Perennial Rice: In Search of a Greener, Hardier Staple Crop

Ten thousand years ago, China’s ancient inhabitants harvested the grains of wild rice, a perennial grass growing up to 15 feet tall in bogs and streams.  The grains were small and red, maturing in waves and often shattering into the water.  Their descendants transformed that grain into the high-yielding annual crop that today feeds half the world’s population.  When agronomist F. H. King toured China’s meticulously maintained rice terraces in 1909, he called the men and women who tilled them “farmers of forty centuries.”  To him, they seemed to have unlocked the secret to perennial rice conserving soil and maintaining agricultural fertility indefinitely.

Today, with the climate changing and far more land under intensive cultivation, rice farmers face a less certain future.  In parts of Asia, melting glaciers threaten to dry up water supplies for irrigated paddies, while higher temperatures and unpredictable rainfall stress rain-fed fields. In uplands worldwide, where farmers grow rice on steep hillsides using slash-and-burn techniques, fallow periods are growing shorter and severe erosion is undermining both productivity and ecosystem health. 

An international network of scientists is working toward a radical solution:  perennial rice that yields grain for many years without replanting.  By crossing domesticated rice with its wild predecessors, they hope to create deep-rooted varieties that hold soils in place, require less labor, and survive extremes of temperature and water supply.  Plant breeders have been trying to do the same for wheat, sorghum, and other crops for decades. 

With rice the vision is finally nearing reality.  Chinese scientists are preparing to release a variety that they say performs well in lowland paddies and, with more breeding work, could eventually thrive on marginal land as well. 

“This line of research foreshadows a more sustainable way of raising crops in the uplands,” says Casiana Vera Cruz, an expert on upland agriculture at the International Rice Research Institute (IRRI) in the Philippines.  She says the research could especially impact women, because they are most Critics argue that perennial grains will never be able to feed the growing population. often responsible for the hard work of hand-planting rice each spring on small mountain farms. 

The biggest strides are taking place in China, where geneticist Fengyi Hu and his colleagues at the Yunnan Academy of Agricultural Sciences are completing nearly a decade of trials on perennial rice varieties, including PR23, a strain they claim yields harvests close to those from conventional rice for four years or more.  One agricultural company in Yunnan will test PR23 and similar varieties on more than 1,500 acres this year, and researchers are trying out PR23 in Laos as well.  If Yunnan’s government approves the new rice for widespread release to farmers, it will be among the world’s first perennial grains to be grown beyond experimental fields. 

Critics argue, however, that perennial grains like PR23 will never be able to feed the world’s growing population. Kenneth Cassman, an agronomist at the University of Nebraska whose work focuses on global food security, says devoting a greater share of the world’s limited agricultural research funding to perennial rice research would be a mistake. 
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“So many problems that we think of as being part of the package of agriculture — nutrient leakage, soil erosion, carbon loss, weed invasion — are actually attributes of this highly disturbed ecosystem,” says Timothy Crews, research director at the Land Institute in Kansas, which was founded in 1976 with the goal of developing grain fields that mimic prairies. “They’re very predictable in ecology.  And yet if you go out and you look at mature native [grassland] ecosystems you do not have those problems.”

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