Open Journal of Forestry
2013. Vol.3, No.4, 152-158
Published Online October 2013 in SciRes (http://www.scirp.org/journal/ojf) http://dx.doi.org/10.4236/ojf.2013.34023
152
Survival, Growth and Orygmophora mediofoveata Shoot Borer
Attack of Nauclea diderrichii Progenies Established in Three
Ecological Zones in Ghana
Paul P. Bosu1*, Stephen Adu-Bredu1, Yaovi Nuto2, Kouami Kokou3
1Forestry Research Institute of Ghana, Council for Scientific and Industrial Research,
Kumasi, Ghana
2Département de Zoologie, Faculté des Sciences, Université de Lomé, Lomé, Togo
3Laboratoire de Botanique et Ecologie Végétale, Faculté des Sciences, Université de Lomé,
Lomé, Togo
Received August 9th, 2013; revised September 11th, 2013; accepted September 23rd, 2013
Copyright © 2013 Paul P. Bosu et al. This is an open access article distributed under the Creative Commons At-
tribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the
original work is properly cited.
Nauclea diderrichii is a tropical African hardwood species and a suitable candidate for plantation devel-
opment. However, attack by the Orygmophora mediofoveata, Hamps shoot borer threatens establishment
of the species in plantations. A genotype * environment assessment of 15 N. diderrichii progenies from
Ghana and Togo was conducted in the Wet Evergreen, Moist Semi-deciduous and Dry Semi-deciduous
forest zones. Progeny performance (Attack intensity, survival and growth) varied significantly between
sites, and marginally within sites after 2.7 years. Overall, incidence of shoot borer attack was lower at the
wet zone than at the moist or dry zones. Percent survival was higher at the wet (79.5%) than at the moist
(50.8%) or dry (55.0%) forest zones. Mean height across the 15 progenies was 5.40 m, 4.30 m, and 2.73
m at the wet, dry and moist forests, respectively. Similarly, mean diameter was 5.31 cm, 4.58 cm, and
2.83 cm at the wet, dry and moist zones, respectively. The relatively low growth rate recorded at the moist
zone was attributed to the paucity of soil conditions at the experimental site. Three wet forest zone proge-
nies (BS9, BS3 and BS2) and two moist forest zone progenies (BE2 and GA1) performed better than av-
erage and have been recommended for planting.
Keywords: Genotype * Environment Assessment; Nauclea diderrichii; Orygmophora mediofoveata;
Growth Rates; Survival Rate; Ghana; Togo
Introduction
Nauclea diderrichii (Sarcocephalus diderrichii De Wild) is a
tropical African hardwood species belonging to the family
Rubiaceae. The species is widely distributed across tropical
Africa, from Liberia eastward through the Congo Basin to
Uganda and Angola. It is a moderately fast-growing species,
with fairly high density timber and durable wood. The tree
grows up to about 60 m in height, with straight, cylindrical bole
clear to 30 - 40 m, and trunk diameter ranging from 1.0 - 2.5 m.
Its natural habitat is subtropical or tropical moist lowland for-
ests. As a sun-loving species, the plant regenerates abundantly
in gaps and openings and is often almost gregarious in the tran-
sition zone between freshwater swamps and lowland forests
(Hawthorne, 1995). Young trees are often found in secondary
bushy growth in humid areas.
The straightmonopodial growth habit of this species has pro-
moted interest in it for the production of transmission poles,
veneers and timber for heavy construction, flooring and furni-
ture. In recent years, N. diderrichii has been planted in high
rainfall areas (2000 - 4500 mm) throughout West Africa, but
especially in south-east Nigeria. The biophysical limits for the
growth of Nauclea diderrichii are; altitude 0 - 500 m; mean
annual rainfall 1600 - 3000 mm; and mean annual temperature
24˚C - 30˚C. It does not grow well on excessively wet soils or
on lateritic ones that dry out completely in the dry season.
