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Rice is the
seed A seed is an embryonic plant enclosed in a protective outer covering, along with a food reserve. The formation of the seed is a part of the process of reproduction in seed plants, the spermatophytes, including the gymnosperm and angiospe ...
of the
grass Poaceae () or Gramineae () is a large and nearly ubiquitous family of monocotyledonous flowering plants commonly known as grasses. It includes the cereal grasses, bamboos and the grasses of natural grassland and species cultivated in lawns an ...
species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...
''
Oryza sativa ''Oryza sativa'', commonly known as Asian rice or indica rice, is the plant species most commonly referred to in English as ''rice''. It is the type of farmed rice whose cultivars are most common globally, and was first domesticated in the Yan ...
'' (Asian rice) or less commonly ''
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 In agriculture, it has largely been replaced by higher-yielding Asian r ...
'' (African rice). The name
wild rice Wild rice, also called manoomin, Canada rice, Indian rice, or water oats, is any of four species of grasses that form the genus ''Zizania'', and the grain that can be harvested from them. The grain was historically gathered and eaten in both ...
is usually used for species of the genera ''
Zizania Wild rice, also called manoomin, Canada rice, Indian rice, or water oats, is any of four species of grasses that form the genus ''Zizania'', and the grain that can be harvested from them. The grain was historically gathered and eaten in both ...
'' and ''
Porteresia ''Porteresia coarctata'' is a species of grass in the family Poaceae, native to India, Sri Lanka, Bangladesh, and Myanmar. ''Porteresia coarctata'' is considered by some botanists to be the only species in the genus ''Porteresia''. Other autho ...
'', both wild and domesticated, although the term may also be used for primitive or uncultivated varieties of ''
Oryza ''Oryza'' is a genus of plants in the grass family. It includes the major food crop rice (species ''Oryza sativa'' and ''Oryza glaberrima''). Members of the genus grow as tall, wetland grasses, growing to tall; the genus includes both annual an ...
''. As a
cereal grain A cereal is any grass cultivated for the edible components of its grain (botanically, a type of fruit called a caryopsis), composed of the endosperm, germ, and bran. Cereal grain crops are grown in greater quantities and provide more food en ...
, domesticated rice is the most widely consumed
staple food A staple food, food staple, or simply a staple, is a food that is eaten often and in such quantities that it constitutes a dominant portion of a standard diet for a given person or group of people, supplying a large fraction of energy needs and ...
for over half of the world's
human population Humans (''Homo sapiens'') are the most abundant and widespread species of primate, characterized by bipedalism and exceptional cognitive skills due to a large and complex brain. This has enabled the development of advanced tools, culture, ...
,Abstract, "Rice feeds more than half the world's population." especially in
Asia Asia (, ) is one of the world's most notable geographical regions, which is either considered a continent in its own right or a subcontinent of Eurasia, which shares the continental landmass of Afro-Eurasia with Africa. Asia covers an area ...
and
Africa Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area ...
. It is the agricultural
commodity In economics, a commodity is an economic good, usually a resource, that has full or substantial fungibility: that is, the market treats instances of the good as equivalent or nearly so with no regard to who produced them. The price of a comm ...
with the third-highest worldwide production, after
sugarcane Sugarcane or sugar cane is a species of (often hybrid) tall, Perennial plant, perennial grass (in the genus ''Saccharum'', tribe Andropogoneae) that is used for sugar Sugar industry, production. The plants are 2–6 m (6–20 ft) tall with ...
and
maize Maize ( ; ''Zea mays'' subsp. ''mays'', from es, maíz after tnq, mahiz), also known as corn (North American and Australian English), is a cereal grain first domesticated by indigenous peoples in southern Mexico about 10,000 years ago. Th ...
. Since sizable portions of sugarcane and maize crops are used for purposes other than human consumption, rice is the most important food crop with regard to human nutrition and caloric intake, providing more than one-fifth of the
calories The calorie is a unit of energy. For historical reasons, two main definitions of "calorie" are in wide use. The large calorie, food calorie, or kilogram calorie was originally defined as the amount of heat needed to raise the temperature of on ...
consumed worldwide by humans. There are many varieties of rice and culinary preferences tend to vary regionally. The traditional method for cultivating rice is flooding the fields while, or after, setting the young seedlings. This simple method requires sound irrigation planning but reduces the growth of less robust weed and pest plants that have no submerged growth state, and deters
vermin Vermin (colloquially varmint(s) or varmit(s)) are pests or nuisance animals that spread diseases or destroy crops or livestock. Since the term is defined in relation to human activities, which species are included vary by region and enterpr ...
. While flooding is not mandatory for the cultivation of rice, all other methods of
irrigation Irrigation (also referred to as watering) is the practice of applying controlled amounts of water to land to help grow Crop, crops, Landscape plant, landscape plants, and Lawn, lawns. Irrigation has been a key aspect of agriculture for over 5,00 ...
require higher effort in
weed A weed is a plant considered undesirable in a particular situation, "a plant in the wrong place", or a plant growing where it is not wanted.Harlan, J. R., & deWet, J. M. (1965). Some thoughts about weeds. ''Economic botany'', ''19''(1), 16-24. ...
and
pest control Pest control is the regulation or management of a species defined as a pest; any animal, plant or fungus that impacts adversely on human activities or environment. The human response depends on the importance of the damage done and will range ...
during growth periods and a different approach for fertilizing the soil. Rice, a
monocot Monocotyledons (), commonly referred to as monocots, (Lilianae ''sensu'' Chase & Reveal) are grass and grass-like flowering plants (angiosperms), the seeds of which typically contain only one embryonic leaf, or cotyledon. They constitute one of ...
, is normally grown as an
annual plant An annual plant is a plant that completes its life cycle, from germination to the production of seeds, within one growing season, and then dies. The length of growing seasons and period in which they take place vary according to geographical ...
, although in
tropical The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in the Southern Hemisphere at S. The tropics are also referred to ...
areas it can survive as a
perennial A perennial plant or simply perennial is a plant that lives more than two years. The term ('' per-'' + '' -ennial'', "through the years") is often used to differentiate a plant from shorter-lived annuals and biennials. The term is also wide ...
and can produce a ratoon crop for up to 30 years. Rice cultivation is well-suited to countries and regions with low
labor costs A wage is payment made by an employer to an employee for work done in a specific period of time. Some examples of wage payments include compensatory payments such as ''minimum wage'', ''prevailing wage'', and ''yearly bonuses,'' and remunerat ...
and high
rain Rain is water droplets that have condensed from atmospheric water vapor and then fall under gravity. Rain is a major component of the water cycle and is responsible for depositing most of the fresh water on the Earth. It provides water f ...
fall, as it is labor-intensive to cultivate and requires ample water. However, rice can be grown practically anywhere, even on a steep hill or
mountain A mountain is an elevated portion of the Earth's crust, generally with steep sides that show significant exposed bedrock. Although definitions vary, a mountain may differ from a plateau in having a limited Summit (topography), summit area, and ...
area with the use of water-controlling terrace systems. Although its parent species are native to Asia and certain parts of Africa, centuries of trade and exportation have made it commonplace in many cultures worldwide. Production and consumption of rice is estimated to have been responsible for 4% of global
greenhouse gas emissions Greenhouse gas emissions from human activities strengthen the greenhouse effect, contributing to climate change. Most is carbon dioxide from burning fossil fuels: coal, oil, and natural gas. The largest emitters include coal in China and lar ...
in 2010.


Characteristics

The rice plant can grow to tall, occasionally more depending on the variety and soil fertility. It has long, slender leaves long and broad. The small
wind-pollinated Anemophily or wind pollination is a form of pollination whereby pollen is distributed by wind. Almost all gymnosperms are anemophilous, as are many plants in the order Poales, including grasses, sedges, and rushes. Other common anemophilous pla ...
flowers are produced in a branched arching to pendulous
inflorescence An inflorescence is a group or cluster of flowers arranged on a stem that is composed of a main branch or a complicated arrangement of branches. Morphologically, it is the modified part of the shoot of seed plants where flowers are formed o ...
long. The edible seed is a grain (
caryopsis In botany, a caryopsis (plural caryopses) is a type of simple fruit—one that is monocarpellate (formed from a single carpel) and indehiscent (not opening at maturity) and resembles an achene, except that in a caryopsis the pericarp is fused ...
) long and thick.


