[Dioscorea Dumetorum (Kunth) Pax] in Benin

Genet Resour Crop Evol https://doi.org/10.1007/s10722-019-00739-z (0123456789().,-volV)(0123456789().,-volV) RESEARCH ARTICLE Diversity, distribution and ethnobotanical importance of cultivated and wild African trifoliate yam [Dioscorea dumetorum (Kunth) Pax] in Benin Fabienne Ade´tola Adigoun-Akotegnon . Hubert Adoukonou-Sagbadja . Charles Fadinan . Ariel Tchougourou . Micheline Agassounon-Tchibozo . Corneille Ahanhanzo Received: 25 August 2018 / Accepted: 4 January 2019 Ó Springer Nature B.V. 2019 Abstract Dioscorea dumetorum is an important traditional. Farmers’ preference criteria in selecting native tuber crop commonly grown in West Africa. cultivars relied essentially on plant attributes and The present study aimed to document the indigenous environment stress adaptations. The crop is grown knowledge related to its diversity and distribution as mainly for food and trading purposes while it is also well its ethnobotanical importance in the production used in traditional medicine and magico-mystic ritu- areas in Benin. In total, 555 farmers belonging to 18 als. Along with agro-ecological parameter, the results socio-linguistic groups were surveyed in 78 villages revealed that the socio-cultural factors such as the covering the major production areas in the country. ethnic group and the age of farmers had significant The study revealed that local farmers have developed impact the overall use value of D. dumetorum. Wild important knowledge on the production and uses of morphotypes of D. dumetorum were recognized and this tuber crop. Twenty-five farmer-named landraces, also exploited in ethnomedicine by farmers. Although further grouped into 3 major morphotypes, were well appreciated by the farmers, the potential of the globally recorded. Their extent and distribution varied crop was less exploited. Concerted efforts are needed significantly, with in general the southern and central to preserve and valorize its genetic resources to agro-ecologies holding the largest cultivar diversity combat food insecurity and malnutrition in Benin. while the northern agro-ecologies being less diversi- fied. The pure yellow cultivars were the most popular Keywords Benin Á Dioscorea dumetorum Á morphotype. The seed management system remained Indigenous knowledge Á Trifoliate yam Á Varietal diversity Á Wild morphotypes F. A. Adigoun-Akotegnon Á H. Adoukonou-Sagbadja (&) Á C. Fadinan Á A. Tchougourou Laboratory of Genetic Resources and Molecular Breeding (LaREGAME), Department of Genetics and Introduction Biotechnology, Faculty of Sciences and Techniques, University of Abomey-Calavi, BP 1947, Abomey-Calavi, Yam (Dioscorea spp.) is one ofthemost importantedible Republic of Benin e-mail: [email protected]; tuber crops grown worldwide in tropical areas (Adou- [email protected] konou-Sagbadja et al. 2014;Srivastavaetal.2012). It is a well appreciated crop with high economic and socio- M. Agassounon-Tchibozo Á C. Ahanhanzo cultural values in Sub-Saharan Africa where the crop Department of Genetics and Biotechnology, Faculty of Sciences and Techniques, University of Abomey-Calavi, significally contributes to the subsistence and incomes of Abomey-Calavi, Republic of Benin several millions people (Jova et al. 2005). With about 123 Genet Resour Crop Evol 96% of global production (FAOSTAT 2013), the so- D. cayennensis-D. rotundata. According to many called ‘yam belt’ of West Africa is the principal area of authors, D. dumetorum is one of the numerous tropical yam production (Hahn et al. 1987). Monocot of the underutilized and neglected yam species (Owua- family of Dioscoreaceae, yam is a polyploid species with manam et al. 2013; Medoua et al. 2005; Alozie et al. vegetative propagation. It belongs to the highly diver- 2009; Akinoso and Abiodun 2013; Akinoso et al. sified genus Dioscorea that includes 644 species 2016; Egbuonu et al. 2014) and therefore less inves- (Coursey 1967) among which only six have economic tigated by agricultural or scientific research agencies. importance in West-Africa (Adeigbe et al. 2015). In this Nowadays, the recurrent food supply problem in region, four of these six species are cultivated: Dioscorea developing countries has highlithed the necessity of cayenensis Lam., D. rotundata Poir., D. alata L. and D. promoting alternative food sources available such as dumetorum (Kunth) Pax (Mignouna and Dansi 2003). those from neglected and underutilized plants (Adou- Except D. alata, the three other cultivated species are konou-Sagbadja et al. 2007). known to be native to West-Africa (Bhattacharjee et al. In Benin, D. dumetorum is cultivated in southern 2011). Besides, in contrast to the complex D. cayenensis- and centre parts as well in the northern part of the D. rotundata, the most cultivated and consumed yam in country. In