In Ghana, the species is found in both the deciduous and ev-
ergreen forest zones. It is found at constant low densities and is
never very abundant (Hawthorne, 1995). Nauclea is considered
vulnerable (1994 IUCN threat category) due to its excessive
exploitation (Hawthorne, 1995). It has been awarded a scarlet
star for Ghana which means that it is common but under pro-
found pressure from heavy exploitation (Hawthorne, 1995). In
year 2000, an opportunity was created to increase the planting
of N. diderrichii in Ghana when the species was selected as one
of the five priority indigenous species for the national forest
plantation development project. Selection of the five priority
species was based on several factors including fast growth rate
and low susceptibility to pest attacks. However, the vulnerabil-
ity of Nauclea to opepe shoot borer Orygmophora mediofove-
ata (Lepidoptera: Noctuidae) was grossly underestimated. Not
long after the project was started, considerable O. mediofoveata
damage was recorded in several nurseries in the Eastern and
*Corresponding author.

P. P. BOSU ET AL.
Ashanti Regions, including two owned by the Forestry Re-
search Institute (FORIG) at Mesewam and Fumesua near Ku-
masi (Bosu, et al., 2004).
Orygmophora mediofoveata attacks in N. diderrichii planta-
tions were observed in Nigeria as far back as the 1930s. How-
ever, the identity of the borer was not discovered until 1962
when Eidt (1965a) reared the moth for the very first time. The
damage caused by the shoot borer is principally through stunt-
ing of the trees in nursery transplant beds, and is rare in seed
beds. Attack results in the rapid formation of a callus tissue
over the injured parts, and may lead to mortality in heavy mul-
tiple attacks. Parry (1956) noted that “attack by Orygmophora
mediofoveata was not severe enough to discourage use of the
tree in pure plantations in Nigeria, but in Ghana, Opepe is so
badly damaged that it is an unreasonable risk as a plantation
crop”.
The life history of Orygmophora mediofoveata is generally
unknown, particularly in the egg stage and the first instar larvae
(Eidt, 1965b). The larvae which attack and damage the plants
are grub-like and morphologically quite unusual. The larva is
short and stout; the head is partly withdrawn into the prothorax
and the legs and prolegs are well developed. Fully grown larvae
of the ultimate instar are about 14mm long, and average head
width is about 1.5 mm. Early instar larvae are translucent and
appear greenish because of the plant tissue in the gut. Ultimate
instar larvae are deep red on the dorsum but remain green on
the venter. They infest the terminal shoots, boring in the last
two or three internodes, and preferring the more apical shoot.
They do not girdle the shoots, but bore in the pith and produce
galleries several inches long. In the cause of tunneling, the lar-
vae eject dark brown frass which accumulates in the leaf axils.
This tunneling can reveal their presence. Pupation occurs
within the galleries although there is no cocoon. The pupal
period lasts about 3 weeks. However, the length of a generation
is unknown and has been estimated to be about three or four
months.
To minimize the impact of the shoot borer in N. diderrichii
plantations, mixed-species planting trials were conducted,
which showed some promise (Addo-Danso, et al., 2012). How-
ever, planting genetic strains inherently resistant to O. medio-
foveata could be a more effective way of minimizing the impact
of this endemic pest on its N. dedirrichii host. In this study, we
examined the susceptibility of fifteen N. diderrichii progenies
from Ghana and Togo to O. mediofoveata shoot borer attack
and its impact on the survival and growth of the plant in three
forest zones.
Materials and Methods
Seed Collection
Seeds were collected from trees in the N. diderrichii dis-
tribution range in Ghana and Togo. In Ghana, the seeds were
obtained from three mother trees in the Wet Evergreen Forest
zone (WEF), eight trees in the Moist Semi-deciduous Forest
zone (MSF) and one tree from the Dry Semi-deciduous Forest
zone (DSF). Seeds from Togo, were collected from threetrees
in the Plain of Litimé (Table 1).
Seeds of all 15 progenies were sent to Mesewamnursery
where they were processed for germination and seedling pro-
duction. As N. diderrichii seeds are very small and photoblastic,
seed germination was done in plastic bowls (45 cm diameter
and 12 cm deep) placed in a shade house of about 50% radia-
tion and watered regularly until germination occurred. Seeds
took an average of 6 - 8 weeks to germinate, and were then
transferred to plastic bags until used.
