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Domestication of Dacryodes edulis: State-of-the-art

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  • International Tree Foundation, UK

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Dacryodes edulis is one of the important local fruit tree species of West and Central Africa. This paper reviews the activities of a regional programme to domesticate high-value indigenous fruit trees in the region. This programme is coordinated by the International Centre for Research in Agroforestry (ICRAF) and implemented in Cameroon in collaboration with the Institute of Agricultural Research for Development (IRAD), National Agricultural Extension and Research Programme (PNVRA) agents and NGOs and universities of the region. It is based on a participatory approach to domestication that is in marked contrast to that of food crop domestication under the Green Revolution. The participatory process with farmers started with priority setting between species, progressed to germplasm collection and the establishment of village nurseries for clonal propagation of superior trees, and is currently involved in the selection of superior trees for cultivar development. Work is also in progress on post-harvest processing, market development and the integration of cultivars into agroforestry systems.
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DOMESTICATION OF D. EDULIS; STATE-OF-THE-ART 3
Forests, Trees and Livelihoods, 2002, Vol. 12, pp. 3–13
1472-8028 $10
© 2002 A B Academic Publishers—Printed in Great Britain
DOMESTICATION OF DACRYODES EDULIS:
STATE-OF-THE-ART
Z. TCHOUNDJEU1, J. KENGUE2 AND R.R.B. LEAKEY3,4
1IRAD/ICRAF, P.O. Box 2067, Yaoundé, Cameroon. Email: z.tchoundjeu@cgiar.org
2IRAD/CIRAD, Nkolbisson, P.O. Box 2067, Yaoundé, Cameroon.Email: irad-fruits@camnet.cm
3Centre for Ecology and Hydrology, Bush Estate, Penicuik, Midlothian, EH26 0QB, Scotland,
UK.
4Current address: Agroforestry and Novel Crops Unit, School of Tropical Biology, James
Cook University, PO Box 6811, Cairns, Queensland 4870, Australia. Email:
roger.leakey@jcu.edu.au
ABSTRACT
Dacryodes edulis is one of the important local fruit tree species of West and Central Africa. This
paper reviews the activities of a regional programme to domesticate high-value indigenous fruit
trees in the region. This programme is coordinated by the International Centre for Research in
Agroforestry (ICRAF) and implemented in Cameroon in collaboration with the Institute of
Agricultural Research for Development (IRAD), National Agricultural Extension and Research
Programme (PNVRA) agents and NGOs and universities of the region. It is based on a
participatory approach to domestication that is in marked contrast to that of food crop
domestication under the Green Revolution. The participatory process with farmers started with
priority setting between species, progressed to germplasm collection and the establishment of
village nurseries for clonal propagation of superior trees, and is currently involved in the selection
of superior trees for cultivar development. Work is also in progress on post-harvest processing,
market development and the integration of cultivars into agroforestry systems.
Key words: Safou, Dacryodes edulis, domestication, vegetative propagation, marcot, germplasm
collection, cultivar development, phenotypic selection, community nurseries.
RESUME
Dacryodes edulis est l’une des plus importantes espèces fruitières arboricoles de l’Afrique de
l’Ouest et du Centre. Le présent article passe en revue les activités du programme de
domestication des arbres fruitiers locaux à grand potentiel dans la région. Sous la coordination du
Centre International de Recherche en Agroforesterie (ICRAF), ce programme est réalisé avec la
collaboration de l’Institut de Recherche Agricole pour le Développement (IRAD), du Programme
National de Vulgarisation et de Recherche Agricoles (PNVRA), des ONGs et des Universités de
la région. Il est basé sur une approche participative à la domestication, ce qui contraste
grandement avec la domestication des plantes vivrières de la Révolution Verte. Le processus
participatif avec les paysans a débuté par la prioritisation des espèces, suivie par la collecte de
germoplasme et l’établissement des pépinières paysannes en vue d’une propagation clonale des
“arbres supérieurs”. Actuellement, ce processus est orienté vers la sélection des “arbres
supérieurs” pour le développement des cultivars. Des travaux sont aussi en cours sur la
technologie post-récolte, la commercialisation et l’intégration des cultivars dans les systèmes
agroforestiers.
Mots clés: Safou, Dacryodes edulis, domestication, propagation vegetative, marcotte, collecte de
germoplasme, développement de cultivars, sélection phénotypique, pépinières communautaires.
4 TCHOUNDJEU, KENGUE AND LEAKEY
INTRODUCTION
The West and Central African region is characterised by a growing season of
271–365 days, with annual rainfall ranging from 1400 to more than 4000 mm.
Over 80% of food crops (cassava, maize, yam, plantain and cocoyam) produced
in the region are grown by small-scale subsistence farmers, who typically use
traditional shifting cultivation systems. Long fallow periods are required to
restore soil fertility, suppress weeds and reduce pest and diseases. However,
increasing population pressure and rural to urban migration of the work force
have reduced the fallow period to less than five years in most areas, with
consequences of soil degradation, reduced nutrient cycling in soils, etc. These
subsistence farmers often grow small areas of cocoa and coffee under the shade
of larger trees. Since the late 1980s, the world market price for the region’s
major cash crops has dropped significantly. This, coupled with the devaluation
of the local currency in French speaking countries, has resulted in accelerated
forest clearing, loss of biodiversity, increased poverty and lower quality of life
both for rural populations and the urban majority. Nevertheless, the degraded
forest has tremendous potential. It is endowed with high-value fruits and
medicinal plants, which are currently traded locally as well as in regional and
international markets. Unfortunately, they are mostly exploited from the wild
and, until recently, there has been little or no focused research effort to
domesticate and cultivate them, or to improve their genetic base.
