rice

The rice plant is unique among cereal crops in that it is grown standing in water. The rice stem is adapted to allow oxygen to pass downwards to the waterlogged roots. The grain is usually white, but there are red, brown, and black varieties. The thin skin of the grain is rich in oils, minerals, and vitamins.

Rice planting in Japan. As well as being a staple food, rice is used to make sake, a Japanese wine that is usually served warm.

Terraced rice paddies, in Kanglung, eastern Bhutan. Villagers in this mountainous country make widespread use of this method of agriculture, and rice is the staple food.

In order to gather the rice harvest in Kashmir, the rice field is drained and the harvesters are sent in to strip the panicles (containing the spikelets of rice in their ‘hulls’) from the stalks, and collect them into small bundles. Only at this stage is it evident that rice is a cereal crop.

Rice seedlings being planted out in a paddy field in Guilin, China. The seedlings have to be carefully sited in soil covered by between 5 cm/2 in and 10 cm/4 in of water, in mounds not less than 7.6 cm/3 in apart, and in rows not less than 20 cm/8 in apart.

Ploughing rice fields in Bangladesh. The countryside is typified by extensive flood plains cultivated with rice, but with a rising population density the pressure on limited land resources is high. Rice fields are growing smaller and farmers find it difficult to produce enough food and generate sufficient income to support their families. Proposed solutions include more intensive and integrated farming, for example introducing fish cultivation.

Fields near Saga, Japan, used for the intensive cultivation of rice. Almost all low-lying areas in Japan are used for farming, and as there is a shortage of flat land, the high-labour practice of terracing is used to irrigate successive rice fields.

A maturing rice plant. Rice requires a large amount of water and plenty of heat, in order to grow, and therefore it is generally only found in warm wet locations. It is cultivated intensively and has a high yield. Rice is a cereal that can easily support large populations and so is favoured in areas with high population pressures.

Rice being harvested in Guilin, China. Rice is the staple food of one third of the world's population.

Rice terraces in Bali, Indonesia. Around 60% of the population of Bali works in agriculture, and rice farming is an integral part of everyday life.

Rice harvest in Nepal. Rice is the most important cereal crop in Nepal's mainly agricultural economy.

Rice harvesting, Nepal. Agricultural smallholdings provide the livelihood of over 80% of the population. The introduction of small-scale mechanization and improved agricultural practices in recent years has helped to lessen the burden on farmers and their families.

Principal cereal (Oryza sativa) of the wet regions of the tropics, derived from wild grasses probably native to India and Southeast Asia. Rice is unique among cereal crops in that it is grown standing in water. The yield is very large, and

rice is the staple food of one-third of the world's population.

Cultivation

Rice takes 150–200 days to mature in warm, wet conditions. During its growing period, it needs to be flooded either by the heavy monsoon rains or by irrigation. This restricts the cultivation of swamp rice, the usual kind, to level land and terraces. Outside Asia, centres of rice production include the Po Valley in Italy, and Louisiana, the Carolinas, and California in the USA.

Nutrition Rice contains 8–9% protein. Brown, or unhusked, rice has valuable B-vitamins that are lost in husking or polishing. Most of the rice eaten in the world is, however, sold in the polished white form.

New varieties with greatly increased protein content have been developed by gamma radiation for commercial cultivation.

By-products Rice husks when burned provide a silica ash that, mixed with lime, produces an excellent cement.

Genetic sequencing A draft of the genetic sequence of rice, the first crop to be sequenced, was announced by US researchers in April 2000, and a more complete result announced in January 2000. Rice has the smallest genome of all the cereals, with 12 chromosomes carrying a total of 50,000 genes.

In 1994 the International Rice Research Institute announced a new rice variety that could potentially increase rice yields by 25%. It produces more seed heads than the standard crop and each seed head contains 200 rice grains. The plant is also more compact, enabling it to be planted more densely.