Food


Cooking

The varieties of rice are typically classified as long-, medium-, and short-grained. The grains of long-grain rice (high in
amylose Amylose is a polysaccharide made of α-D-glucose units, bonded to each other through α(1→4) glycosidic bonds. It is one of the two components of starch, making up approximately 20–30%. Because of its tightly packed helical structure, amylose ...
) tend to remain intact after cooking; medium-grain rice (high in
amylopectin Amylopectin is a water-insoluble polysaccharide and highly branched polymer of α-glucose units found in plants. It is one of the two components of starch, the other being amylose. Plants store starch within specialized organelles called amylopl ...
) becomes more sticky. Medium-grain rice is used for sweet dishes, for ''
risotto Risotto (, , from meaning "rice") is a northern Italian rice dish cooked with broth until it reaches a creamy consistency. The broth can be derived from meat, fish, or vegetables. Many types of risotto contain butter, onion, white wine, and Par ...
'' in Italy, and many rice dishes, such as '' arròs negre'', in Spain. Some varieties of long-grain rice that are high in
amylopectin Amylopectin is a water-insoluble polysaccharide and highly branched polymer of α-glucose units found in plants. It is one of the two components of starch, the other being amylose. Plants store starch within specialized organelles called amylopl ...
, known as Thai Sticky rice, are usually steamed. A stickier short-grain rice is used for ''
sushi is a Japanese cuisine, Japanese dish of prepared , usually with some sugar and salt, accompanied by a variety of , such as seafood, often raw, and vegetables. Styles of sushi and its presentation vary widely, but the one key ingredient is " ...
''; the stickiness allows rice to hold its shape when cooked. Short-grain rice is used extensively in Japan, including to accompany savoury dishes. Short-grain rice is often used for
rice pudding Rice pudding is a dish made from rice mixed with water or milk and other ingredients such as cinnamon, vanilla and raisins. Variants are used for either desserts or dinners. When used as a dessert, it is commonly combined with a sweetener such ...
.
Instant rice Instant rice is a product in which white rice is partially precooked, dehydrated, and repackaged in dried form similar in appearance to regular white rice. That process allows the product to be later cooked as if it were normal rice but with a ty ...
differs from
parboiled rice Parboiled rice (also called converted rice and easy-cook rice) is rice that has been partially boiled in the husk. The three basic steps of parboiling are soaking, steaming and drying. These steps make the rice easier to process by hand, while ...
in that it is fully cooked and then dried, though there is a significant degradation in taste and texture. Rice flour and
starch Starch or amylum is a polymeric carbohydrate consisting of numerous glucose units joined by glycosidic bonds. This polysaccharide is produced by most green plants for energy storage. Worldwide, it is the most common carbohydrate in human diets ...
often are used in
batters Batter or batters may refer to: Common meanings * Batter (cooking), thin dough that can be easily poured into a pan * Batter (baseball), person whose turn it is to face the pitcher * Batter (cricket), a player who is currently batting * Batter ...
and breadings to increase crispiness.


Preparation

Rinsing rice before cooking removes much of the
starch Starch or amylum is a polymeric carbohydrate consisting of numerous glucose units joined by glycosidic bonds. This polysaccharide is produced by most green plants for energy storage. Worldwide, it is the most common carbohydrate in human diets ...
, thereby reducing the extent to which individual grains will stick together. This yields a fluffier rice, whereas not rinsing yields a stickier and creamier result. Rice produced in the US is usually fortified with vitamins and minerals, and rinsing will result in a loss of nutrients. Rice may be soaked to decrease cooking time, conserve fuel, minimize exposure to high temperature, and reduce stickiness. For some
varieties Variety may refer to: Arts and entertainment Entertainment formats * Variety (radio) * Variety show, in theater and television Films * ''Variety'' (1925 film), a German silent film directed by Ewald Andre Dupont * ''Variety'' (1935 film), ...
, soaking improves the texture of the cooked rice by increasing expansion of the grains. Rice may be soaked for 30 minutes up to several hours. Brown rice may be soaked in warm water for 20 hours to stimulate
germination Germination is the process by which an organism grows from a seed or spore. The term is applied to the sprouting of a seedling from a seed of an angiosperm or gymnosperm, the growth of a sporeling from a spore, such as the spores of fungi, fer ...
. This process, called
germinated brown rice Germinated brown rice (GBR; ko, 발아현미(發芽玄米), bara-hyeonmi, ja, 発芽玄米(はつがげんまい), hatsuga-genmai) is unpolished brown rice that has been allowed to germinate to improve the flavor and texture, and to increase lev ...
(GBR), activates enzymes and enhances amino acids including gamma-aminobutyric acid to improve the nutritional value of brown rice. This method is a result of research carried out for the United Nations
International Year of Rice The year 2004 was declared the International Year of Rice by the United Nations, noting that rice is a staple food for more than half the world's population, and affirming the need to heighten awareness of the role of rice in alleviating poverty ...
. Rice is cooked by
boiling Boiling is the rapid vaporization of a liquid, which occurs when a liquid is heated to its boiling point, the temperature at which the vapour pressure of the liquid is equal to the pressure exerted on the liquid by the surrounding atmosphere. Th ...
or
steaming Steaming is a method of cooking using steam. This is often done with a food steamer, a kitchen appliance made specifically to cook food with steam, but food can also be steamed in a wok. In the American southwest, steam pits used for cooking ha ...
, and absorbs water during cooking. With the absorption method, rice may be cooked in a volume of water equal to the volume of dry rice plus any evaporation losses. With the rapid-boil method, rice may be cooked in a large quantity of water which is drained before serving. Rapid-boil preparation is not desirable with enriched rice, as much of the enrichment additives are lost when the water is discarded. Electric
rice cooker A rice cooker or rice steamer is an automated kitchen appliance designed to boil or steam rice. It consists of a heat source, a cooking bowl, and a thermostat. The thermostat measures the temperature of the cooking bowl and controls the heat. ...
s, popular in Asia and Latin America, simplify the process of cooking rice. Rice (or any other grain) is sometimes quickly fried in oil or fat before boiling (for example
saffron rice Saffron rice is a dish made from saffron, white rice and also usually vegetable bouillon. Saffron rice is found in the cuisines of many countries (in one form or another). The recipe is similar to plain cooked rice with addition of ingredients. ...
or
risotto Risotto (, , from meaning "rice") is a northern Italian rice dish cooked with broth until it reaches a creamy consistency. The broth can be derived from meat, fish, or vegetables. Many types of risotto contain butter, onion, white wine, and Par ...
); this makes the cooked rice less sticky, and is a cooking style commonly called
pilaf Pilaf ( US spelling) or pilau ( UK spelling) is a rice dish, or in some regions, a wheat dish, whose recipe usually involves cooking in stock or broth, adding spices, and other ingredients such as vegetables or meat, and employing some techniq ...
in
Iran Iran, officially the Islamic Republic of Iran, and also called Persia, is a country located in Western Asia. It is bordered by Iraq and Turkey to the west, by Azerbaijan and Armenia to the northwest, by the Caspian Sea and Turkmeni ...
and
Afghanistan Afghanistan, officially the Islamic Emirate of Afghanistan,; prs, امارت اسلامی افغانستان is a landlocked country located at the crossroads of Central Asia and South Asia. Referred to as the Heart of Asia, it is bordere ...
or
biryani Biryani () is a mixed rice dish originating among the Muslims of the Indian subcontinent. It is made with Indian spices, rice, and usually some type of meat ( chicken, beef, goat, lamb, prawn, fish) or in some cases without any meat, ...
in
India India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the so ...
and
Pakistan Pakistan ( ur, ), officially the Islamic Republic of Pakistan ( ur, , label=none), is a country in South Asia. It is the world's List of countries and dependencies by population, fifth-most populous country, with a population of almost 24 ...
.


Dishes

In
Arab cuisine Arab cuisine ( ar, المطبخ العربي) is the cuisine of the Arabs, defined as the various regional cuisines spanning the Arab world, from the Maghreb to the Fertile Crescent and the Arabian Peninsula. These cuisines are centuries old an ...
, rice is an ingredient of many soups and dishes with fish, poultry, and other types of meat. It is used to stuff vegetables or is wrapped in grape leaves (
dolma Dolma (Turkish for “stuffed”) is a family of stuffed dishes associated with Ottoman cuisine, and common in modern national cuisines of regions and countries that once were part of the Ottoman Empire. Some types of dolma are made with whol ...
). When combined with milk, sugar, and honey, it is used to make desserts. In some regions, such as
Tabaristan Tabaristan or Tabarestan ( fa, طبرستان, Ṭabarestān, or mzn, تبرستون, Tabarestun, ultimately from Middle Persian: , ''Tapur(i)stān''), was the name applied to a mountainous region located on the Caspian coast of northern Iran. ...
, bread is made using rice flour. Rice may be made into
congee Congee or conjee ( ) is a type of rice porridge or gruel eaten in Asian countries. It can be eaten plain, where it is typically served with side dishes, or it can be served with ingredients such as meat, fish, seasonings and flavourings, most o ...
(also called rice porridge or rice gruel) by adding more water than usual, so that the cooked rice is saturated with water, usually to the point that it disintegrates. Rice porridge is commonly eaten as a breakfast food, and is a traditional food for the sick.


