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71-787: The Dong Son people were skilled at cultivating rice , keeping water buffalos and pigs , fishing and sailing in long dugout canoes . They also were skilled bronze casters , which is evidenced by the Dong Son drum found widely throughout northern Vietnam and Guangxi in China. To the south of the Dong Son culture was the Sa Huỳnh culture of the proto-Chams . The Dongsonians spoke either Austroasiatic or Northern Tai languages ; or were Austroasiatic -speakers with significant contact and admixture with Tai-speakers. Archaeogenetics have demonstrated that before

142-416: A sustainable way. Many varieties of rice have been bred to improve crop quality and productivity. Biotechnology has created Green Revolution rice able to produce high yields when supplied with nitrogen fertiliser and managed intensively. Other products are rice able to express human proteins for medicinal use; flood-tolerant or deepwater rice ; and drought-tolerant and salt-tolerant varieties. Rice

213-403: A branched inflorescence which arises from the last internode on the stem. There can be up to 350 spikelets in a panicle, each containing male and female flower parts ( anthers and ovule ). A fertilised ovule develops into the edible grain or caryopsis . Rice is a cereal belonging to the family Poaceae . As a tropical crop, it can be grown during the two distinct seasons (dry and wet) of

284-508: A genetic test can be used. Grains are brittle. African rice is well adapted to the African environment. It is drought- and deep-water -resistant, and tolerates fluctuations in water depth, iron toxicity, infertile soils, severe climatic conditions, and human neglect better than Asian rice. Some varieties also mature more quickly, and may be sown directly on higher ground, eliminating the need to transplant seedlings. Most are rain-watered, and

355-411: A role in various religions and traditions, such as in weddings . The rice plant can grow to over 1 m (3 ft) tall; if in deep water, it can reach a length of 5 m (16 ft). A single plant may have several leafy stems or tillers . The upright stem is jointed with nodes along its length; a long slender leaf arises from each node. The self-fertile flowers are produced in a panicle ,

426-458: A single domestication event for O. sativa . Both indica and japonica forms of Asian rice sprang from a single domestication event in China from the wild rice Oryza rufipogon . Despite this evidence, it appears that indica rice arose when japonica arrived in India about 4,500 years ago and hybridised with another rice, whether an undomesticated proto- indica or wild O. nivara . Rice

497-522: A slave smuggling grains in her hair and a ship driven in to trade by a storm. African rice is a rare crop in Brazil, Guyana, El Salvador and Panama, but it is still occasionally grown there. There are also native South American rices, which makes it hard to recognize the arrival of African rice in histories. Asian rice came to West Africa in the late 1800s, and by the late twentieth century had substantially supplanted native African rice. However, African rice

568-440: A wide variety of pests including insects, nematodes, rodents such as rats, snails, and birds. Major rice insect pests include armyworms, rice bugs , black bugs , cutworms, field crickets, grasshoppers, leafhoppers, mealybugs, and planthoppers. High rates of nitrogen fertiliser application may worsen aphid outbreaks. Weather conditions can contribute to pest outbreaks: rice gall midge outbreaks are worsened by high rainfall in

639-436: Is rainfed like wheat or maize. Across Asia, unmilled rice or "paddy" (Indonesian and Malay padi ), was traditionally the product of smallholder agriculture, with manual harvesting . Larger farms make use of machines such as combine harvesters to reduce the input of labour. The grain is ready to harvest when the moisture content is 20–25%. Harvesting involves reaping , stacking the cut stalks, threshing to separate

710-661: Is 69% water, 29% carbohydrates , 2% protein , and contains negligible fat (table). In a reference serving of 100 grams (3.5 oz), cooked white rice provides 130 calories of food energy , and contains moderate levels of manganese (18% DV), with no other micronutrients in significant content (all less than 10% of the Daily Value ). In 2018, the World Health Organization strongly recommended fortifying rice with iron , and conditionally recommended fortifying it with vitamin A and with folic acid . Golden rice

