Nigerian Journal of Horticultural Science © Horticultural Society of Nigeria, 2012

lSSN 1118-2733 VoL 17 (2013) pp./26-134

Effects of some bean characters on germination and seedling growth of cocoa (Theobroma cacao, L.)

'L.A. Hammed, 'A. 0. Olalya, 'I. 0. Lawai, 'o. T. H. Idowu and 'I. 0. 0. Aiyelaagbe 'Department of Horticulture,

'Department of Plant Physiology and Crop Production 'Institute of Food Security, Environmental Resources and Agricultural Research (IFSERAR)

Federal University of Agriculture Abeokuta (FUNAAB), P.M.B. 2240, Abeokuta, Ogun State, Nigeria

Abstract

Raising of cocoa (fheobroma cacao, L.) seedlings is hampered by same often neglected traits. Three experiments were set up to test the effects ofbean size (by weight): plumpy beans (mean weight (MW) 3.2g; n~20), medium-sized (MW~2.Ig; n~20) and slaty (MW~J.3g; n~20), location of beans within pods: (beans extracted from stalk-end, middle and pointed­end of pods) as well as beans extracted from pods harvested from different locations on the tree: trunk, lower canopy and upper canopy on germination and seedlings growth. The experiments were laid out in completely randomised design with 4 replications. Data collected on % germination of the beans and growth of the seedlings were analysed using ANOVA atP<0.05. At 4 WAS, %germination was between 82.5%for plumpy beans and 75% for each of medium and slaty beams. At 14WAS, seedlings raised from plumpy beans had significantly higher plant height (23.02cm) compared to those from slaty beans (20.53cm). Beans at the pointed-end of a pod had highest% germination of88.3% while the beans atthe middle and the petiole-end of the pod had 81. 7%. At 14 WAS, the seedlings raised from beans located at the pointed-end of the pod were significantly taller (25.2cm) than those of the beans located at the middle (23.85cm) a:nd petiole-end (23.26cm) of the pod. Beans extracted from pods harvested from the lower canopy had highest %germination (92.5%), followed by beans of pods harvested from the trunk (85. 0%) while beans of pods harvested from the upper canopy had the least germination percentage of 5% at 4WAS. Seedlings from beans extracted from pods on the trunk and lower canopy of a cacao were significantly taller (25. 6cm) than those from upper canopy (1 0. 68cm) at 16WAS. Seedlings from p/umpy beans had highest DMY of2.89g compared to l.92gand l.22gproduced by seedlings raised from medium-sized and slaty beans respectively, while the best DMY were obtained from trunk­bean-seedlings (2.58g/plant) and lawer canopy-bean-seedlings (2.3g/plant). The upper canopy-bean-seedlings had significantly lower DMY (1 Ag/plant). Germination and growth of cocoa seedlings were found not to be affected by weight classes of beans tried in this study and longitudinal positioning of cocoa beans in a pod, but, affected by position/location of cocoa pods on the tree.

Keywords: Cocoa, Bean~ weight, Beans position in pod, Pod's position on tree, Germination, Seedlings 'growth.

Introduction Cocoa (Theobroma cacao) is a commodity tree crop with export value (FMA&RD, 2011 ). The cocoa beans are highly rich in nutrient contents, and therefore provide energy-rich and delicious foodstuffs which are manufactured into the cocoa powder and chocolate (Minife, 1989). The bulk of the

world trade in cocoa is produced in the tropical areas of the African continent especially from Cote D'voire, Ghana, Nigeria and Cameroon (FAOSTAT, 2010). In 2010 alone, total production from these four largest producing countries in Africa, accounted for 65% of the global output (ICCO, 2011 ).

Author for correspondence: L. A. Hammed (!gm/ecashew@vahoo.com)

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According to Copeland (1976) and Bewley ( 1997), the process of seed germination involves among others, emergence and establishment of the seedlings (otherwise described as seedling's vigour) prior to transplanting into the field. In cocoa, the seedling's vigour in the nursery had been reportedly influenced by varieties as well as maturity of the beans within and between cocoa pods, (Adenikinju, 1969, 1974). Maturity of cocoa seeds within a pod is normally expressed as the plumpness or slatiness of the seeds (which is metrically expressed as weight), while size of cocoa pods is determined by the relative positioning of such pods along the height of cacao. Bigger pods are normally located I positioned at the trunk and lower branches of the cocoa plant (described as lower canopy) while smaller pods are normally found at the upper canopy (upper branches of the cocoa plant). This might explain why cocoa farmers, in Nigeria, always demand for bigger cocoa pods for the purpose of seedlings production.

