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© 2015 Conscientia Beam. All Rights Reserved. 

60 
 

GERMINATION EFFECTS OF PURPOSIVE BRUCHID SCREENING OF 

AFRICAN EBONY (DALBERGIA MELANOXYLON) SEEDS IN THE ARID AND 

SEMI-ARID REGION OF SOUTH EASTERN KENYA 

 

Nahashon Musimba1 --- Josphert N. Kimatu2† --- Benard Mweu3 --- MWK Mburu4 -

-- Simon Nguluu5 
1School of Agriculture and Veterinary Services, South Eastern Kenya University, Kitui, Kenya 

2Biological Department, South Eastern Kenya University, Kitui, Kenya 

3,4,5Department of Dryland Agriculture, South Eastern Kenya University, Kitui, Kenya 

 

ABSTRACT 

The African ebony (Dalbergia melanoxylon) is a tree that is crucial in making of high value wooden 

traditional artifacts, however its slow growth in the arid and semi-arid lands (ASALs), poor germination 

and low seedling growth rate, seed pest predation coupled with overharvesting pause a great threat for the 

future availability of the species. Unscreened natural methods of seed germination might not sustainably 

solve the problem of low germination. Overharvesting for wood carving, and low natural regenerative 

ability of the species and lack of the local and national conservation efforts present a serious threat its 

availability to the future availability of Dalbergia melanoxylon. Availability of viable seed plays a crucial 

role the establishment of African ebony. There is need for immediate methods for multiple seedling 

production for propagation of D. melanoxylon. Our studies showed 2% germination without screening but 

increased to 40% after screening (p< 0.001). Careful moisture monitoring of the seedling seemed to increase 

the growth rate in the ASAL region. Therefore, selected propagation methods of this species can rescue it 

from the current extinction trend which is caused by its low regenerative ability when natural methods are 

used and over exploitation. There is need to support on farm cultivation of the tree to sustain the carving 

industry.  

Keywords: Endangered species, Carving, Dalbergia, Germination, Predation, African ebony, Borers 

 

1. INTRODUCTION 

Dalbergia melanoxylon Guill & Perr (Family Leguminosae and subfamily Papilionoidae) [1] 

grows under a wide range of conditions including semi-arid, sub-humid and tropical lowland 

areas. It is often found on dry, rocky sites but is most frequent in mixed deciduous forests and 

savannahs of the coastal region [2]. Hence, this species is water and light demanding; it is 

Current Research in Agricultural Sciences 
2015 Vol. 2, No. 2, pp. 60-66 
ISSN(e): 2312-6418 
ISSN(p): 2313-3716 
DOI: 10.18488/journal.68/2015.2.2/68.2.60.66 
© 2015 Conscientia Beam. All Rights Reserved. 

 
 
 
 
 

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commonly found near water and does not regenerate under heavy cover. Mature trees are fire 

tolerant. The species is wide spread in tropical Africa from Senegal and Cote d’Ivore in the West, 

to Kenya and Ethiopia in the East, and extending south to South Africa [3]. The species is highly 

favoured for carving because it does not crack, it is fungal resistant and is one of the most 

expensive timbers in the world. 

Wood carving industry in Kenya is the largest of its kind in Africa and it generates about 

US$20 million per year [4]. This has led to over exploitation from its natural habitat and now 

the tree is now commercially depleted in Kenya. Observations in the ASALs where the species 

grows in Kenya in the Machakos and Kitui counties, has low arable potential, therefore wood 

carving became a major income earning option.  A survey of 1990 showed an approximately 

60,000 to 80,000 wood carvers, supporting over 400,000 households [5]. The locals also engage 

in charcoal burning of the few woodlots present. However, the unit price of wood carving is two 

to three orders of magnitude compared to charcoal production of wood and even two to ten times 

higher than using the tree for timber, firewood or poles. Furthermore, the species is naturally 

extremely slow growing; trees attain timber size in 70-100 years in some instances. In Kenya, the 

town of Wamunyu in Machakos County, with 2000 carvers, 100 miles east of Nairobi, where the 

carving industry began, show that local supplies of the valuable mpingo (Dalbergia melanoxylon), 

were exhausted by the 1940s. At this time the tree was the number one choice of the wood carvers 

and was exported to Europe for the manufacture of clarinets and oboes. 