781-613: Is a major food staple in Asia, Latin America, and some parts of Africa, feeding over half the world's population. However, a substantial part of the crop can be lost post-harvest through inefficient transportation, storage, and milling. A quarter of the crop in Nigeria is lost after harvest. Storage losses include damage by mould fungi if the rice is not dried sufficiently. In China, losses in modern metal silos were just 0.2%, compared to 7–13% when rice

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852-498: Is a variety produced through genetic engineering to synthesize beta-carotene , a precursor of vitamin A, in the endosperm of the rice grain. It is intended to be grown and eaten in parts of the world where Vitamin A deficiency is prevalent. Golden rice has been opposed by activists, such as in the Philippines . In 2016 more than 100 Nobel laureates encouraged the use of genetically modified organisms , such as golden rice, for

923-558: Is also grown for cultural reasons; for instance, it is sacred to followers of Awasena (a traditional African religion ) among the Jola people , and is a heritage variety in the United States. Crossbreeding between African and Asian rice is difficult, but there exist some crosses. Jones et al. 1997 and Gridley et al. 2002 provide hybrids combining glaberrima ' s disease resistance and sativa ' s yield potential. It

994-581: Is based on four principles: biodiversity, host plant resistance, landscape ecology, and hierarchies in a landscape—from biological to social. Farmers' pesticide applications are often unnecessary. Pesticides may actually induce resurgence of populations of rice pests such as the brown planthopper , both by destroying beneficial insects and by enhancing the pest's reproduction. The International Rice Research Institute (IRRI) demonstrated in 1993 that an 87.5% reduction in pesticide use can lead to an overall drop in pest numbers. Farmers in China, Indonesia and

1065-477: Is being done on crosses with Indian rice varieties. There are a great many varieties of African rice. In the 1960s older women in Jipalom ( Ziguinchor Region , Senegal) could unhesitatingly name more than ten varieties of African rice that were no longer planted, besides the half-dozen that were then still being planted. Each woman would plant multiple different varieties, to suit varying microhabitats and to stagger

1136-585: Is broken in processing. The genome of O. glaberrima has been sequenced, and was published in 2014. This allowed genomic as well as physiological comparison with related species, and identified some effects of some genes. African and Asian rice do not readily interpollinate, even under controlled conditions , and when they do, the offspring are very rarely fertile. Even the fertile crossbred offspring have low fertility. Crossbreeding seems to have succeeded in at least one area of Maritime Guinea , as some varieties there show crossbred genes. More recently,

1207-504: Is from Asia. The average world yield for rice was 4.7 metric tons per hectare (2.1 short tons per acre), in 2022. Yuan Longping of China's National Hybrid Rice Research and Development Center set a world record for rice yield in 1999 at 17.1 metric tons per hectare (7.6 short tons per acre) on a demonstration plot. This employed specially developed hybrid rice and the System of Rice Intensification (SRI), an innovation in rice farming. Rice

1278-504: Is highly likely that humans have independently domesticated two different rice species. African rice is very genetically similar to wild African rice ( O. barthii ), as Asian rice ( O. sativa ) is to wild Asian rice ( O. rufipogon ), and these two divisions have wide genetic differences between them. O. barthii still grows wild in Africa, in a wide variety of open habitats. The Sahara was formerly wetter , with massive paleolakes in what

1349-482: Is not advantageous in regions prone to short floods, as it weakens the plant. The grains of African rice are more brittle than those of Asian rice. The grains are more likely to break during industrial polishing. Broken rice is widely used in West Africa, and some cookbooks from the region will suggest manually breaking the grains for certain recipes, but most broken rice eaten is from Asian rice, about 16% of which

1420-532: Is now the Western Sahara . As the climate dried, the wild rice retreated and probably became increasingly domesticated as it relied on humans for irrigation . Rice growing in deeper, more permanent water became floating rice . It was domesticated about 3000 years ago in the inland delta of the Upper Niger River , in what is now Mali . It then spread through West Africa. It has also been recorded off

