinkage in height.

The results shown in the above table indicate that
neutral or slightly alkaline pH. values, in general,have a
greater retarding effect on growth of lettuce plants than '
lower pH. values, as has been claimed by Crist‘lz).

The results with the new and used clay pots show that
when other conditions were similar, the effects of the pH.
value of a medium.on plant growth may be limited to some

extent by the presence of nutrients. Evidence was presented

-37..

in the containers experiment showing that pots of relatively
low acid reaction and those of neutral pH. value produced
remarkably better plants when nutrient treatments were made
than when untreated. In other words, the pH. factor, within
certain limits, had only an indirect influence on the growth
of lettuce plants. hhen available nutrients were present in
sufficient quantities to promote normal growth, the pH. factor
within these limits was not important.

Following the carry-over stimulating effects of the
nutrient treatments there occurred, shortly after starting the
extract treatments, a decided checking in growth of plants.
This check in plant growth may have been due to toxic.materials
liberated in the extracts, to unbalanced nutrient conditions,
to a complete lack of nutrients, or perhaps to all three con-
ditions. Many of the extracts showed an acid reaction;
lettuce plants grew better when treated with extracts from
peat pots having a comparatively low acid reaction, than when
treated with extracts from.the same containers lime-treated.
Therefore, the checking effects of these extracts on plant
growth cannot be directly attributed to acidity. From the
results with the nutrient solution in this experiment and in
the preceeding experiment with containers, it is safe to con-
clude that a balanced plant nutrient may be depended on to
overcome largely any checking effect he containers may have

on the growth of lettuce plants.

 

 

Plate'X. Figs. 70-72.- Lettuce plants grown in (70)
untreated basswood bands, (71) untreated beechwood
bands and (725 ordinary clay pots. Note the well-
preserved condition of the basswood band, compared
with fungus-infected condition of the beechwood band.

Experiment with Cabbage.

Materials and Methods.

The experiment with cabbage was conducted primarily
to compare peat pots with clay pots and with bulk peat used
as a component of potting soil; and to compare the effects
of different volumes of soil on the growth of the plants
supported.

"Growell" peat pots, "Peco" peat pots and bulk Michigan
peat were used in the experiment. The capacities of the
"Growell" and "Peco" peat pots were used as a measure for the
soil used in the volume experiment. The accompanying diagram
shows method of plunging soil volumes in peat. Golden Acre
cabbage was seeded in flats and seedlings of uniform size were
selected for potting. The same nutrient solution was used,
and treatments were made the same as described for the lettuce
experiment; i.e.. Plants receiving "Peco" nutrient treatments
received nutrients equivalent to the amount absorbed by "Peco"
peat pots, and plants receiving "Growell" nutrient treatments
received nutrients equivalent to the amount absorbed by
"Growell" peat pots.

To determine comparative growth aL1.p1ants were measured
at the time of being placed in the cold frame for hardening.
Ten plants were cut from each series and weighed, as a second
means of determining comparative growth of plants under the
different treatments. Plants were potted February 23, 1929
and placed in the cold frame for hardening March 25, after a
period of 31 days.

SOlJ.'anluECS

508

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~39-

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-41-

Presentation of Results.

Peat planting pots, clay pots, and bulk peat (used
as a component of potting soil) were compared as to their
effects on the growth of potted cabbage phants. Small
and large volumes of soil, under different conditions;
treated with nutrient solution and untreated were also
studied as to their comparative effects on plant growth.

The results are shown in Tables 11 and 12.

"HGL

 

 

Plate‘Zi. Figs. 1-3.- Cabbage plants grown in ordinary
potting soil in (1) untreated "Growell" peat pets, (2)
untreated clay pots and (3) untreated "Peco" peat pots.

-43-

Table ll.-Comparative Results with Cabbage Plants Grown in
Clay Pets, in Peat Pots and in Potting Soil Mixed
with Bulk Peat.