 

1.1. Recent Approaches in Dalbergia Melanoxylon Seed Germination 

Recently in the late 2000’s to 2012 researchers have directed their research to alternative and 

advanced techniques and methods for D. melanoxylon seedling production and propagation. Amri 

[6] investigated the effect of timing of seed collections and provenances on seed viability and 

germination capacity of Dalbergia melanoxylon. In this study seed viability varied with different 

time of seed harvesting, for the seeds harvested between 8-12 weeks from their maturity viability 

was 57% and germination was 35% but for seeds harvested from 16 weeks and above viability was 

37% and germination was 21% which correlate with germination reported by Washa and 

Nyomora [7] and not far from germination reported as by TTSA [8] as 37%. 

 

1.2. Germination Studies on the Dalbergia Melanoxylon 

Earlier research conducted on D. melanoxylon from 1960’s to early 2000’s were mainly on the 

biology and silviculture of the species rather than regenerative methods for propagation and 

conservation of the species. This is because overharvesting of mpingo from 1960’s to early 1990’s 

was not a threat issue [9]. Later studies show that this species has serious reproductive 

limitations, both asexually and sexually with very low germination capacity [10]. Therefore 

information on genetic variability is important for successful management and conservation of the 

species. Preservation of genetic variation and evolutionary processes in viable populations can 

have ecological role and in conserving the species.  



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Recent studies by Washa, et al. [11], found that available moisture to D. melanoxylon seeds 

was found to be a factor affecting germination in the natural environment. They found that seeds 

of the species are vulnerable to high moisture level, they easily get rotten and loss viability at 

high moisture but also seeds are vulnerable to fungal and insect attack. This is why most seeds of 

the species produced yearly in the forest do not germinate and loss their viability few months 

from the time they mature. Hence, there was need to monitor the optimum moisture content for 

efficient germination of the species seeds.  

 

1.3. Fruits, Seeds, and Flowers of Dalbergia Melanoxylon 

Studies on the seed showed that D. melanoxylon seeds are hard and enclosed in pods. The 

flowers are perfect or bisexual, insect pollinated and white flowers about 5 mm long with 9 

stamens [9, 12]. The seeds are kidney-shaped, laterally compressed, smooth, about 7.5 to 9.5mm 

long and 0.5 to 0.7mm wide giving an average fresh seed mass of between 0.06 and 0.17g. The 

mature seeds are black and can easily be selected from immature white ones. The seeds have thin 

seed coats and the embryo is yellowish [8].  The seeds generally remain viable for only a few 

months, although viability could probably be increased by storage in sealed containers after 

collection. In about 16000 seeds only 6000 seeds or 35% can germinate [8], although we found 

this to be not attainable in our preliminary studies. But some seeds extracted from pods 

germinated readily on sand beds. However, we observed that most seedlings could not attain 

maturity if moisture content was not monitored properly. This could be the case of seedling death 

during droughts as observed by Mugasha [13]. Previous studies show that seed storage behavior 

is orthodox and viability can be maintained for several years in hermetic storage at 3oC with 9-

12% moisture content, otherwise viability can be lost in a few months from the time of maturity 

[8]. The fruits usually green when young and pale green when mature. They contains one to 

three seeds and are flattened. They are not able to dehisce and are grayish when completely dry 

and could be observed to be infested with fungal growths [9].  

 

2. MATERIALS AND METHODS 

The study was carried on at the South Eastern Kenya University which is near Wamunyu, a 

town which is the epicenter of wood carving in Kenya. It has arid and semi-arid climate. It 

receives quite erratic rain fall. However, it the times when adequate rain is present, the plant life 

thrives excellently. The pods were collected by hand from trees. Collected seed were kept in 

labeled khaki envelopes. The pods and seeds were used as study samples. 