Nutrition

Rice is the
staple food A staple food, food staple, or simply a staple, is a food that is eaten often and in such quantities that it constitutes a dominant portion of a standard diet for a given person or group of people, supplying a large fraction of energy needs and ...
of over half the world's population. It is the predominant dietary energy source for 17 countries in Asia and the Pacific, 9 countries in North and South America and 8 countries in Africa. Rice provides 20% of the world's dietary energy supply, while wheat supplies 19% and maize (corn) 5%. Cooked unenriched long-grain white rice is composed of 68% water, 28%
carbohydrates In organic chemistry, a carbohydrate () is a biomolecule consisting of carbon (C), hydrogen (H) and oxygen (O) atoms, usually with a hydrogen–oxygen atom ratio of 2:1 (as in water) and thus with the empirical formula (where ''m'' may or may ...
, 3%
protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respo ...
, and 1%
fat In nutrition science, nutrition, biology, and chemistry, fat usually means any ester of fatty acids, or a mixture of such chemical compound, compounds, most commonly those that occur in living beings or in food. The term often refers spec ...
(table). A reference serving of it provides of
food energy Food energy is chemical energy that animals (including humans) derive from their food to sustain their metabolism, including their muscle, muscular activity. Most animals derive most of their energy from aerobic respiration, namely combining the ...
and contains no
micronutrient Micronutrients are nutrient, essential dietary elements required by organisms in varying quantities throughout life to orchestrate a range of physiological functions to maintain health. Micronutrient requirements differ between organisms; for exam ...
s in significant amounts, with all less than 10% of the
Daily Value The Reference Daily Intake (RDI) used in nutrition labeling on food and dietary supplement products in the U.S. and Canada is the daily intake level of a nutrient that is considered to be sufficient to meet the requirements of 97–98% of health ...
(DV) (table). Cooked short-grain white rice provides the same food energy and contains moderate amounts of
B vitamins B vitamins are a class of water-soluble vitamins that play important roles in cell metabolism and synthesis of red blood cells. Though these vitamins share similar names (B1, B2, B3, etc.), they are chemically distinct compounds that often coexist ...
,
iron Iron () is a chemical element with symbol Fe (from la, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, right in f ...
, and
manganese Manganese is a chemical element with the symbol Mn and atomic number 25. It is a hard, brittle, silvery metal, often found in minerals in combination with iron. Manganese is a transition metal with a multifaceted array of industrial alloy use ...
(10–17% DV) per 100-gram serving (table). A detailed analysis of nutrient content of rice suggests that the nutrition value of rice varies based on a number of factors. It depends on the strain of rice, such as
white White is the lightest color and is achromatic (having no hue). It is the color of objects such as snow, chalk, and milk, and is the opposite of black. White objects fully reflect and scatter all the visible wavelengths of light. White on ...
,
brown Brown is a color. It can be considered a composite color, but it is mainly a darker shade of orange. In the CMYK color model used in printing or painting, brown is usually made by combining the colors orange and black. In the RGB color model used ...
,
red Red is the color at the long wavelength end of the visible spectrum of light, next to orange and opposite violet. It has a dominant wavelength of approximately 625–740 nanometres. It is a primary color in the RGB color model and a secondar ...
, and
black Black is a color which results from the absence or complete absorption of visible light. It is an achromatic color, without hue, like white and grey. It is often used symbolically or figuratively to represent darkness. Black and white have o ...
(or purple) varieties having different prevalence across world regions. It also depends on nutrient quality of the soil rice is grown in, whether and how the rice is polished or processed, the manner it is enriched, and how it is prepared before consumption. A 2018
World Health Organization The World Health Organization (WHO) is a specialized agency of the United Nations responsible for international public health. The WHO Constitution states its main objective as "the attainment by all peoples of the highest possible level of h ...
(WHO) guideline showed that
fortification A fortification is a military construction or building designed for the defense of territories in warfare, and is also used to establish rule in a region during peacetime. The term is derived from Latin ''fortis'' ("strong") and ''facere'' ...
of rice to reduce
malnutrition Malnutrition occurs when an organism gets too few or too many nutrients, resulting in health problems. Specifically, it is "a deficiency, excess, or imbalance of energy, protein and other nutrients" which adversely affects the body's tissues a ...
may involve different micronutrient strategies, including
iron Iron () is a chemical element with symbol Fe (from la, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, right in f ...
only, iron with
zinc Zinc is a chemical element with the symbol Zn and atomic number 30. Zinc is a slightly brittle metal at room temperature and has a shiny-greyish appearance when oxidation is removed. It is the first element in group 12 (IIB) of the periodi ...
,
vitamin A Vitamin A is a fat-soluble vitamin and an essential nutrient for humans. It is a group of organic compounds that includes retinol, retinal (also known as retinaldehyde), retinoic acid, and several provitamin A carotenoids (most notably bet ...
, and
folic acid Folate, also known as vitamin B9 and folacin, is one of the B vitamins. Manufactured folic acid, which is converted into folate by the body, is used as a dietary supplement and in food fortification as it is more stable during processing and ...
, or iron with other B-complex vitamins, such as
thiamin Thiamine, also known as thiamin and vitamin B1, is a vitamin, an essential micronutrient, that cannot be made in the body. It is found in food and commercially synthesized to be a dietary supplement or medication. Phosphorylated forms of thia ...
,
niacin Niacin, also known as nicotinic acid, is an organic compound and a form of vitamin B3, an essential human nutrient. It can be manufactured by plants and animals from the amino acid tryptophan. Niacin is obtained in the diet from a variet ...
,
vitamin B6 Vitamin B6 is one of the B vitamins, and thus an essential nutrient. The term refers to a group of six chemically similar compounds, i.e., "vitamers", which can be interconverted in biological systems. Its active form, pyridoxal 5′-phosphat ...
, and
pantothenic acid Pantothenic acid, also called vitamin B5 is a water-soluble B vitamin and therefore an essential nutrient. All animals require pantothenic acid in order to synthesize coenzyme A (CoA) – essential for fatty acid metabolism – as well as to, i ...
. A
systematic review A systematic review is a Literature review, scholarly synthesis of the evidence on a clearly presented topic using critical methods to identify, define and assess research on the topic. A systematic review extracts and interprets data from publ ...
of
clinical research Clinical research is a branch of healthcare science that determines the safety and effectiveness ( efficacy) of medications, devices, diagnostic products and treatment regimens intended for human use. These may be used for prevention, treatm ...
on the efficacy of rice fortification showed the strategy had the main effect of reducing the risk of
iron deficiency Iron deficiency, or sideropenia, is the state in which a body lacks enough iron to supply its needs. Iron is present in all cells in the human body and has several vital functions, such as carrying oxygen to the tissues from the lungs as a key ...
by 35% and increasing blood levels of
hemoglobin Hemoglobin (haemoglobin BrE) (from the Greek word αἷμα, ''haîma'' 'blood' + Latin ''globus'' 'ball, sphere' + ''-in'') (), abbreviated Hb or Hgb, is the iron-containing oxygen-transport metalloprotein present in red blood cells (erythrocyte ...
. The guideline established a major recommendation: "Fortification of rice with iron is recommended as a public health strategy to improve the iron status of populations, in settings where rice is a staple food." Rice grown experimentally under elevated
carbon dioxide Carbon dioxide (chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is transpar ...
levels, similar to those predicted for the year 2100 as a result of human activity, had less iron, zinc, and protein, as well as lower levels of thiamin,
riboflavin Riboflavin, also known as vitamin B2, is a vitamin found in food and sold as a dietary supplement. It is essential to the formation of two major coenzymes, flavin mononucleotide and flavin adenine dinucleotide. These coenzymes are involved in ...
, folic acid, and pantothenic acid. The following table shows the nutrient content of rice and other major staple foods in a raw form on a dry weight basis to account for their different water contents.