The domestication of traditionally important indigenous trees has recently
become a major programme in international agroforestry research (Sanchez and
Leakey 1997). Their commercial importance has led farmers to identify these
local species as candidates for domestication through agroforestry (Franzel et al.
1996), and to the initiation of a domestication programme for indigenous fruit
and medicinal trees (Simons 1996, Leakey and Simons 1998, Tchoundjeu et al.
1998). Dacryodes edulis (G. Don) H.J. Lam, also known as safou or African
plum, in the Burseraceae, is one of these candidate species. The present paper
reviews the current state of this domestication programme, with particular
emphasis on safou. Non-timber forest products from safou and a few other
species constitute an important source of revenue for the region. In 1997, the
trade of safou in Cameroon alone was worth about US$7.5 million (Awono et
al. 2002). In the international market, Tabuna (1999) has reported that 105
tonnes of safou fruit are exported every year from Central Africa to Europe. Of
this, Cameroon produces 100 tonnes and the Republic of Congo and the
Democratic Republic of Congo produce 2 and 3 tonnes respectively.
There is some confusion with regard to the natural range of safou, which
Vivien and Faure (1985) and Keay (1989) have indicated to be limited to SE
Nigeria, while others have reported it to range from Uganda to Sierra Leone
(Troupin 1950), or Cameroon, Gabon, Congo and Equatorial Guinea (Aubreville
1962). The species is, however, now distributed widely in Central Africa in
farmers’ fields, but nothing is known about the history of this distribution, if
indeed it is not indigenous to the region. A molecular ecology study could
determine the genetic structure of the population and resolve this uncertainty.
DOMESTICATION OF D. EDULIS; STATE-OF-THE-ART 5
Safou is mainly cultivated for its nutritional and market values. Locally prices
are about US$1per kg of flesh, but on the international market whole fruits fetch
from 350BF (US$7)/kg in Brussels to FF40 (US$5)/kg and FF50 (US$6)/kg in
Paris and Lyons. The mesocarp, which is eaten raw, boiled in water or roasted,
is an important source of lipids and proteins. The oil content of the fresh pulp
varies between 33 and 65% depending on the variety and the state of maturity
(Omoti and Okiy 1987). Kiamouama and Silou (1987) have characterised the
lipid fraction as consisting of mainly palmito-oleic acids with 47.33% of palmitic
acid (C16:0), 27.35% of oleic acid (C18:2) and 20.46% of linoleic acid. The high
content of fatty acids combined with its amino-acid content makes safou an
alternative source of vegetable oils for the food, pharmaceutical and cosmetic
industries.
Despite some existing studies on safou (Okafor 1983, Nya Ngatchou and
Kengue 1986, Kengue and Schwendiman 1990, Kengue 1996, Leakey and
Ladipo 1996, Ayuk et al. 1999) more research is needed to provide the data on
which to base the domestication, large-scale cultivation and genetic improvement
of this important species. The provenance collections made by Cameroon’s
Institute of Agricultural Research for Development (IRAD) 12 years ago have,
however, provided knowledge about phenology, growth and yield (Kengue and
Singa 1998). They have also served as a stock of material for propagation. This
has led to the establishment of the first series of clonal variety trials on station
and on farms (Kengue et al. 1998). The present paper reviews current activities
towards the domestication of safou with active participation of farmers of
Southern Cameroon and Nigeria.
PROGRESS ON DIFFERENT ASPECTS OF PARTICIPATORY DOMESTICATION
The domestication of safou is constrained by a limited knowledge base, since the
existing literature has focussed on reproductive biology (Kengue 1990), chemical
analysis (Silou 1991) and management and economic potential (Ayuk et al.
1999). Furthermore, there is a need for a novel strategy as the domestication of
most plants is based on the needs of agricultural/horticultural crops, or industrial
forest species, grown in large-scale monocultures in northern-temperate
countries. These are not appropriate for agroforestry trees in the tropics. The
domestication of these species needs to take into consideration the requirements
of small-scale, resource-poor farmers and their subsistence farming systems.
Consequently, the International Centre for Research in Agroforestry (ICRAF)
and its partners in West and Central Africa are developing a new and more
participatory approach to the domestication of high-value agroforestry tree
species based on: priority setting by farmers, germplasm collection, low-
technology vegetative propagation in village nurseries, the genetic charac-
terisation of the marketable products for consumption and processing, the
integration of the species into agroforests managed by subsistence farmers and
the expansion of markets for the products. This participatory approach to
domestication is innovative and fundamentally important because it meets the
6 TCHOUNDJEU, KENGUE AND LEAKEY
needs of local farmers and conforms to the requirements of the Convention on
Biological Diversity (CBD), by allowing farmers to maintain the rights to their
indigenous knowledge and their genetic material. It also creates a model for
domestication, which is in marked contrast to the approach of the Green
Revolution, which was the prerogative of well-funded international research
centres. The Green Revolution model is also inappropriate for the large numbers
of agroforestry tree species, because it is very unlikely that international funds
will be made available on an adequate scale for species, which will not
individually become major cash crops. Consequently, a self-help approach for
farmers that will allow them to undertake their own domestication programme is
much more relevant. This more appropriate model could result in improvements
in a very wide array of species of local or regional importance to the livelihoods
of poor farmers practising subsistence agriculture.
