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00221589.1965.11514145

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Journal of Horticultural Science
ISSN: 0022-1589 (Print) (Online) Journal homepage: http://www.tandfonline.com/loi/thsb19
Methods of Raising Cocoa Seedlings in the Nursery
and their Effect on Subsequent Growth in the Field
G. H. Freeman
To cite this article: G. H. Freeman (1965) Methods of Raising Cocoa Seedlings in the Nursery
and their Effect on Subsequent Growth in the Field, Journal of Horticultural Science, 40:4, 341-349,
DOI: 10.1080/00221589.1965.11514145
To link to this article: http://dx.doi.org/10.1080/00221589.1965.11514145
Published online: 27 Nov 2015.
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Date: 27 October 2017, At: 03:58
]. hort. Sci. (r965) 40, 341-9
METHODS OF RAISING COCOA SEEDLINGS IN
THE NURSERY AND THEIR EFFECT ON
SUBSEQUENT GROWTH IN THE FIELD
By G. H. FREEMAN*
Cocoa Research Institute of Nigeria, lbadan, Nigeria
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SUMMARY
Trials were conducted near Ibadan, Western Nigeria, to find the best method
of raising cocoa seedlings in the nursery, and the plants were subsequently
transplanted to the field and observed for two further years. In one trial
the experimental treatments were amount of shade, time of sowing, amount
of watering and type of pot ; in a second trial times of sowing and transplanting were varied and seed was also sown at its permanent site.
Seedlings grew well in the nursery in polythene pots under a shade of
from eight to ten palm fronds per ro ft. length and with light watering.
Late sowing and early transplanting were satisfactory, so seedlings need
only remain in the nursery for five or six months ; in the Ibadan area this
was achieved by sowing in December and transplanting in late May or early
June. Younger plants also grow well in the field, but there are risks in
sowing seed in January, when cold, dry harmattan winds may be expected.
Provided a plant is big enough to transplant, its original size has no bearing
on its subsequent growth in the field, as measured by trunk girth at threemonthly intervals. Sowing seed at permanent sites is risky, as beans may
be eaten by rodents.
THE long-established practice of cocoa farmers in West Africa was to sow seed at
its permanent site at the beginning of the rainy season, but Benstead (1950) showed
that in Ghana the raising of seedlings in baskets gave better establishment of plants
and superior growth in the field. This led to the Departments of Agriculture starting
in 1952 to produce seedlings extensively for distribution to farmers. It was later
shown (Benstead and Wickens, 1955) that basket seedlings had a higher yield. The
procedure for raising basket seedlings was to take beans at any time from October
onwards and sow them in topsoil in baskets placed under heavy shade. The seedlings
were watered during the subsequent dry season as required and planted out in the
field from April to June, at the beginning of the next rainy season. The baskets,
6 in. in diameter and 8 in. tall, were woven from palm fronds and were very bulky,
so that farmers were reluctant to use them. Bare-root seedlings were not satisfactory
* Present address: East African Agriculture and Forestry Research Organization, Kikuyu,
Kenya.
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342
Methods of raising Cocoa Seedlings in the Nursery
(Benstead, r9so), so whalehide pots made of bitumenized paper pulp were finally
used (Longworth, r96o).
The early growth of cocoa seedlings was studied by Goodall (r949, r95o) who
used plants grown in baskets under heavy shade. However, Cunningham and
Burridge (r96o) found that growth was better under light shade, and best if the shade
was initially heavy and then gradually reduced; they grew plants in concrete pots
standing in water in concrete tanks so that there was a continuous water supply.
Growth in these trials was studied in the nursery stage only.
Longworth (r96o, r96r) conducted two nursery trials to cop1pare no shade with
heavy and light palm-frond shade. Other treatments included close and wide spacing
of the pots and different watering regimes. Rather different results were obtained
from the two trials, one of which was started in December and the other in October.
The seedlings were transplanted to the field, but subsequent establishment was not
good. Improved establishment methods are now available (Longworth, r963), and
the nursery trials to be described here were conducted with the emphasis on growth
in the field after transplanting.