Heighth Average of Percent
per plant 10 plants of gain
when Weight per inweight
placed in plant when compared
cold frame? placed in with the

 

ems. cold frame, clay pots
No. Containers Treatments gms. (checkL:
1. Clay pots--potting soil untreated
(check) 14.27 8.10 0.0
2. Clay pots--"Peco” nutrient treat—
ments on plants 18.68 20.16 '+ 148.88
3. Clay pots—.”Growell" nutrient "..“
treatments on plants 17.60 15.33 -+ 89.25
4. Clay pots--potting soil 1/5 un-
treated Michigan peat 15.96 12.66 4. 56.29
5. Clay pots--potting soil 1/5
treated Michigan eat 11.17 7.70 -' 4.93

6. Clay pots--potting soil 1 5 untreated

Michigan peat with

"Peco" nutrient treat—

ments on plants 19.92 20.90 ‘4 158.02
7. Clay pots-«potting soil 1/5 untreated

"Growell nutrient treat—

ments on plants 18.71 15.90 -— 96.29
8. "Peco" peat pots-- untreated 10.46 5.33 ._ 34.19
9. “Peco” peat pots-m soaked in nutrient
solution before using 15.24 10.21 ‘+ 26.04
10. "P800" peat pots-- soaked in lnme
solution before using 13.97 6.53 --18.14
11. "Growell" peat pots-- untreated 12.70 7.00 '- 13.58

12. "Growell" peat pots-- soaked in
nutrient solution be-

fore using 15.93 9.40 .+ 16.04
13. "Growell" peat pots-- soaked in
lime before using 11.32 5.03 - 37.90

* Average for 20 plants ,+ Averages for 10 plants

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~43-

Discussion:

Clay Pots Vs. Peat Pots

Clay pots with untreated potting soil (Check No. 1)
produced plants 34.19 per cen heavier than untreated
"Peco" peat pots (No. 8) and 13.58 per cent heavier than
untreated "Growell" peat pots (No. 11). When peat pots
were soaked in nutrient solution before using the nutri-
ent treated "Peco" peat pots (No. 9) produced plants
26.04 per cent heaviar than those grown in clay pots
(No. 12) were 16.04 per cent heavier than those grown
in the check container. However, when "Peco" nutrient
treatments were applied on plants grown in clay pots
(No. 2) an increase in weight of plants of 148.88 per cent
occurred when compared with the cheek (No. l) and a gain
of 97.45 per cent occurred over plants grown in nutri-
ent treated "Peco" peat pots (No. 9). "Growell" nutri-
ent treatments on plants grown in clay pots (No. 3)
resulted in a gain of 89.25 per cent in weight of plants
when compared with the check, and plants receiving "Grow-
ell" nutrient treatments in clay pots (No. 3) were 63.08
per cent heavier than those grown in "Growell" peat pots
soaked in nutrient solution before using (No. 12). Plants
grown in nutrient—treated "Peco" peat pots were 41.60
per cent heavier than plants grown in untreated "Peco"
peat pots (No. 8) While nutrient treatments on "Growell"
peat pots produced plants 34.28 per cent heavier than

those grown in untreated "Growell" peat pots (No. 11).

 

 

Plate 311. Figs. 4-6.- Cabbage plants grown in (4)
ordinary EBTl in untreated "Growell" peat pots, (5)
soil to which was added one-fifth part Michigan peat
in clay pots and (6) ordinary soil in untreated "Peco"
peat pots.

-44-

From.these results, it appears that more satis-
factory cabbage plants may be grown in untreated soil
in clay pots than in untreated peat pots under similar
conditions. Eutrients have a marked stimulating ef-
fect on growth of potted plants in both clay and peat
containers. When applied on plants in clay pots nutriv
ents produced outstandingly heavier and thriftier plants
than an eguiva ent amount of nutrients absorbed in peat
pots before using. In this experiment cabbage plants
grown in untreated clay pots were outstandin;ly better
than when grown in peat pots. Nutrients applied on
cabbage plants grown in clay pots showed a remarkably
reater stimulating effect on plant growth than an equiv-
alent anount of the same nutrient absorbed by peat pots
before using. From these results it is evident, under
certain conditions, that clay pots are superior to peat
pots as containers in which to start cabbage plants.

