Scientists look at needs to develop sweet potato sector

Next year is the 'International Year of the Potato'. Sweet potatoes, often misunderstood, underrated and disliked by local populations as a marginal food, are receiving new attention as a life-saving crop in developing countries. Scientists conducted a survey to understand why the sweet potato remains a relatively marginal crop, despite its large potential. The results offer an interesting insight into the reasons as to why agriculture in many developing countries is so unproductive. If poor countries were to apply modern farming techniques to produce food, an enormous potential land base for the production of bioenergy becomes available. Improved food production implies greater climate saving biomass potential.

Rich in carbohydrates, the crop is already being used for the production of ethanol and bioplastics. Several African countries have an 'industrial' sweet potato program in place. China considers it to be a non-food crop and has therefor included it in its range of crops suitable for the production of industrial products, including biofuels (more here).

According to the International Potato Center, more than 95 percent of the global sweetpotato crop is grown in developing countries, where it is the fifth most important food crop. Despite its name, the sweetpotato is not related to the potato. Potatoes are tubers (referring to their thickened stems) and members of the Solanaceae family, which also includes tomatoes, red peppers, and eggplant. Sweetpotatoes are classified as "storage roots" and belong to the morning-glory family.

Sweetpotato has received relative little attention from crop improvement research. To bring attention to the issue, results of a survey were published by the American Society for Horticultural Science in which researchers asked 36 scientists from 21 developing countries to solicit opinions on key constraints affecting the productivity of small sweetpotato producers.

Keith Fuglie, of the Resources and Rural Economics Division at the United States Department of Agriculture's Economic Research Service, led the study. He found consistent key constraints in all major sweetpotato producing areas.

Survey respondents indicated that the priority needs in developing countries were:

1. control of viruses
2. small-enterprise development for sweetpotato processing
3. improvement in availability and quality of sweetpotato planting material
4. improved cultivars exhibiting high and stable yield potential

Some differences emerged, however, in priority needs of the two major centers of sweetpotato production - Sub-Saharan Africa and China. In the People's Republic, the crop is primarily used as an animal feed, whereas in Africa, it is a major food crop.

Additional priorities for Sub-Saharan Africa included (1) improved control of the sweetpotato weevil and (2) cultivars with high beta carotene content to address Vitamin A deficiency. For China, priorities included: (1) conservation and characterization of genetic resources, (2) prebreeding, (3) cultivars with high starch yield, and (4) new product development, including biofuels and bioplastics:
sustainability :: energy :: biomass :: bioenergy :: biofuels :: sweet potato :: agronomy :: crop research :: plant breeding ::

According to Fuglie, the different sets of priorities reflect differences in the role of sweetpotato in the rural economy and also different capacities of the agricultural research system in these regions of the world.

These findings could help agricultural scientists working for national and international institutions establish their priorities for sweet potato crop improvement research. Focusing research on the key productivity constraints facing sweetpotato farmers in a particular country or region will increase the likelihood of farmer adoption and potential impact of the technology resulting from that research. - Keith Fuglie, lead researcher, Resources and Rural Economics Division, ARS

Principal beneficiaries of the research study will be small-scale sweet potato farmers in developing countries. Fuglie hopes that emerging technologies based on research will be available for sweetpotato farmers within 5 to 10 years.

Scientists believe that sweetpotatoes were domesticated more than 5,000 years ago and reportedly introduced into China in the late 16th century. Because of its hardy nature and broad adaptability, sweetpotato spread through Asia, Africa, and Latin America during the 17th and 18th centuries. It is now grown in more developing countries than any other root crop.

Sweetpotato has a long history as a lifesaving crop. When typhoons demolished thousands of rice fields, Japanese farmers turned to sweetpotato to sustain their country. Sweetpotato kept millions from starvation in famine-plagued China in the early 1960s, and in Uganda, where a virus ravaged cassava crops in the 1990s, the hardy hero came to the rescue, nourishing millions in rural communities.

Rich in carbohydrates and vitamin A, sweetpotatoes are nutrition superstars. Uses range from consumption of fresh roots or leaves to processing into animal feed, starch, flour, candy and alcohol. Because of its versatility and adaptability, sweetpotato ranks as the world's seventh most important food crop (following wheat, rice, maize, potato, barley, and cassava). Globally, more than 133 million tons of the underrated, vitamin-packed root are produced each year.

References:
Keith O. Fuglie, "Priorities for Sweetpotato Research in Developing Countries: Results of a Survey", HortScience 42: 1046-1311 (2007)

Biopact: Sweet potatoes and the carbohydrate economy - January 07, 2007