1491-797: Is sister to the bamboos, Bambusoideae , and the cereal subfamily Pooideae . The rice genus Oryza is one of eleven in the Oryzeae; it is sister to the Phyllorachideae . The edible rice species O. sativa and O. glaberrima are among some 300 species or subspecies in the genus. other grasses (inc. the C4 grasses , maize , sorghum ) Streptogyneae Ehrharteae Phyllorachideae Wild rices inc. Zizania other rice species and subspecies O. sativa (Asian rice) O. glaberrima (African rice) Bambusoideae (bamboos) Pooideae (grasses and cereals inc. wheat , barley ) Oryza sativa rice

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1562-685: Is stickier, and is used for sweet dishes, and in Italy for risotto ; and sticky short-grain rice is used in Japanese sushi as it keeps its shape when cooked. White rice when cooked contains 29% carbohydrate and 2% protein, with some manganese . Golden rice is a variety produced by genetic engineering to contain vitamin A . Production of rice is estimated to have caused over 1% of global greenhouse gas emissions in 2022. Predictions of how rice yields will be affected by climate change vary across geographies and socioeconomic contexts. In human culture, rice plays

1633-438: Is subjected to a steaming process before it is milled. This makes the grain harder, and moves some of the grain's vitamins and minerals into the white part of the rice so these are retained after milling. Rice does not contain gluten , so is suitable for people on a gluten-free diet . Rice is a good source of protein and a staple food in many parts of the world, but it is not a complete protein as it does not contain all of

1704-481: Is the seed of the grass species Oryza sativa (Asian rice)—or, much less commonly, Oryza glaberrima (African rice). Asian rice was domesticated in China some 13,500 to 8,200 years ago; African rice was domesticated in Africa about 3,000 years ago. Rice has become commonplace in many cultures worldwide; in 2021, 787 million tons were produced, placing it fourth after sugarcane , maize , and wheat . Only some 8% of rice

1775-406: Is to flood the field to a depth of 5 cm (2 in), then to let the water level drop to 15 cm (6 in) below surface level, as measured by looking into a perforated field water tube sunk into the soil, and then repeating the cycle. Deepwater rice varieties tolerate flooding to a depth of over 50 centimetres for at least a month. Upland rice is grown without flooding, in hilly or mountainous regions; it

1846-509: Is traded internationally. China, India, and Indonesia are the largest consumers of rice. A substantial amount of the rice produced in developing nations is lost after harvest through factors such as poor transport and storage. Rice yields can be reduced by pests including insects , rodents , and birds , as well as by weeds , and by diseases such as rice blast . Traditional rice polycultures such as rice-duck farming , and modern integrated pest management seek to control damage from pests in

1917-471: Is used as a model organism in biology. Dry rice grain is milled to remove the outer layers; depending on how much is removed, products range from brown rice to rice with germ and white rice. Some is parboiled to make it easy to cook. Rice contains no gluten ; it provides protein but not all the essential amino acids needed for good health. Rice of different types is eaten around the world. Long-grain rice tends to stay intact on cooking; medium-grain rice

1988-601: Is used to make Ofada rice because of its high nutrition content, despite being less popular than O. sativa cultivars (as of 2019 ). African rice is a tall rice plant, usually under 120 centimetres (47 in) but up to 5 metres (16 feet) for floating varieties, which may also branch and root from higher stem nodes. Generally, African rice has small, pear-shaped grain, reddish bran and green to black hulls , straight, simply-branched panicles , and short, rounded ligules . There are, however, exceptions, and it can be hard to distinguish from Asian rice. For complete certainty,

2059-456: The nerica cultivars ( ne w ri ce for Afri ca ) have been developed using green revolution techniques like embryo rescue . Over 3000 crosses were made as part of the NERICA program. Breeding within the species is easier, and there are uncounted numbers of African rice varieties, although the majority may have been lost. A similar crossed variety was bred in the United States in 2011, and work

2130-459: The Africa Rice Center calls TOG 12303 and TOG 9300 have low shattering , and thus yields comparable with low-shattering Asian rice varieties. Scientists from the Africa Rice Center managed to cross-breed African rice with Asian rice varieties to produce a group of interspecific cultivars called New Rice for Africa (NERICA). Carolina Gold is an heirloom cultivar grown in

