Publications /  Annual Report 1998

CIP’s collection of ancient potato varieties may help reduce Andean farmers’ need for an increasingly scarce and precious resource—water.

Once regarded as a free good, water has become one of the most important limiting factors facing potato growers. New studies conducted by CIP’s Seed Unit indicate that several clones from the Center’s genebank provide good tuber yields under dry conditions.

Preliminary trials point to the enormous drought-tolerance potential of the native potato germplasm held in trust by CIP.

"The world’s thirst for water is likely to become one of the most pressing resource issues of the twenty-first century," asserts the World Resources Institute. The severity of recent El Niño and La Niña episodes in Latin America support widely held theories that the planet is entering a period of increased climatic volatility, marked by cycles of drought and excessive rainfall. At the same time, rapid urbanization and population growth create unprecedented competition between domestic water users and agricultural producers. In response to this emerging problem, scientists are seeking crop varieties that need less irrigation, and agricultural technologies that use water more efficiently.

CIP is doing its part. By one way of reckoning, its major mandate crop, potato, is already an efficient water user. When grown under cool climate conditions, potato produces more food per unit of water than any of the other big staple crops—wheat, rice, or maize. But in another way, potato is a water hog. Modern cultivars, bred for maximum yield, tend to require frequent and shallow irrigation. This is especially so during the periods of fast tuber development, after the leaf cover is established—that is, more than 40 days after planting—and when the potatoes are grown in environments where evapotranspiration is high.

The answer to this dilemma, says CIP plant physiologist Noël Pallais, may lie within the genes of some 3,500 native Andean potato accessions in CIP’s genebank. Though they have been conserved for more than 30 years, the collected plant matter has not been thoroughly investigated.

Now, says Pallais, molecular biology techniques have changed the timeframe for breeders to transfer genes rapidly and get results much sooner. "Thus, it is now high time to begin paying attention to the unknown value that may lie within our potato germplasm," he says.

CIP screened 134 native Andean landraces of eight potato species that were cultivated before the Incas. The ancient varieties were planted, along with a control group of 78 modern, improved cultivars, and all water applications were withheld after the first 38 days. (There was no irrigation from rain, since the experiment was carried out at CIP Headquarters outside Lima, where rain is an unusual phenomenon.)

Pallais found that several of the clones had good yields under the dry conditions. This "drought-adaptive response," the researcher said, "was due to a combination of valuable traits" that included high total dry matter, early bulking, low tuber number, and high harvest index (the ratio of edible matter to leaves and stems).

All this points to the usefulness of further screening and research on potato varieties’ ability to extract, transport, and use the water that is available in the soil. Pallais urges that it would be worth the expenditure to screen all 3,500 native Andean accessions. These samples of plant material that have been resting in CIP’s genebank for decades may now play important roles in alleviating the thirst of the Earth in the near future.