In addition, differential maturity of cocoa beans within a pod had enabled plumpness or slatiness of the beans. This observation enables delineation into stalk-end, pointed­end and middle positions, a character that may contribute to seedlings vigour in the nursery. This is because unpublished data at the Cocoa Research Institute of Nigeria (CRIN) has indicated that cocoa beans positioned at the middle (expanded portion) of a pod are normally heavier than those from the two extremes ends (i.e. stalk- and pointed-ends). The studies therefore, aimed at evaluating the contributions of plumpness I slatiness (expressed as weight) of cocoa beans, position of the beans within a pod and cocoa beans extracted from pods harvested from three physiographic positions of a cocoa tree on emergence and establishment of cocoa seedlings in the nursery.

Materials and Methods Three experiments were carried out at the Federal University of Agriculture Abeokuta,

(FUNAAB)Nigeria(7p 10'N,3p 2'E)Ogun State Nigeria using F,Amazon cocoa variety.

The first experiment involved cocoa bean weight made up ofplumpy cocoa beans (mean weight= 3.2 g; n = 20), medium-sized cocoa beans (mean weight= 2.1 g; n = 20) and slaty cocoa beans (mean weight = 1.3 g; n = 20). After the extraction of the beans from cocoa pod, they were separated into the three weight classes mentioned above and planted out in polythene bags of dimension 30 em x 19 em filled with forest top soil in a shaded nursery. The experiment was completely randomised design with four replications. The three weight classes constituted the treatments tested in this study. Germination, growth (plant height (em) and number ofleaves) and dry matter yield of the seedlings were quantitatively observed for 16 weeks.

In the second experiment, a matured cocoa tree, of more than twenty years old, was divided into three physiographic positions (using height to choose pods on the basis of the observable variations in sizes of the cocoa pods on the tree): the trunk, the lower canopy and the upper canopy. Pods were harvested from each of these three positions and the beans were extracted therefrom separately. The beans were planted out in polythene bags of dimension 15 em x 24 em filled with forest top soil and arranged under a shaded nursery. The experiment was laid out in a completely randomised design with four replications. Germination, growth (plant height (em) and number ofleaves) and dry matter yield of the seedlings were quantitatively observed for 16 weeks.

The third experiment consisted of delineation of the cocoa beans in a pod into three with respect to the stalk-end of the pod. After careful pod-breaking and removal of pod husk, the beans were separated into beans at the stalk -end, beans at the pointed-end and the beans at the middle position of the pods. The beans were planted out in polythene bags of dimension 30 em x 19 em were filled with forest top soil and arranged in a completely randomised design with four replications.

128 Effects of some bean chlll'llCtei'IJ •• germinfllion ond seetlling growth of cocoo (Thoobromo cocoo, L.)

Germination, growth (plant height and number ofleaves) and dry matter yield of the seedlings were quantitatively observed for 16 weeks.

In all the experiments, the seedlings were observed for the incidence of disease infections. All data generated were analysed using analysis of variance (ANOVA) and means separated using standard error of difference atP:<; 0.05.

Results In the first experiment, cocoa beans that have plumpy size (mean weight = 3.2 g) recorded significantly higher percentage germination of 90.5% compared to mean germination of medium (mean weight= 2.lg) (85.5%) and slaty beans (mean weight= 1.3g) (84.8%), at 4WAS, (Figure 1). Seedlings raised from plumpy beans had significantly higher plant height of 16.5 em (at 4WAS) and 23.02 em (at 16WAS) compared to seedlings raised from slatybeanswhichhad 15.43 cm(at4WAS) and 20.53 em (at 16WAS) (Table 1). At 16WAS, cocoa seedlings raised from plumpy beans produced more mean number ofleaves (12.5 leaves) than seedlings raised from slaty beans (10.88 leaves) (Table 1). Cocoa seedlings raised from slaty beans had significantly lower value of dry matter yield of 1.22 g/plant than that of seedlings raised from plumpy beans (2.89 g!plant)at 16WAS (Figure2).