Priority setting
The first step in participatory tree domestication is the determination at village
level of which species should receive priority for genetic improvement. This
important step of priority setting has already been widely reported (Jaenicke et
al. 1995, Franzel et al. 1996). It involves integration of researchers’ and farmers’
perspectives, taking into consideration market and genetic potential for choosing
the species that will give the greatest benefits and improve resource-poor
farmers’ conditions. The priority setting process was first conducted in four
countries (Cameroon, Gabon, Ghana and Nigeria) of West and Central Africa,
and revealed the great interest of farmers of the region for their indigenous fruit
trees. Safou was ranked second on the priority list for the Humid Lowlands of
West Africa (Table 1).
Currently the focus of the ICRAF/IRAD tree domestication programme is on
the top five priority species, Irvingia gabonensis (Bush mango / Dika nut), D.
edulis (Safou / African Plum), Ricinodendron heudelotii (Njangsang), Garcinia
TABLE 1
Priority tree species selected for domestication by
implementation of farmer preference surveys and
priority setting guidelines (Franzel et al. 1996) by
ICRAF and partners
Humid lowlands of West
and Central Africa
Priority order
1Irvingia gabonenis/ I.wombolu
2Dacryodes edulis/D. klaineana
3Ricinodendron heudelottii
4Chrysophyllum albidum
5Garcinia kola/G. afzelii
DOMESTICATION OF D. EDULIS; STATE-OF-THE-ART 7
kola (Bitter kola), and Chrysophyllum albidum (Starapple). To this list have been
added some medicinal plants of commercial importance (Prunus africana and
Pausinystalia johimbe) because of opportunities to increase farmer income, fears
about the future of the resource for industry, and the perceived needs for
conservation of the species in their natural habitat.
Germplasm collection
Rangewide germplasm collection is the second step in tree domestication, and is
both expensive and time consuming. Maintaining the genetic diversity of a
species is essential to its domestication and the maximum amount of diversity
should be present in the collected germplasm. The collected material can be
distributed to users (farmers, horticulturists) for widescale planting. For safou the
germplasm collection strategy has primarily targeted the identification of
superior trees of immediate benefit to farmers, as existing provenance collections
by IRAD (Kengue 1990) provide some conservation of genetic diversity.
Consequently, the main activity has been to work together with farmers to
identify, select and collect germplasm (seeds and marcots) from superior trees.
This activity has been centred on four sub-regions in Cameroon (Mbouda and
Kekem in West Province, and Boumnyebel and Makénéné in Centre Province.
These sub-regions were chosen as they are likely to cover the geographical range
and the different uses of safou. The collections focus on both mature fruits and
rooted marcots (air layering) set at the beginning of the rainy season.
Seed collections
Seed collection involved detailed planning and extensive training of field teams
in Cameroon, Equatorial Guinea, Gabon and Nigeria, and then, through Material
Transfer Agreements, the exchange of the germplasm between these countries
for the establishment of live regional genebanks. In each selected village, farmers
identified 20-30 trees with desirable fruits and kernel traits, with the restriction
that not more than 10 trees should be chosen from any one farm. Participating
villages were separated by at least 25 km. Further selection by the collection
team (ICRAF scientists, NARS, NGOs and farmers) narrowed the number down
to two trees per village. During the collection, a GPS (Geographical Positioning
System) was used to record the position of the tree for future reference. In
addition, information on the age of the tree, the frequency and the duration of
fruiting were requested from the owner of the tree. All seed collections are
identified, through the identity number given to each tree, with the farmer
owning the tree, to ensure that his or her rights are secure under the CBD. More
than 3000 seedlings are currently being raised in nurseries for the establishment
of regional genebanks and for subsequent vegetative propagation.
8 TCHOUNDJEU, KENGUE AND LEAKEY
Collection of marcots for cultivar development
Marcots were collected from the Cameroon sites mentioned above. In 1998, at
the beginning of the rainy season (May-June), a maximum of 10 marcots on each
selected tree was jointly set by a team consisting of ICRAF and NGO staff and
farmers. During the marcot setting, farmer selection criteria, identity of farmers
and other normal germplasm passport data (exact location of the tree using GPS,
soil and tree characteristics) were recorded. Marcots were mainly set on younger,
more accessible, trees with a history of several years of productive fruiting, to
enable meaningful selection. Marcots were set on the same branch class (3–5 cm
diameter) and approximately at the same position in the middle of the canopy,
with a similar light environment. Three or four months later, the rooted marcots
were harvested and labelled to record the farmer’s identity. Sixty percent of the
rooted marcots were taken back for weaning in the on-station nursery, while 40%
were left with the farmers for weaning in a village nursery. This division of the
rooted marcots between the stations and the farmers is to maximise the chances
that each genotype is successfully propagated, without jeopardising farmers’
property rights. It also ensures that the genetic diversity of the selected on-station
germplasm collection, and any germplasm exchange between villages, is
maximised. Moreover, the on-station material can be used to replenish the village
stock in case of any losses.
