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 Front Cover
 Methodology
 Results
 Summary and conclusions
 Practical methods of storing tobacco...














Group Title: Bulletin - Florida Agricultural Experiment Station ; 593
Title: Tobacco seed storage for 25 years
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Permanent Link: http://ufdc.ufl.edu/UF00027585/00001
 Material Information
Title: Tobacco seed storage for 25 years
Series Title: Bulletin - Florida Agricultural Experiment Station ; 593
Physical Description: Book
Language: English
Creator: Kincaid, Randall R.
Publisher: University of Florida Agricultural Experiment Station
Publication Date: 1958
 Record Information
Bibliographic ID: UF00027585
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.

Table of Contents
    Front Cover
        Page 1
        Page 2
    Methodology
        Page 3
    Results
        Page 4
        Page 5
        Page 6
        Page 7
        Page 8
    Summary and conclusions
        Page 9
    Practical methods of storing tobacco seed
        Page 10
Full Text



Bulletin 593


UNIVERSITY OF FLORIDA
AGRICULTURAL EXPERIMENT STATIONS
J. R. BECKENBACH, Director
GAINESVILLE, FLORIDA

(A contribution from the North Florida Experiment Station)
















Tobacco Seed Storage for 25 Years

By RANDALL R. KINCAID
Plant Pathologist, North Florida Experiment Station








TECHNICAL BULLETIN








Single Copies free to Florida residents on request to
AGRICULTURAL EXPERIMENT STATION
GAINESVILLE, FLORIDA


March 1958












Tobacco Seed Storage for 25 Years

RANDALL R. KINCAID

Tobacco seed produced in 1931 and stored under refrigeration
or desiccation retained their viability for 11 years, as reported
in a previous paper.1 This series of tests has been continued
through 25 years. A supplementary series conducted with 1942
seed has been in progress for 13 years. It was undertaken in an
attempt to explain certain anomalous variations in results of
germination tests, and to determine the moisture content of the
seed during the course of the experiment. Results of both series
of tests are reported in this paper.

METHODS
Methods used in the 1931 series of tests, conducted with seed
of the cigar-wrapper variety 301, have been described in detail.1
Seed which remained viable for 11 years had been stored in small
vials enclosed in screw-cap glass jars over various chemicals, and
in various other containers without a desiccant. Locations in-
cluded a refrigerator fairly constant at 50 C.; a basement room
unheated; a laboratory intermittently heated in winter; and an
attic, cold in winter and extremely hot in summer. Germination
tests were made annually at fairly constant room temperature
for the first 11 years as previously reported.
Methods used in the 1942 series, conducted with seed of the
cigar-wrapper variety Rg, were different in certain details. The
original moisture content of the air-dry seed, 7.6 percent of the
oven-dry weight, was determined by drying triplicate samples to
constant weight at 1020 C. Samples of 25.00 grams air-dry
weight were placed in tared 2-ounce glass bottles or in cloth bags.
Sulfuric acid of technical grade was heated to 980 C. and
aerated to remove volatile acids. Dilutions to certain weight-
percentages were made with distilled water to give suitable in-
crements of relative humidity at 25 C. The respective relative
humidity values at refrigerator temperature (approximately 5
C.) were lower by 2 percent or less.2 After 14 years the sulfuric
acid solutions, which had obviously increased in volume, were

1Kincaid, R. R. Effect of storage conditions on the viability of tobacco
seed. Jour. Agr. Res. 67 : 407-410. 1943.
Wilson, R. E. Humidity control by means of sulfuric acid solutions.
Jour. Ind. and Eng. Chem. 13 :323-350. 1921.