The trials were conducted at the Gambari Experimental Station near Ibadan,
Western Nigeria, where the average annual rainfall is just over so inches with a
marked dry season from about mid-November to mid-March. The mean rainfall in
inches for the months of November, December, January, February and March is
2·28, o· 52, o·26, o·94 and 3·78 respectively, giving a total for the five months of
7 · 78 inches. In most dry seasons there are some periods when the harmattan, a cold
dry wind from the Sahara desert, reaches as far south as Ibadan. The harmattan
does not usually last for more than a few days at a time, but has a very drying effect
while it does blow; as an example, in February r962, during the present series of
trials, the minimum temperature was 53° F. and the minimum relative humidity
r8%. Gambari has a climate typical of much of the area near Ibadan, this being
slightly drier than some other cocoa-growing areas in Western Nigeria.
rg6o-6r TRIAL
Experimental treatments
A trial was conducted in the nursery during the r96o-6r season with all combinations of three shade treatments, four times of sowing, two frequencies of watering
and two types of pot. The shade treatments were heavy shade, light shade and no
shade, the heavy and light shades consisting of I4 and 8 palm fronds per ro ft. length
respectively. The times of sowing were at four-weekly intervals, from mid-November
rg6o to early February rg6r. The watering was done either every second day or
twice a week, and the pots were whalehide or polythene.
As the cut palm fronds dry out, the shade becomes progressively lighter, and
storms accompanying the early rains in March and early April damage the palm
fronds further. In the trial the light shade was entirely removed in mid-April and the
heavy shade four weeks later; by the time of complete removal the palm fronds
had become very battered. F3 Amazon seed (Toxopeus, rg65) was used throughout
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G. H.
FREEMAN
343
the trial. The pots were watered thoroughly at the time of sowing, and the amount
of water given at each subsequent watering to each pot was 350 c. c. Both the whalehide and polythene pots were ro in. tall and were 4 in. in diameter when filled, sieved
forest top-soil being used.
The layout in the nursery consisted of two replicates of the shade treatments,
each replicate having r6 plots to accommodate all combinations of the other treatmenj:s. Each plot contained 24 experimental plants in 4 rows of 6 with a guard plant
at each end of the row; the rows were in two pairs close together, with a gap of one
foot between the pairs of rows. The rows ran North-South and there was one whole
guard row at the East and the West side of each replicate of the shade treatments.
In June rg6r four plants from each plot, chosen at random, were sampled and the
remaining 20 plants transplanted to the field. In the field the plants were spaced at
5 ft. X 5 ft. on clear-felled land, the plots being completely randomized and the
arrangement of plants within a plot different from that in the nursery. The land was
kept free from weeds and an overhead shade of palm fronds on bamboo maintained
from November rg6r to April rg6z, after which the plants were unshaded.
Results
Germination and subsequent growth were recorded and finally an assessment
was made of the extent of the canopy after two years in the field. The plants sampled
at transplanting time were weighed. The best general picture is derived from records
of the girth of the trunk at transplanting time, the percentages of plants surviving
after the first and second dry seasons in the field and the trunk girths of the surviving
plants at these times. These records are shown in Tables I and II, Table I giving
percentages of survivors and Table II girths of surviving plants.
TABLE
I
Percentage of trees from the rg6o-6r nursery trial surviving after one or two dry seasons
in the field
Time of sowing
Shade
November I960
I*
None
L1ght
Heavy
I
2
I
January I96I
I
2
92·1
90•9
89·2
87·2
36·4
72·4
70·8
69·I
39•7
73·7t
39•I
J7·I
February 196I
I
69·0
56·r
2
67•7
55•3
92•7
95•9
92•7
92•9
92•I
86·2
80·7
74·3
78·3
74•3
74·6
73•7
68·2
66·5
97•3
93•4
96·6
94•7
75·7
79•4
76·7
97•4
8o·5
t
2
December 1960
84·0
9I. 5
84·9
96•7
96·7
7J·I
67·2
79·5
79•5
* Times of recording : 1, March I962 ; 2, March I963.