Currently, safou marcots have been planted in demonstration plots in eight
pilot villages in Southern Cameroon and two pilot villages in South East Nigeria,
while marcots taken to the station have been planted in 3 ha of experimental
plots at Minkoameyos near Yaoundé to assess their performance in different
cropping systems. In the villages, these plantings also serve as demonstration
plots to show that they fruit earlier than plants established from seeds or juvenile
cuttings, and that they are genetic ‘copies’ of their mother plant. Some marcots
have also been established as stockplants for subsequent mass production using
stem cuttings.
Provenance and reproductive biology
Provenance trials involving 20 accessions of safou from the western highlands
and humid forest lowlands of Cameroon were established in September 1995 by
IRAD. These accessions are being grown in the Barombi-Kang and Yaoundé
research stations. The study had three main objectives: safeguarding the genetic
diversity of safou, systematic characterisation, and the evaluation of production
by different accessions. Results obtained so far have shown important variation
between accessions and between individual trees within the same accession
(Kengue and Singa 1998).
Research has also been carried out into the reproductive biology of safou,
based on field and laboratory observations. The results indicate that safou is a
dioecious species with an allogamous reproduction system (Kengue et al. 2002).
The species is insect-pollinated with bees (Apis mellifera) being the main
pollinator. This type of reproduction results in great population heterogeneity.
DOMESTICATION OF D. EDULIS; STATE-OF-THE-ART 9
Vegetative propagation techniques
Vegetative propagation techniques are indispensable for the capture and
multiplication of the phenotypic variation expressed by superior individuals with
desirable characters. Leakey and Simons (2000) have listed eight situations when
the use of vegetative propagation is appropriate in tree domestication. Six of
these situations apply to the domestication of safou:
the tree has extensive tree-to-tree variability and rare individuals have fruits
that combine several desirable traits;
high uniformity is required in the fruit crop to meet the market
specifications;
the high value of the crop warrants the extra expense to ensure a high-quality
product;
there is an urgent need to shorten the timescale for the achievement of
domestication below that achievable through breeding;
seed viability is limited to a short season; and
knowledge of proven traits is available from farmers.
Vegetative propagation of trees can be done using a variety of techniques: -
rooting juvenile stem cuttings, grafting, budding, layering and in vitro tissue
culture. None of these techniques are well developed for the indigenous fruit
trees of West and Central Africa. As early as 1957, Philippe tried to propagate
safou vegetatively, but he reported that cuttings were difficult to root. Currently,
however, grafting, marcotting and the rooting of stem cuttings are being used
with some success. The use of single node cuttings (a portion of a stem with a
leaf and axillary bud) set in a high-humidity, non-mist, polyethylene propagator
has been found to be successful for many tropical trees (Leakey et al. 1990,
Tchoundjeu and Leakey 1996). In this volume, Mialoundama et al. report good
rooting (60-80% in 6–8 weeks) with juvenile cuttings, using non-mist
propagators. To implement these techniques of clonal propagation, farmers are
being helped to develop simple and inexpensive village nurseries and are being
trained in vegetative propagation. With this ‘self-help’ approach to domestication
and these nursery skills, farmers will be able to develop cultivars from the best
safou and other fruit trees in their village to meet their domestic needs and local
market demands.
Characterisation of safou
As part of a wider study to examine the constraints to tree domestication
(Schreckenberg et al. 2001), studies to characterise the tree-to-tree variation in
fruit characteristics have been conducted in 300 trees from five villages (four in
Cameroon and one in Nigeria) in West Africa (Waruhiu 1999). The aim of the
studies was to understand the variability of 13 characteristics of the fruits from
different trees so that the participatory domestication being implemented by
10 TCHOUNDJEU, KENGUE AND LEAKEY
ICRAF and its partners is firmly based (see Leakey et al. 2002). In all five sites,
very considerable and continuous tree-to-tree variation was found in each of the
13 measured traits, with the exception of kernel mass. The realisation that
variability is greatest at the level of the individual village underlines the
appropriateness of a village-based tree domestication programme for this species.
Importantly, the results of the characterisation will help to identify the best
individual trees for cultivar development using vegetative propagation, so taking
the domestication process forward more rapidly (Leakey et al. 2000).
A sensory analysis was conducted to assess the effect of size on the relative
intensity of organoleptic characteristics of safou fruits. Three fruit sizes (small,
medium and large) were used to evaluate the level of acidity, aroma, bitterness
and oiliness. Moreover undesirable characteristics such as fibrosity, sourness,
saltiness, mustiness and wateriness were assessed. The results indicated that
acidity and oiliness varied significantly among fruit sizes. Medium sized fruits,
followed by large sized ones, had the lowest levels of undesirable characteristics
(Kengni et al. 2001). The results of this sensory evaluation illustrate the need to
add these techniques to the others being used to characterise tree-to-tree variation
within the tree domestication process.