8u1g~Peat as a Component of Potting Soil vs. Potting

Soil in Clay Pots

Bulk dichigan peat was used in this eXperiment and
the results Show that potting soil to which has been added
1/5 untreated Kichigan peat (N . 4), produced plants 56.29
per cent heavier than plants grown in untreated potting
soil alone in clay pots (Check No. 1). When nutrients were
applied on plants grown in potting soil and 1/5 untreated
Hichigan peat, the "Peco" nutrient treatment (No. 6) re-
sulted in gain of 158.02 per cent in weight of plants

over those grown in clay pots (Check), while the "Growell”

-45-

nutrient treatment (No. 7) produced plants 96.29 per
cent heavier than those grown in the check treatment.
Nutrient treatments appliei on potting soil and

.....

1/5 untreated Iichigan peat (no. - and :0. 7) did not
stimulate plant growth to any marked degree over similar
nutrient treatments on plants grown in potting soil alone
(No. 2 and Ho. 3). "Peco" nutrient treatments on pot—
ting soil and 1/5 untreated Kienigan peat increased the
weight of plants 65.08 per cent over plants grown in

the same materials untreated (No. 4) while "Growell"

nutrient treatments (No. 7) produced plants 20.06 per

0)

cent heavier than the 3 grown in potting soil and 1/5
untreated hich'3an peat (No. a).
Bulh Peat asflargomppnent of Potting_Soil vs.

W"

Peat rots.

 

Potting soil to which was added 1/5 untreated nich-
igan peat (Not 4) produced plants 132.52 per cent heavier
than those grown in untreated "Peco" peat pots (No. 8)
and 80.08 per cent heavier than plants gr wn in untreat-
ed "Growell" peat pots (No. ll). "Peco" nutrient treat—
ments on plants grown in potting soil and l/5 untreated
hichigan peat (Ho. 6), increased the weight of plants
104.70 per cent over plants grown in "Peco" peat pots
(No. 9) which had absorbed an equivalent amount of nutri—
ent t eatment (No. 7) resulted in a gain of 122.34 per
cent in weight of plants over those grown in "Growell"
peat pots which had absorbed an equivalent amount of

nutrients.

 

 

 

P"

 

Plate XIII. Figs. 7-10.- Cabbage plants grown in (7)
untreated wGrowell" peat pots, (8) "Growell" peat pda
soaked in a nutrient solution before using, (9) untreated
"Peco" peat pots and (10) "Peco" peat pots soaked in a
nutrient solution before using.

Lime treatments on peat pots and on Micligan peat
(Nos. 5, 10 and 3) resulted in a marked reduction in
weight of plants, when compared with plants grown in
the same materials untreated (No. 4, 8 and ll).

Under the conditions of this erperiment bulk peat
as a component of the potting soil produced markedly
heavier plants than potting soil alone. When nutrients
were used the gain in weight of plants resulting from
including 1/5 nichigan peat in the potting soil was not
great enough to be significant when compared with plants
grown in nutrient-treated potting soil. Potting soil
and 1/5 Michigan peat with nutrient treatments produced
materially heavier plants than the same material un-
treated. Untreated bulk peat as a component of potting
soil produced outstandingly better plants than those
grown in untreated peat pots. When nutrients were used
on potting soil and 1/5 Michigan peat there occurred a
marked gain in weignt of plants, when compared with those
grown in peat pots which had absorbed equivalent amounts
of nutrients.

These results indicate that a given amount of bulk
peat mixed with the potting soil may be expected to pro-
duce better cabbage plants than potting soil alone or peat
pots under similar conditions. A given amount of nutrients
applied on plants grown in potting soil containing a given

amount of bulk peat resulted in marked gains in weight over

4t“

 

 

 

Plate 3T7. Figs. 11-14.- Cabbage plants grown in (11)
"Peco" peat—plots treated with lime water before using,
(12) untreated "Peco" peat pots, (13) untreated "Growell"
peat pots and (14) "Growell" peat pots treated with lime
water before using.

