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Making Harvests More Nutritious

By Hank Becker
May 20, 1999

While most crop breeding focuses on better yield or pest resistance, Ross Welch is exploring ways to breed crops to help alleviate shortages of trace elements and vitamins in the diets of many people around the world.

For billions of people, plant foods don’t provide enough of these micronutrients, which are critical to health. The most prevalent micronutrient problem, iron deficiency, affects more than 2 billion people. Zinc, iodine, essential trace elements and vitamins are other critical micronutrients that can be deficient in some diets, according to Welch, a plant physiologist with the Agricultural Research Service in Ithaca, N.Y.

He and colleagues have launched an international effort to pinpoint rice, wheat, corn, bean and cassava varieties that are high in micronutrients.

Their goal: plants that more efficiently take up micronutrients from soil and transport them to edible plant parts in forms the human digestive system can take up and use.

Already, Welch’s team has found enhanced ability to accumulate iron and zinc in 24 genetic types of common bean from the seed bank of the International Center for Tropical Agriculture in Cali, Colombia. In the 24 genotypes, they found iron levels of 51 to 157 micrograms per gram of dry weight and zinc levels of 30 to 65 mg/g. In rat feeding studies, the iron bioavailability ranged from 53 to 76 percent. This diversity is strong evidence that breeders could produce new varieties with higher content and bioavailability of iron and zinc.

Recent tests of bioavailable iron and zinc levels in fifteen IRRI rice lines also found some exploitable diversity. The scientists plan future rat studies to determine iron and zinc bioavailability in selected micronutrient-enriched lines of rice, wheat, corn and cassava.

A story about the research appears in the May issue of Agricultural Research magazine and on the World Wide Web at:


ARS is U.S. Department of Agriculture's chief research agency.

Scientific contact: Ross W. Welch, ARS U.S. Plant, Soil and Nutrition Research Laboratory, Ithaca, N.Y., phone (607) 255-5434, fax (607) 255-1132,