Data in 1talics are percentages transformed to angles of equal information, and the 5% significant
differences for comparing the angles shown above are: I, 7·6r; 2, 8·42.
344
Methods of raising Cocoa Seedlings in the Nursery
II
TABLE
Mean girth in em. per surviving tree for the I96o-6I nursery trial at transplanting time
and in the two succeeding years
Time of sowing
Shade
Watering
November I96o
December I960
January I96I
February I96I
- - - - - -- - - - - -- - - - - - - - r - - I*
2
3
I
2
3
I
2
3
I
2
3
- - - - - - - - - - - - - - - - - -1 - - -
None
Infrequent 0•50 I•49 4•70 0·46 I•22 3•84 0·27 0•91 3. I3 0·23 I•I2 4•03
Frequent 0 "74 I·85 4•57 0·59 I·36 3·72 0·28 0·69 2 •53 0·26 0·95 3•24
Light
Infrequent 0·88 I•75 3•93 0•59 I•34 3·84 0•53 I•32 4·08 0•4I 0•94 2·76
Frequent 0·8I I·68 3·86 0•7I I•49 3•78 0·5I I· II 3•48 0·32 I· II 3•37
Heavy
Infrequent 0·69 I·85 4•65 0•49 I•29 3·63 0•40 I·I8 3•07 0•33 I•47 4•70
Frequent 0•7I I ·67 3•87 0 •43 I •44 4•34 0· 37 I ·09 3• I4 0 •33 I ·Q9 3•30
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- - - - - - - - - - - - - - - - - -1 - - -
- - - - - - - - - - - - - - - - - - - -- -
*Times of recording : I, June I96I ; 2, March I962; 3, March I963.
5% significant differences : I, o · I 26 ; 2, o · 360 ; 3. I · 024.
The only treatment not shown in Table I or Table II is type of pot, which had
no consistent effect on growth, so that in practice the cheaper and lighter polythene
pot could replace the whalehide pot.
The frequency of watering in the nursery did not have any effect on survival in
the field, so the figures in Table I are the means for frequent and infrequent watering.
The plants derived from beans sown without shade in January, when there was
severe harmattan, had a much lower survival rate than the rest, and those without
shade in February were also poor. Most deaths, for all treatments, occurred during
the first rather than the second dry season, but this is, at least partly, a measure of
the relative severity of the 1961-62 and 1962-63 dry seasons.
In Table II the results are shown separately for frequent and infrequent watering.
The largest plants at transplanting time were not necessarily the largest two years
later, by far the fastest growth being from the plants raised under heavy shade with
infrequent watering in February. The plants from beans planted without shade in
January were poor, both in growth per surviving plant and in survival rate.
rg6r-6z TRIAL
Experimental treatments
The early results of the rg6o-6I trial suggested that seedlings could be raised
successfully in the nursery, but that more information was needed about the length
of time they should remain there. Thus, another trial was conducted in the nursery
during the rg6r-6z season, and the seedlings were planted out in the field in 1962.
The plants were watered twice a week, and the shade of palm fronds on bamboo was
slightly heavier than the light shade of the previous trial, viz. Io palm fronds per
Io ft. length. Polythene pots of the same size were used throughout and the arrangement of plants within a plot was the same as before.
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G. H.
FREEMAN
345
The beans were sown at four-weekly intervals in sieved forest top-soil in October,
November or December 1961, and the seedlings transplanted to the field in May,
June or July 1962, also at four-weekly intervals. At each time of transplanting some
seedlings of each age were transplanted, and so plants were 5, 6, 7, 8 or 9 months old
when put into the field. At the same times as the seedlings were transplanted, seed
was sown in permanent sites with two seeds at each position.
The material was F3 Amazon, half from F2 trees with seed parent T 6o and half
from F2 trees with seed parent T 79· Since T 6o and T 79 are progeny of reciprocal
crosses, and the pollen parents of the two subsequent generations are unknown, no
differences due to this treatment were expected and none of importance was found.
