Support Provided ByLearn More
Ancient WorldsAncient Worlds

Miracle of Rice

You've probably never stopped to consider rice for any longer than it takes to trap a piece of sushi between your chopsticks. But this humble grain is truly remarkable. In Asia, for example, it provides 50 to 80 percent of people's daily caloric intake. And rice is getting more remarkable by the year. A series of advances in biotechnology have paved the way for high-yield rice varieties resistant to blights and bugs and fortified with vitamin A.

ByLexi KrockNova

With at least a million children weakened by vitamin-A deficiency every year and an additional 350,000 going blind, the possibility that genetically engineered rice may soon be widely available in Asia and Africa makes rice seem nothing short of miraculous.

Receive emails about upcoming NOVA programs and related content, as well as featured reporting about current events through a science lens.

sushi in chopsticks
In the year 2000, annual production of rice worldwide was well over 400 million tons.
© Mark Gillow/iStockphoto


Support Provided ByLearn More

A Malaysian aboriginal myth holds that all of the sky once lay flat on the Earth in the form of rice until the women of the tribe, wielding their long wooden rice brooms, heaved it upwards in the first harvest. From then on, rice fell back to Earth each year in time for a bountiful harvest.

Rice's evolutionary origins go far back into history, so far that scientists can only make intelligent guesses as to where the rice genus (Oryza) first grew. One theory maintains that rice arose in the ancient supercontinent known as Gondwana. Then, when Gondwana fragmented into Africa, South America, Antarctica, Australia/New Zealand, India, and Madagascar beginning about 200 million years ago, Oryza went with the fragments.

Rice, an annual grass belonging to the same family as barley, oats, rye, and wheat, grows today in a range of habitats almost unparalleled in the plant kingdom. It is cultivated in the cool Himalayan climates of Nepal and in the scorching deserts of Pakistan, Iran, and Egypt. In Latin America it grows as a dry-land crop, in Southeast Asia as a paddy crop watered by monsoon rains and floodwater. All told, some 358 million acres, or roughly 11 percent of the world's arable land, are given over to rice cultivation, according to the International Rice Research Institute (IRRI) in the Philippines.

rice fields in Bali, Indonesia
Terraced rice fields in Bali, Indonesia. Farmers must incessantly weed such paddies to maintain water flow through the terraces.
© LP7/iStockphoto

Raising rice

Rice-growing methods are almost as varied as the grain's geographical habitats. In the United States, farmers use highly mechanized systems, but in most developing nations, rice farming remains extremely labor-intensive. The work is backbreaking and relentless, and in Japan and other Asian countries where farmers tend terraced paddies, it is also muddy.

Paddy rice is irrigated by water diverted from rivers and mountain streams into a complex system of canals and riverways developed and perfected through centuries of use. Terracing, which requires constant maintenance, allows water to flow continuously down through successive rice fields (see Build a Rice Paddy). Farmers usually plant rice seed in a seedbed, then transplant young plants into the paddies, which have about six inches of water at this stage. As the plants mature, cultivators allow the water level in the field to drop. By the time the plants reach full maturity, the ground is entirely dry, and farmers can easily harvest the rice.

Harvesters cut the ripe grain from the stalk and then, after it has dried, thresh it to separate the grains from the so-called rice straw. In Asia, oxen typically do the threshing by trampling the rice laid out before them. Milling then removes each grain's hull to reveal the part of the rice plant that eventually ends up in our mouths. Milling both the hull and bran layers of the kernel renders so-called white rice; brown rice retains the bran. After the harvest, farmers turn over the soil, readying the paddy for another season.

dried rice plant and rice grains
Keeping the dried rice grains dry is key to their preservation.
© lamiel/iStockphoto

The role rice plays in national culture varies dramatically depending on where you are. Most Americans, for example, view rice as just another commodity available on supermarket shelves. But in Japan, o-kome, or "honorable rice," is much more than a commodity. In the Shinto religion, sake, rice cakes, and other rice products are the most sacred of offerings, and to a nation that must import most of its meat, fish, and fruit, rice is a symbol of independence. Indeed, as a matter of tradition, the Japanese government strictly prohibits the import of rice as long as local crops provide harvests bountiful enough to satisfy the national appetite.

rice flour in spoon
In Japan, ground rice flour is the basis of everything from savory noodles to sweet mochi pastry.
© FotografiaBasica/iStockphoto

Rice is the staple in many Asian countries besides Japan, and in the early 1960s it became apparent that the fast-growing Asian population would soon begin devouring rice at a far greater pace than it could produce it, leading to widespread famine.

The newly formed IRRI's solution to this potentially crippling pan-Asian problem was dramatic and far-reaching. It transformed the rice plant, eking out new varieties with built-in solutions to three main obstacles. First, the institute's researchers genetically reduced plant height from about five feet to roughly three feet. This change allowed farmers to douse rice plants with larger amounts of powdered fertilizer without causing their stalks to sag and even topple from the weight of increased panicles (clusters of grain). Second, they shortened the plant's growing period from about 160 days to 110, so that in warm climates, irrigation could supplement seasonal rainfall, and farmers could raise two or three crops every year instead of just one. Lastly, rice varieties were bred to be resistant to the most crippling diseases and insect pests. In most areas where these new varieties were sown, the results were—and continue to be—staggering. According to IRRI, from 1967 to 1992 during the so-called Green Revolution, the world's rice harvest doubled. In some countries such as Indonesia, the national rice harvest more than tripled.

But it's not over yet. Scientists have to reinvent the rice plant again in order to keep up with the still rapidly growing Asian population. The IRRI estimates that rice production must increase approximately 60 percent before the year 2020. One possible fine-tuning involves the addition of stalks to each plant (from about 15 to 25), allowing for more panicles per plant. The IRRI's Genetic Resources Center has a cold-storage unit that houses some 80,000 rice samples waiting to be crossbred into new varieties. The newest techniques in biotechnology and genetic engineering, which enable IRRI scientists to transfer the genes from one rice plant directly into the cells of another, reduce breeding time and allow for the transfer of specific traits. Instead of crossbreeding plants by hand in the field, scientists are now able to make finite genetic changes to plant embryos in test tubes, virtually ensuring the success of the transfer.

variety of rice types in bowls
Over centuries, agricultural techniques have lead to the cultivation of tens of thousands of rice varieties. Shown here are black wild rice, red wild rice, brown rice, mixed wild rice, green pandanus leaf flavored rice, red roselle flower flavored rice, and blue butterfly pea flower flavored rice.
© ShutterWorx/iStockphoto

A miracle's miracle

Not surprisingly, the genetic manipulation of rice has become part of the increasingly polarized public debate about whether to welcome or ward off the addition of genetically modified foods into our diets. GM foods—so-called "Frankenfoods" in the minds of many people—made their commercial debut in the 1990s. Ever since, they have become the target of environmentalists and consumer advocates, who fear that genetically tinkering with the food we eat may have harmful repercussions for our health and the environment.

Specialists working on the rice plant would argue that the case of genetically engineered rice is different than that of other kinds of GM foods, such as mush-resistant bananas, self-fertilizing corn, and lettuce made unappealing to caterpillars. IRRI scientists have come up with Golden Rice, which is fortified with vitamin A and may benefit not just the wallets of the farmers who grow it but also the health of the consumers who eat it. This new rice, engineered to make its own supply of vitamin A (which gives the rice a golden color), could conceivably prevent blindness and even death among the developing world's poorest, most vitamin-A-deficient people. If that happened, it would be a miracle's miracle.

Editor's Notes

This feature originally appeared on the site for the NOVA program Japan's Secret Garden.