Issues Magazine

Unleashing the Potential of Wild Fruits

By Kate Langford

Bringing superior varieties of fruit trees out of the forest and domesticating them to be grown on farms and in gardens is increasing biodiversity and generating income for farmers in Africa, Latin America, Asia and Australia.

In 1999 Christophe Missé, a farmer in Cameroon, attended a training session held by the World Agroforestry Centre in Nkolfep, Cameroon, that changed his life. He learnt techniques for developing superior varieties of indigenous fruit trees, and now runs a nursery with his neighbours, selling over 7000 trees a year. He has also planted hundreds of indigenous fruit trees on his farm.

“With the money I’ve made I’ve built a new house,” he says proudly, “and I can now pay for two of my children to go to private school”.

Missé is one of many thousands of small­holders who are benefiting from participatory tree domestication programs. Bringing superior varieties of fruit trees out of the forest and onto farmland is increasing biodiversity and generating income for resource-poor farmers in Africa, Latin America and Asia.

Domestication, or the process of capturing the desired traits of wild species, has been the basis of crop development for centuries. It involves developing new varieties to be grown in monocultures, often in large plantations.

In the case of edible macadamia nuts (Macadamia integrifolia and M. tetraphylla) – the only native Australian product to be developed and exported commercially as a food crop – the process of domestication has been going on for more than 100 years. The nut was first taken from the forests of eastern Australia and grown in a commercial orchard in the early 1880s.

However, it was in Hawaii where the industry really developed. Seedlings were taken there to be used as wind breaks in sugar cane production. In 1937 the first successful grafting of macadamia nuts was reported in Science but it wasn’t until the 1970s that the Australian macadamia nut industry really started to flourish. Today it is worth around A$120 million per year, with Australia growing about 40% of the global produce.

CSIRO is still actively breeding macadamias to produce more profitable and tastier varieties. Within wild populations there is genetic diversity and favourable characteristics that may not have been taken advantage of during the earlier development of commercial varieties.

What is different about the participatory tree domestication work of the World Agroforestry Centre in developing countries is that local farmers play a key role in selecting, propagating and planting new varieties, as well as managing them in the environment. And it is these farmers who stand to benefit most from this approach.

“We ask local people which indigenous trees they value most and for what traits,” explains Zac Tchoundjeu, Co-leader of the Centre’s Global Research Project on Tree Domestication and Agroforestry Germplasm. “Most commonly the response is ones with large, sweet fruit grown on trees which mature quickly.”

In Cameroon, these species include bush mango (Irvingia gabonensis), African plum (Dacryodes edulis), African nut (Ricinodendron heudelotii) and bitter kola (Garcinia kola). In the Amazon they include three palm species: aguaje (Mauritia flexuosa), majo or ungurahui (Jessenia batauba) and peach palm (Bactris gasipaes), and two other fruit trees: camu-camu (Myrciaria dubia) and cupuaçu (Theobroma copuazu). In China they include pine nut and walnut.

In Africa alone there are around 3000 species of wild fruit, representing an enormously important, and largely untapped, natural resource.

In Australia there are several native citrus species that are adapted to the country’s dry and varied climate. In the past, yields from wild-harvested trees have been inconsistent and the fruit small, but by selecting and crossing native citrus with modern cultivars, scientists at CSIRO have now produced three high-yielding citrus varieties with larger than normal fruit, consistent yields and the unique flavour and texture of Australian native limes. These are proving popular in domestic gardens.

Among the high biodiversity of the Amazon are hundreds of wild fruit trees. The FRUTAM project – a major collaboration between the World Agroforestry Centre and partners in the Amazon Initiative – aims to unleash the potential of just some of these for income generation and poverty alleviation, while ensuring that genetic diversity is not lost.

“We are combining technological, socio-organisational and market innovations to tap into the biodiversity potential of Amazon fruit trees,” says Julio Ugarte from the Centre in Peru. “The aim is to provide tangible livelihood assets among local communities.”

Once the species for domestication have been chosen, local people work with geneticists to identify individual trees in the wild that possess the desired traits. Germ plasm, in the form of vegetative material, is then collected and used to establish superior “accessions” at research sites and nurseries.

“Domestication takes advantage of the huge genetic variation which exists in the wild,” says Tchoundjeu. “Different trees of the same species can bear fruits that are sweet or sour, large or small.”

The scientists then research how to best propagate superior trees so that large numbers of identical copies (or clones) can be available as soon as possible. Conventionally, new varieties are developed through breeding, but this can take considerable time. For superior fruit trees needed now, vegetative propagation techniques such as rooting, grafting and marcotting (i.e. stimulating a branch or twig to produce roots while it is still attached to the parent plant) are used.

Farmers are provided with training in which techniques to use for which species, enabling them to propagate wild species in their own nurseries and on their farms.

In the case of macadamia nuts in Australia, CSIRO scientists are looking at different types of rootstock to identify those that combine most effectively with different macadamia varieties. Macadamias have typically only been grown on one sort of seedling rootstock.

According to Tchoundjeu, “the success of the participatory tree domestication program lies in its use of simple, low-cost horticultural techniques which have an almost immediate impact on reducing poverty and improving human welfare”. Ten years ago in Cameroon there were just four farmers’ nurseries. Now there are several thousand. “People become less dependent on commodity markets,” he says, “and they produce a crop they can both eat and sell”.

“In China, mountain farmers earn 30% more from selling certified organic pine nuts and walnuts, says Jianchu Xu, senior scientist from the Centre’s China Program. “They practice chemical-free management that enhances both soil fauna and water quality.”

With more indigenous trees being grown on farms, the biodiversity benefits are evident. Natural forests are benefitting too, as farmers who have improved their incomes are much less likely to exploit forests.