Commercialisation and processing
There is growing international interest in the commercial use of genetic
resources, especially those from the tropics and consequently there are important
issues (reviewed by ten Kate and Laird 1999) regarding access to these resources
and the means of ensuring the sharing of benefits. Discussion of the role of tree
domestication cannot, however, be divorced from that of product com-
mercialisation, since without expanded or new markets, the incentives to
domesticate are insufficient. Conversely, if the market explodes, the incentive for
large-scale producers to establish monocultural plantations may sweep away the
benefits that agroforestry could deliver to small-scale, resource-poor farmers
around the tropics (Leakey and Izac 1996). As has been pointed out by Dewees
and Scherr (1996), policies that promote the linkages between the domestication
and commercialisation of non-timber forest products (NTFPs) are one of the
important areas for further work. In this regard, there is also a need for better
integration of the needs of the food and other industries using NTFPs with those
of the subsistence farmer (Leakey 1999, Leakey and Tchoundjeu 2001).
It has been recognised that expanded markets for these products would
increase the value of natural forests and benefit forest dwellers (Peters et al.
1989). Similarly, markets for NTFPs produced on areas already deforested could
improve the income of subsistence farmers, and provide an alternative to slash-
and-burn agriculture, one of the major causes of deforestation. For this to happen
there is an urgent need for the domestication of trees to run in parallel with the
development of post-harvest processing and the commercialisation of the
products (Leakey and Izac 1996, Leakey 1999). Studies are underway to promote
these activities in the rural communities, and on a small commercial scale (see
Kapseu et al. 2002).
DOMESTICATION OF D. EDULIS; STATE-OF-THE-ART 11
Integration into agroforestry
Agroforestry is increasingly providing on-farm sources of cultivated timber and
non-timber forest products for domestic use and for marketing, in ways that
potentially should reduce poverty and also provide some important
environmental services, such as biological diversity and carbon sequestration
(Leakey 2001). Consequently, filling some of the niches in farmland with
indigenous species that provide economically valuable products should result in
land use that is both sustainable and productive, such as the cocoa agroforests of
Cameroon (Leakey and Tchoundjeu 2001). The domestication of high value
agroforestry trees like safou, through genetic selection and cultivation, should
increase the quality, yield and marketability of their products, so enhancing the
incentive for more sustainable land-use practices.
CONCLUSION
The techniques of domesticating safou and other indigenous fruit trees and
medicinal plants of the humid zone of West and Central Africa are evolving
rapidly. Through the promotion of income generation they should help to reduce
rural poverty and enhance the livelihoods of subsistence farmers in the region.
The new emphasis placed on participatory domestication of the traditionally
important, and previously ignored, indigenous fruit trees, appears to be a good
strategy to help farmers to help themselves while, through the diversification of
cocoa agroforests, also having benefits for the sustainable management of
farmland in proximity to threatened tropical forests.
ACKNOWLEDGEMENTS
This publication is an output from a research project partly funded by the United
Kingdom Department for International Development (DFID) for the benefit of
developing countries. The views expressed here are not necessarily those of
DFID (R7190 Forestry Research Programme). The authors also wish to thank the
International Foundation for Agricultural Development (IFAD) for its funding of
this work at ICRAF. The views expressed are those of the authors alone. The
contributions of ICRAF staff in Nigeria and Cameroon are also gratefully
acknowledged.
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14 TCHOUNDJEU, KENGUE AND LEAKEY
... La especie es un árbol que ocurre en hábitats de bosques húmedos de tierras bajas (elevación menor a 1.000 msnm). Esta especie es posiblemente polinizada por insectos (Tchoundjeu et al. 2002) y posiblemente dispersada por vertebrados (Norconk et al. 1998, Rozo-Mora y Parrado-Rosselli 2004). Se ha reportado su floración en el mes de julio y su fructificación en el mes de diciembre. ...
... La especie es un árbol que ocurre en hábitats de bosques húmedos y secos de tierras bajas (elevación menor a 1.000 msnm). Esta especie es posiblemente polinizada por insectos (Tchoundjeu et al. 2002) y posiblemente dispersada por vertebrados (Norconk et al. 1998, Rozo-Mora y Parrado-Rosselli 2004). Se ha reportado su floración y fructificación en el mes de febrero. ...
... La especie ocurre en hábitats de bosques húmedos de tierras bajas (elevación menor a 1.000 msnm). Esta especie es posiblemente polinizada por insectos (Tchoundjeu et al. 2002) y posiblemente dispersada por vertebrados (Rozo-Mora y Parrado-Rosselli 2004). Se ha reportado su floración en el mes de diciembre y su fructificación en el mes de junio. ...
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... It plays an important role as food for household consumption and generating income for the countries which are cultivating the plant (Ikhatua and Okeke, 2011) [10] . It also considers as one of the most important fruit tree species in West and Central Africa (Tchoundjeu et al., 2002) [11] . In Cameroon, it is the third most important fruit cultivated after bananas and cola, in terms of production (Temple, 1999) [12] . ...