 

-49-

plants grown in peat pots which had absorbed an equivalent

amount of nutrients.

Effects of Soil Volume on Growth of Potted Plants

:1,

series of erperiments was conducted to determine
the effects of the soil capacity of a container on the
growth of the plant supported and likewise the comparative
effects of nutrient treatments under different conditions.
The measurements and weights shown in Table 12, were tdien
at the time the lants were placed in the cold frame for

V

hardeninv.

 

L446»

 

Plate'XY. Figs. 15-18.- Cabbage plants grown in (15)
a volume 3? potting soil equivalent to that of a "Peco"
pot and plunged in sand in a clay pot, (16) untreated "Peco"
peat pots, (17) untreated "Growell" peat pots and (18)
a volume of potting soil equivalent to that of a "Growell"
pot and plunged in sand in a clay pot.

 

Table 12.- Effects of Soil Volume and Nutrient Treatments
on the Growth of Potted Cabbage Plants.

centimeters Weight Percent of
Heighth per per plant gain or
plant when when lose

placed in placed in compared
cold frame"I cold framef'with the

 

ems. gme. clay pots

No. Containers Treatments. (check)
1. Clay pots-opotting soil untreated

(check) 14.27 8.10 0.0
2. Clay pote--"Peco" nutrient ‘

treatments on plants 18.08 20.16 +148.88
3. Clay pots-~"Growe11" nutrient

treatments on plants 17.60 15.33 1~89.25
4. "Peco" peat pote--untreeted 10.46 5.33 —-34.19

5. "Peco" peat pots-~soil volume

plunged in untreated

Michigan peat 18.08 19.12 ‘r136.04
6. "Peco" peat pots-~soil volume

plunged in treated

Michigan peat. 18.71 16.05 +-98.14
7. "Peco" peat pots--soil volume

plunged in untreated

Michigan peat with

”Peco" nutrient

treatments on plants 20.77 27.55 +—240.12
8. "Peco" peat pots--p1unged in
propagating sand. 11.73 7.21 _ 10.98

9. "Peco" peat pots--soil volume
plunged in propa-
gating sand with
"Peco" nutrient
treatment on plants 12.39 7.63 - 6.16
10. ”Peco" peat pots-~soil volume
plunged in propagat-
ing sand 11.97 7.03 1.13.22
11. ”Else-611" peat pots-msoil volume
plunged in untreated
Michigan peat. 19.68 25.68 +—220.49
12.”Growe11" peat potso-eoil volume
plunged in lime treated
Michigan peat. 17.78 18.22 +-124.93
l3. ”Growell” peat pote-soil volume
plunged in untreated
Michigan peat with
"Growell" nutrient

treatments on plants 26.49 34.93 +~331.23
14. 'Grovell' peat pote-p1unged
in propagating sand 10.95 5.93 —.26.91

15. "Growell” peat pots-soil volume
plunged in prepagating
sand with "Growell"
nutrient treatments on

Plants 14.69 9.75 +.20.37

,..

-49-

_$ab1e 12- continued.

16. "Growell" peat pots--soil volume
plunged in propagating
Band.

17. "Growell" peat pots--untreated

18. "Growell" peat pots-soaked in
nutrient solution
before using.

19. "Peco" peat pots--soaked in
nutrient solution
before using

10.27

12.70

15.93

15.24

7.68

7.00

9.40

10.21

__5.46

—13.58

1'16004

 

‘ Average of 20 plants

'0' Average of 10

plants

 

 

 

Plate 271. Figs. 19-21.- Cabbage plants grown in
ordinary tray pots filled with (19) one-half ordinary
potting soil and one-half Michigan peat that had been
treated with lime, (20) four-fifths ordinary potting
soil and one-fifth Michigan peat that had been treated
with lime and (21) ordinary potting soil.

490.

