Mass Screening of Sweetpotato Germplasm Shows Promise for Climate-Resilient Varieties

Scientists in the International Potato Center’s (CIP) Global Program for Genetic Resources undertook a mass field screening of 1,973 sweetpotato accessions from the CIP Genebank in the lowlands of northern Peru that resulted in the identification of 146 accessions that performed well under heat-stress conditions.

The results of the study, funded by the CGIAR Research Program on Roots, Tubers and Bananas (RTB), show that CIP has ample genetic material for breeding improved sweetpotato varieties for marginal regions or the extreme conditions predicted under climate change.

Sweetpotato germplasm at the CIP genebank. Photo: CIP

Sweetpotato germplasm at the CIP genebank. Photo: CIP

“We knew that sweetpotato was a robust crop, but the results of this study show that it is very heat tolerant,” said researcher Bettina Heider, who led the field screening.

She explained that the accessions were planted in Peru’s northern desert, near the city of Piura, for two cropping cycles: the southern winter of 2013 and summer of 2014. Summer temperatures near Piura can reach highs of 40 °C during the day and between 20 °C and 30 °C at night.

Warm soil at night typically causes sweetpotato to produce “pencil roots” with little or no value. At the end of each cycle, the researchers recorded details for each accession such as total yield, root conditions, leaf and vine biomass and any pest problems detected.

At least 21 of the accessions showed high yields and early bulking under heat-stress conditions, which makes them good candidates for further selection and breeding efforts. Heider noted that the test site has poor, sandy soil and some plants suffered drought stress, which means the accessions that performed well have real potential for relieving hunger and malnutrition on marginal lands.

“This is really promising because we now know that we have germplasm that we can send to areas that suffer heat and related stress. In many areas of Africa and Asia, all the good farmland is already dedicated to other crops, and as the population grows, farmers are moving into marginal areas,” Heider said.

She explained that her team separated accessions according to know traits such as roots with high beta-carotene, or that are sweet or not sweet, which scientists in different countries are already breeding for. She added that the accessions in the CIP genebank are from all over the world, and some of the ones that performed best under heat stress are from Asia.

“The idea is that this information strengthens the breeding program,” she said. “The next step is to send the accessions that performed well for multiple testing in other regions.”

In addition to producing useful information for CIP’s genebank and sweetpotato breeding program, the field study was innovative in its use of remote sensing data, thanks to a collaboration with the IRD office in Ecuador, a member of RTB’s global partnership with French organizations. Information from remote sensing has not only enhanced the sweetpotato mass screening, it will strengthen the future use of this type of data for evaluation of sweetpotato in the field.

“The good news is that enough of the clones performed well that we have a lot of germplasm that could be used in marginal areas or under climate change conditions. If you look at the clones that performed well under both the heat-stress and winter scenarios, they could be well adapted to the kind of weather extremes that climate change models predict,” Heider said.