A cereal plant, rice is the main food of about half the world's population. Rice is the basic feature of most meals in East and Southeast Asia, the islands of the western Pacific, and much of Latin America. The word rice refers to the edible, starchy rice grain and to the plant from which it is produced.

Where rice is grown

Asia produces 90 percent of the world's total supply of rice. Almost half of the world's rice cultivation takes place in China and India. Less than 1 percent is grown in the United States. Thailand, Pakistan, India, and China are notable rice exporters. The plant known as wild rice, despite its name, is not related to rice.

Physical features

Cultivated rice is a member of the grass family. The cultivated rice plant grows to a height of about 4 feet (1.2 meters). The plant has several stalks that bear long, flattened leaves. A fan-shaped head called the panicle is at the end of each stalk. The panicle is made up of spikelets bearing green and yellow flowers that produce the edible fruit—the grains of rice. The panicle is erect when the flowers bloom but begins to droop as the grains develop.

How rice is grown

The cultivated rice plant is an annual crop plant. An annual crop plant is one that lasts for only one growing season a year. It must be replanted for the next growing season the following year.

A variety of rice called lowland rice is grown underwater in paddies or marshland. Another variety, called upland rice, is grown on dry, sloping fields. Lowland rice is by far the more commonly grown rice.

Lowland rice is grown in coastal plains, tidal deltas, and river basins of tropical, semitropical, and temperate regions. Usually, the seeds are first sown in special beds. When the seedlings are from 25 to 50 days old, they are transplanted, or shifted, to a field, or paddy. A paddy is a mud bed with low mud banks around it. Before transplanting, the field is flooded with 2 to 4 inches (5 to 10 centimeters) of water and the soil is thoroughly stirred. The mud banks prevent the water from draining out of the bed. Rice grows best in soil that prevents the water from seeping into the ground.

Two to five seedlings are planted in rows 8 to 12 inches (20 to 30 centimeters) apart. The planted land remains submerged during most of the growing season. The areas in which lowland rice is grown have sufficient fresh water to flood the land.

Harvesting and threshing

When the leaves of the rice plants begin to change color from green to yellow, the field is drained again for harvesting. In most countries the grain is harvested with knives or sickles. Harvesting in this way requires a great deal of labor. In the United States rice is mostly planted and harvested with the help of machines.

The grains are separated from the rest of the rice plant in a process called threshing. A common method of threshing is to beat the heads of grain against the inside walls of a barrel or box. Another method is to pull the stalks through a saw-toothed frame resembling a comb that is placed over a box to catch the separated grains.

Milling

The harvested rice grain is covered in a dry, inedible outer shell called the hull, or husk. Within the hull, there is another coat around the rice grain. This coat is edible and is known as the bran. Another inner portion of the grain is known as the germ. This is actually a rice embryo, which is a rice plant at the most basic stage of development. The hull is removed in a process called milling. In many countries, the milling of rice for home use may consist simply of removing the hulls in a hand-operated wooden mill. Most marketed rice is shipped in bags to mills where machinery does the hulling.

Most modern milling machinery removes both the hull and bran layers of the kernel. Rice that is processed to remove only the hulls, leaving the germ and outer bran layer intact, is called brown rice. Brown rice is a source of thiamine, niacin, and riboflavin. These are forms of a nutrient known as vitamin B. Brown rice also contains essential minerals such as iron and calcium.

Rice that is milled by machine to remove the bran, part of the germ, and the husk is called white rice. White rice is greatly diminished in nutrients because the milling process removes most of the thiamine, minerals, and part of the fat. Sometimes a coating is applied to give the kernel a glossy finish. Such specially coated rice is known as polished rice.

Varieties

Cultivated varieties of rice are classified by the length of their grains: short (or pearl), medium, and long. There are many varieties of the cultivated rice plant. In India alone there exist more than 8,000 varieties, and in the Philippines there are more than 3,500. The unmilled grains of these plants may be white, brown, amber, red, or black in color, and they vary in shape from long and slender to short and thick. Scientists have developed a number of high-yield, disease-resistant varieties of rice.

Uses

Rice grains can be cooked by boiling. Rice is eaten alone and in a great variety of soups, side dishes, and main dishes in Asian, Middle Eastern, and many other cuisines. In East Asia it is eaten not only as a grain, but in other forms as well. Rice cannot be used for baking bread because it contains very little gluten, which is a material that holds bread dough together. However, East Asian peoples grind it into flour for rice cakes and pastry. The Japanese, Chinese, and Indians use the grain to make liquor. Some of the starch used in cosmetics and laundry products is manufactured from rice grains.

Other parts of the rice plant are also put to a wide variety of uses. The straw of the rice plant is used for thatching roofs and making mats, garments, baskets, rope, and brooms. In Japan the roots of the rice plant are burned and used as a fertilizer for the rice fields. In the Philippines farmers sometimes grow mushrooms in beds of rice straw. The by-products of milling, including bran and rice polish (finely powdered bran and starch resulting from polishing), are used as livestock feed. Oil is processed from the bran for both food and industrial uses. The hulls are used to make fuel, packing material, and crop fertilizer.

History

Rice probably originated from wild species of grass that grew along the shores of lakes in Africa, India, and southeastern Asia. Historians think that rice was first planted and grown deliberately in about 3000 BC in India. From there it spread in all directions—to Japan, the Philippines, Persia, and Egypt—rivaling other grains, such as millet, barley, and wheat, in popularity. Rice was first grown in Italy in the 15th century, and it was introduced to North America in the 17th century.