Arsenic concerns

As arsenic occurs in soil, water, and air, the United States
Food and Drug Administration The United States Food and Drug Administration (FDA or US FDA) is a List of United States federal agencies, federal agency of the United States Department of Health and Human Services, Department of Health and Human Services. The FDA is respon ...
(FDA) monitors the levels of arsenic in foods, particularly in rice products used commonly for infant food. While growing, rice plants tend to absorb arsenic more readily than other food crops, requiring expanded testing by the FDA for possible arsenic-related risks associated with rice consumption in the United States. In April 2016, the FDA proposed a limit of 100 parts per billion (ppb) for inorganic arsenic in infant
rice cereal Rice cereal is the name commonly given to industrially manufactured baby food based on rice. It is also commonly used in Rice Krispy treats. Its ingredient list is not well defined and depends on the manufacturer. It has been recommended by pedi ...
and other foods to minimize exposure of infants to arsenic. For water contamination by arsenic, the United States
Environmental Protection Agency A biophysical environment is a biotic and abiotic surrounding of an organism or population, and consequently includes the factors that have an influence in their survival, development, and evolution. A biophysical environment can vary in scale f ...
has set a lower standard of 10 ppb. Arsenic is a Group 1 carcinogen. The amount of arsenic in rice varies widely with the greatest concentration in brown rice and rice grown on land formerly used to grow cotton, such as in
Arkansas Arkansas ( ) is a landlocked state in the South Central United States. It is bordered by Missouri to the north, Tennessee and Mississippi to the east, Louisiana to the south, and Texas and Oklahoma to the west. Its name is from the Osage ...
,
Louisiana Louisiana , group=pronunciation (French: ''La Louisiane'') is a state in the Deep South and South Central regions of the United States. It is the 20th-smallest by area and the 25th most populous of the 50 U.S. states. Louisiana is borde ...
,
Missouri Missouri is a U.S. state, state in the Midwestern United States, Midwestern region of the United States. Ranking List of U.S. states and territories by area, 21st in land area, it is bordered by eight states (tied for the most with Tennessee ...
, and
Texas Texas (, ; Spanish language, Spanish: ''Texas'', ''Tejas'') is a state in the South Central United States, South Central region of the United States. At 268,596 square miles (695,662 km2), and with more than 29.1 million residents in 2 ...
. White rice grown in Arkansas, Louisiana, Missouri, and Texas, which account collectively for 76 percent of American-produced rice, had higher levels of arsenic than other regions of the world studied, possibly because of past use of arsenic-based pesticides to control cotton weevils. Jasmine rice from Thailand and Basmati rice from Pakistan and India contain the least arsenic among rice varieties in one study. China has set a limit of 150 ppb for arsenic in rice.


''Bacillus cereus''

Cooked rice can contain ''
Bacillus cereus ''Bacillus cereus'' is a Gram-positive rod-shaped bacterium commonly found in soil, food, and marine sponges. The specific name, ''cereus'', meaning "waxy" in Latin, refers to the appearance of colonies grown on blood agar. Some strains are ha ...
'' spores, which produce an
emetic Vomiting (also known as emesis and throwing up) is the involuntary, forceful expulsion of the contents of one's stomach through the mouth and sometimes the nose. Vomiting can be the result of ailments like food poisoning, gastroenteri ...
toxin when left at . When storing cooked rice for use the next day, rapid cooling is advised to reduce the risk of toxin production. One of the
enterotoxin An enterotoxin is a protein exotoxin released by a microorganism that targets the intestines. Enterotoxins are chromosomally encoded or plasmid encoded exotoxins that are produced and secreted from several bacterial organisms. They are heat la ...
s produced by ''Bacillus cereus'' is heat-resistant; reheating contaminated rice kills the bacteria, but does not destroy the toxin already present.


Rice-growing environments

Rice growth and production are affected by: the environment, soil properties, biotic conditions, and cultural practices. Environmental factors include rainfall and water, temperature, photoperiod, solar radiation and, in some instances, tropical storms. Soil factors refer to soil type and their position in uplands or lowlands. Biotic factors deal with weeds, insects, diseases, and crop varieties. Rice can be grown in different environments, depending upon water availability. Generally, rice does not thrive in a waterlogged area, yet it can survive and grow herein and it can survive flooding. # Lowland, rainfed, which is drought prone, favors medium depth; waterlogged, submergence, and flood prone # Lowland, irrigated, grown in both the wet season and the dry season # Deep water or floating rice # Coastal wetland #
Upland rice Upland rice is a type of rice grown on dry soil rather than flooded paddy field, rice paddies. It is sometimes also called dry rice. Introduction Today nearly 100 million people depend on upland rice as their daily staple food. Almost two-thi ...
(also known as hill rice or Ghaiya rice) is well known for its drought tolerance


History of cultivation


Production and commerce


Production

In 2020, world production of paddy rice was s, led by China and India with a combined 52% of this total. Other major producers were
Bangladesh Bangladesh (}, ), officially the People's Republic of Bangladesh, is a country in South Asia. It is the eighth-most populous country in the world, with a population exceeding 165 million people in an area of . Bangladesh is among the mos ...
,
Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania between the Indian and Pacific oceans. It consists of over 17,000 islands, including Sumatra, Java, Sulawesi, and parts of Borneo and New Guine ...
and
Vietnam Vietnam or Viet Nam ( vi, Việt Nam, ), officially the Socialist Republic of Vietnam,., group="n" is a country in Southeast Asia, at the eastern edge of mainland Southeast Asia, with an area of and population of 96 million, making i ...
. The five major producers accounted for 72% of total production, while the top fifteen producers accounted for 91% of total world production in 2017 (see table on right). Developing countries account for 95% of the total production. Rice is a major food staple and a mainstay for the rural population and their food security. It is mainly cultivated by small farmers in holdings of less than one
hectare The hectare (; SI symbol: ha) is a non-SI metric unit of area equal to a square with 100-metre sides (1 hm2), or 10,000 m2, and is primarily used in the measurement of land. There are 100 hectares in one square kilometre. An acre is a ...
. Rice is also a wage commodity for workers in the cash crop or non-agricultural sectors. Rice is vital for the nutrition of much of the population in Asia, as well as in Latin America and the Caribbean and in Africa; it is central to the food security of over half the world population. Many rice grain producing countries have significant losses post-harvest at the farm and because of poor roads, inadequate storage technologies, inefficient supply chains and farmer's inability to bring the produce into retail markets dominated by small shopkeepers. A World Bank – FAO study claims 8% to 26% of rice is lost in developing nations, on average, every year, because of post-harvest problems and poor infrastructure. Some sources claim the post-harvest losses exceed 40%. Not only do these losses reduce food security in the world, the study claims that farmers in developing countries such as China, India and others lose approximately US$89 billion of income in preventable post-harvest farm losses, poor transport, the lack of proper storage and retail. One study claims that if these post-harvest grain losses could be eliminated with better infrastructure and retail network, in India alone enough food would be saved every year to feed 70 to 100 million people.