2201-592: The Việt ". Ferlus (2009) showed that the inventions of pestle, oar, and a pan to cook sticky rice, which is the main characteristic of the Đông Sơn culture, correspond to the creation of new lexicons for these inventions in Northern Vietic (Việt–Mường) and Central Vietic ( Cuoi-Toum ). The new vocabularies to denote these inventions were proven to be derivatives from original verbs rather than borrowed lexical items. The current distribution of Northern Vietic also correspond to

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2272-654: The east coast of Africa, in the Zanzibar Archipelago . O. barthii seedheads shatter , while O. glaberrima does not shatter as much. In the late fifteenth and sixteenth centuries, the Portuguese sailed to the Southern Rivers area in West Africa and wrote that the land was rich in rice. "[T]hey said they found the country covered by vast crops, with many cotton trees and large fields planted in rice ...

2343-457: The efforts to increase yield was the adoption of nerica cultivars, crossbred to specifications from local farmers using African rice varieties provided by local farmers. These were bred during the 1990s and released in the early 21st century. Results so far have been mixed; the nerica varieties are less hardy and more labour-intensive, and effects on real-world yields vary. Subsidies of nerica seeds have also been criticized for encouraging

2414-440: The essential amino acids in sufficient amounts for good health. World trade figures are much smaller than those for production, as less than 8% of rice produced is traded internationally. China, an exporter of rice in the early 2000s, had become the world's largest importer of rice by 2013. Developing countries are the main players in the world rice trade; by 2012, India was the largest exporter of rice, with Thailand and Vietnam

2485-489: The 1550s and in the U.S. in 1784. The seed was carried as provisions on slave ships, and the technology and skills needed to grow it were brought by enslaved rice farmers. Newly imported African slaves were marketed for their rice-growing skills, as the high price of rice made it a major cash crop. Not all Africans came to the Americas with knowledge in rice growing, due to the vast variabilities in cultures and ethnicities, but

2556-478: The 21st century as people in Asia and elsewhere ate less grain and more meat. An exception is Sub-Saharan Africa, where both per capita consumption of rice and population are increasing. Rice is a commonly-eaten food around the world. The varieties of rice are typically classified as short-, medium-, and long-grained. Oryza sativa indica varieties are usually long-grained; Oryza sativa japonica varieties are usually short- or medium-grained. Short-grain rice, with

2627-637: The Americas by the Spanish. In British North America by the time of the start of the American War of Independence , rice had become the fourth most valuable export commodity behind only tobacco, wheat, and fish. In 2021, world production of rice was 787 million tonnes , led by China and India with a combined 52% of the total. This placed rice fourth in the list of crops by production, after sugarcane , maize , and wheat . Other major producers were Bangladesh , Indonesia and Vietnam . 90% of world production

2698-556: The Dong Son period, the Red River Delta's inhabitants were predominantly Austroasiatic. Genetic data from Vietnam's Phùng Nguyên culture 's Mán Bạc burial site demonstrated close proximity to modern Austroasiatic speakers such as the Khmer and Mlabri ; meanwhile, "mixed genetics" from Đông Sơn culture 's Núi Nấp site showed affinity to " Dai from China, Tai-Kadai speakers from Thailand, and Austroasiatic speakers from Vietnam, including

2769-760: The Iron Age. The bronze drums were used for war, "the chief summons the warriors of the tribe by beating the drum", when mourning, and during feasts. "The scenes cast onto the drums would inform us that the Dong Son leaders had access to bronze founders of remarkable skill." Lost-wax casting was based on Chinese founders , but the scenes are local, including drummers and other musicians, warriors, rice processing, birds, deer, war vessels, and geometric designs. The bronze drums were made in significant proportions in northern Vietnam, Laos and parts of Yunnan . The Dong Son bronze drums exhibit "remarkable skill". The Cổ Loa drum weighs 72 kilograms (159 lb) and would have required

2840-460: The Philippines have traditionally managed weeds and pests by the polycultural practice of raising ducks and sometimes fish in their rice paddies. These produce valuable additional crops, eat small pest animals, manure the rice, and in the case of ducks also control weeds. Rice plants produce their own chemical defences to protect themselves from pest attacks. Some synthetic chemicals, such as