-50-

Discussion:

When the volume of soil contained in a peat pot
is removed from the effects of the pots and plunged in
untreated hichigan peat the greater volume of soil
from the "Growell" peat pots (No. 11) produced plants
220.49 per cent heavier than plants grown in clay pots
(check, No. 1). Plants grown in "Peco" peat pots soil
volume (No. 3) plunged in untreated Michigan peat were
only 136.04 per cent heavier than plants grown in the
check container. then "Growell" nutrient treatments

t ots

CS

£0

e

'd

were applied on plants grown in "Growell"

.3

soil volume plunged in untreated Michigan peat (To. 13)
a gain of 331.23 per cent in weight of plants oceixred,
when compared with plants grown in the potting soil
(check, No. 1). his treatment also showed an increase
of 271.59 per cent in weight of plants over plants grown
in "Growell" peat pots (No. 18) which had absorbed an
equivalent amount of nutrients before using. The "Peco"
peat pots soil volume plunged in untreated Michigan peat
with "Peco" nutrient treatments on plants (No. 7) pro—
duced plants 240.12 per cent heavier than plants gr wn
in the check treatment and 169.83 per cent heavier than
plants grown in nutrient treated "Peco" peat pots (No. 19).
"Growell" peat pots soil volume plunged in untreated
flichigan peat with "Growell" nutrient treatments on plants
resulted in an increase in weight of plants of 127.85

per cent, when compared with plants grown in clay pots

 

 

Plate EVTI. Figs. 22-25.- Cabbage plants grown in
clay pots IIned with sand and containing (22) un-
treated potting soil equivalent in volume to that of
a "Peco” peat pct, (23) potting soil of the same
volume but treated with "Peco" nutrient solution,

(24) potting soil equivalent in volume to that of a
"Growell" peat pot but treated with "Growell" nutrient
solution and (25) untreated potting soil of the same
volume.

-51-

"Growell" nutrient treatments on plants (No. 3) while
the "Peco" peat pots soil volume plunged in untreated
Michigan peat with "Peco" nutrient treatments on plants
produced plants only 36.63 per cent heavier than those
grown in clay pots with "Peco" nutrient treatments on
plants (No. 2).

Peat pot soil volumes plunged in sand have given
very poor issults in contrast with the outstanding
results secured by plunging peat pot soil volumes in
Michigan peat. These contrasting results are, no doubt,
due to the fact that the nutrients readily washed out
of the sand and hence, did not stimulate plant growth
to any great er ent over the sand treatments receiving

no nutrients. 0n the other hand, the Michigan peat

readily absorbed the nutrients and they were availahle. ,Mui-pv

to promote rapid growth of plants grown in the soil
volumes plunged in the peat.

Soil volumes in sand and nutrient treatments on
soil volumes in sand have given negative results in
weights of plants when compared with the check treat-
ment (No. 1), excepting "Growell" peat pots soil
volume plunged in propagating sand with "Growell" nu-
trient treatments on plants (No. 13), which shows an
increase of 20.37 per cent in weight of plants over
those grown in the check treatment. The "Growell"

soil volume in this treatm nt was great enough to

retain nutrients in sufficient quantities to stimulate

 

  

fiff?‘

. g _“ {ff 7 " A . _
‘ \ ' .-"‘ 1‘ " ‘ ,.'. ,1} . .
. u a :1 .

Plate XVIII. Figs. 26-27.- Cabbage plants grown in a
volume of ordinary potting soil equivalent to that of a
"Growell" peat pot and plunged in Michigan peat in clay
pots. Number 26 was untreated soil and number 27 was
treated with "growell" nutrient solution.

  

Figs. 28-29.- Cabbage plants grown in a volume of
ordinary potting soil equivalent to that of a "Peco"
peat pot and plunged in Michigan peat in day pots.
Number 28 was untreated soil and number 29 was treated
with "Peco" nutrient solution.

-52-

greater plant growth than occurred in the untreated
potting soil in the check container (No. 1).

