In 1996, scientists from the World Agroforestry Centre asked some 6000 farmers in Cameroon, Gabon, Ghana and Nigeria to name the trees they valued most highly. “I was shocked when we analysed the data,” recalls Zac Tchoundjeu, principal tree scientist in Cameroon. “As a forester, I was expecting them to mention commercially important species like mahogany, but none of them did. What they valued most were indigenous fruit trees, about which we knew very little.” Although there were some variations in preferences both within and between countries, a small number of fruit trees – especially Bush mango (Irvingia gabonensis), African Plum (Dacroydes edulis) and the African nut (Ricinodendron heudelotii) – were popular with all those questioned. If researchers, working with farmers, could domesticate and commercialize these species, then the welfare and incomes of some of the poorest people in Africa would improve.

With this in mind, Tchoundjeu and his colleagues launched a programme of participatory tree domestication. They analysed what traits were most appreciated by farmers – they wanted trees that produced large fruit at an early age with a sweet taste – and established nurseries where they began to develop new varieties. In 1996, there were just two farmers’ tree nurseries; now there over 150, and some communities are making thousands of dollars a year selling improved varieties of indigenous fruit tree.

This is one of the many research programmes described in the book, Indigenous Fruit Trees in the Tropics: Domestication, Utilization and Commercialization. Although much of the book is devoted to research conducted by the World Agroforesty Centre and its partners in Eastern, Central, Southern and West Africa, it also provides an overview of the opportunities for domestication and commercialization in South America, Oceania and Southeast Asia.

Indigenous fruit trees have always been important to the rural poor. For example, in Malawi, Mozambique and Zambia, up to 80 per cent of rural households lack access to adequate supplies of food for around a quarter of the year, and up to half of those interviewed in one survey said they relied on indigenous fruits to sustain them during this critical period. “Our research shows that the probability of households in Zimbabwe falling below the poverty line is 30 per cent less if they have access to indigenous fruit trees,” explains Festus Akinnifesi, the senior author of the indigenous fruit tree book and the World Agroforestry Centre’s Regional Coordinator for Southern Africa. “These species were largely ignored by researchers until recently, and local farmers lacked the understanding and skills to domesticate them and integrate them into their farming systems.”

Domestication takes advantage of variations in the wild, which can be considerable. For example, a sample of 15 trees belonging to one nut-bearing species in Southern Africa, Sclerocarya birrea, found that the oil yield per nut ranged from 5 to 53 grams. The numbers of fruit of another species, Ziziphus mauritania, varies from less than 20 to more than 2000. (See box page 12: Getting the best out of ber.) The aim of domestication is to choose certain traits and use techniques such as grafting to create the most desirable varieties, which can then be propagated and distributed to farmers. A trial with grafted or marcotted Uapaca kirkiana, the most popular indigenous fruit tree in Southern Africa, produced more than 4000 fruits compared to less than a thousand in the wild, and fruited in 4 years as compared to more than 12 years in the wild.

What distinguishes the research conducted on indigenous fruit trees by the World Agroforestry Centre from traditional agricultural and silvicultural tree crop development is its strong emphasis on the development of participatory clonal propagation as a way of fast-tracking selection processes, rather than on conventional breeding, which requires a long period to develop true-to-type varieties. “From the outset, we recognized that it was essential to involve farmers at every stage,” recalls Tchoundjeu. “Whatever experiments were conducted in our own nurseries, they were replicated in the farmers’ fields. The fact is that when we began our research, the farmers knew more about these species than we did.”

Having identified the species that mattered most to the farmers, Akinnifesi and his colleagues in Southern Africa relied on local people to show them trees in the wild that possessed the traits they considered most valuable. “We would follow them into the forest, mark the trees, catalogue and name them – so that the farmers retained their property rights – and then take samples back to our nurseries for evaluation in clonal orchards,” explains Akinnifesi.

The greatest progress was made by grafting scions from favoured mother trees on to nursery rootstock. Indigenous Fruit Trees in the Tropics describes the considerable research that went into developing the best vegetative propagation techniques and selection of elite trees from the wild. Initially, the scientists had only 10 per cent grafting success for species like Uapaca kirkiana; the success rate is now close to 80 per cent. Research has also helped to establish what conditions are required if domesticated fruit trees are to flourish on farmers’ fields. It seems that the use of fertilizers and irrigation makes little difference, as most species are adapted to poor soils. This is greatly to the advantage of farmers, although they need to ensure they have the right sort of soil, as many indigenous fruit trees will only thrive in the presence of certain mycorrhizae.

Commercialization must go hand-in-hand with domestication if indigenous fruit trees are to improve the welfare of rural communities. So far, researchers have concentrated mostly on farmers’ concerns, and paid little attention to those of consumers and marketers. More research needs to be carried out on developing products with an improved shelf life and higher nutritional value. In recent years scientists from the World Agroforestry Centre have provided inputs to training schemes that focus on the processing of fruits into juices, jams, sweets and wine. “We have been assessing the feasibility of these sort of enterprises, and results from enterprises in Malawi, Tanzania, Zambia and Zimbabwe showed that the profits could be quite high, especially for those processing indigenous fruits near city markets,” says Akinnifesi.

Indigenous Fruit Trees in the Tropics is an essential source book for students, academics and practitioners, and it provides a solid foundation on which new science, partners and market opportunities can be developed in future. Indigenous fruit and nut trees in the tropics have long been described as ‘Cinderella species’ as their importance has been largely overlooked. This book should help to change that.

Further reading
Akinnifesi FK, Leakey RRB, Ajayi OC, Sileshi G, Tchoundjeu Z, Matakala P, Kwesiga FR eds. 2008. Indigenous Fruit Trees in the Tropics: Domestication, Utilization and Commercialization. Nairobi: World Agroforestry Centre. http://worldagroforestry.org/Library/listdetails.asp?id=50396 Pye-Smith C. 2008. Farming Trees, Banishing Hunger. How an Agroforestry programme is helping smallholders in Malawi to grow more food and improve their livelihoods. Nairobi: World Agroforestry Centre. http://www.worldagroforestry.org/library/listdetails.asp?id=50842

For more information, contact
Festus Akinnifesi,
f.akinnifesi@cgiar.org