Establishment of G * E Plots
Standard genotype by environment (G * E) experiments in-
volving 15 Nauclea diderrichii progenies were established in
three ecological zones namely, WEF, MSF and DSF zones. The
WEF plot was established inside the Nueng Forest Reserve near
Benso in the Western Region (5˚16'N, 1˚89'W). The MSF plot
was established at the FORIG nursery area at Mesewam
(6˚44'N, 1˚30'W), near Kumasi in the Ashanti Region. The DSF
plot was established inside the Afram Headwaters Forest
Reserve near Abofour, also in the Ashanti Region (7˚10'N,
1˚40'W). On each site, the plots were established using four
blocks each consisting of 15 progenies, with each progeny
replicated 10 times per block, using a Randomized Complete
Block Design (RCBD). All three trials were established in
April 2008. The plots were maintained by regular weeding, and
monitored for a period of three months during which beating-up
was done with seedlings from the original stock.
Assessment of Plots
Assessments of the plots for incidence of the shoot borer
attack, seedling survival, and growth rates (height and diameter)
were carried out between 4 - 6 months intervals, from August
2008 to December 2010. Except for the December 2010 (age
2.7 years) assessment at which diameter was measured at breast
height (dbh = 1.3 m), all previous measurements were carried
Table 1.
Characteristics of ecological zones and number of accessions collected.
Forest zone Rainfall (mm) Country Population Population code No. of progenies
Moist/Wet evergreen 1750 - 2000 Ghana Benso BS 3
Moist semi-deciduous, southeast 1500 - 1800 Ghana Amantia AM 2
Moist semi-deciduous, southeast 1200 - 1800 Ghana Begoro BE 2
Moist semi-deciduous, northwest 1200 - 1800 Ghana Gambia village GA 4
Moist semi-deciduous, plateau region 1200 - 1800 Togo Badou TG 3
Dry semi deciduous 1250 - 1500 Ghana Berekum BR 1

P. P. BOSU ET AL.
out at 10 cm above the soil level. Shoot borer attack intensity
was ranked on a scale of 1-5; with 1 indicating no visible
damageand 5 indicating severely damaged.
Data Analyses
Two factorial analyses of variance were used to estimate
average differences in the variables (height, diameter and attack)
using progeny and site as the main factors. Percentage data
(survival) were arcsine transformed to conform to normality
prior to analysis of variance.
Family heritability was estimated based on variance compo-
nents obtained from analysis of variance as described by Zobel
and Talbert (1991). The least square mean values were trans-
formed to percentage deviation from the trial mean and were
further multiplied by the heritability to provide the predicted
family value also known as genetic gain (G) as: G = h2S, where
S is selection differential or deviation from trial mean (Ofori et
al., 2007).
Results
Attack
Orygmophora shoot borer attack was recorded at all the three
sites four months after the establishment of the plots. However,
incidence of attacks were generally low and not statistically
significant among progenies or across sites. After 12 months,
attack rates were largely unchanged at the moist and dry forest
sites, whiles only marginal increase in attack was recorded at
the wet site. After 20 months (1.7 years), differences in the
incidence of attack began to show among progenies, sites, and
between the interaction of progeny and site (Table 2). Across
progenies, attack was generally lower at the wet site than at
either the dry or moist sites (Figure 1). Progenies with low in-
Table 2.
Results of two-way analyses of variance of Orygmophora mediofoveata
shoot borer attack, percent survival, height and diameter of 15 Nauclea
diderrichii progenies established in three forest zones in Ghana.
Sources F
P
Attack* Site 102.37 <.0001
Progeny 1.53 0.0945
Site* progeny 1.95 0.0022
%survival Site 12.240 <.0001
Progeny 2.05 0.0183
Site* progeny 1.12 0.3283
Height Site 335.22 <.0001
Progeny 1.87 0.0254
Site* progeny 0.75 0.8217
Diameter Site 153.05 <.0001
Progeny 2.46 0.002
Site* progeny 1.14 0.2835
*Assessment carried out at 1.7 years.
0.0
0.5
1.0
1.5
2.0
2.5
3.0
AM5 AM7
BE2 BE4
BR3
BS2 BS3 BS9
GA1 GA3 GA6 GA9
TG2 TG3 TG5
Attack Intensity (rank)
Dry Semi-deciduous forest
0.0
0.5
1.0
1.5
2.0
2.5
3.0
AM5 AM7
BE2 BE4
BR3
BS2 BS3 BS9
GA1 GA3 GA6 GA9
TG2 TG3 TG5
Attack intensity (rank)
Moist Semi-deciduous forest
0.0
0.5
1.0
1.5
2.0
2.5
3.0
AM5 AM7
BE2 BE4
BR3
BS2 BS3 BS9
GA1 GA3 GA6 GA9
TG2 TG3 TG5
Attack intensity (rank)
Progeny
Wet Evergreen forest
Figure 1.