These results indicate that in every instance
the greater volume of soil has produced heavier plants
than the smaller volume of soil, similar treatments
considered. Greater soil volume with smaller nutrient
treatments gave better results than greater nutrient

eatments on smaller volumes of soil. Nutrient treat—

tr
ments on peat pot soil volumes gave better results than
equivalent amounts of nutrients applied on plants grown
in potting soil only, in clay pots, or an equivalent
amount of nutrients absorbed by peat pots. In general
the soil volume seems to have greater influence on the
growth of cabbage plants under conditions of this eXperi-

ment than other factors.

Effects of PlunginghPeat Pots in Sand

The peat pots in this experiment were plunged in
7 inch pots, as described in the lettuce eXperiment, to
compare the growth of plants in plunged peat pots, un-
plunged peat pots, and peat pot soil volumes plunged
in sand.

Plunging "Peco" peat pots in sand (No. 8) had but
little beneficial results over untreated "Peco" peat
pots (No. 4) while a detrimental result occurred from
plungiig "Growell" peat pots in sand (No. 14) when
conpared with untreated "Growell" peat pots (No. l7).
"Peco" peat pots soil volumes plunged in sand (No. 10)

produced better plants than untreated "Peco" peat pots

52a

 

 

 

.Plate.XIX. Figs. 30-32.- Cabbage plants grown in (30)
eat pots plunged in sand, (31) ordinary

untreated "Peco"
clay pots and (32 untreated "Growell" peat pots plunged
in sand. All contained ordinary potting soil.

-53-

(No. 4), but "Peco" peat pots plunged in sand (No. 8)
yielded heavier plants than the "Peco" peat pots soil
volume plunged in sand. On the other hand, "Growell"

pots soil volume plunged in sand (No. 16) pro-

peat ,

duced heavier plants than were grown in "Growell" peat
pots plunged in sand (No. 14) or in untreated "Growell"
peat rots (No. 17). In all instances these treatments

.42“

have resulted in poorer :;row th than was obtained with

Effect of Containers and Treatments on Tees and Boots
Leaves and s~ems of plants receiving nutri ient
treatments, and plants grown in soil containing bulk
peat, were normal in color, exec pting: nutrient treat-
ments on sand (Nos. 9 and 15, table 12). Plants in un-
treated peat pots and in untreated potting soil in clay
pots had a light purple cast on stems characteristic of
51 ght y lard ned cabbage plants. Plants in other con-
tainers and with other treatments showed decide edly
purple stems and leaves as though extremely hardened,
while the lower leaves on the sand treatments became
yellow before the plants were moved to the cold frame.
Plunged peat containers produced Very unsatisfactory
plant 3rov.'th, though an ex remely vigorous root devel—
opment occurred outside the pe at containers (Plate XXll)

Comparative heig 3ht of plants is she: .'n in Tables

11 and 12, and Plates Kl - inl.

 

 

Plate IX. Figs. 33-34.- Cabbage plants grown in untreated
"Peco" peat pots, number 33 being plunged in sand.

-54..

General Discussion

 

It is evident from the results of these eXperi—
ments that a liberal nutrient supply is essentia in
growing satisfactory lettuce and cabbage plants re-
gardless of the type of containers used. Had the
nutrient treatments been extended over a longer period
no doubt even greater variation would have occurred
betwee plants started in untreated containers and
nutrient-treated containers. Possibly still greater
gains would have been in evidence in the final yields
had the nutrient treatments been continued after
transplanting the lettuce into the cold frame.

Certain containers had a marked retarding effect
on 3rowth of lettuce plants. When the plants wer
removed from the immediate influence of the containers
extremely rapid.growth occurred. These results seem
to indicate that if given sufficient time the retarded
plants would produce a normal crop. Earliness, however,
is an important factor in securing a profitable crop.

It is, therefore, essential that the grower avoid those
containers having a tendency to retard plant growth.

The soil volume experiment diets that larger vol—
umes of soil are more productive than smaller volumes
under similar conditions. When bench space is not a
factor a grower may profit by starting cabbage plants
in 3 inch or even 4 inch containers ra her than in smaller
sizes. Plants started in large containers would elimin—

ate the labor of shifting plants once or twice from small

 

54 a

 

 

Plate EXT. Figs. 35-36.- Cabbage plants grown in
untreated “Growell" peat pots, number 35 being plunged
in sand.

