C4 Rice to contribute greatly to second green revolution

October 11, 2010 7:21 am 

LOS BANOS, Laguna, Oct. 9 -– Rice with C4 photosynthesis could make a major contribution to a second Green Revolution, the International Rice Research Institute (IRRI) on Friday said.

IRRI, however, said assessing how that change could affect rice, is necessary to understand how the rice crop works.

IRRI scientists said rice is the most important crop in the world for human food, pointing out that over the past 40 years, its production has kept pace with the increase in population, thus, making it clear that the gains of the first Green Revolution are largely exhausted.

Scientists said rice production should be about converting the maximum fraction of solar energy into the maximum amount of chemical energy in grain in the shortest possible time, and that conversion should be achieved using the smallest amount of land, water, and fertilizer.

IRRI said the C4 rice project is about using cutting edge science to discover the genes that will supercharge photosynthesis, boost food production and improve the lives of billions of poor people in the developing world.

The C4 consortium is a group of multidisciplinary scientists from advanced institutions around the world. The Bill and Melinda Gates Foundation provides funds to the IRRI to lead the consortium on this exciting, but urgent voyage of discovery, officials said.

Rice agriculture is the indispensable base of human society and the nature and productivity of agriculture is determined by land and water, management, and agricultural research.

IRRI said that only 29 percent of the earth’s surface is land and only a little over a third of that is suitable for agriculture, the rest is ice, desert, forest or mountain and is unsuitable for farming. Simply stated, only 10 percent of the surface of the earth has topographic and climate conditions suitable for producing the food requirements of human beings.

It said that today, only 75 percent of the world’s 6.6 billion people live in the developing world where most of the world’s existing poverty is concentrated.

Currently, about a billion people live on less than a dollar a day and spend half their income on food; 854 million people are hungry and each day about 25,000 people die from hunger-and related causes.

Sixty percent of the world’s population lives in Asia, where each hectare of land used for rice production currently provides food for 27 people, but by 2050 that land will have to support at least 43 people. Nonetheless, the area for rice cultivation is continually being reduced by expansion of cities and industries, to say nothing of soil degradation.

Climate change will likely result in more extreme variations in weather and cause adverse shifts in the world’s existing climatic patterns. Water scarcity will grow; the increasing demand for biofuels will result in competition between grain for fuel and grain for food resulting in price increases. Furthermore, more than 75 percent of the world's people will live in cities, the populations of which will need to be largely supported by a continuous chain of intensive food production and delivery.

All of these adverse factors are growing now, at a time when the growth in rice production has slowed as efficient farmers have approached yield limits. Research shows that current maximum rice yields are close to a fundamental yield barrier shaped by the efficiency of solar energy conversion.

There is now a growing body of scientific opinion, that the only way to achieve the rice harvests needed for the future is to change the biophysical structure of the rice plant, making it a much more efficient user of energy from the sun, IRRI said.

It said that plants use solar radiation to grow, develop leaves, roots, stems, flowers, and seeds in a process known as photosynthesis. Rice has what is known as a C3 photosynthetic pathway, less efficient than that of maize, which has a C4 pathway.

Taking a lesson from evolution and converting a plant from C3 to C4 would involve a rearrangement of cellular structures within the leaves and more efficient expression of various enzymes related to the photosynthetic process. However, all the components for C4 photosynthesis already exist in the rice plant, but they are distributed differently and are not as active, IRRI said. (PNA)

DCT/FMB

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