Orygmophora mediofoveata shoot borer attack of 15 Nauclea di-
derrichii progenies 1.7 years after planting in three forest zones in
Ghana.
cidence of attack at the wet site were BR3, BS3 and BS9,
whiles TG5, AM5, BE2 and BE4 sustained significantly higher
incidence of attack. At the dry forest site, AM5, BS3, GA6 and
TG3 experienced lower incidence of attack whiles TG5, GA3
and BS9 recorded higher rates of attack. However, incidence of
attack did not vary significantly among progenies at the moist
site.
Survival
The survival rates of seedlings were generally high for all 15
154

P. P. BOSU ET AL.
progenies and at all three sites four months after planting (P >
0.05). Overall survival across progenies was 96.3% at the wet-
site, 90.3% at the moist site and 88.8% at the dry site. However,
differences in survival rates were observed among sites and
among progenies at plantation age 2.7 years (Table 2). Mean
percent survival was significantly higher at the wetsite (79.5%)
compared to the moist (50.8%) or dry (55.0%) forest sites. Av-
erage overall survival across all three sites was 61.7%. At the
wet site, all except AM7 recorded higher than average percent
survival. At the dry site, five progenies (BE2, BE4, GA1, GA9
and TG2) were higher than average. However, only two proge-
nies (BE2 and GA3) recorded higher than average percent sur-
vival at the moist site (Figure 2).
0
10
20
30
40
50
60
70
80
90
100
AM 5 AM 7
BE 2 BE 4
BR 3
BS 2 BS 3 BS 9
GA 1 GA 3 GA 6 GA 9
TG 2 TG 3 TG 5
Survival (%)
Dry Semi-deciduous forest
0
10
20
30
40
50
60
70
80
90
100
AM 5 AM 7
BE 2 BE 4
BR 3
BS 2 BS 3 BS 9
GA 1 GA 3 GA 6 GA 9
TG 2 TG 3 TG 5
Survival (%)
Moist Semi-deciduous forest
0
10
20
30
40
50
60
70
80
90
100
AM 5 AM 7
BE 2 BE 4 BR 3
BS 2 BS 3 BS 9
GA 1 GA 3 GA 6 GA 9
TG 2 TG 3 TG 5
Survival (%)
Progeny
Wet Evergreen forest
Figure 2.
Percent survival of 15 Nauclea diderrichii progenies 2.7 years after
planting in three forest zones in Ghana.
Growth
Height: Significant differences in mean height were ob-
served among progenies, sites, and the interaction of progeny
and site in the early stage of the plantation (4 months). Across
progenies, mean height was significantly higher at the wet site
(39.40 ± 1.12 cm) compared to themoist (22.57 ± 0.61 cm) or
dry (24.55 ± 0.23 cm) forest sites. Within sites, however, height
varied only at the moist (F = 6.129, P < 0.0001) and dry (F =
5.413, P < 0.0001) sites.
At one year, differences in height were observed among
progenies, sites, and between the interaction of progeny and site
(Table 2). Mean height across all 15 progenies was highest at
the wet site (74.62 ± 4.11 cm), followed by the dry site (57.40 ±
3.14cm), and the moist site (34.43 ± 2.96 cm). Mean differ-
ences in height of the 15 progenies varied somewhat randomly,
from site to site. The pattern in height growth observed during
the 4th and 12th months remained largely unchanged at the last
assessment (age 2.7 years), although by this time the prog-
eny-progeny differences were not significant at any of the three
sites. Mean height across sites were; wet (540.34 ± 6.20 cm),
dry (430.05 ± 7.83 cm), and moist (273.11 ± 8.17 cm). At age
2.7 years, the following progenies were among the fastest
growing in the plots: wet site (BS2, BS3, BS9 and TG2), dry
site (AM7, BS2, and BS9), and moist site (BS9, BS3, and GA3)
(Figure 3).