-55..

CD

to large“ containers, thus reducin; the cost of growin
the plants.

Lime treating of acid containers had no favorable
influence on the growth of lettuce plants. Lettuce
plants grew satisfactorily under certain conditions in
rather low acid media which is evidence that caution
should be used in applying lime to soil in which lettuce
plants are to be started or on which a crop of lettuce
is to be grown.

The use of peat as'a component of potting soil gave

remarkably good results with cabbage plants.

 

Plate Tiff. Figs. 9-lO.- Cabbage plants grown in (9)
"Peco" peat pots and (10) "Growell" peat pots, plunged
in sand. Note the vigorous growth of roots as compared
with that obtained in the lettuce experiment. (“See
Figs. 20 and 21).

-56- ?

Acknowledgements.

The writer Wishes to thank Professors V. R.
Gardner and J. B. Edmond for assistance in planning
the work; Dr. J. W. Crist for directions in maring
the pH. determinations, and Professor W. 0. Button
for the photographic work. The criticisms of Messrs.
V. R. Gardner, J. W. Crist and E. F. Babb regarding
the preparation of the manuscript are especially ap-

preciated.

-57-

Conclusions aid Summary

Lettuce plants were grown in several types of
containers, and in sand cultures treated with extracts
of containers, and of other materials. Cabbage plants
were grown in clay and peat pots with a variation in
soil, soil volume and methods of treatments.

1. The experiments with lettuce indicate that
certain containers have a deleterious influence on the
growth of lettuce plants.

2. The deleterious effect on growth of lettuce
plants during the potting stage varied with the differ-
ent types of containers used.

5. Nutrient treatments largely overcame the re-
tarding effect of containers on growth of lettuce plants.

4. Treating the containers with lime or paraffining
them did not reduce the retarding effects of the contain-
ers.

5. Band types of containers vere more suitable in
which to start lettuce plants than pot types of contain—
ers.

6. Bulk peat used as a component of the potting soil
gave better results with cabbage than potting soil alone,
or peat pots.

7. Cabbage plants made more satisfactory growth in
large volumes of soil than in smaller volumes, when other
conditions were similar.

8. Plunging peat pots in sand did not give satisfac-

tory results.

‘I‘ 1:50 .W'. ""

I1)

I? -

 

-58-

Literature Cited.

 

l. Knott, J. E. Growell Pots, Further Results with.
Market Grower's Journal, p. 527, Apr. 16, 1928.

2. hompson, R. H., Peat Pots. Market Grower's Journal
p. 767. Dec. 1, 1928.

5. Koyler, Richard, New Plant and Flower Pots Amer-
ican Produce Grower, p. 13, Sept. 1928.

4. Edmond, J. B. Unpublished work done at the Kichigan
agricultural Emperiment Station

5. Laurie, A. Mich. Agr. EXp. Sta. Sp. Bul. 194. 1929.

6. Anonymous Pot Emperiment. Market Grower's Journal
Nov. 15, 1928.

7. Krebs, Carl W., Peat Pots Failed Him Soaked in Nitrate.
Market Grower's Journal, p. 228, march 15, 1929.

8. Growell Pot Co., Inc., Planting Pots--one Kanufactur-

er's Policy. Marks Grower's Journal p. 2a9, Mar. 15, 1929

9. J. F. M. How to Use Peat Pots. Market Grower's
Journal p. 221, march 16, 1929.

10. Knott, J. E. _Individual Care of Early Plants. American
Produce Grower, p. 3, harch 1928.

11. Anonymous Work not published.

12. Edmond, J. B. and Lewis, B. P. Influence of Nutrient
Supply on Earliness of Maturity in Cabbage. Mich. Agr.
Exp. Sta. Tech. Bul. 75. 1926

15. Grist, J. W. Growth of Lettuce as Influenced by Reac-
tion of Culture Medium. Mich. Agr. EXp. Sta. Tech. Bul.
71. 1926.

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