A simple non-mist polythene propagator being used to root single-node, leafy, stem cuttings of a selected tree for its mass propagation, domestication and subsequent cultivation as individual plants. Photo Credit: Prof RRB Leakey

Africa leads the way in developing super tree crops

Roger RB Leakey
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[rt_dropcap_style dropcap_letter=”A” dropcap_content=”ROUND the world, especially in the tropics and sub-tropics, there are tens of thousands of plant species which produce edible fruits, nuts and leaves. There are even more which produce medicinal products. In traditional culture, many, if not most, of these have been important locally in everyday life. Today, as a result of deforestation, the availability of these products has declined.”]

ROUND the world, especially in the tropics and sub-tropics, there are tens of thousands of plant species which produce edible fruits, nuts and leaves. There are even more which produce medicinal products. In traditional culture, many, if not most, of these have been important locally in everyday life. Today, as a result of deforestation, the availability of these products has declined.

In addition, the demand has declined as lifestyles have changed with increased urbanisation. Nevertheless, a transformation is underway. Rural households struggling to survive on small and typically unproductive farms producing a very limited range of food crops now seek to bring these traditionally important species back into their lives.

As highlighted in an article in the Pan African Agriculture issue of JanuaryMarch 2023, over the last 30 years an indigenous food revolution has begun and scientists in 532 research teams in 310 organisations of 34 African countries have been working to domesticate some 60 of these indigenous species as new crops to diversify farming systems and local economies. These initiatives span all the agroecological regions of Africa, with some species being important in more than one region.

Notable among the nutritious and marketable products of these new crops are: the leaves and fruits of Baobab (A. digitata), fruits and oilrich kernels of Marula (S. birrea), oily fruits of Safou (D. edulis), the food thickening kernels of Bush mango (I. gabonensis / I. wombolu), the nuts of Cola, Kola, Shea (C. spp., G. kola, V. paradoxa) and the leaves of Eru (G. africana).

This initiative to develop new tree crops started in 1992 with an international conference in Edinburgh, “The Rebuilding of Tropical Forest Resources”. It was then taken up in 1993 by the World Agroforestry Centre and has become a global programme, in which Africa has led the way with about 60 tree species.

The focus is on identifying and selecting elite individual trees producing fruits, nuts or leaves with useful physical or biochemical traits within wild populations.

Typically, regardless of the trait being selected, the best two or three trees in a population of 100 are 50-100 percent better than the average for the site. This means that their products are substantially more useful and more marketable than those of the wild population.

To capture this superior quality and develop a new crop, these elite trees must be propagated vegetatively. This is most easily and cheaply done by the application of very simple horticultural techniques, such as the rooting of leafy softwood stem cuttings.

These techniques have been developed over the last 50 years using home-made propagators that do not require running water or electricity (see training videos: https://www.youtube.com/ watch?v=KS97PSwbQ5E).

Thus, these techniques are appropriate for use in remote communities with minimal training. This, therefore, opens up the possibility that any rural community can engage in the activity and become the beneficiary of the outcomes. It becomes a livelihood enhancing activity driven by self-help incentives.

The programme started in Cameroon, where thousands of farmers from hundreds of villages adopted the concept and benefited both domestically and commercially from producing superior products. They were also able to sell plants to their neighbours. One of the unique features of this initiative is that it is voluntary and self-supporting. The cost to the participants is virtually zero, apart from the commitment of time and some effort.

Unlike typical development projects, this awardwinning programme was developed from scratch with a participatory, grassroots, approach. This has been a key driver of its success as once the participant has learnt the basic skills, he or she can select, propagate and then cultivate whatever species suits them, in whatever way and on whatever scale they wish.

They manage the activity, and they are the beneficiary of their own efforts. As mentioned earlier, now after 30 years of research done in parallel with the above participatory community initiatives,

the domestication of indigenous trees producing food and medicinal products has become a major research theme in African research institutes and universities.

This research is filling a void in the scientific literature and providing important knowledge about the many species overlooked by science and specifically by agriculture. Embedded within this new knowledge is a growing recognition that these indigenous tree species have a wide range of biochemical properties.

When harnessed by domestication, these properties could create highly nutritious and commercially important functional foods to meet the complex needs of malnourished and sick people. These products then have important implications for the development of local businesses in trade, product processing and the development of new industries. Ideally, these opportunities can be realised incountry, so enriching the national economy and providing employment for local urban populations.

These more technically complex commercial activities can be linked to the domestication programmes through selection criteria supported by the ‘Ideotype Concept’. This is a means by which the tree selection process in the field can be marriedup with the laboratory characterised biochemical traits needed for industrial development. This allows the identification and selection of the ‘Ideal Tree’ in wild populations for subsequent propagation. As described in a previous article in the Pan African Agriculture issue of January-March 2023 these developments have important international policy and business implications. Potentially, adding these new crops to tropical agriculture can help to achieve the UN sustainable development goals by restoring and recapturing natural, social and human capital within African agriculture and new related food industries.

Roger RB Leakey is Vice President, International Tree Foundation, Oxford, UK. REF: Leakey, R.R.B., Tientcheu Avana, M.-L., Awazi, N.P., Assogbadjo, A.E., Mabhaudhi, T., Hendre, P.S., Degrande, A., Hlahla, S. and Manda L. 2022. The future of food: domestication and commercialization of indigenous food crops in Africa over the third decade (2012-2021), Sustainability 14:2355. https:// doi.org/10.3390/ su14042355

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