Heat beater beans

"Global warming could reduce areas suitable for growing beans by 50 percent," says Steve Beebe, a senior CGIAR bean researcher.

The white seeds are from the tepary bean species, a distant cousin of the common bean. The red seeds are from one of the best heat-tolerant lines identified. And the light brown ones are a cross between the tepary and common bean.

Beans come in all different colors, shapes and sizes, so a comparison of bean types needs to be made within a particular bean class - comparing apples with apples and oranges with oranges.

The best heat-tolerant materials that we have to date are in the small red bean class popular in Central America and parts of East Africa.

Breeding starts with the process of evaluating hundreds or thousands of bean types - most of them old farmer varieties from around the world - searching for that desired trait.

To cross with tepary bean, a "bean surgeon" needs to pluck out the tiny embryo from the pod, like a premature baby, to culture it in the laboratory, because it won't grow on its own.

...special greenhouses, like this one, constructed at CIAT headquarters in Colombia.