Instead,they mated hundreds of varieties of rice.

VOA: special.2011.02.22

Since the 19th century it has systematically collected all varieties of fossilized skeletons.

VOA: standard.2009.12.08

Helping breeders quickly develop better varieties of all these crops will be crucial as the world population tops 9 billion by 2050 in the face of a changing climate.

VOA: standard.2010.02.01

In 1944,when many experts warned of mass starvation in developing nations where populations were expanding faster than crop production, Borlaug began work at a Rockefeller Foundation-funded project in Mexico to increase wheat production by developing higher-yielding varieties of the crop.

VOA: standard.2009.09.13

"And so once we understand the genetics, we can try and just take those particular genes and work with popular varieties of rice to cross those particular genes into a popular variety and still maintain the expected cooking and eating qualities of the grain."

VOA: standard.2010.06.25

Most potato varieties carry four separate copies of their genes.

VOA: special.2009.11.03

"This is a new strain of stem rust organism that has the power to destroy most of the wheat varieties being grown around the world."

VOA: standard.2009.09.16