... It plays an important role as food for household consumption and generating income for the countries which are cultivating the plant (Ikhatua and Okeke, 2011) [10] . It also considers as one of the most important fruit tree species in West and Central Africa (Tchoundjeu et al., 2002) [11] . In Cameroon, it is the third most important fruit cultivated after bananas and cola, in terms of production (Temple, 1999) [12] . ...
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Dacryodes edulis (Burseraceae) is an important plant native from Central Africa. In Cameroon, it is cultivated in almost all regions for economic, medicinal and nutritional purposes. D. edulis is visited by four psyllid species: Pseudophacopteron serrifer, P. tamessei, P. eastopi and P. pusillum. Those psyllids cause important damages on their host plant, necessitating to put in place an integrated pest control against them. The aim of this survey is to study the biology of P. pusillum and P. eastopi on D. edulis in the nursery, which is helpful for an integrated pest management. The study was carried out from April 2011 to March 2012 through daily observations. It is observed that the two psyllid species are sharing different sites on their host plant to lay eggs. The eggs hatching and develop through five instar larval stages before become adult. The fertility, adult life span, sexual maturity, and the developmental duration of each instar larva were determined.
... The World Agroforestry Centre (ICRAF) has identified C. albidum as one of the top five priority species for domestication in the African humid tropics (Tchounjeu et al., 2002). Extensive human activities deplete the population of unregenerated C. albidum during irreversible conversion of forest areas to other uses. ...
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To meet the population demand for enormous benefits of an endangered species, Chrysophyllum albidum, its' slow growth need to be improved through the use of environmentally friendly leaf litters of nitrogen fixing acacia trees. Investigation conducted into effect of leaf litters of nitrogen fixing acacia trees (Acacia tortilis, Acacia seyal, Acacia nilotica, Acacia senegal, Acacia leucophloea and Acacia albida) at the rates of 300 g on the growth of C. albidum was laid down using a Completely Randomized Design with five replications. Results showed that leaf liters of nitrogen fixing acacia tree species significantly (P<0.05) enhanced the growth of C. albidum seedlings. Tallest plant (25 cm), widest leaf area (55.71 cm 2) and highest number of leaves (11), significant total fresh weight (48.45 g) and total dry weight (21.55 g) of C. albidum were recorded from seedlings planted in soil amended with A. senegal. Widest girth (1.92 cm) was recorded from seedlings planted in the soil influenced with A. leucophloea. Highest percentage values of 2.22 %, 0.90 % and 1.74 % were recorded for nitrogen, phosphorus and potassium content of A. senegal. Soil influenced with A. senegal enhanced the growth of C. albidum seedlings. Planting of C. albidum seedlings in the soil amended with A. senegal is recommended for mass production of its seedlings for agro-forestry systems as well as to increase biodiversity conservation.
... When a NTFP species is domesticated and cultivated, it becomes private property, making it easier to better and more sustainably manage it. Numerous studies of NTFPs in Cameroon have shown that cultivation results in such more sustainable management, which can increase the quantity and quality of the plants grown and ensure its continued availability (Shiembo 1994;Sunderland and Nkefor 1997;Wiersum 1997;Blackmore and Nkefor 1998;Nkefor et al. 1998;Sunderland et al. 1998;Shiembo 1999;; Secretariat of the Convention on Biological Diversity 2001; Tchoundjeu et al. 2002;Tekwe et al. 2002;Tekwe et al. 2003;Muchugi et al. 2005;Degrande et al. 2006;Lahjou 2008;Adjumati 2009;Pye-Smith 2010;Wirsiy et al. 2010;Ingram 2013). ...
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This report proposes implementing texts to support the regulatory and fiscal framework, standards and administration, to promote the sustainable management of non-timber forest products (NTFPs) in Cameroon. It provides an analysis of the current framework and its application, based on meetings and existing recommendations. On the basis of this analysis and the guidance of the sub-regional directives on NTFPs from the Central African Forest Commission, proposals for regulatory and normative texts on NTFPs are made. These consider the issues of legal access to NTFPs, their sustainability drawing on existing experiences and an appropriate taxation regime according to socio-economic and ecological criteria. The relevance of the access to and benefit sharing from the use of genetic resources (ABS) framework for NTFPs in Cameroon is considered and recommendations are proposed how to take into account. This study develops criteria and a flexible classification of NTFPs and Special Forestry Products, clarifies permits for NTFPs (taking account of the project to revise the 1994 Forest and Wildlife Law and 1995 implementing Decree), and makes proposals for harvesting standards and inventories. The annexes provide statistics on NTFP trade and permits confirming their high and multiple values; a database of 710 NTFPs in Cameroon; and, in the form of implementing texts taking account of valuable feedback from meetings with a wide range of stakeholders including the Ministry, traders, community based organisations and researchers - a "Regulation" on the operational modalities of NTFP exploitation, a new " decision " listing Special Forestry Products and an explanatory Memorandum on the need to review the taxation of NTFPs to revise the Finance Act.