these producing areas, diverses landraces Africa, D. dumetorum is known to be less important in and wild forms were traditionally exploited by local production but well appreciated by local populations communities. While it is well appreciated, no partic- (Adoukonou-Sagbadja 2001). ular attention is devoted to the valorization and Commonly known as African bitter yam or cluster utilization of this yam crop species. Indeed, omitted yam (Palaniswami and Peter 2008), D. dumetorum is a some general studies on yam that mentions D. trifoliate or three-leaved yam found in the wild dumetorum, no diagnostic study has been carried out throughout tropical Africa between 158°N and 158°S on this crop to know its diversity, its distribution and and is cultivated in West and Central African countries traditional management, conservation status, technical (Dansi et al. 1999, Adaramola et al. 2016, Oladeji et al. itinerary and production constraints, etc. Besides, no 2016). It is reported to be the most nutritious of the breeding efforts have yet been specifically accom- commonly consumed yams (Afoakwa and Sefa-Dedeh plished on D. dumetorum in the country (Dansi et al. 2002). The species is rich in vitamins and minerals 2012). In such situations where documented data are with its tuber protein content (9.43–10.3%) more hardly available, local farmers are the first source of balanced than those in other cultivated yams such as information to initiate diversity studies (Tamiru et al. D. alata (8.2%) and D. rotundata (7.6%) (Afoakwa 2008). Farmers’ knowledge and perceptions on crop and Sefa-Dedeh 2002). Moreover, D. dumetorum is landraces are important as these are only the unit of regarded as an energy rich food with an easy digestible diversity they recognize but also the unit they manage starch (Ukpabi 2015). According to Ferede et al. and conserve (Tamiru et al. 2008). (2010), the deep yellow flesh of D. dumetorum The major objective of this study was therefore to contains Provitamin A and carotenoids comparable contribute to the knowledge and better valorization of with those in yellow maize lines selected for increased D. dumetorum in Benin. Specifically, the present study concentration of provitamin A. Therefore, the species aims to (1) assess the varietal diversity of D. dume- is considered as a good source of phyto-proteins, torum used by farmers, its folk taxonomy and carbohydrate, vitamins and minerals for human nutri- geographical distribution in the production areas in tion (Degras 1993; Alozie et al. 2009). It is also Benin Republic, (2) analyse farmers’preference crite- reported that D. dumetorum possesses allelopathic, ria in selecting D. dumetorum cultivars for cultivation genotoxic and cytotoxic potentials that could possibly and use in the growing areas, (3) infer the traditional be further exploited for the development of anti- seed system management by local farmers in the tumoral compounds or natural herbicides for weeds producing areas, (4) document the ethnobotanical and other unwanted plants (Usman et al. 2014). importance in terms of traditional uses and the impacts Despites its high economic value and effective of the use values on the varietal diversity of the crop in potential in food and nutrition security supply, D. the production areas of Benin, and finally (5) docu- dumetorum remains a secondary crop in most produc- ment farmers’ knowledge in use and management of ing countries in West-Africa compared to the complex wild related forms of D. dumetorum. To achieve these 123 Genet Resour Crop Evol goals, several ethnobotanical surveys were conducted selected villages. In each village, traditional chiefs and through the cultivation areas in Benin. The important local authorities were involved in the study to information gathered from this study can help defining facilitate the meetings and data collection. D. dume- conservation strategies and facilitating breeding rele- torum farmers were selected using snow ball method vant cultivars that meet the farmers’ needs. (N’Danikou et al. 2015). In this sampling approach, structured and semi-structured interviews based on questionnaire were conducted through the application Materials and methods of Participatory Research Appraisal tools and techniques such as individual and focus group discussions, Description of the study area and selection matrix scoring and pairwise ranking and field visits of the surveyed sites using a questionnaire as recommended by Adouko- nou-Sagbadja et al. (2006) and recently applied by The study was conducted in the tribal areas of Assogba et al. (2015) and Zavinon et al. (2018). The production of D. dumetorum in Benin Republic questionnaire used during the interviews was first pre- (Fig. 1). The country is located on West African

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