Super sweetpotato gains ground in San Ramon

This was the question posed by breeders at the International Potato Center (CIP) some time ago, encouraged by the extraordinary successes of the Center’s orange-fleshed sweetpotato program in the poorest areas of Africa, where Vitamin A deficiency condemns millions of children to blindness.

The pigmentation of the purple fleshed sweetpotato varieties is due to the presence of anthocyanins. Studies from Kansas State University have revealed that two of these anthocyanins contain properties inhibiting the growth of cancer cells in the human colon.

“My nutritionist colleagues tell me that the anthocyanins in sweetpotato have good bioavailabilty, meaning they are easily absorbed from the digestive tract into the bloodstream, where they may have beneficial effects,” indicates Dr. Ted Carey CIP sweetpotato breeder in Ghana.

Peru, as a secondary center of sweet potato biodiversity, has a rich genetic variability in the crop, which facilitates scientific research

And so, at CIP’s experimental station in San Ramon, Peru situated on the eastern rainforest covered slopes of the Andes, national scientists got down to business: they selected different samples of orange, purple, and white-fleshed sweetpotatoes from the Center’s genebank and started creating new crop populations with better agronomic and nutritional characteristics.

CIP researcher Federico Diaz is enthusiastic about the possibilities. “We have research materials (advanced and elite clones) with high mineral and beta carotene content, and we are evaluating promising clones which contain a higher dry matter content,” he says. “We are also looking at purple sweetpotato progenies with high anthocyanin content, and there are some clones that contain both anthocyanin and beta-carotene. We are confident that these will have a major impact in the future. We calculate that in three years these materials will be ready to send to other continents for assessment in different agro-ecologies.”

The possibilities of this ‘super sweet potato’ for hunger relief and food security are impressive.

Currently, in addition to field testing, CIP scientists also do laboratory tests for nutritional characteristics of these and other sweetpotato clones in the germplasm collection.

“We are evaluating nutritional components such as beta-carotene, protein, starch and dry matter, and also minerals and micronutrients such as iron, zinc, and magnesium”, explains Genoveva Rossel, CIP’s sweetpotato germplasm collection curator.

Screening takes place in the Quality and Nutrition laboratory at CIP’s global headquarters in Lima, Peru. Using advanced technologies, the laboratory analyzes the micronutrient content of potato, sweetpotato, and other staple crops.

But the Center’s sweetpotato program does not only focus on nutritional testing. Taking advantage of San Ramon’s subtropical conditions, high in Peru’s rainforest at an altitude of 800 meters, scientists hope within six years to have planted the center’s whole sweetpotato collection at the station; including samples not only from Peru and Latin America but also from other parts of the world. They also aim to have an in vitro (test tube) duplicate of all sweetpotato accessions in the genebank.

“One of our main objectives is to identify and select materials that can be improved and introduced to other parts of the world with similar ecologies, such as Asia or Africa,” says Rossel. An example of how biodiversity can be used to help the world’s poorest populations.

A key issue is genetic improvement. Some of the attributes that breeders are working on in white, orange, and purple-fleshed sweetpotato are: increased productivity, resistance to the crop’s main nematode and virus enemies, earliness, and genetic stability. They also breed to produce other specific requirements for farmers and industry. White sweetpotatoes for example are more geared towards industry and could even serve in the future for the production of ethanol.

Another research priority is dual purpose sweet potato grown for both human consumption and animal feed. Diaz reports that this dual use is fairly widespread in some Asian countries, but not in Peru. However, thanks to an open field day that the station held in late August, local farmers have become aware of this alternative and are already requesting varieties with dual use characteristics.

“The local people here in San Ramon are very excited because they realize they can have a complement to their traditional crops to help them feed their families and their animals. They can also get sweetpotato varieties from CIP to increase their crop yields which at the moment are very low,” says Dr Bettina Heider, pre breeder and San Ramon station supervisor.

Other experiments at San Ramon are evaluating the effectiveness of different crossing techniques for the production of botanic seed, which could potentially lower seed production costs.

“For the second half of next year we should have botanical seed produced by two different methods for planting and evaluation. By 2012 we will have conclusive results about the most appropriate methodology for generating populations in sweetpotato breeding”, concludes Diaz.