Processing

The seeds of the rice plant are first milled using a
rice huller A rice huller or rice husker is an agricultural machine used to automate the process of removing the chaff (the outer husks) of grains of rice. Throughout history, there have been numerous techniques to hull rice. Traditionally, it would be p ...
to remove the
chaff Chaff (; ) is the dry, scaly protective casing of the seeds of cereal grains or similar fine, dry, scaly plant material (such as scaly parts of flowers or finely chopped straw). Chaff is indigestible by humans, but livestock can eat it. In agri ...
(the outer husks of the grain) (see:
rice hulls Rice hulls (or rice husks) are the hard protecting coverings of grains of rice. In addition to protecting rice during the growing season, rice hulls can be put to use as building material, fertilizer, insulation material, or fuel. Rice hulls are p ...
). At this point in the process, the product is called
brown rice Brown rice is a whole grain rice with the inedible outer Rice hulls, hull removed. This kind of rice sheds its outer hull or husk but the bran and germ layer remain on, constituting the brown or tan colour of rice. White rice is the same grain w ...
. The milling may be continued, removing the
bran Bran, also known as miller's bran, is the hard outer layers of Cereal, cereal grain. It consists of the combined aleurone and pericarp. Corn (maize) bran also includes the pedicel (tip cap). Along with cereal germ, germ, it is an integral pa ...
, ''i.e.'', the rest of the husk and the
germ Germ or germs may refer to: Science * Germ (microorganism), an informal word for a pathogen * Germ cell, cell that gives rise to the gametes of an organism that reproduces sexually * Germ layer, a primary layer of cells that forms during embry ...
, thereby creating
white rice White rice is milled rice that has had its husk, bran, and germ removed. This alters the flavor, texture and appearance of the rice and helps prevent spoilage, extend its storage life, and makes it easier to digest. After milling (hulling), the ...
. White rice, which keeps longer, lacks some important nutrients; moreover, in a limited diet which does not supplement the rice, brown rice helps to prevent the
disease A disease is a particular abnormal condition that negatively affects the structure or function of all or part of an organism, and that is not immediately due to any external injury. Diseases are often known to be medical conditions that a ...
beriberi Thiamine deficiency is a medical condition of low levels of thiamine (Vitamin B1). A severe and chronic form is known as beriberi. The two main types in adults are wet beriberi and dry beriberi. Wet beriberi affects the cardiovascular system, ...
. Either by hand or in a
rice polisher A rice polisher is a machine for buffing (or "polishing") kernels of rice to change their appearance, taste, and texture or for transforming brown rice into white rice. Rice polishers are used after the rice has gone through the whitening process ...
, white rice may be buffed with glucose or
talc Talc, or talcum, is a Clay minerals, clay mineral, composed of hydrated magnesium silicate with the chemical formula Mg3Si4O10(OH)2. Talc in powdered form, often combined with corn starch, is used as baby powder. This mineral is used as a thi ...
powder (often called polished rice, though this term may also refer to white rice in general),
parboiled Parboiling (or leaching) is the partial or semi boiling of food as the first step in cooking. The word is from the Old French 'parboillir' (to boil thoroughly) but by mistaken association with 'part' it has acquired its current meaning. The wo ...
, or processed into flour. White rice may also be enriched by adding nutrients, especially those lost during the milling process. While the cheapest method of enriching involves adding a powdered blend of nutrients that will easily wash off (in the United States, rice which has been so treated requires a label warning against rinsing), more sophisticated methods apply nutrients directly to the grain, coating the grain with a water-insoluble substance which is resistant to washing. In some countries, a popular form,
parboiled rice Parboiled rice (also called converted rice and easy-cook rice) is rice that has been partially boiled in the husk. The three basic steps of parboiling are soaking, steaming and drying. These steps make the rice easier to process by hand, while ...
(also known as converted rice and easy-cook rice) is subjected to a steaming or
parboiling Parboiling (or leaching) is the partial or semi boiling of food as the first step in cooking. The word is from the Old French 'parboillir' (to boil thoroughly) but by mistaken association with 'part' it has acquired its current meaning. The wo ...
process while still a brown rice grain. The parboil process causes a gelatinisation of the starch in the grains. The grains become less brittle, and the color of the milled grain changes from white to yellow. The rice is then dried, and can then be milled as usual or used as brown rice. Milled parboiled rice is nutritionally superior to standard milled rice, because the process causes nutrients from the outer husk (especially
thiamine Thiamine, also known as thiamin and vitamin B1, is a vitamin, an essential micronutrient, that cannot be made in the body. It is found in food and commercially synthesized to be a dietary supplement or medication. Phosphorylated forms of thi ...
) to move into the
endosperm The endosperm is a tissue produced inside the seeds of most of the flowering plants following double fertilization. It is triploid (meaning three chromosome sets per nucleus) in most species, which may be auxin-driven. It surrounds the embryo and ...
, so that less is subsequently lost when the husk is polished off during milling. Parboiled rice has an additional benefit in that it does not stick to the pan during cooking, as happens when cooking regular white rice. This type of rice is eaten in parts of India and countries of West Africa are also accustomed to consuming parboiled rice.
Rice bran Bran, also known as miller's bran, is the hard outer layers of cereal grain. It consists of the combined aleurone and pericarp. Corn (maize) bran also includes the pedicel (tip cap). Along with germ, it is an integral part of whole grains, ...
, called ''nuka'' in Japan, is a valuable commodity in Asia and is used for many daily needs. It is a moist, oily inner layer which is heated to produce oil. It is also used as a pickling bed in making rice bran pickles and ''
takuan ''Takuan'' (; also spelled ''takuwan''), or ''takuan-zuke'' (; 'pickled takuan'), known as ''danmuji'' () in the context of Korean cuisine, is a pickled preparation of daikon radish. As a popular part of traditional Japanese cuisine, ''takuan ...
''. Raw rice may be ground into flour for many uses, including making many kinds of beverages, such as ''
amazake is a traditional sweet, low-alcohol or non-alcoholic Japanese drink made from fermented rice. ''Amazake'' dates from the Kofun period, and it is mentioned in the Nihon Shoki. It is part of the family of traditional Japanese foods made usin ...
,
horchata Horchata (; ), or (), is a name given to various beverages, which are generally plant-based, but sometimes contain animal milk. In Spain, it is made with soaked, ground, and sweetened tiger nuts. In Latin America and other parts of the Americas ...
'',
rice milk Rice milk is a plant milk made from rice. Commercial rice milk is typically manufactured using brown rice and brown rice syrup, and may be sweetened using sugar or sugar substitutes, and flavored by common ingredients, such as vanilla. It is comm ...
, and
rice wine Rice wine is an alcoholic beverage fermented and distilled from rice, traditionally consumed in East Asia, Southeast Asia and South Asia. Rice wine is made by the fermentation of rice starch that has been converted to sugars. Microbes are the so ...
. Rice does not contain
gluten Gluten is a structural protein naturally found in certain cereal grains. Although "gluten" often only refers to wheat proteins, in medical literature it refers to the combination of prolamin and glutelin proteins naturally occurring in all grain ...
, so is suitable for people on a
gluten-free diet A gluten-free diet (GFD) is a nutritional plan that strictly excludes gluten, which is a mixture of proteins found in wheat (and all of its species and hybrids, such as spelt, kamut, and triticale), as well as barley, rye, and oats. The incl ...
. Rice can be made into various types of
noodle Noodles are a type of food made from unleavened dough which is either rolled flat and cut, stretched, or extruded, into long strips or strings. Noodles are a staple food in many cultures (for example, Chinese noodles, Filipino noodles, Indo ...
s. Raw, wild, or brown rice may also be consumed by raw-foodist or fruitarians if soaked and sprouted (usually a week to 30 days – gaba rice). Processed rice seeds must be boiled or steamed before eating. Boiled rice may be further fried in
cooking oil Cooking oil is plant, animal, or synthetic liquid fat used in frying, baking, and other types of cooking. It is also used in food preparation and flavoring not involving heat, such as salad dressings and bread dips, and may be called edible oil. ...
or butter (known as
fried rice Fried rice is a dish of cooked rice that has been stir-fried in a wok or a frying pan and is usually mixed with other ingredients such as eggs, vegetables, seafood, or meat. It is often eaten by itself or as an accompaniment to another dish. Fr ...
), or beaten in a tub to make ''
mochi is a Japanese rice cake made of , a short-grain japonica glutinous rice, and sometimes other ingredients such as water, sugar, and cornstarch. The rice is pounded into paste and molded into the desired shape. In Japan, it is traditionally ma ...
''. Rice is a good source of protein and a staple food in many parts of the world, but it is not a
complete protein A complete protein or whole protein is a food source of protein that contains an adequate proportion of each of the nine essential amino acids necessary in the human diet. Amino acid profile The following table lists the optimal profile of the ...
: it does not contain all of the
essential amino acids An essential amino acid, or indispensable amino acid, is an amino acid that cannot be synthesized from scratch by the organism fast enough to supply its demand, and must therefore come from the diet. Of the 21 amino acids common to all life form ...
in sufficient amounts for good health, and should be combined with other sources of protein, such as nuts, seeds, beans, fish, or meat. Rice, like other cereal
grains A grain is a small, hard, dry fruit (caryopsis) – with or without an attached hull layer – harvested for human or animal consumption. A grain crop is a grain-producing plant. The two main types of commercial grain crops are cereals and legumes ...
, can be puffed (or popped). This process takes advantage of the grains' water content and typically involves heating grains in a special chamber. Further puffing is sometimes accomplished by processing puffed pellets in a low-
pressure Pressure (symbol: ''p'' or ''P'') is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure (also spelled ''gage'' pressure)The preferred spelling varies by country and e ...
chamber. The
ideal gas law The ideal gas law, also called the general gas equation, is the equation of state of a hypothetical ideal gas. It is a good approximation of the behavior of many gases under many conditions, although it has several limitations. It was first stat ...
means either lowering the local pressure or raising the water temperature results in an increase in
volume Volume is a measure of occupied three-dimensional space. It is often quantified numerically using SI derived units (such as the cubic metre and litre) or by various imperial or US customary units (such as the gallon, quart, cubic inch). The de ...
prior to water
evaporation Evaporation is a type of vaporization that occurs on the surface of a liquid as it changes into the gas phase. High concentration of the evaporating substance in the surrounding gas significantly slows down evaporation, such as when humidi ...
, resulting in a puffy
texture Texture may refer to: Science and technology * Surface texture, the texture means smoothness, roughness, or bumpiness of the surface of an object * Texture (roads), road surface characteristics with waves shorter than road roughness * Texture ...
. Bulk raw rice density is about 0.9 g/cm3. It decreases to less than one-tenth that when puffed.