2911-507: The area of Dong Son culture. Thus, Ferlus conclude that the Dongsonian culture was of Vietic origin and they were the direct ancestors of modern Vietnamese people . The origins of Dong Son culture may be traced back to ancient bronze castings. Scholars traditionally traced the origins of bronze-casting technology to China but during the 1970s archaeological discoveries in Isan , Thailand found that

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2982-465: The benefits these could bring. In 2022, greenhouse gas emissions from rice cultivation were estimated at 5.7 billion tonnes CO2eq, representing 1.2% of total emissions. Within the agriculture sector, rice produces almost half the greenhouse gas emissions from croplands , some 30% of agricultural methane emissions , and 11% of agricultural nitrous oxide emissions. Methane is released from rice fields subject to long-term flooding, as this inhibits

3053-517: The casting of bronze either began in Southeast Asia first then spread into China, or that it developed the practise independently from China. The Dong Son bronze industry therefore has a local origin in Southeast Asia rather than being introduced by migrations out of China. The Gò Mun culture gave rise to the Dong Son culture; the Dong Son was the culmination of the Bronze Age and the opening stage of

3124-494: The country looked to them as having the aspect of a pond (i.e., a marais)". The Portuguese accounts speak of the Falupo Jola , Landuma , Biafada , and Bainik growing rice. André Álvares de Almada wrote about the dike systems used for rice cultivation, from which modern West African rice dike systems are descended. African rice was brought to the Americas with the transatlantic slave trade , arriving in Brazil probably by

3195-506: The crop would be lost under these conditions. In the Po Valley in Italy, the arborio and carnaroli risotto rice varieties have suffered poor harvests through drought in the 21st century. The Ente Nazionale Risi  [ it ] is developing drought-resistant varieties; its nuovo prometeo variety has deep roots that enable it to tolerate drought, but is not suitable for risotto. Rice yield can be reduced by weed growth, and

3266-474: The early United States, sometimes known as golden-seed rice for the colour of its grains. Long-grain gold-seed rice boasted grains 5 ⁄ 12 inch (11 mm)inch long (up 11% from 3 ⁄ 8 inch (9.5 mm)), and was brought to market by planter Joshua John Ward in the 1840s. Despite its popularity, the variety was lost in the American Civil War. Charleston Gold was released in 2011 and

3337-425: The exception of Spanish Bomba, is usually sticky when cooked, and is suitable for puddings. Thai Jasmine rice is aromatic, and unusually for a long-grain rice has some stickiness, with a soft texture. Indian Basmati rice is very long-grained and aromatic. Italian Arborio rice , used for risotto , is of medium length, oval, and quite sticky. Japanese sushi rice is a sticky short-grain variety. Cooked white rice

3408-425: The field where they will grow, or seedlings can be grown in a seedbed and transplanted into the field. Direct seeding needs some 60 to 80 kg of grain per hectare, while transplanting needs less, around 40 kg per hectare, but requires far more labour. Most rice in Asia is transplanted by hand. Mechanical transplanting takes less time but requires a carefully-prepared field and seedlings raised on mats or in trays to fit

3479-503: The grain, and cleaning by winnowing or screening . The rice grain is dried as soon as possible to bring the moisture content down to a level that is safe from mould fungi. Traditional drying relies on the heat of the sun, with the grain spread out on mats or on pavements. The edible rice species are members of the BOP clade within the grass family, the Poaceae . The rice subfamily, Oryzoideae ,

3550-484: The great diversity and continuous evolution of pests. Resistance genes are being sought from wild species of rice, and genetic engineering techniques are being applied. Oryza glaberrima Oryza glaberrima , commonly known as African rice , is one of the two domesticated rice species. It was first domesticated and grown in West Africa around 3,000 years ago. In agriculture, it has largely been replaced by higher-yielding Asian rice ( O. sativa ), and

3621-442: The harvest. A 2006 survey showed that a village typically cultivated 25 varieties of rice; an individual household would on average have 14 varieties and grow four per year; this, however, is down from the seven to nine varieties per woman that was average in previous decades. Women, who are traditionally responsible for the seeds, trade them often over long-distance networks. Varieties, each with subtypes, include: The cultivars