... Concernant le nombre de feuilles adéquat par boutures, il est admis que la présence de feuilles sur les boutures a un effet sur l'initiation des racines, donc la survie des boutures. Il existerait alors une surface foliaire optimale capable d'induire un taux d'enracinement optimum pour une espèce donnée (Tchoundjeu et al., 2002 ;Atangana et al., 2006).Une surface foliaire optimale est celle qui permet un équilibre entre le gain en assimilations photosynthétiques et la perte d'eau par transpiration de la bouture (Tchoundjeu, 2004 Paluku et al., 2018). C'est un substrat jugé approprié pour l'enracinement de boutures avec un volume optimal de pores, une bonne réserve en éléments nutritifs et un taux de diffusion d'oxygène adéquat pour la respiration des racines des boutures (Andersen, 1986 ;Kontoh, 2014). ...
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Despite its socio-economic importance, kola nut production faces several challenges. Domestication and cultivation of kola requires the adoption of propagation techniques adapted to the crop species. The objective of this study is to optimize kola (Cola nitida) vegetative propagation by cutting under tunnel. The experimental design used was a split splot with two factors: genotype with five modalities (5 genotypes,) and leave number with five (05) modalities (1, 2, 3, 4 and 5 leaves cut in half). The ability of genotype to cutting propagation was assessed by measuring growth parameters. The survival rate of the cuttings was evaluated at six months. Root growth, number of new leaves, height gain and biomass were subsequently measured. Genotype L18A1D9 has the best ability for vegetative propagation by cuttings with a survival rate of 41.7%. To optimize vegetative propagation by cuttings under tunnel, 4 leaves cut in half by cuttings must be used for acceptable success rate (41.7%), good rooting (88.9%), a high total fresh biomass (4.2 g) and total biomass (1.7 g). The success of kola vegetative propagation depends of genotype and the leave number per cutting. The number of leaves per cuttings recommended per cuttings is four (4) for kola vegetative propagation.
... Si les dispositions ne sont pas prises pour la mis en culture de cette espèce, sa disparition est certaine. La domestication suppose l'adoption des techniques de multiplication adaptée à l'espèce (Leakey et Simons, 1998 ;Tchoundjeu et al., 2002a). La multiplication d'une espèce peut se faire soit générativement (multiplication par graine) soit végétativement (multiplication par autres parties de la plante que la graine), Beniest (1987). ...
... Parkia biglobosa is one of the several indigenous fruits under domestication [14,15] and widely commercialized in Nigeria. Works on Parkia biglobosa, especially in Nigeria, revealed its phenotypic and genotypic variation and allowed the selection of superior trees based on fruit and pulp weight, fruit width, pulp taste and pulp colour [16] and Cameroon [17,18]. ...
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Tropical forests contain many important indigenous tree species that are edible and of socioeconomically. The morphological traits of Parkia biglobosa (Jacq) G pods and seeds from three different States in Southwestern Nigeria were investigated. Tree growth measurements (height, crown diameter and diameter at breast height) were made on 10 trees of Parkia biglobosa selected from two villages from a Local Government in three States (Ekiti, Ondo and Osun), resulting into 60 trees for the study were sampled and analyzed. The pods were measured for morphological parameters (pod number, pod weight, pod length, pod breadth, and number of seeds). Means for each parameter were computed and analysis of variance (ANOVA) was carried out to determine if there were significant differences between States. The result of tree growth parameters differs from one State to another. It reveals that height ranges from 3.3- 13m (Osun), 2.7-13.5m (Ekiti) and 5.3-9.5m (Ondo State). Crown diameter shows that the tree in Osun varies between 4-18m, 7.5-20.2m, and 6- 23.2m for Ekiti and Ondo. Tree mean dbh varies from one state to the others, ranges between 9.1-18.9cm (Osun); 11.8-20.8cm (Ekiti) and between 10.7cm and 13.4cm (Ondo State) respectively. There were significant variations in morphological traits from one State to the other. Mean pod number varied from 31- 40.6, with trees from Ondo show higher number than Ekiti and Osun States. The morphological values were found to be higher in Ondo State than those recorded in Ekiti and Osun States respectively. The differences between States are a reflection of the different agroclimatic and soil conditions of Southwestern States. These morphological differences expressed will be very useful for promoting domestication and commercialization of Parkia biglobosa in Nigeria.
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The study was conducted to identify superior D. edulis trees using phenotypic characters (fruit and seed size) as the criteria to select candidate trees for subsequent multiplication through vegetative propagation. Five D. edulis compound trees were randomly selected within Onne community in Eleme LGA Rivers state in a preliminary effort to assist households in the selection and multiplication of desirable tree phenotypes. Seeds were extracted by softening fruit with warm water at 57 o C. Fruit and seed length (mm), breadth (mm), and thickness (mm) were taken using veneer caliper. Size of fruit and seed was calculated as: length × breadth × thickness. The experiment was a completely randomized design in its layout and data analysis was carried out using analysis of variance and regression after a normality test was conducted using Shapiro-Wilk. The results showed that highest mean fruit size (79.38 ± 3.99 mm) was recorded in tree 3 and the lowest was tree 5 (29.60 ± 1.48 mm): while, highest seed size (34.78 ± 2.47 mm) was recorded in tree 3 and the lowest in tree 4 (15.58 ± 0.99 mm). Highest within tree fruit size variability was recorded in tree 1 (24%) and the lowest in tree 4 (12%): while the highest within tree seed size variability was recorded in tree 2 (28%) and the lowest in tree 5 (15%). There was however a significant difference in fruit and seed size between the trees. Pairwise comparison showed that tree 1 was not significantly different from tree 2 in fruit and seed size. There was a significant positive correlation between fruit and seed size among the trees. This implies that selection for large fruit size automatically selects for large seeds size. Large fruited trees can therefore be multiplied from these trees using vegetative propagation.