Diameter
Diameter of seedlings measured 10 cm from above the soil
level after one year varied significantly among sites. Mean
diameter was 1.43 ± 0.02 cm at the wet site, which was signifi-
cantly higher than that at the moist (1.16 ± 0.28 cm) or dry
(0.92 ± 0.27 cm) forest sites. A similar trend was observed
when diameter was measured at breast height (dbh = 1.3 m) at
age 2.7 years (Figure 4). Mean diameter was highest at the wet
site (5.31 ± 0.21 cm), followed by the dry site (4.58 ± 0.30 cm)
and moist site (2.83 ± 0.32 cm). All progenies except BR3 re-
corded high growth in diameter at the wet site. At the dry site,
AM5, BE2 and BR3 recorded relatively low growth indiameter.
Three progenies BS3, BS9 and GA1 recorded moderately
higher diameter growth than the others at the moist site.
Heritability and Genetic Gain in Height at the Moist
Semi-Deciduous Forest Zone
Heritability for total height at the Moist Semi-deciduous
Forest Zone was 0.438, indicating that approximately 44% of
the variation observed in height growth at the MSF site was
under genetic control. The variation in genetic gain from the
site ranged from 28.36% (BS9) above mean performance to
−20.08% (TG 5) below mean performance (Table 3).
Discussion
Shoot Borer Damage
None of the 15 progenies assessed escaped O. mediofoveata
attack during the period of the study. In other words, none
exhibited complete resistance or immunity to the shoot borer.
However, it was clear from the results that significant variabil-
ity to O. mediof ov ea t a shoot borer attack occurs among the pro-
genies, which were strongly influenced by habitat or site factors.
While infestation was recorded at all the three sites during

P. P. BOSU ET AL.
0
100
200
300
400
500
600
AM 5 AM 7
BE 2 BE 4
BR 3
BS 2 BS 3 BS 9
GA 1 GA 3 GA 6 GA 9
TG 2 TG 3 TG 5
Mean height/ cm
Dry Semi
-
deciduousforest
0
50
100
150
200
250
300
350
400
AM 5 AM 7
BE 2 BE 4 BR 3
BS 2 BS 3 BS 9
GA 1 GA 3 GA 6 GA 9
TG 2 TG 3 TG 5
Mean height/ cm
Moist Semi-deciduousforest
0
100
200
300
400
500
600
700
AM 5 AM 7
BE 2 BE 4 BR 3
BS 2 BS 3 BS 9
GA 1 GA 3 GA 6 GA 9
TG 2 TG 3 TG 5
Mean height/ cm
Progeny
Wet Ever
g
reen forest
Figure 3.
Mean heights of 15 Nauclea diderrichii progenies 2.7 years after
planting in three forest zones in Ghana.
assessment in the fourth month, it was not until the 20th month
that clear-cut differences were noticed. For example, while
attacks were marginally lower at the Moist Semi-deciduous and
Dry Semi-deciduous Forest zones at the 4th and 12th month,
the reverse was observedduring the peak of the infestation at 20
months. The higher initial attacks at the Wet Evergreen Forest
zone might be due to the presence of an older N. diderrichii
plantation established in 1972 and located at about 100 m away
from the experimental plot. This plantation was very likely the
source of O. mediofoveata population which facilitated an early
colonization of the plots at the WEF site as compared to the
remaining two sites.
Shoot borer attacks were observed in the plantation after the
peak infestation at 1.7 years, however, the impact of the attack
did not show on the trees. The occurrence of fresh attacks were
evident but visually this did not appear to substantially impact
on the growth of the plant. This is quite contrary to the situation
with, for example, the mahogany shoot borer (Hypsipyla ro-
busta) attack which is a serious pest of species of the Meliaceae
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
AM 5 AM 7
BE 2 BE 4
BR 3
BS 2 BS 3 BS 9
GA 1 GA 3 GA 6 GA 9
TG 2 TG 3 TG 5
Mean diameter/ cm
Dry forest zone
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
AM 5 AM 7
BE 2 BE 4
BR 3
BS 2 BS 3 BS 9
GA 1 GA 3 GA 6 GA 9
TG 2 TG 3 TG 5
Mean diameter/ cm
Moist forest zone
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
AM 5 AM 7
BE 2 BE 4 BR 3
BS 2 BS 3 BS 9
GA 1 GA 3 GA 6 GA 9
TG 2 TG 3 TG 5
Mean diameter/ cm
Progeny
Wet forest zone
Figure 4.
