Drought-resistant rice offers hope in face of water crisis

New strains of artificially selected, drought-resistant rice could help to improve water efficiency in rice-growing regions of the world, according to scientists at the International Rice Research Institute (IRRI) in the Philippines.

At present, rice is the staple food for 2.7 billion people – around half of the world’s population. In Asia, where 90 % of all rice is grown and the vast majority of it consumed, 72% of freshwater resources are used for irrigating rice crops, but availability is now shrinking at an alarming rate as domestic and industrial demand increases.

To combat this problem, the IRRI, based in Los Banos, Manila, now has over 1000 scientists involved in active research. Although it is widely acknowledged that a great deal could be achieved by improving irrigation strategies in areas with seasonal and unreliable rainfall, the development of drought-resistant rice plants is an important alternative, as 45% of rice growing areas in Asia still lack irrigation infrastructure and many are in difficult terrain.

With the aid of a genetic database listing over 80,000 known varieties, the IRRI’s researchers are homing in on the genes for drought-resistance. Using a technique called marker assisted selection, the process of cross-breeding for desired traits is being speeded up in comparison with more traditional methods. Marker assisted selection does not modify the actual genetics of a plant, but simply identifies individual plants with the required genes. Desired traits include deeper and thicker growing roots, and the ability to take up nutrients when growing in a relatively dry soil.

Dr Adam Price, of the Department of Plant & Soil Sciences at Aberdeen University in the UK, said: “It is important to understand that there is no way to find a single gene on one of the 12 rice plant chromosomes which will lead to a universal drought-resistance. And selecting for particular chromosomes or genes is an expensive process.”

Dr Price’s research team is currently using marker assisted selection to breed a popular variety of Indian rice for deep-rooted and aromatic habit. He said: “We are still in the early stages, but subject to success, Kalinga III could be used by Indian farmers in 2-3 years time.”

On being asked whether a particular strain could be patented, Dr Price said: “Rice is unusual, because so far it has not really been a commercial crop in the sense that farmers do not have to buy in large quantities of seed. Once farmers have the seed, it is a relatively simple matter for them to breed the plants on site. However, although export markets for rice are not that important, I do expect this (patent rights) to be an increasingly important area.”

Advances in the ability of popular rice strains to withstand drought could have a significant effect on agricultural efficiency. However, the rate at which research is translated into action will be limited by the availability of suitably equipped laboratories and agricultural universities, which can breed up the new strains for distribution to farmers.

At the moment, Dr Mahabub Hossain, the IRRI’s economist, estimates that 24M t of rice, amounting to 4.3% of production and worth $4.8 billion to the Asian economy is lost every year, as a direct result of drought and poor irrigation techniques. He expects the situation to get worse unless serious efforts are made to improve water resource management.

Similar predictions have also been made (Guerra et al 1998) for rice growing regions of Africa, where water demand is outstripping available supplies. 1999 is already proving to be a difficult year for farmers, with reports of drought blamed on La Nina (the backlash of El Nino in the eastern hemisphere) ranging from Thailand to New Zealand.

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