Improving Household Livelihood in Rural Benin through Better Utilization of Plant Biodiversity: Valorisation of Sorghum Cultivars Yielding a Natural Dye

Dye-sorghum as a distinct crop was discovered only recently. It is traditionally grown in rural Benin and neighbouring areas. The dye is extracted by rural women and is used to dye food (cheese and porridge), textiles and handicrafts. It is also used as a medicine.

The proposed project will contribute to the development of dye-sorghum into an improved cash crop. The objective of this development is to increase incomes and improve livelihoods of the small farmers of rural Benin, in most instances rural women. To assess the current role of sorghum, a socio-economic survey will be carried out covering the dye-sorghum growing area of central and northern Benin. It will assess costs and benefits of production, the place in the cropping systems, allocation of labour, land and external inputs, the supply chain from farmer to trader and consumer. Modernizing the cultivation of a traditional crop often leads to the selection and breeding of a few high-yielding cultivars. Description and conservation of the currently genetic diversity of dye-sorghum will safeguard the genetic diversity and retain it for breeding and adaptation to changing environments. The proposed project will collect c. 300 samples of dye-sorghum from 26 ethnic groups who each grow their own landrace. It will describe the plants in farmers’ fields and under uniform conditions in a research station. Samples will be submitted to a genebank.

Apigeninidin, the dye produced by the dye-sorghum landraces of Benin, is often described a phytoalexin, i.e. a chemical compound produced as a response to stress, the stress factors being attack by insects or fungi, poor phosphate nutrition or low temperatures. In dye-sorghum, a fungus has often been mentioned as the trigger causing the dye production. However, other reports do not mention a fungus at all. As the presence of a fungus with a role in dye production would have great consequences for agricultural research on dye-sorghum and for the development of the crop, the presence of fungi will be tested in a representative number of samples. The effects of stress on the dye-sorghum plant and on dye production will also be studied in an observation trial. Plants will be grown under minimal stress (irrigation during dry spells and early removal of the panicle) to see if and how this affects dye production.

In an effort to improve the management of dye-sorghum and increase yields, the effects of plant nutrition on the growth of a number of landraces of dye-sorghum and on biomass and dye production will be studied in a fertilizer trial. Both the production of dye and of total biomass (important e.g. for animal feed) will be studied. The agronomic studies will be discussed with local farmers during a preliminary meeting. This may lead to adaptations of the programme. The results of the experiments will be presented to and discussed with stakeholders in meetings at the end of the first and second year of the project.

Capacity building is an important component of the project. The stakeholder meetings aim at an exchange of information between farmers, traders and consumers on the one hand and researchers on the other. The project will also train 8 MSc students in Benin and 1 student in the Netherlands. The exchange of information between researchers from the Université d’Abomey Calavi in Benin and Wageningen UR will be mutually beneficial.

The proposed project is submitted to the DGIS/WUR Partnership Programme, theme 3: ‘Sustainable use of agro-biodiversity’. It also has links with theme 1 of the programme: ‘Sustainable agro-supply chains’. The proposed project is a sequel to a PROTA Pilot Project in which a method producing the dye in powdered form was tested and adopted. The socio-economic survey will assess marketing of the sorghum dye. International food companies have already expressed interest in the dye which gives.