CIMMYT Wheats Take the Heat

"This scenario wasn't even on our original list of reasons to bring more heat tolerance to a crop normally grown in temperate areas," says Tony Fischer, director of CIMMYT's Wheat Program. "But if warmer weather does come to those areas, we have varieties that can take the additional heat--along with clues on how to manage the crop under such harsh conditions."

In the early 1980s, wheat production in warmer climates became an issue after years of food aid and generous subsidies popularized wheat products in subtropical and tropical countries of the developing world. Says Fischer, "CIMMYT began paying particular attention to wheat production in countries like Bangladesh, Myanmar, Thailand, Nigeria, Sudan, Paraguay, and Bolivia because governments there wanted to initiate or increase local production instead of using scarce foreign exchange for imported wheat. This effort in 'tropical wheat' research has had a decade of financial support from the United Nations Development Programme (UNDP)."

The term "tropical wheat" used during the early days of the project is an unfortunate tag that stuck. Explains Fischer, "It was never our aim to develop wheats that could be grown in hot, humid, tropical rain forest environments. Rather, we've been identifying varieties that will grow in subtropical areas that are closer to the equator than traditional wheat regions and that have mean temperatures higher than 17.5 degrees C (63.50F) during the coolest month of the year.

Although the major accomplishment of the CIMMYT effort has been to prove it is technically feasible to grow wheat in these warmer regions, the Center has never advocated that countries there should necessarily grow the crop. Says Larry Harrington, CIMMYT economist, "The economic argument in favor of a local wheat industry, in Thailand for example, is often not convincing.

However, doubling farmers' yields--through better varieties and improved agronomic practices--can make a big difference." Large production increases, for example, have occurred in tropical Bolivia, Paraguay, and Sudan, the hottest place on Earth where wheat is grown.

Sanjaya Rajaram, CIMMYT's principal bread wheat breeder, crystalizes the purpose of the UNDP-sponsored endeavor: "We're developing wheat varieties that perform well in warmer areas during the cooler, winter periods of the year when, up to now, the land has usually been left fallow," he says.

"These new heat-tolerant varieties let farmers produce a second crop and earn additional income. Wheat stands virtually alone as a robust, water-efficient, winter-season crop that farmers can grow efficiently in rotation with such summer crops as rice, maize, sorghum, cotton, and soybeans."

Wheat research in the warmer areas has lead to important spin-off benefits for wheat cultivated in more temperate zones. An excellent example, according to Fischer, is spot blotch, the number one disease threat to wheat in warm, relatively humid areas. "This disease is present in warmer traditional wheat-growing areas, too," he says, "but it usually shows up only after genetic control of major wheat diseases--primarily the rusts--has been achieved.

The UNDP-sponsored project enabled us to more rapidly identify varieties with resistance to spot blotch, and these are proving useful in traditional wheat areas as well."

Rajaram concludes that: "New heat-tolerant varieties are already grown by farmers in traditional wheat-growing regions like South Asia, where intensive farming practices often mean that wheat is planted late and flowers during a hotter time of the year. In those areas, our wheats can take the heat, and they offer insurance to the world should global warming comes to pass."

(CIMMYT news release)