Florida Agricultural Experiment Stations


measured and weighed, and the relative humidity values were
again determined.
Mason jars of one-quart size, fitted with screw caps and rub-
ber gaskets, were used as desiccators. Sulfuric acid or calcium
chloride of desiccator grade was placed in the jars to the depth
of one inch, and the bottles containing seed were stored standing
in the acid or on the salt. A strip of filter paper impregnated
with cobaltous chloride (CoCl2.7H20) was placed in each bottle
to give an indication of the relative humidity-blue at low values,
and changing with increasing values through lavender to pink.
At the time of germination tests, bottles which had been
standing in sulfuric acid were washed in dilute ammonium hy-
droxide and dried with a cloth. Each bottle was rapidly weighed
to the nearest 0.01 gram, the seed were mixed, and a weighed
sample was removed for germination tests. The apparent moist-
ure content of the seed at each sampling was calculated from
the moist weight of the seed, and the dry weight was corrected
by subtracting the dry weight of the sample removed.
Germination tests of 100 seeds each in triplicate were incu-
bated at 240 C. constant temperature, and also at 240 C. alternat-
ing with 50 C. for four to five hours per day. Seedlings were
counted at suitable intervals.

RESULTS
Results of the 1931 series are given in Table 1. Germination
data after three, six, and nine years are repeated from the pre-
vious paper, along with those after 12 to 25 years.
Results of the 1942 series are given in Table 2.
Longevity of Seed Stored Under Various Conditions.-To-
bacco seed of the 1931 crop maintained high viability for 25
years when stored in the refrigerator over calcium chloride,
Rochelle salt or ferrous sulfate, or in various other locations
over calcium chloride. The attic, with its extreme variation in
temperature, was a less desirable location than the laboratory or
the basement. Seed stored in the refrigerator in a relatively
air-tight rubber-stoppered vial maintained high viability for 25
years. In contrast, those in a paper envelope or cloth bag main-
tained high viability for 15 years but not for 20 years. There
appeared to be no consistent change during the period from 12
to 25 years in the time required for germination.
Tobacco seed of the 1942 crop maintained high viability for
13 years when stored in the refrigerator over sulfuric acid 48










TABLE 1.-GERMINATION OF 1931 TOBACCO SEED AFTER STORAGE UNDER VARIOUS CONDITIONS FOR 3 TO 25 YEARS.


How Stored Where
S Stored


Over Chemicals
CaC12 ................................... Refrigerator
KNa (C4H40,).4HO ..........
FeSO,.7H20 ..................
NH4NO3 (satd. soln.) ......

CaC2 .......................... Basement

CaC12 -----------------........... Laboratory

CaCl2 ................................ A ttic

In Various Containers
Stoppered Vial ............. Refrigerator
Paper Envelope .................
Cloth Bag .........................


Approximate
Relative
Humidity
Inside
Container
%

1
30
50t
70

1

1


Germination Test after Number of Years Indicated


3
R*


23
19
23
63

53

46

60

24
14
20


12
C* .
%
47
81
83
44

90

79


81
81
79
73


20
C
%
77
87
85
7

85

77

69


124**
IA
%
68
44
60


56

12

25


240-50 C. alternating temperatures (A).


*Germination tests made at room temperature fairly constant (R), 240 C. constant temperature (C). and
** After 24 years in storage as indicated and 1 year in paper envelopes in laboratory.
t Estimated from values found for CoSO4.7H2O.
T Misplaced.










TABLE 2.-GERMINATION OF 1942 TOBACCO SEED AFTER STORAGE UNDER VARIOUS CONDITIONS FOR 1 TO 13 YEARS.


How and Where
Stored


In Refrigerator
Over 79% HS04
Over 65% H.SO ..
Over 58% HSO4 ..
Over 48% H2SO0 .
Over 33% H2SO ..

In Cloth Bag ........

In Laboratory
Over 79% H SO, ..
Over 70% H2SO4..
Over 65% H2SO ..
Over 58% H2SO ..
Over 48% H2SO ..

Over CaC1 .........

Air-Dried ................
Dried over CaC2 ..

In Cloth Bag .........