Mean diameter (at breast height) of 15 Nauclea diderrichii progenies
2.7 years after planting in three forest zones in Ghana.
in Ghana and many tropical countries (Ofori et al., 2007,
Opuni-Frimpong et al., 2008; Bosu & Nkrumah, 2011). Oryg-
mophora medofoveata damage did not cause N. diderrichii to
develop profuse epicormic branching as is often the case with H.
robusta attack of the Meliaceae. Although epicormic branches
occurred in some cases, there was usually a clearly distin-
guishable lead terminal that suppressed the growth of the re-
maining shoots as the tree grew. The worst case scenarios re-
corded in the plantation were just a dominant stem and a
smaller or poorly growing stem. In general, the damage levels
observed did not cause significant mortalities to the seedlings.
Healthy and vigorously growing seedlings tended to recover
(coppice) from attack and subsequent dieback (withering of the
shoot) when growing conditions were optimum, thus mortality
156

P. P. BOSU ET AL.
Table 3.
Selection differential and genetic gain in total height growth (cm) for
15 Nauclea diderrichii progenies at Mesewam nursery in the Moist
Semi-deciduous Forest zone.
Progeny Mean height Deviation% Deviation % gainRank
BS 9 333.62 3.34 24.020 28.36 1
GA 1 312.78 3.13 16.274 19.21 2
BS 3 290.29 2.90 7.916 9.34 3
GA 3 285.69 2.86 6.204 7.32 4
BE 2 285.58 2.86 6.162 7.27 5
BS 2 272.50 2.73 1.301 1.54 6
BE 4 271.37 2.71 0.880 1.04 7
TG 2 265.00 2.65 −1.487 −1.76 8
AM 7 258.41 2.58 −3.937 −4.65 9
GA 6 258.33 2.58 −3.965 −4.68 10
GA 9 254.05 2.54 −5.558 −6.56 11
TG 3 252.94 2.53 −5.970 −7.05 12
AM 5 235.63 2.36 −12.404 −14.6413
BR 3 235.50 2.36 −12.454 −14.7014
TG 5 223.25 2.23 −17.007 −20.0815
due to O. mediofoveata shoot borer attack was lower than ex-
pected.
However, the impact of the damage to N. diderrichii seed-
lings at the nursery stage appeared much higher and devastating
than were observed in the field. It appears that bigger and stur-
dier seedlings used for outplanting in the field make the seed-
lings more tolerant to shoot borer damage than smaller and
more tender seedlings that are frequently attacked at the nursery.
By maintaining seedling vigour, minimizing shock during
transportation from the nursery to field sites, and planting at the
beginning of the rainfall season (April-May), the impact of O.
mediofoveata attack could be substantially reduced in planta-
tions.
Survival
The percentage survival of 88.8% - 96.3% recorded four
months after establishment is encouraging for a native timber
species growing under pressure of its primary insect pest. In a
study to evaluate the growth of N. diderrichii in pure and mixed
species trials conducted at the BiaTano Shelterbelt forest re-
serve in Ghana (Moist Semi-deciduous Forest zone), Addo-
Danso et al. (2012) recorded an initial (after 6-month) survival
of 70.8% in monoculture plots, 63.0% in a two-species mixed
plots, and 38.9% in a 4-species mixed plots. In the same study,
overall survival of Nauclea in the plantation was 40% in the
monoculture after 24 months (2 years) and remained largely
unchanged after 36 months (3 years). Compared to the present
study, survival of the worst performing progenies were better
than those reported by Addo-Danso et al., (2012).
Growth
As Nauclea is a wet/moist forest species, we expected that
overall performance (resistance to attack by the shoot borer,
survival, and growth rates) of the progenies would be better at
the wet (WEF), followed by the moist (MSF) site, before the
dry (DSF) zones. Our hypothesis was partially supported, in
that performance was better at the WEF. However, between the
moist and dry forest zones, average performance was better at
the DSF site than the MSF site (Table 4). It seems that the poor
survival and growth at the MSF was due largely to poor site
factors that prevailed in the location where the plots were es-
tablished. Besides, having been heavily cropped for many years,
the soil in this location was mostly clayey and liable to flooding
during periods of heavy rainfall.