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3692-575: The herbicide 2,4-D , cause the plant to increase the production of certain defensive chemicals and thereby increase the plant's resistance to some types of pests. Conversely, other chemicals, such as the insecticide imidacloprid , appear to induce changes in the gene expression of the rice that make the plant more susceptible to certain pests. Plant breeders have created rice cultivars incorporating resistance to various insect pests . Conventional plant breeding of resistant varieties has been limited by challenges such as rearing insect pests for testing, and

3763-410: The later years of the 20th century decreased rice yield by between 10% and 20% across 200 farms in seven Asian countries. This may have been caused by increased night-time respiration. IRRI has predicted that Asian rice yields will fall by some 20% per 1°C rise in global mean temperature. Further, rice is unable to yield grain if the flowers experience a temperature of 35 °C or more for over one hour, so

3834-442: The loss of native varieties and reducing the independence of farmers. Multiple varieties of African rice are often grown so that the harvest is staggered. In this way, the harvest can be eaten fresh. Freshly harvested rice is moist, and can be puffed in fire, and eaten. Fried rice has a brownish color when fried; this is because of the husk which is green in color and turns brown when heated. African rice can be prepared in much

3905-417: The machine. Rice does not thrive if continuously submerged. Rice can be grown in different environments, depending upon water availability. The usual arrangement is for lowland fields to be surrounded by bunds and flooded to a depth of a few centimetres until around a week before harvest time; this requires a large amount of water. The "alternate wetting and drying" technique uses less water. One form of this

3976-464: The number of varieties grown is declining. It still persists, making up an estimated 20% of rice grown in West Africa. It is now rarely sold in West African markets, having been replaced by Asian strains. In comparison to Asian rice, African rice is hardy, pest-resistant, low-labour, and suited to a larger variety of African conditions. It is described as filling, with a distinct nutty flavour. It

4047-428: The other largest exporters. As of 2016, the countries that consumed the most rice were China (29% of total), India, and Indonesia. By 2020, Bangladesh had taken third place from Indonesia. On an annual average from 2020-23, China consumed 154 million tonnes of rice, India consumed 109 million tonnes, and Bangladesh and Indonesia consumed about 36 million tonnes each. Across the world, rice consumption per capita fell in

4118-430: The parasitic plant Striga . African rices shatter more than Asian rices, possibly because they have not been domesticated for as long. A few varieties of African rice are as resistant to shattering as shatter-resistant Asian varieties, but most are not; on average, about half of the grains are scattered and lost. This is why yield is lower; when the heads of African rice are bagged before they become ripe, so that

4189-454: The practice of cultivation was shared throughout the Carolina plantations, which allowed the enslaved people to develop a new sense of culture and made African rice the primary source of nutrition. The tolerance of African rice for brackish water meant it could be grown on coastal deltas, as it was in West Africa . There are numerous stories about how the rice came to North America, including

4260-445: The same way as Asian rice, but has a distinct nutty flavor, for which it is favored in West Africa. African rice grains are often reddish in colour; some varieties are strongly aromatic, other, like Carolina Gold, are not at all aromatic. African rice is also used in local traditional medicine. Overall, O. glaberrima is considered a much more desirable and healthier choice in places like Nigeria by West African farmers, where it

4331-421: The shattered grains are caught in paper bags, the yield of African rice is the same as the yield of Asian rice. Like other grains, rice may lodge, or fall over, when grain heads are full. African rice's greater height and weaker stems makes it more likely to lodge, although it also lets it survive in deep water , and makes it easier to harvest. African rice tends to elongate rapidly if completely submerged, which

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4402-484: The smelting of between 1 and 7 tonnes (1.1 and 7.7 tons) of copper ore. Displays of the Đông Sơn drum surface can be seen in some of Vietnam's cultural institutions. Some of Dong Son bronze daggers closely resemble Scytho-Siberian styles . Rice Rice is a cereal grain and in its domesticated form is the staple food of over half of the world's population , particularly in Asia and Africa . Rice

