In 2018, farmers will plant the varieties with the most promise in the Ebro Delta and Europe's other two main rice-growing regions—along the Po in Italy, and France's Rh?ne.

In 2018, farmers will plant the varieties with the most promise in the Ebro Delta and Europe's other two main rice-growing regions—along the Po in Italy, and France's Rhone.

"The challenge is if certain types of people are doing something, it's difficult for other people to break into it," said Po-Shen Loh, the head coach of last year's winning U.S. Math Olympiad team.