The collected seeds were sown in beakers filled with moist sand at a germination room 

temperature of between 23-32ºC. The seeds were kept as a uniform depth of 0.5-1.0 cm. The seeds 

were moistened every alternate day. The number of germinated seeds were counted and the total 

numbers of germinated seeds evaluated using the formula; total number of germinated seeds X 

100 total number of sowing. 



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We used a Grain moisture meter; model GMK-303RS (Korea).  Most meters and probes rely 

on an inbuilt calibration between moisture and either electrical capacitance or resistance. They 

are calibrated against oven-based moisture determinations. We used whole bean grains and 

obtained averages of the percent grain moisture contents. The GMK-303RS is calibrated to 

measure bean grain of moisture content 12.5 - 19.7%. It had an accuracy of + 0.5%. It has an 

operation which is by the electrical resistance method; it also has a microprocessor control and 

automatic temperature compensation capable of obtaining average data by just a tap of a button.   

 

3. RESULTS  

3.1. Examination of Seeds 

The seeds were found to be fairly fragile. It required one to be careful when extracting the 

seeds from the pods when dry. We examined the seed physical characteristics, damage and 

germination rate (Figure 1). Majorly, the study revealed that more than 70% of D. melanoxylon 

seeds were abortive or damaged by insects at the time of collection and if the monitoring of the 

days after seed maturation is beyond two months. 

 

 

Figure-1. Seed of Dalbergia melanoxylon from the arid and semi-arid land of south eastern Kenya region, A, show a 

partially opened seed, B shows a fully opened seed, C shows the separated seed while D shows seeds from various pods 

which have different dimensions and levels of fungal infestations. 

 

 



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3.2. Germination Rate and Moisture Content of Dalbergia Melanoxylon 

The seed showed between 35-40% germination. The continuous watering so that the seeds 

are not water stressed seemed to increase the germination rate. Furthermore, when the seeds 

were crowded they yellowed and did not show vigour as when they were transferred to loam red 

soil singly. This increased their growth rate (Figure 2).  

 

 

Figure-2. Laboratory grown, three week old, germinated seedlings of Dalbergia melanoxylon, which took 10 days for the 

first emergence to be observed.   

 

3.3. Moisture Content Test  

The good seeds where pooled and after several measurements, using a Grain moisture meter; 

model GMK-303RS (Korea).  We found the average moisture content (n=10) of the D. 

melanoxylon seeds to be 12.4%.  

 

D. Melanoxylon Seed Predation by Insect Borers (Bruchids) 

During seed collection from tree crown in the forest, it was noticed that the pods and seeds 

were damaged by insect borers and could not germinate. By using hand and hand lens the pods 

were opened into two halves. It seemed that the insects could also be causing damage to flowers, 

fruits and seeds before descending on the mature pods. Our, observations showed that the good 

seeds were not more than 40% and further delay in collecting the seeds made more seeds to be 

damaged by insects’ borers and fungal infestation increased (Figure 3).  

 

Figure-3. The black round spots are pores made by insect borers (Bruchids) on Dalbergia melanoxylon seeds, which make 

them not to germinate. Notice also the black colour due to fungal infestation.  



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4. DISCUSSION AND RECOMMENDATIONS 

The study shows that collection of seeds should be done in the first two months in the 

ASALs so as to increase the number of seeds not damaged by insects and are able to germinate. 

Furthermore the ASALs also present the most suitable environmental condition for the fast 

growth of the tree, if moisture conditions are improved [7] and the species is cultivated to reduce 

predation pressure from insects which could be overwhelming the trees from the time it gives the 

first leaves to the time it has mature pods. The ASALs high temperature have been reported to 

have a higher number of predatory insects which suck moisture from plants at all stages of plant 

growth and development.  