Four replicates of 20 plants were planted in the field at a 5 ft. x 5 ft. spacing
on clear-felled land, this time a randomized block layout being used. Again, four
plants from each plot were sampled and measured at the times of transplanting. An
overhead shade of palm fronds on bamboo was erected over the plants in the field
during the 1962-63 dry season, after which the plants were left unshaded.
Results
Table III shows the percentages of plants surviving the first and second dry
seasons in the field, for all treatments. Table IV shows the girth per surviving plant,
soon after transplanting, for trees that had been raised in the nursery, and the girths
of the surviving plants after the dry seasons, for all treatments.
The survival of the trees from the earliest sowing and either of the two later
transplanting times was noticeably poorer after one dry season, but effects on growth
of the survivors were less marked. Growth differences were proportionately much
TABLE
III
Percentage of trees from the I96I-62 nursery trial surviving after one or two dry seasons
in the field
Time of sowing
Time of
transplanting
October I96I
I*
May I962
June 1962
July 1962
2
November I96I
I
2
December I96I
I
2
Seed sown at
permanent site
I
2
95•7
9I ·6
95•9
9I ·9
95·2
90•I
66·9
6o·8
78-ot
73·2
78·3
73·5
77•4
7I•7
54•9
5I·2
84·I
8I·6
94·2
91 ·8
64·6
94·5
84·6
66·5
57•3
54•7
73•4
49•2
47•7
76·4
66·9
76•I
87·6
83·8
96·9
91.8
93•0
82·1
75·8
66·3
95•5
69·4
79·9
73·4
77•7
74·6
65-o
6o-5
*Times of recording : I, March I963; 2, February I964.
+Data in italics are percentages transformed to angles of equal information, and the 5%
significant differences for comparing the angles shown above are : I, 8 · 40 ; 2, 8 · 66.
Methods of raising Cocoa Seedlings in the Nursery
~
TABLE
IV
Mean girth in em. per surviving tree for the I96I-62 nursery trial soon after transplanting
and in the two succeeding years
Time of sowing
Time of
transplanting
November I96I
October I96I
- - , - - -- - - - r - - -
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I
2
,I
2
2
3
3
- - - -- - - -r - - - - - -r------ - -r-----I·28
0
2·66
I
•09
3·06
I•I4
3.
I9
0•93
0•79
3•37 0•79
"74
0·90 I •19 3•22 0•77 I •07 2•97 0·74 1•07 2·89 0·67 2·64
o-88
1·22
1·20
2·98
2·85 0•79 I· I6 3•46 0·65 2·25
0·97
I*
May I962
June 1962
July 1962
2
December I96I
Seed sown at
permanent
site
3
3
* Times of recording : I, August 1962 ; 2, February I963; 3. February 1964.
5% significant differences: I, O· 108; 2, o-132; 3. 0·430.
less after the second dry season, though the oldest plants were considerably larger
.when transplanted.
Survival of the plants from seed sown at the permanent sites was poor, especially
when sown in May or June. The figures in Table III closely reflect emergence as
determined in September 1962 ; at this time the percentages of plants that had
em~rged from the ground were 78·6 from May sowings, 68·3 from June and 90·5
from July. The growth of the survivors was good, the girth after the second dry
season approaching that of the older plants, as shown in Table IV. By this time,
however, less than 2o% had jorquetted, compared with almost so% of the surviving
nursery plants.
The death rate during the second dry season shown in Table III was high for all
treatments. Further, the dry season of 1963-64 was fairly severe, and many more
plants died after February. These deaths were not related to the nursery treatments,
so the figures are omitted:
FURTHER TRIALS
Two points not so far considered are the size of pot, as opposed to the material
of which it is made, and the full influence of seasonal conditions on germination.
Trials have been conducted on these topics, and the early results were described by
Swarbrick (1964). The following further results are now available.