Approximate
Relative Humidity
Inside Container
0 Yrs. |14 Yrs. I


Germination Test after Number of Years Indicated


53 73
61 73
58 75
76 78
42 61

55 77

24 21
86 85


A C
% %


74 68
54 27

84 71
0 -
73 63


10
I A
I%


18 U

77 79

75 42
- I-


113**
A
%

49
58
58
62
13

52

29
41
58
17

51

6


Apparent Moisture Content of Seed
and Color of Cobalt Chloride Papert
after Number of Years Indicated


1b


1 3.2 B
14.9 B
6.1 B
7.4 L
9.7 P

8.3-

2.1 B
S3.3 B
|3.9 B
5.1 B
6.7 L

3.5 B

7.5 P
S3.1 B

S5.5-
I


3 I 6 8 I 10
% % % %

2.3 B 2.2 B 2.4 B 2.3 B
4.7B 4.9B 4.9B 4.9 B
5.9B 5.9B 6.0B 6.1 B
7.4 P 7.4 P 7.5 P 7.4 P
9.8 P 9.8 P 9.8P | 9.7 P

8.0- 8.6 -[ 8.7- 8.8-

2.0 B 2.2B 3.4B 4.1 B
3.1B 3.5 B 4.3B 4.4 B
3.8 B 4.2 B 4.2 B 4.3 B
4.8 B 4.8 B 5.1 B 6.0 L
6.6L 6.6L 6.5L 6.5 L

3.3 B 3.3B 3.3 B 3.2B

7.5 P 7.6 P 7.7 P I--
4.1 B 5.3 B 5.6 L 5.9 L

4.4 .. ----


S13
%

2.4 B
4.9 B
6.1 B
7.6 P
9.8 P

9.2 -

4.3 B
4.6 B
4.4 B
5.9 L
6.5 L

3.2 B

16.2 L


*Tests made at 240 C. constant (C) and 240-50 C. alternating (A) temperatures.
** After 13 years in storage as indicated and 1 year in paper envelopes in laboratory.
t Colors of cobalt chloride paper: B, blue; L, lavender; and P, pink.
t Original concentration of acid by weight.






Tobacco Seed Storage for 25 Years


percent or more concentrated, and when stored in the laboratory
over sulfuric acid 65 percent or more concentrated. Those stored
in cloth bags kept well in the refrigerator but deteriorated rap-
idly in the laboratory.
Seed which maintained high viability for 13 years in the re-
frigerator had an apparent moisture content of less than 9 per-
cent, and in the laboratory an apparent moisture content of less
than 5 percent. Satisfactory conditions for storage for 13 years
were associated with blue color of cobalt chloride paper, except
for one test in the refrigerator in which the indicator was pink.
Seed dried over calcium chloride for one year to 3.1 percent
apparent moisture content and then stored in a cork-stoppered
bottle gradually increased in moisture content, but deteriorated
less rapidly than those stored air-dry.
Constant and Alternating Temperatures.-Results of germ-
ination tests made at alternating temperatures of 240 C. and 5
C. averaged higher than those at a constant temperature of
240 C. Differences were widest in tests made after four years
in storage (not reported in Table 2).
Although some of the differences between years were prob-
ably due to sampling error, evidently neither constant nor alter-
nating temperatures were completely effective in inducing germ-
ination of all viable seeds in laboratory tests. Seed stored for
14 years in the laboratory over calcium chloride and then sowed
in an ordinary outdoor plant bed gave normal stand and growth.
Decline in Germination Tests During First Three Years.-In
the previous paper on the 1931 series, it was reported, "Several
samples, especially those stored in the refrigerator, showed a
decline in germination test during the first three years in stor-
age, and afterward returned to a high test." In the 1942 series,
germination steadily declined to minimum levels after three
years, especially for tests made at constant temperature. The
decline in germination was generally most pronounced for seeds
stored extremely dry, and was much less for germination tests
made at alternating temperatures than at constant temperature.
Deterioration after Removal from Storage.-Seed which were
removed from storage after 24 years (1931 series) or 13 years
(1942 series), held in paper envelopes in the laboratory, and
tested one year later, germinated in some instances as well as
seed after the first year in storage in paper envelope or cloth bag
in the laboratory. Seed which had been stored moderately dry
generally germinated best. Those stored under more moist con-






Florida Agricultural Experiment Stations


editions appeared to deteriorate rapidly. Those stored extremely
dry apparently failed in some measure to respond to the germina-
tion procedure used.