4473-1011: The soil from absorbing atmospheric oxygen, resulting in anaerobic fermentation of organic matter in the soil. Emissions can be limited by planting new varieties, not flooding continuously, and removing straw. It is possible to cut methane emissions in rice cultivation by improved water management, combining dry seeding and one drawdown, or executing a sequence of wetting and drying . This results in emission reductions of up to 90% compared to full flooding and even increased yields. Predictions of climate change's effects on rice cultivation vary. Global rice yield has been projected to decrease by around 3.2% with each 1°C increase in global average temperature while another study predicts global rice cultivation will increase initially, plateauing at about 3°C warming (2091–2100 relative to 1850–1900). The impacts of climate change on rice cultivation vary across geographic location and socioeconomic context. For example, rising temperatures and decreasing solar radiation during

4544-403: The soil is often not cultivated. African rice has profuse vegetative growth, which smothers weeds. It exhibits better resistance to various rice pests and diseases , such as blast disease , African rice gall midge ( Orseolia oryzivora ), parasitic nematodes ( Heterodera sacchari and Meloidogyne spp.), rice stripe necrosis virus (a Benyvirus ), rice yellow mottle virus , and

4615-628: The voyage to the rest of the Pacific. It reached Austroasiatic and Kra-Dai -speakers in Mainland Southeast Asia and southern China by 5000 years ago. Rice spread around the rest of the world through cultivation, migration and trade, eventually to the Americas as part of the Columbian exchange after 1492. The now less common Oryza glaberrima (African rice) was independently domesticated in Africa around 3,000 years ago, and introduced to

4686-785: The wet season, while thrips outbreaks are associated with drought. Rice blast , caused by the fungus Magnaporthe grisea , is the most serious disease of growing rice. It and bacterial leaf streak (caused by Xanthomonas oryzae pv. oryzae ) are perennially the two worst rice diseases worldwide; they are both among the ten most important diseases of all crop plants. Other major rice diseases include sheath blight (caused by Rhizoctonia solani ), false smut ( Ustilaginoidea virens ), and bacterial panicle blight ( Burkholderia glumae ). Viral diseases include rice bunchy stunt, rice dwarf, rice tungro , and rice yellow mottle. Crop protection scientists are developing sustainable techniques for managing rice pests. Sustainable pest management

4757-539: The year provided that sufficient water is made available. It is normally an annual, but in the tropics it can survive as a perennial , producing a ratoon crop. Like all crops, rice depends for its growth on both biotic and abiotic environmental factors. The principal biotic factors are crop variety, pests , and plant diseases . Abiotic factors include the soil type, whether lowland or upland, amount of rain or irrigation water, temperature, day length , and intensity of sunlight. Rice grains can be planted directly into

4828-465: Was first domesticated in China 9,000 years ago, by people of Neolithic cultures in the Upper and Lower Yangtze , associated with Hmong-Mien -speakers and pre-Austronesians , respectively. The functional allele for nonshattering , the critical indicator of domestication in grains, as well as five other single-nucleotide polymorphisms , is identical in both indica and japonica . This implies

4899-559: Was introduced early into Sino-Tibetan cultures in northern China by around 6000 to 5600 years ago, and to the Korean peninsula and Japan by around 5500 to 3200 years ago. It was also carried into Taiwan by the Dapenkeng culture by 5500 to 4000 years ago, before spreading southwards via the Austronesian migrations to Island Southeast Asia , Madagascar , and Guam , but did not survive

4970-404: Was still used in specific, often marginal habitats, and preferred for its taste. Farmers may grow African rice to eat and Asian rice to sell, as African rice is not exported. The 2007 food price shocks drove efforts to raise rice production. Rice-growing regions of Africa are generally net rice importers (partly due to a lack of good local rice-processing capacity) so price increases hurt. Among

5041-439: Was stored by rural households. The dry grain is milled to remove the outer layers, namely the husk and bran . These can be removed in a single step, in two steps, or as in commercial milling in a multi-step process of cleaning, dehusking, separation, polishing, grading, and weighing. Brown rice only has the inedible husk removed. Further milling removes bran and the germ to create successively whiter products. Parboiled rice

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