Size of pot
The pots used for the 196o:..t>1 and 1961-62 trials were 10 in. tall and had a
diameter of 4 in. ; pots 12 in. tall are also used, as they allow more room for tap-root
development. A trial was conducted in the 1962-63 nursery season to compare
polythene pots 10 in. X 4 in., 12 in. X 4 in., 12 in. X 6 in., 10 in. X 3 in. and 15 in.
x 3 in. F3 Amazon seed was sown in the five sizes of pot at three six-weekly intervals,
early November 1962, mid-December 1962 and late January 1963. Seedlings were
transplanted to the field in early June 1963 and spaced at 4ft. x 4ft. An overhead
G. H.
FREEMAN
347
shade of palm fronds on bamboo was maintained throughout the 1963-64 dry season,
in the early part of which the area was watered. In consequence, over go% of the
plants survived.
The girths of the surviving plants at transplanting time and after the dry season
are shown in Table V. The plants from the 3 in. diameter pots were the smallest
and those from the 6 in. diameter pots the biggest. However, the increment in growth
in the field for the 6 in. diameter pots was not much larger than that from the normal
4 in. diameter pots. There was little effect of time of sowing on growth in the field.
TABLE
V
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Mean girth in em. per surviving tree for the I962-63 nursery trial at transplanting time
and after one dry season in the field
Time of sowing
Size of pot in inches
(height X diameter)
IOX4
12 X 4
lOX 3
15 X 3
12 X 6
November 1962
••
0•94
0•93
0·64
0·83
I •03
December I 962
January 1963
2
I
2
I
2
1·83
1·81
I·28
I '45
2•05
0·82
0·8I
0·60
0•75
0•9I
1•55
I ·60
I·I8
1•37
I •77
0·68
0·68
0•52
0•57
0•73
1·38
I •41
1•13
1•17
I ·6I
• Times of recording: I, June I963; 2, March 1964.
5% significant differences :
2
I
0·136
0•059
Comparing means with the same sowing time
O•I70
Comparing means with dzfferent sowing times
0•059
Seasonal effects on germination
Swarbrick (1964) sowed seed at various times throughout the year to determine
seasonal effects on germination and growth. He found that seeds sown early in 1963
just before spells of harmattan germinated more slowly but subsequently seemed to
recover. However, this recovery was not maintained, for after 24 weeks in the nursery
only 67% of F3 Amazon seedlings sown on 18th February and 8o% of F3 Amazon
sown on 25th February were fit to transplant. For Amelonado seedlings sown at the
same time the corresponding figures were 32% and 17% respectively. Seedlings
sown on 2nd March 1964 were worse, and only 37% of F3 Amazon and 39% of
Amelonado were even alive after five months. The harmattan conditions in 1963
and 1964 were dissimilar and so were probably not the only explanation of these
failures. At all other times of the year germination was satisfactory.
DISCUSSION
More records were taken on these trials than have been discussed here in detail.
Thus, it was found that, provided germination is satisfactory, the length of time taken
does not matter. Leaf number and height were recorded every four weeks for the
first 18 months from sowing, and these confirmed the other growth records shown in
6
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Methods of raising Cocoa Seedlings in the Nursery
the Tables. They also showed that growth was proceeding steadily; in addition,
the leaf number records showed that many treatments resulted in a leaf drop immediately after transplanting, and that only the best plants did not show this effect.
-Girth was measured every three months from transplanting, and these records
showed the rate at which the superiority of the better treatments became apparent.
Records of jorquetting and canopy closure were also taken, these showing the progress
from a set of seedlings towards a mature plantation. They are of most value in trials
-comparing establishment methods; here, they tended to confirm the results shown
by girth records.
When plants were sampled at the time of transplanting, the wet and dry weights
of the various parts were determined. These weights, however, showed no correlation
with the final size of those plants allowed to grow on. Indeed the main results of the
trials emphasize how little future growth can be fudged from size at transplanting,
unless the nursery conditions are known.
