Wheat

The U.S. has red states and blue states. China has rice provinces and wheat provinces, and the profound differences between them provide evidence of how cultural assumptions arise.

• By Tom Jacobs

At a time when the worldwide wheat supply needs to grow, we might not even be able to keep it from diminishing.

• By Michael White

Carbon dioxide fertilizes plants, but it can also make crops less nutritious. A new discovery could help farmers develop new strains to feed the world even as carbon dioxide levels rise.

• By John Upton