0 1 YEAR IN REFRIGERATOR: Y=.55X'6+ 2.68
0 13 YEARS IN REFRIGERATOR: Y= .72X6 + 0.28 /
A I YEAR IN LABORATORY: Y .54X6 + 1.73 /
g A 13 YEARS IN LABORATORY: Y=.80X- 2.13




EL /
1 -
Q7
8 / /

I It
C,,,

2/





< A/ / /





0 2 4 6 8 10 12 14
RELATIVE HUMIDITY.6 (%)
Fig. 1.-Apparent moisture content of tobacco seed as a function of the
relative humidity inside the container.

Apparent Moisture Content as a Function of Relative Humidi-
ty.-Highly significant linear correlations were found between
the apparent moisture content of seed after one year in storage,
in either the refrigerator or the laboratory, and the .6 power of
the relative humidity at the beginning of the experiment. The
same relationship was found between the apparent moisture






Tobacco Seed Storage for 25 Years


content of seed after 13 years and the relative humidity after
14 years (Fig. 1).
The apparent moisture content of seed after one year in stor-
age in the refrigerator was approximately 1 percent higher, and
after 13 years approximately 2 percent higher, than in the lab-
oratory at the same relative humidity.
The apparent moisture content of seed after one year in stor-
age in the refrigerator was higher than after 13 years at the
same relative humidity. The same was true of seed stored in
the laboratory.
Temperature as well as relative humidity affected the appar-
ent moisture content of the seed. Losses in dry matter no doubt
occurred, but no attempt has been made to evaluate such losses.

SUMMARY AND CONCLUSIONS
Tobacco seed of the 1931 crop maintained high viability when
stored at Quincy, Florida, for 25 years in tight containers, either
refrigerated or desiccated or both. Seed stored in a paper en-
velope or a cloth bag in the laboratory deteriorated rapidly, while
those in the refrigerator maintained high viability for 15 years
but not for 20 years. Free access of air appeared unfavorable
to maintenance of viability for more than 15 years.
Seed of the 1942 crop maintained high viability for 13 years
when stored over sulfuric acid solutions or calcium chloride,
which kept the apparent moisture content of the seed less than
9 percent in the refrigerator and less than 5 percent in the lab-
oratory. The lowest of the sulfuric acid concentrations found
to maintain high viability for 13 years was 48 percent by weight
for storage in the refrigerator and 65 percent for storage in the
laboratory. Satisfactory conditions for storage were indicated
by a blue color of filter paper impregnated with cobaltous chlo-
ride.
Germination tests made at alternating temperatures of 24
C. and 5 C. gave higher average results than those made at a
constant temperature of 240 C. Differences were widest after
four years of storage under driest conditions. A temporary de-
cline in germination during the first three years' storage was
partly offset by incubating the seed at alternating rather than
constant temperatures.
Seed which maintained high viability in storage for 13 or 24
years under various conditions, followed by one year in paper
envelopes in the laboratory, gave about the same germination






10 Florida Agricultural Experiment Stations

tests as seed after the first year in storage in paper envelope or
cloth bag in the laboratory.
The apparent moisture content (Y) of the seed varied closely
with a power of the relative humidity (X) inside the container:
Y = nX.6 + c.

PRACTICAL METHODS OF STORING TOBACCO SEED
Tobacco seed may be conveniently stored in good condition for
many years in either of two ways.
They may be stored air-dry in an ordinary refrigerator for
as long as 25 years in any convenient air-tight container, such as
a fruit jar with a tight lid, or for 15 years in a paper or cloth bag.
They may be stored at room temperature for as long as 25
years in any air-tight container, such as a glass jar or a metal
can, including in the container with the seed a separate glass or
china-ware vessel of anhydrous calcium chloride. This material,
which readily absorbs moisture from the air, may be obtained
through drugstores. Whenever the calcium chloride becomes
wet, it must be replaced with fresh material. For best results,
a location should be chosen where the temperature remains
fairly constant.




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