Scientists Explore Drought-Tolerant Plants to Offset Water Shortages

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Chinese scientists believe that breeding new drought-tolerant crop varieties is key to easing the country's chronic water scarcity, according to Xinhua News Agency. Experts made the remarks in early January at a forum on water conservation and agriculture, noting that the lack of water poses a significant threat to China's food security.

Water shortages are a chronic constraint in Chinese agriculture, and the situation has only worsened. Although China ranks sixth in the world in total water resources, per capita volume in this nation of 1.3 billion is only about 2,200 cubic meters, one-quarter the world average, according to China's Ministry of Water Resources. The country also sees highly imbalanced distribution of water across regions and by season.

The agriculture sector accounts for 70 percent of China's total water consumption and is highly inefficient, with each irrigated cubic meter producing only 0.8 kilograms of grain, less than 40 percent the output of industrialized countries. High water consumption and low efficiency has led to over-exploitation of water resources as well as to ecosystem degradation.

In recent years, cycles of extreme drought and severe flooding have affected China's water availability and crop production as well—a trend many scientists attribute to climate change. Zhang Qifa, with the Chinese Academy of Sciences, reports signs of decreased precipitation, particularly after mid-July when major staple grains such as rice need water the most.

Since 1998, China has appropriated special funds to upgrade water-saving techniques in more than 350 large irrigation regions nationwide. Despite notable outcomes, however, the country has lacked an overall solution to its water problems. With the development of new drought-tolerant crops, agro-scientists hope to ease water constraints and better guarantee food security and ecosystem health.

While water-saving irrigation techniques often require significant investments in infrastructure and equipment, giving farmers new varieties of drought-tolerant seed is considered an easier and possibly cheaper approach. Drought-tolerant varieties of corn, rice, wheat, and other food grains could also have significant potential for saving water. Most recently, scientists have embraced a new "super strain" of rice they say could double China's yield, if widely promoted.

But generating drought tolerance in plants is a complicated process, involving manipulation of genes, cell structures, and biochemical metabolic mechanisms. Among the groups breeding new drought-tolerant rice varieties are the Shanghai Academy of Agricultural Sciences and Huazhong Agricultural University in Wuhan in central China.

Brian Halweil, senior researcher with the Worldwatch Institute, notes that there are other ways to address agricultural water shortages that are less costly than crop breeding, and that are available now. He cites the system of rice intensification (also known as SRI) developed in Madagascar, and now being spread throughout much of Asia. "It doesn't flood the fields. It uses compost instead of chemical fertilizer. And it focuses on more careful weeding and transplanting of rice seedlings," Halweil explains. "It often doubles or triples yields using standard rice breeds, while using half the water."

The water-saving success of this system depends partly on encouraging rice plants to develop larger root systems, according to Norman Uphoff, director of Cornell University's International Institute for Food, Agriculture and Development, who has been working with SRI in Asia and other rice producing regions. The larger root systems do not simply increase the ability of the plants to tolerate drought. They also help plants access additional nutrients, support beneficial soil organisms, improve disease resistance, and generally improve soil quality. "There are a lot of things that can be done to enhance drought resistance that are simpler, quicker, and more certain than introducing new genetic potentials in crop varieties," Uphoff notes, based on SRI experience.