Harvesting, drying and milling

Unmilled rice, known as "paddy" (Indonesia and Malaysia: padi; Philippines, palay), is usually harvested when the grains have a moisture content of around 25%. In most Asian countries, where rice is almost entirely the product of
smallholder A smallholding or smallholder is a small farm operating under a small-scale agriculture model. Definitions vary widely for what constitutes a smallholder or small-scale farm, including factors such as size, food production technique or technology ...
agriculture, harvesting is carried out manually, although there is a growing interest in mechanical harvesting. Harvesting can be carried out by the farmers themselves, but is also frequently done by seasonal labor groups. Harvesting is followed by
threshing Threshing, or thrashing, is the process of loosening the edible part of grain (or other crop) from the straw to which it is attached. It is the step in grain preparation after reaping. Threshing does not remove the bran from the grain. History ...
, either immediately or within a day or two. Again, much threshing is still carried out by hand but there is an increasing use of mechanical threshers. Subsequently, paddy needs to be dried to bring down the moisture content to no more than 20% for milling. A familiar sight in several Asian countries is paddy laid out to dry along roads. However, in most countries the bulk of drying of marketed paddy takes place in mills, with village-level drying being used for paddy to be consumed by farm families. Mills either sun dry or use mechanical driers or both. Drying has to be carried out quickly to avoid the formation of molds. Mills range from simple hullers, with a throughput of a couple of tonnes a day, that simply remove the outer husk, to enormous operations that can process a day and produce highly polished rice. A good mill can achieve a paddy-to-rice conversion rate of up to 72% but smaller, inefficient mills often struggle to achieve 60%. These smaller mills often do not buy paddy and sell rice but only service farmers who want to mill their paddy for their own consumption.


Distribution

Because of the importance of rice to human nutrition and food security in Asia, the domestic rice markets tend to be subject to considerable state involvement. While the private sector plays a leading role in most countries, agencies such as BULOG in Indonesia, the NFA in the Philippines, VINAFOOD in Vietnam and the
Food Corporation of India Food is any substance consumed by an organism for nutritional support. Food is usually of plant, animal, or fungal origin, and contains essential nutrients, such as carbohydrates, fats, proteins, vitamins, or minerals. The substance is in ...
are all heavily involved in purchasing of paddy from farmers or rice from mills and in distributing rice to poorer people. BULOG and NFA monopolise rice imports into their countries while VINAFOOD controls all exports from Vietnam.


Trade

World trade figures are very different from those for production, as less than 8% of rice produced is traded internationally. In economic terms, the global rice trade was a small fraction of 1% of world mercantile trade. Many countries consider rice as a strategic food staple, and various governments subject its trade to a wide range of controls and interventions. Developing countries are the main players in the world rice trade, accounting for 83% of exports and 85% of imports. While there are numerous importers of rice, the exporters of rice are limited. Just five countries—Thailand, Vietnam, China, the United States and India—in decreasing order of exported quantities, accounted for about three-quarters of world rice exports in 2002. However, this ranking has been rapidly changing in recent years. In 2010, the three largest exporters of rice, in decreasing order of quantity exported were Thailand, Vietnam and India. By 2012, India became the largest exporter of rice with a 100% increase in its exports on year-to-year basis, and Thailand slipped to third position. Together, Thailand, Vietnam and India accounted for nearly 70% of the world rice exports. The primary variety exported by Thailand and Vietnam were
Jasmine rice Jasmine rice ( th, ข้าวหอมมะลิ; ; ) is a long-grain variety of fragrant rice (also known as aromatic rice). Its fragrance, reminiscent of ''pandan'' (''Pandanus amaryllifolius'') and popcorn, results from the rice plant's n ...
, while exports from India included aromatic
Basmati Basmati, , is a variety of long, slender-grained aromatic rice which is traditionally grown in India, Pakistan, and Nepal.
variety. China, an exporter of rice in early 2000s, was a net importer of rice in 2010 and will become the largest net importer, surpassing Nigeria, in 2013. According to a
USDA The United States Department of Agriculture (USDA) is the federal executive department responsible for developing and executing federal laws related to farming, forestry, rural economic development, and food. It aims to meet the needs of com ...
report, the world's largest exporters of rice in 2012 were India (), Vietnam (), Thailand (), Pakistan () and the United States (). Major importers usually include Nigeria, Indonesia, Bangladesh, Saudi Arabia, Iran, Iraq, Malaysia, the Philippines, Brazil and some African and
Persian Gulf The Persian Gulf ( fa, خلیج فارس, translit=xalij-e fârs, lit=Gulf of Persis, Fars, ), sometimes called the ( ar, اَلْخَلِيْجُ ٱلْعَرَبِيُّ, Al-Khalīj al-ˁArabī), is a Mediterranean sea (oceanography), me ...
countries. In common with other West African countries, Nigeria is actively promoting domestic production. However, its very heavy import duties (110%) open it to smuggling from neighboring countries. Parboiled rice is particularly popular in Nigeria. Although China and India are the two largest producers of rice in the world, both countries consume the majority of the rice produced domestically, leaving little to be traded internationally.


Yield records

The average world yield for rice was , in 2010. Australian rice farms were the most productive in 2010, with a nationwide average of .
Yuan Longping Yuan Longping (; September 7, 1930May 22, 2021) was a Chinese agronomist and member of the Chinese Academy of Engineering known for developing the first hybrid rice varieties in the 1970s, part of the Green Revolution in agriculture. For his ...
of China National Hybrid Rice Research and Development Center set a world record for rice yield in 2010 at on a demonstration plot. In 2011, this record was reportedly surpassed by an Indian farmer, Sumant Kumar, with in
Bihar Bihar (; ) is a state in eastern India. It is the 2nd largest state by population in 2019, 12th largest by area of , and 14th largest by GDP in 2021. Bihar borders Uttar Pradesh to its west, Nepal to the north, the northern part of West Be ...
, although this claim has been disputed by both Yuan and India's Central Rice Research Institute. These efforts employed newly developed rice breeds and
System of Rice Intensification A system is a group of interacting or interrelated elements that act according to a set of rules to form a unified whole. A system, surrounded and influenced by its environment, is described by its boundaries, structure and purpose and expressed ...
(SRI), a recent innovation in rice farming.


Price

In late 2007 to May 2008, the price of grains rose greatly due to droughts in major producing countries (particularly Australia), increased use of grains for animal feed and US subsidies for bio-fuel production. Although there was no shortage of rice on world markets this general upward trend in grain prices led to panic buying by consumers, government rice export bans (in particular, by Vietnam and India) and inflated import orders by the Philippines marketing board, the National Food Authority. This caused significant rises in rice prices. In late April 2008, prices hit 24
US cent The cent, the United States one-cent coin (symbol: ¢), often called the "penny", is a unit of currency equaling one one-hundredth of a United States dollar. It has been the lowest face-value physical unit of U.S. currency since the abolition o ...
s a pound, twice the price of seven months earlier. Over the period of 2007 to 2013, the Chinese government has substantially increased the price it pays domestic farmers for their rice, rising to per metric ton by 2013. The 2013 price of rice originating from other southeast Asian countries was a comparably low per metric ton. On April 30, 2008, Thailand announced plans for the creation of the Organisation of Rice Exporting Countries (OREC) with the intention that this should develop into a price-fixing
cartel A cartel is a group of independent market participants who collude with each other in order to improve their profits and dominate the market. Cartels are usually associations in the same sphere of business, and thus an alliance of rivals. Mos ...
for rice. However, little progress had been made to achieve this.