Differences in growth (height and diameter) were recorded at
various stages, however, at the last assessment at age 2.7 years,
progenies BS9, BS3, BS2 and GA1 were amongthose with the
highest overall height and diamter growth rates in the planta-
tions. However, the Bensoprogenies (BS9, BS3 and BS2) were
also those with the lowest overall survival rates among the 15
progenies. Perhaps, the high level of mortality afforded the
surviving seedlings less competition for growth. The growth
rates achieved under the pressent study compares favourably
well with previous studies of Nauclea in Ghana and elsewhere
in West Africa. In Ghana, Addo-Danso et al., (2012) recorded
overall height growth of 1.9 m in monoculture Nauclea plots at
the Bia-Tano shelterbelt after 24 months, 2.8 m at 36 months
and 6.8 m at 60 months. The corresponding diameters of these
heights were 3.8 cm, 4.1 cm and 9.7 cm, respectively. It is
worth noting that all 15 progenies assessed in this study
achieved a mean height of more than 3.5 m and diameter more
than 3.5 cm at 32 months (2.7 years), both of which are greater
than what was achieved at 36 months by Addo-Danso et al.,
(2012). Heights and diameter in mixed plots were lower than in
the monoculture plots. In Nigeria, Onyekwelu (2007) reported a
mean total height of 9.0 m height and diameter of 9.6 cm for a
5-year old Nauclea plantation in the Omo forest reserve. Mean
tree diameter at breast height (dbh), total height and standbole
volume ranged from 9.6 to 29.3 cm; 9.0 to 23.6 m and 23.27 to
535.52 m3/ha, respectively from plantations ranging from 5 - 30
years of age. Also in Nigeria, Fawape et al., (2001) recorded
mean height of 14.07 m and 0.29 m dbh in a 20-year-old even-
aged stand of Nauclea diderrichiiin the Akure forest reserve
located in the humid rainforest zone of Ondo State.
Conclusion
None of the 15 progenies was distinctly different from the
others in any measure during the entire evaluation period.
Rather, site-site differences were clear. It appears therefore that
good or suitable site factors, especially the soil and water, are
the important factors to be considered when establishing planta-
tions of N. diderrichii. It will be important to ensure that seed-
lings used are sturdy and the plantation is properly managed. In
addition, it is also important that progenies planted are not far
away from the ecological zones where they were obtained, such
as planting Dry Semi-deciduous progenies in the Wet Ever-
green Forest zone and vice versa.
The low growth rate recorded at the Mesewam nursery area
(MSF) though unexpected provided insight as to which of the
rogenies could be best suited for planting under harsh or p

P. P. BOSU ET AL.
158
Table 4.
Mean overall performance of 15 Nauclea diderrichii progenies established in three forest zones in Ghana at 2.7 years.
Site Height ± S.E (cm) Diameter ± S.E (cm)Survival ± S.E (%) *Attack ± S.E. (rank)
Dry Semi-deciduous forest zone DSF (Abofour) 430.78 ± 7.8 a 14.38 ± 0.34 a 55.00 ± 3.09 a 1.92 ± 0.03 a
Moist Semi-deciduous forest zone–MSDF (Mesewam) 273.28 ± 8.1 b 8.93 ± 0.35 b 50.83 ± 3.68 a 1.86 ± 0.03 a
Moist/Wet Evergreen forest zone (Benso) 540.20 ± 6.2 c 16.67 ± 0.67 a 79.50 ± 2.44 b 1.44 ± 0.01 b
*Based on assessment carried out at 1.7 years.
stressed environmental conditions. As observed (Table 3), the
Benso, Gambia and Begoro progenies were the most suitable
under the prevailing poor soil condition. Indeed, the Benso
(WEF) progenies BS9, BS3 and BS2 came close to what may
be described as best performing progenies of the study. These
progenies were obtained from an existing N. diderrichi i (estab-
lish in 1972) plantation located in the Nueng Forest where wet
forest zone trial was conducted. The origin of the 1972 planta-
tion is unknown, but it appears that they were carefullly se-
lected for planting.
We recommend that the following progenies BS9, BS3, BS2,
GA1, GA3 and BE2 should be considered for plantation estab-
lishment. With the distribution range of N. diderrichii spanning
across the African continent, it is recommended that future
studies should consider a range-wide progeny and provenance
assessments.
Acknowledgements
This study was conducted with funds from the African For-
estry Research Network (AFORNET) Grant No. 252005.
Messrs. Elvis E. Nkrumah,K. Prempeh Bandoh and Emmanuel
A. Manu provided technical support for the field work.
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