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Main conclusion: Over the last 25 years, the process of domesticating culturally-important, highly-nutritious, indigenous food-tree species. Integrating these over-looked 'Cinderella' species into conventional farming systems as new crops is playing a critical role in raising the productivity of staple food crops and improving the livelihoods of poor smallholder farmers. This experience has important policy implications for the sustainability of tropical/sub-tropical agriculture, the rural economy and the global environment. A participatory domestication process has been implemented in local communities using appropriate horticultural technologies to characterize genetic variation in non-timber forest products and produce putative cultivars by the vegetative propagation of elite trees in rural resource centers. When integrated into mainstream agriculture, these new crops diversify farmers' fields and generate income. Together, these outcomes address land degradation and social deprivation-two of the main constraints to staple food production-through beneficial effects on soil fertility, agroecosystem functions, community livelihoods, local trade and employment. Thus, the cultivation of these 'socially modified crops' offers a new strategy for the sustainable intensification of tropical agriculture based on the maximization of total factor productivity with minimal environmental and social trade-offs.
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To address the issues of food insecurity within the context of land degradation, extreme poverty and social deprivation, this review seeks first to understand the main constraints to food production on smallholder farms in Africa. It then proposes a highly-adaptable, yet generic, 3-step solution aimed at reversing the downward spiral which traps subsistence farmers in hunger and poverty. This has been found to be effective in greatly increasing the yields of staple food crops and reducing the ‘yield gap’. This solution includes the restoration of soil fertility and ecological functions, as well as the cultivation, domestication and commercialization of traditionally-important, highly nutritious, indigenous food products for income generation and business development. A participatory approach involving capacity building at the community-level, leads to the development of ‘socially modified crops’ which deliver multiple environmental, social and economic benefits, suggesting that increased agricultural production does not have to be detrimental to biodiversity, to agroecological function, and/or to climate change. These are outcomes unattainable by attempting to raise crop yields using conventional crop breeding or genetic modification. Likewise, the livelihoods of smallholder farmers can be released from the constraints creating spatial trade-offs between subsistence agriculture and (i) international policies and (ii) globalized trade.
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Stem cuttings of five tree species from dry and semi-arid woodlands and seven species from moist tropical forests have been easily rooted in improved low-technology, high humidity polythene propagators in Kenya, Cameroon, Costa Rica and Britain. These propagators, which are cheap to construct, are very effective and have no essential requirements for either piped water or an electricity supply. Experiments have tested different rooting media, auxin applications and compared mist versus non-mist propagation. -from Authors
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The continued threat to the world's land resources is exacerbated by the protracted food crisis in sub-Saharan Africa. Per capita food production continues to decrease even though this region compares favorably with other tropical regions in terms of climate and soil resources. The main determinant of this situation is the widely recognized need for an enabling policy environment that favors smallholder rural development. However, there are two other key determinants to food security and environmental sustainability in Africa that have not received sufficient attention in the past and are the focus of this contribution: (1) the need to tackle soil fertility depletion as the fundamental biophysical constraint to food security and (2) the need for more intensive and diverse land use, based on the domestication of indigenous trees to produce high value products while increasing agroecosystem resilience. Approaches that include these three issues will transform smallholder farming in Africa into productive and sustainable enterprises and will contribute greatly to food security and environmental conservation, in a win-win situation. (C) 1997 Elsevier Science B.V.
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Air layering (or marcotting) of ‘safou’ (Dacryodes edulis) is most successful with large diameter, horizontal branches with thick bark. However, rooting remains slow and severance is only possible five months after setting the marcots. Application of growth regulators helps to accelerate rooting and reduces the severance period from five to three months. The best results were obtained with IBA. The most effective rooting medium for D. edulis juvenile leafy stem cuttings was found to be sawdust or a sand/sawdust mixture, but no significant effect of hormonal stimulation on rooting was recorded. A technique for disinfecting mature plant material of D. edulis for in vitro propagation is reported. The reputation of D. edulis as a species that is difficult to propagate vegetatively is incorrect. This has important implications for the domestication of the species.
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Drying and extraction are methods used in the processing of safou (Dacryodes edulis) fruit to separate oils from other products. Typically, the choice of the processing method is determined by economic rather than technical criteria. The increasing demand for safou oil by cosmetic industries has led to the development of electric driers and presses, which are gradually replacing solar driers and manual presses. These developments have maintained processing efficiency, while increasing the purity and the quality of the oil. Solar driers reduced the moisture content of safou fruit from 70 to 13% after 5 days, while electric driers reduced moisture content from 57 to 7% in just 15 hours. Extraction yields vary according to the size of safou fruit, between 25 to 40% for an electric press in the Congo and between 23 to 28% for a hand press in Cameroon.