Worldwide consumption

, world food consumption of rice was of paddy equivalent ( of milled equivalent), while the largest consumers were China consuming of paddy equivalent (28.7% of world consumption) and India consuming of paddy equivalent (23.1% of world consumption). Between 1961 and 2002, per capita consumption of rice increased by 40% worldwide. A paper from the Korean Society of Crop Science anticipated that consumption would increase to 590 million tons by 2040, and that consumption would decline in Asia and increase in other parts of the world. Rice is the most important crop in Asia. In Cambodia, for example, 90% of the total agricultural area is used for rice production. Per capita,
Bangladesh Bangladesh (}, ), officially the People's Republic of Bangladesh, is a country in South Asia. It is the eighth-most populous country in the world, with a population exceeding 165 million people in an area of . Bangladesh is among the mos ...
ranks as the country with the highest rice consumption, followed by
Laos Laos (, ''Lāo'' )), officially the Lao People's Democratic Republic ( Lao: ສາທາລະນະລັດ ປະຊາທິປະໄຕ ປະຊາຊົນລາວ, French: République démocratique populaire lao), is a socialist ...
,
Cambodia Cambodia (; also Kampuchea ; km, កម្ពុជា, UNGEGN: ), officially the Kingdom of Cambodia, is a country located in the southern portion of the Indochinese Peninsula in Southeast Asia, spanning an area of , bordered by Thailand t ...
,
Vietnam Vietnam or Viet Nam ( vi, Việt Nam, ), officially the Socialist Republic of Vietnam,., group="n" is a country in Southeast Asia, at the eastern edge of mainland Southeast Asia, with an area of and population of 96 million, making i ...
and
Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania between the Indian and Pacific oceans. It consists of over 17,000 islands, including Sumatra, Java, Sulawesi, and parts of Borneo and New Guine ...
. U.S. rice consumption has risen sharply over the past 25 years, fueled in part by commercial applications such as beer production. Almost one in five adult Americans now report eating at least half a serving of white or brown rice per day.


Environmental impacts


Climate change

The worldwide production of rice accounts for more
greenhouse gas emissions Greenhouse gas emissions from human activities strengthen the greenhouse effect, contributing to climate change. Most is carbon dioxide from burning fossil fuels: coal, oil, and natural gas. The largest emitters include coal in China and lar ...
(GHG) in total than that of any other plant food. It was estimated in 2021 to be responsible for 30% of agricultural
methane emissions Increasing methane emissions are a major contributor to the rising concentration of greenhouse gases in Earth's atmosphere, and are responsible for up to one-third of near-term global heating. During 2019, about 60% (360 million tons) of methane r ...
and 11% of agricultural
nitrous oxide Nitrous oxide (dinitrogen oxide or dinitrogen monoxide), commonly known as laughing gas, nitrous, or nos, is a chemical compound, an oxide of nitrogen with the formula . At room temperature, it is a colourless non-flammable gas, and has a ...
emissions. Methane release is caused by long-term flooding of rice fields, inhibiting the soil from absorbing atmospheric oxygen, a process causing
anaerobic fermentation Fermentation is a metabolic process that produces chemical changes in organic substrates through the action of enzymes. In biochemistry, it is narrowly defined as the extraction of energy from carbohydrates in the absence of oxygen. In food p ...
of organic matter in the soil. A 2021 study estimated that rice contributed 2 billion tonnes of
anthropogenic greenhouse gases Greenhouse gas emissions from human activities strengthen the greenhouse effect, contributing to climate change. Most is carbon dioxide from burning fossil fuels: coal, oil, and natural gas. The largest emitters include coal in China and larg ...
in 2010, of the 47 billion total. The study added up GHG emissions from the entire lifecycle, including production, transportation, and consumption, and compared the global totals of different foods. The total for rice was half the total for beef. A 2010 study found that, as a result of rising temperatures and decreasing solar radiation during the later years of the 20th century, the rice yield growth rate has decreased in many parts of Asia, compared to what would have been observed had the temperature and solar radiation trends not occurred. The yield growth rate had fallen 10–20% at some locations. The study was based on records from 227 farms in Thailand, Vietnam, Nepal, India, China, Bangladesh, and Pakistan. The mechanism of this falling yield was not clear, but might involve increased respiration during warm nights, which expends energy without being able to photosynthesize. More detailed analysis of rice yields by the
International Rice Research Institute The International Rice Research Institute (IRRI) is an international agricultural research and training organization with its headquarters in Los Baños, Laguna, in the Philippines, and offices in seventeen countries. IRRI is known for its wor ...
forecast 20% reduction in yields in Asia per degree Celsius of temperature rise. Rice becomes sterile if exposed to temperatures above 35 degrees for more than one hour during flowering and consequently produces no grain.


Water usage

Rice requires slightly more water to produce than other grains. Rice production uses almost a third of Earth's fresh water. Water outflows from rice fields through
transpiration Transpiration is the process of water movement through a plant and its evaporation from aerial parts, such as leaves, stems and flowers. Water is necessary for plants but only a small amount of water taken up by the roots is used for growth a ...
,
evaporation Evaporation is a type of vaporization that occurs on the surface of a liquid as it changes into the gas phase. High concentration of the evaporating substance in the surrounding gas significantly slows down evaporation, such as when humidi ...
, seepage, and
percolation Percolation (from Latin ''percolare'', "to filter" or "trickle through"), in physics, chemistry and materials science, refers to the movement and filtering of fluids through porous materials. It is described by Darcy's law. Broader applicatio ...
. It is estimated that it takes about of water need to be supplied to account for all of these outflows and produce of rice.


Pests and diseases

Rice pests are any
organism In biology, an organism () is any living system that functions as an individual entity. All organisms are composed of cells (cell theory). Organisms are classified by taxonomy into groups such as multicellular animals, plants, and ...
s or
microbe A microorganism, or microbe,, ''mikros'', "small") and ''organism'' from the el, ὀργανισμός, ''organismós'', "organism"). It is usually written as a single word but is sometimes hyphenated (''micro-organism''), especially in olde ...
s with the potential to reduce the yield or value of the rice crop (or of rice seeds). Rice pests include weeds,
pathogen In biology, a pathogen ( el, πάθος, "suffering", "passion" and , "producer of") in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a germ ...
s, insects, nematode, rodents, and birds. A variety of factors can contribute to pest outbreaks, including climatic factors, improper irrigation, the overuse of
insecticides Insecticides are substances used to kill insects. They include ovicides and larvicides used against insect eggs and larvae, respectively. Insecticides are used in agriculture, medicine, industry and by consumers. Insecticides are claimed to b ...
and high rates of
nitrogen fertilizer A fertilizer (American English) or fertiliser (British English; see spelling differences) is any material of natural or synthetic origin that is applied to soil or to plant tissues to supply plant nutrients. Fertilizers may be distinct from ...
application. Weather conditions also contribute to pest outbreaks. For example, rice
gall midge Cecidomyiidae is a family of flies known as gall midges or gall gnats. As the name implies, the larvae of most gall midges feed within plant tissue, creating abnormal plant growths called galls. Cecidomyiidae are very fragile small insects us ...
and army worm outbreaks tend to follow periods of high rainfall early in the wet season, while
thrips Thrips ( order Thysanoptera) are minute (mostly long or less), slender insects with fringed wings and unique asymmetrical mouthparts. Different thrips species feed mostly on plants by puncturing and sucking up the contents, although a few are ...
outbreaks are associated with drought.


Animal pests


Insects

Major rice insect pests include: the
brown planthopper The brown planthopper (BPH), ''Nilaparvata lugens'' (Stål) (Hemiptera: Delphacidae) is a planthopper species that feeds on rice plants (''Oryza sativa'' L.). These insects are among the most important pests of rice, which is the major staple cr ...
(BPH), several species of stemborers—including those in the genera ''
Scirpophaga ''Scirpophaga'' is a genus of moths of the family Crambidae described by Georg Friedrich Treitschke in 1832. Asian species include significant rice stemborer pests. Taxonomy The genus ''Scirpophaga'' was first introduced by Treitschke in 1832 as ...
'' and '' Chilo'', the rice
gall midge Cecidomyiidae is a family of flies known as gall midges or gall gnats. As the name implies, the larvae of most gall midges feed within plant tissue, creating abnormal plant growths called galls. Cecidomyiidae are very fragile small insects us ...
, several species of rice bugs, notably in the genus ''
Leptocorisa ''Leptocorisa''Latreille PA (1829) ''Le règne animal distribué d'après son organisation, pour servir de base à l'histoire naturelle des animaux et d'introduction à l'anatomie comparée. Déterville, Paris.'' Vol. t.5 (1829): i-xxiv; 1-556. i ...
'', defoliators such as the rice: leafroller, hispa and
grasshoppers Grasshoppers are a group of insects belonging to the suborder Caelifera. They are among what is possibly the most ancient living group of chewing herbivorous insects, dating back to the early Triassic around 250 million years ago. Grasshop ...
. The fall army worm, a species of Lepidoptera, also targets and causes damage to rice crops.
Rice weevil Rice is the seed of the grass species ''Oryza sativa'' (Asian rice) or less commonly ''Oryza glaberrima'' (African rice). The name wild rice is usually used for species of the genera ''Zizania'' and '' Porteresia'', both wild and domesticated, ...
s attack stored produce.