In the second experiment, cocoa beans extracted from pod on the trunk and lower canopy section of cocoa tree recorded significantly higher germination percentages of 92.5% and 85% respectively at 4WAS compared to that of the beans from pods from the upper canopy of the tree which recorded 5% germination at the same period (Figure 3). There was no marked difference in growth of cocoa seedlings raised from beans from the trunk and lower canopy of the tree (25.65 and 25.60 em, respectively) but there were differences, when compared to seedlings raised from beans from upper canopy (10.68 em) at 16WAS (Table 2). The trunk-bean­seedlings and lower canopy-bean-seedlings

produced higher mean number of leaves (11.31 and 11.25 leaves respectively), than the upper canopy-bean-seedlings with 6.0 leaves (Table 2). The trunk-bean-seedlings produced highest dry matter yield (2.75 g/plant), while the upper canopy-bean-seedlings produced lowest(1.65 g/plant) at 16WAS (Figure4).

In the third experiment, cocoa beans at the petiole-end of the pod had higher germination of 88.30% compared to germination percentage of 81.70% of each of the beans obtained from the middle and pointed-end positions of a pod at 4WAS (Figure 5). The seedlings raised from cocoa beans from the pointed-end of a pod grew taller with plant height of25.87 em although not significantly different from those of seedlings raised from beans at the petiole-end and middle-position of a cocoa pod with 25.05 em and 24.87 em respectively at 16WAS (Table 3). At the same period, the mean number ofleaves of the three types of seedlings was between 22.10 and 22.45 leaves (Table 3). There was no significant difference in the dry matter yield of seedlings raised from beans obtained from all the positions (2.87, 2.80 and 2.33 g/plant) (Figure 6). However, in all the experiments, no incidence of disease infection was observed on the seedlings.

Discussion A cocoa pod contains plumpy and slaty beans with medium-sized beans lying between these two extremes. The improved germination and growth from the plumpy and medium-sized beans were clear indications ofhigher nutrient reserves which depicts them as good generative propagules. Similar reports were made by Adenikinju, (1974, 1977, 1989), Opeke (2007) that bigger cocoa beans result in improved growth and establishment of seedlings in the nursery. The bigger cocoa beans are expected to contain more food reserves than smaller beans.

Cocoa pod of F, Amazon used for the experiment, is longitudinal in shape with a constricted I bottle-neck stalk-end, an

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expanded middle portion and a pointed-end, containing an extension of the fruit stalk on which beans are attached inside the pod. Beans at the middle portion are observably larger than those from the two opposite ends. Both the slightly reduced size of beans from the two opposite ends and the extension of the fruit stalk inside the pods were found out not to negatively influence the growth of the seedlings.

The absorption of mineral nutrients from the soils and their passage through the trunk up to the lower canopy and eventually to upper section of the canopy of a cocoa tree might be the responsible factor for the variations in the size of cocoa pods from the trunk up the canopy of the tree. This gives the bean contents of the trunk and lower canopy pods advantages of improved germination and growth of the seedlings raised from them. This partly explains the reasons why cocoa farmers always request for such pods for the purpose of raising the seedlings (Adenikinju, 1978). More so, it has been found out that these beans serve as reservoirs of nutrients which

serve as sources of nutrients for the germinating seedlings ((Minife, 1989; Hammed and Adeyemi, 2005). Botanically, cocoa trees produce fruits at the stem and branches (Opeke, 2007), this might again be another contributing factor to the bigness of the trunk and lower canopy pods compared to the upper canopy pods. This is because the presence of phloem tissues in the stems and branches of the trees affords the passage of mineral nutrients from the soils up the plants. This process puts the upper canopy pods at some disadvantage and thus becomes smaller. While conducting a similar trial, Adenikinju, ( 1977) reported that cocoa beans with less or equal to 1.00g resulted in reduced growth and dry matter of the seedlings. Therefore, in cocoa, there is the possibility of the presence of more of these extremely small beans (less than or equal to l.OOg) inside pods produced at the upper canopy which might be responsible for the pronounced low germination of the beans and the reduced seedlings growth. The smallness of these pods is a direct reflection of their bean content as shown in this study.