Therefore to curb the near extinction of the very few remaining natural populations of D. 

melanoxylon, and improving its germination rate so as to attain sustainable exploitation for the 

carving industry; moisture content of germinating seedlings, reduction of predatory insects and 

timely collection and screening of seeds are crucial factors to be considered in the future plans of 

domesticating the plant and in the studies on genetic and epigenetic variations of the D. 

melanoxylon. 

 

5. ACKNOWLEDGEMENT  

We are grateful for the financial support of the SEKU management, 2014/2015 financial 

year, VC and DVC, FPD.  

 

REFERENCES  

[1] C. H. Tack, Nomenclature of East African timbers. Nairobi: East African Timber Advisory Board, 

1962. 

[2] J. F. Redhead and A. B. Temu, "Valued timber but neglected tree: Mpingo (Dalbergia 

Melanoxylon)," Tanzania Association of Foresters Newsletter, vol. 2, pp. 8-9, 1981. 

[3] J. B. Gillet, R. M. Polhill, and B. Verdourt, Flora of tropical East Africa. Part 3: Leguminosae, sub-

family Papilionoidae. London: Crown Agents for Overseas Governments and Adminstrations, 1971. 

[4] S. K. Choge, A. B. Cunningham, and W. Ellery, Chasing the wooden rhino: The case of woodcarving in 

Kenya. In: Cunningham, A.B., Belcher, B. and Campbell, B.M. (Eds.) carving out a future: Tropical forests, 

livelihoods and the International woodcarving trade. London: Earthscan, 2005. 

[5] R. Obunga, "Sustainable development of woodcraft industry in Kenya," Technical Progress Report. 

National Museums of Kenya. Nairobi, 1995. 

[6] E. Amri, "Effect of timing of seed collections and provenances on seed viability and germination 

capacity of dalbergia melanoxylon. Bot Res. J. 1 (4) 82-88," International Journal of Plant and 

Forestry Sciences, vol. 1, pp. 1 – 6, 2008. 

[7] B. W. Washa and A. M. S. Nyomora, "The effect of moisture and seed treatment on the in-situ and 

ex-situ regeneration of dalbergia melanoxylon (African Blackwood) in Pugu forest reserve," 

HURIA Journal, vol. 10, pp. 56-70, 2012. 



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[8] TTSA, "Handling of seeds of dalbergia melanoxylon (African Blackwood). Seed issue note No. 9," 

1995. 

[9] J. M. Bryce, The commercial timbers of Tanzania. Moshi (Tanzania): Tanzania Forest Division, 

Utilization Section, 1967. 

[10] B. W. Washa, A. M. S. Nyomora, and H. V. Lyaruu, "Improving propagation success of 

D.melanoxylon (African Blackwood) in Tanzania. I: Characterization of mycorrhizal associated 

with dalbergia melanoxylon (African Blackwood) in Tanzania. Tanzania Journal of Science. 38: (1). 

35-42," International Journal of Plant and Forestry Sciences, vol. 1, pp. 1–6, 2012. 

[11] B. W. Washa, A. M. S. Nyomora, and H. V. Lyaruu, "Improving propagation success of 

D.melanoxylon (African Blackwood) in Tanzania. II: Rooting ability of stem and root cuttings of 

dalbergia melanoxylon (African Blackwood) in response to rooting media sterilization in 

Tanzania," Tanzania Journal of Science, vol. 38, pp. 43-53, 2012. 

[12] L. Nshubemuki, "Recent research progress in the silviculture of dalbergia melanoxylon in 

Tanzania," presented at the Paper Presented to the International Workshop on Dalbergia Species, 

31 May to 4 June, 1993, Hetauda, Nepal, 1993. 

[13] A. G. Mugasha, "The effects of planting season, different planting materials and weeding methods 

on early performance of Dalbergia melanoxylon at Kwamarukanga, Korogwe, Tanzania," Tanzania 

Silviculture Research Note, vol. 43, p. 14, 1978. 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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