The standard nursery practice of using forest top-soil, sieved to remove all
·extraneous matter, was followed in these trials. F3 Amazon cocoa was used and
similar results should be obtained with any cocoa of this widely used type, but they
may be different for slower-growing cocoa types such as Amelonado. The method of
establishment used was chosen because it gives a high survival rate (Longworth, rg63)
and can easily be used uniformly over the whole experimental area. However,
_overhead inert shade is much too costly and laborious to use extensively. Further,
it gives shade for only one dry season, and it was clear from the trials that some plants
will die in the second dry season, particularly if this is severe. Provided that the
method of establishment gives high survival rates the size of the plants at transplanting will have little effect on subsequent rate of growth.
The growth of seedlings in the nursery, and subsequently in the field, is more
influenced by amount of shade and time spent in the nursery than by any other
factors. From eight to ten palm fronds per ro ft. length gives a satisfactory shade. The
natural drying out of palm fronds results in the thinning of the shade during the dry
season and the whole fronds can be removed at the beginning of the rains. No advantage is gained by keeping the plants in the nursery more than five or six months ;
where seedlings are transplanted in late May or early June, as in the Ibadan area,
sowing should take place in December. It is sometimes possible to defer sowing till
January, but, owing to the risk of harmattan, January sowings should be limited to
the replacement of poor seed only.
Polythene pots ro or rz inches high and 4 inches in diameter are now commonly
used and seem perfectly satisfactory. Light watering only is needed, there being no
benefit from heavier or more frequent watering.
Germination of seed in the nursery at the time of year necessary for sowing at
permanent sites is satisfactory, but emergence of seed from the ground was poor in
the present trial. Rodents have been observed to dig up and eat germinating cocoa
beans at Gambari (Everard, 1964), and this may explain the failures. Thus, a nursery
will be necessary for extensive plantings, but gaps in an existing plantation may be
filled up by sowing several seeds at the permanent site and keeping the best seedling.
G. H.
FREEMAN
349
Thanks are due to Mr. E. A. Bamidele for his help in the nursery, to Mr. S. 0.
Osokpor and his team of recorders for help both in the nursery and in the field, to
Mr. J. F. Longworth for discussions during the progress of the trials and to Mr. H.
Toxopeus for his comments on a draft of this paper. Thanks are also due to the
Chairman of the Governing Council, Cocoa Research Institute of Nigeria, for permission to publish this paper.
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REFERENCES
BENSTEAD, R. J. (1950). Rep. W. Afr. Cocoa Res. Inst., I948-49, 57-9·
BENSTEAD, R. J., and WICKENS, R. (1955). Rep. W. Afr. Cocoa Res. lnst., I953-54,
36-7.
CuNNINGHAM, R. K., and BuRRIDGE, J. C. (1960). The growth of cocoa (Theobroma
cacao) with and without shade. Ann. Bot., N.S., 24, 458-62.
EvERARD, C. 0. R. (1964). Some aspects of vertebrate damage to cocoa in West
Africa. Proc. Conference on mirids and other pests of cocoa, II4-19.
GooDALL, D. W. (1949). A quantitative study of the early development of the seedling
of cacao (Theobroma cacao). Ann. Bot., N.S., 13, 1-2r.
GooDALL, D. W. (1950). Growth analysis of cacao seedlings. Ann. Bot., N.S., 14,
291-306.
LONGWORTH, J. F. (1960). Rep. W. Ajr. Cocoa Res. lnst., I958-59, 78-9.
LONGWORTH, J. F. (1961). Rep. W. Afr. Cocoa Res. Inst., I959-60, 76-7.
LONGWORTH, J. F. (1963). Improved methods of establishing cocoa on clear-felled
land in Nigeria. ]. hort. Sci., 38, 222-31.
SwARBRICK, J. T. (1964). Rep. W. Afr. Cocoa Res. Inst. (Nigeria), I962-63, 75-6.
ToxoPEus, H. (1965). F3 Amazon cocoa in Nigeria. Rep. W. Afr. Cocoa Res. Inst.
(Nigeria), I963-64, 13-23.
(Received ZJ/ro/64.)
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