Table 1: Variations in growth of cocoa seedlings raised from beans of different sizes

Growth Bean size Weeks After Sowing parameters

4 6 8 10 12 14 16

Plant height Plumpy beans: 16.50 18.31 18.88 19.59 21.07 21.33 23.02 (em):

Medium beans: 16.22 18.00 18.82 19.19 20.55 20.55 22.31

Slaty beans: 15.43 16.81 17.55 18.03 19.25 19.82 20.53

±se 0.37 0.45 0.43 0.45 0.48 0.44 0.57

Number of Plumpy beans: 4.24 5.56 6.94 8.68 10.08 10.08 12.50 leaves:

Medium beans: 3.56 5.06 6.38 8.56 9.31 9.44 12.25

Slaty beans: 3.44 4.81 6.38 8.19 8.19 9.03 10.88

±se 0.33 0.31 0.28 0.25 0.49 0.36 0.47

Note: se =standard error of difference(~ 0.05)

130 Eff«ts of sonu be111t chiU'tleters on genrdltlllion fllf4 JudlJitg growth of cocoa (TheobrofiUl cactUJ, L.)

Table 2: Growth of cocoa seedlingsas affected by height section oftrees from which pods of

sown beans were harvested.

Growth Height section of Weeks After Sowing (!arameters cocoa tree

4 6 8 10 12 14 16

Plant height Trunk: 17.95 18.38 20.71 20.77 20.77 23.23 25.65 (em):

Lower canopy: 16.61 17.83 19.57 20.59 22.51 23.17 25.60

Upper canopy: 7.13 7.25 8.25 9.38 9.38 9.95 10.68

±Se 1.21 1.25 1.31 1.28 1.38 1.38 1.47

Number of Trunk: 4.13 4.96 6.63 7.75 9.19 9.69 11.31 leaves:

Lower canopy: 3.81 4.38 6.25 7.63 9.38 9.38 11.25

Upper canopy: 1.50 2.00 2.75 4.00 5.50 5.50 6.00

±Se 0.60 0.63 0.73 0.73 0.74 0.76 0.87

Note: se =standard error of difference(~ 0.05)

Table 3: Growttl of cocoa seedlings as influenced by position of sown beans inside pods.

Growttl Position of sown Weeks After Sowing parameters beans in pod

4 6 8 10 12 14 16

Plant tlelgtlt Petiole-end (em): beans: 17.92 19.27 20.36 21.87 22.99 23.26 25.05

Middle beans: 17.98 19.94 20.64 21.67 22.00 23.32 24.99

Pointed-end beans: 15.89 17.97 20.08 21.97 24.03 24.03 25.87

±se 0.55 0.50 0.27 0.39 0.50 0.33 0.35

Number of Petiol!!-i!nd leaves: beans: 3.50 7.40 11.32 13.33 15.50 21.08 22.10

Middle beans: 4.20 8.24 10.42 13.42 16.17 21.00 22.31

Pointed-end beans: 2.00 6.23 10.00 12.64 15.17 20.92 22.45

±se 0.53 0.50 0.41 0.33 0.36 0.14 0.21

Note: se = standard error of difference (~ 0.05)

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133

134 Effects of some beon chlll'llCtei'IJ •• germinfllion ond seetlling growth of cocoo (Thoobromo cacao, L.)

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Adenikinju, S. A. 1977. Observations on growth and dry matter accumulation in cocoa seedlings as influenced by bean size. ActaHorticulturae, pp. 279-285.

Adenikinju, S.A.l978. The selection of cocoa pods for raising seedlings. Cocoa Growers'Bulletin27 June 1978,pp. 27 -33.

Bewley, J.D. 1997. Seed Germination and Dormancy. Plant Cell. Volume 9. Pp. 1055-1086.

Copeland, L. 0. 1976. Principles of Seed Science and Technology. Burgess Publishing Company, Minnesota. Pp.369.

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ICCO, 2010. International Cocoa Conference Organization Quarterly Bulletin of Cocoa Statistics. Volume XXXVIII. No.2. Cocoa year2011/2012.

ICRAF, 1987. International Centre for Research inAgroforestry. Proposal for Agroforestry Research and Development in the humid tropical lowlands of Cameroon.

Minife, B.W. 1989. Chocolate, cocoa and confectionery: Science and Technology, 3• Edition, A VI Books. Published by Van Nostra and Reinhold, New York.

Opeke. L. K. 2007. Tropical Commodity Tree Crops. Spectrum Books Limited, Ibadan, Nigeria, pp. 503.