Nematodes

Several
nematode The nematodes ( or grc-gre, Νηματώδη; la, Nematoda) or roundworms constitute the phylum Nematoda (also called Nemathelminthes), with plant-Parasitism, parasitic nematodes also known as eelworms. They are a diverse animal phylum inhab ...
species infect rice crops, causing diseases such as Ufra (''
Ditylenchus dipsaci ''Ditylenchus dipsaci'' is a plant pathogenic nematode that primarily infects onion and garlic. It is commonly known as the stem nematode, the stem and bulb eelworm, or onion bloat (in the United Kingdom).
''), White tip disease ('' Aphelenchoide bessei''), and root knot disease ('' Meloidogyne graminicola''). Some nematode species such as ''
Pratylenchus ''Pratylenchus'' is a genus of nematodes known commonly as lesion nematodes.Crow, W. TAmaryllis lesion nematode, ''Pratylenchus hippeastri''.EENY-546. University of Florida IFAS. 2012. They are parasitic on plants and are responsible for root le ...
'' spp. are most dangerous in upland rice of all parts of the world. Rice root nematode (''
Hirschmanniella oryzae ''Hirschmanniella oryzae'', i.e. rice root nematode (RRN), is among the major pests of rice and is the most common plant-parasitic nematode found on irrigated rice. Recent modifications in cultivation practices have led to a substantial increas ...
'') is a migratory endoparasite which on higher inoculum levels will lead to complete destruction of a rice crop. Beyond being obligate parasites, they also decrease the vigor of plants and increase the plants' susceptibility to other pests and diseases.


Other pests

These include the apple snail (''
Pomacea canaliculata ''Pomacea canaliculata'', commonly known as the golden apple snail or the channeled apple snail, is a species of large freshwater snail with gills and an operculum, an aquatic gastropod mollusc in the family Ampullariidae, the apple snails ...
''), panicle rice mite, rats, and the weed ''
Echinochloa ''Echinochloa'' is a very widespread genus of plants in the grass family and tribe Paniceae. Some of the species are known by the common names barnyard grass or cockspur grass. Some of the species within this genus are millets that are grown ...
crusgali''.


Diseases

Rice blast ''Magnaporthe grisea'', also known as rice blast fungus, rice rotten neck, rice seedling blight, blast of rice, oval leaf spot of graminea, pitting disease, ryegrass blast, Johnson spot, neck blast, wheat blast, and Imochi (Japanese:稲熱) is a ...
, caused by the fungus ''
Magnaporthe grisea ''Magnaporthe grisea'', also known as rice blast fungus, rice rotten neck, rice seedling blight, blast of rice, oval leaf spot of graminea, pitting disease, ryegrass blast, Johnson spot, neck blast, wheat blast, and Imochi (Japanese:稲熱) is a ...
'' ( syn. ''M. oryzae'', ''Pyricularia oryzae''), is the most significant disease affecting rice cultivation. It and bacterial leaf streak (caused by ''Xanthomonas oryzae'' pv. ''oryzae'') are perennially the two worst rice diseases worldwide, and such is their importance and the importance of rice that they are both among the worst 10 diseases of all plants.p.214, "Rice blast (caused by the fungal pathogen ''Magnaporthe oryzae'') and bacterial blight (caused by the bacterial pathogen ''Xanthomonas oryzae'' pv. ''oryzae'') are the most devastating rice diseases (119) and are among the 10 most important fungal and bacterial diseases in plants (32, 95). Owing to their scientific and economic importance, both pathosystems have been the focus of concentrated study over the past two decades, and they are now advanced molecular models for plant fungal and bacterial diseases." Fukuoka ''et al.'', 2009
clones Clone or Clones or Cloning or Cloned or The Clone may refer to: Places * Clones, County Fermanagh * Clones, County Monaghan, a town in Ireland Biology * Clone (B-cell), a lymphocyte clone, the massive presence of which may indicate a pathologi ...
one of the few
quantitative disease loci Quantitative may refer to: * Quantitative research, scientific investigation of quantitative properties * Quantitative analysis (disambiguation) * Meter (poetry), Quantitative verse, a metrical system in poetry * Statistics, also known as quantit ...
for
quantitative disease resistance Quantitative may refer to: * Quantitative research, scientific investigation of quantitative properties * Quantitative analysis (disambiguation) * Meter (poetry), Quantitative verse, a metrical system in poetry * Statistics, also known as quantit ...
ever cloned in plants, one for blast resistance in this crop. The plant responds to the blast pathogen by releasing jasmonic acid, which then cascades into the activation of further downstream
metabolic pathway In biochemistry, a metabolic pathway is a linked series of chemical reactions occurring within a cell. The reactants, products, and intermediates of an enzymatic reaction are known as metabolites, which are modified by a sequence of chemical reac ...
s which produce the defense response. This accumulates as methyl-jasmonic acid. The pathogen responds by synthesizing an oxidizing enzyme which prevents this accumlation and its resulting alarm signal. Other major fungal and bacterial rice diseases include sheath blight (caused by '' Rhizoctonia solani''), false smut ('' Ustilaginoidea virens''), bacterial panicle blight (''
Burkholderia glumae ''Burkholderia glumae'' is a Gram-negative soil bacterium Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorgani ...
''),p.214, "...other diseases, including rice sheath blight (caused by the fungal pathogen ''Rhizoctonia solani''), false smut (caused by the fungal pathogen ''Ustilaginoidea virens''), bacterial leaf streak (caused by ''X. oryzae'' pv. ''oryzicola''), bacterial panicle blight (''Burkholderia glumae''), are emerging globally as important rice diseases (53, 72, 180) (Figure 1)." sheath rot (''
Sarocladium oryzae ''Sarocladium oryzae'' (Sawada) is a plant pathogen causing the sheath rot disease of rice and bamboo blight in Asia. Taxonomy and morphology ''Sarocladium oryzae'' has irregularly penicillate conidiophores and slimy, 1-celled conidia. ''Sa ...
''), and ''
bakanae or bakanae disease (, , ), from the Japanese for "foolish seedling", is a disease that infects the rice plant. It is caused by the fungus '' Gibberella fujikuroi'', the metabolism of which produces a surplus of gibberellic acid. In the plant, this ...
'' (''
Fusarium fujikuroi ''Gibberella fujikuroi'' is a fungal plant pathogen. It causes '' bakanae'' disease in rice seedlings. Another name is foolish seedling disease. It gets that name because the seeds can be infected, leading to disparate outcomes for the plant. T ...
'').p.214, Table 1: Important fungal and bacterial diseases in rice. Viral diseases exist, such as rice ragged stunt (
vector Vector most often refers to: *Euclidean vector, a quantity with a magnitude and a direction *Vector (epidemiology), an agent that carries and transmits an infectious pathogen into another living organism Vector may also refer to: Mathematic ...
: BPH), and tungro (vector: ''
Nephotettix ''Nephotettix'' is a genus of planthoppers in the subfamily Deltocephalinae and tribe Chiasmini. Species are mostly found in Asia, although two are from Africa. Known as 'green leafhoppers' of paddy/rice, ''Nephotettix cincticeps'' and ''N. v ...
'' spp). Many viral diseases, especially those vector (epidemiology), vectored by planthoppers and leafhoppers, are major causes of losses across the world. There is also an ascomycete fungus, ''Cochliobolus miyabeanus'', that causes brown spot disease in rice.


Integrated pest management

Crop protection scientists are trying to develop rice pest management techniques which are Sustainable agriculture, sustainable. In other words, to manage crop pests in such a manner that future crop production is not threatened. Sustainable pest management is based on four principles: biodiversity, host plant resistance (HPR), landscape ecology, and hierarchies in a landscape—from biological to social. At present, rice pest management includes cultural techniques, pest-resistant rice varieties, and pesticides (which include insecticide). Increasingly, there is evidence that farmers' pesticide applications are often unnecessary, and even facilitate pest outbreaks. By reducing the populations of natural enemies of rice pests, misuse of insecticides can actually lead to pest outbreaks. The
International Rice Research Institute The International Rice Research Institute (IRRI) is an international agricultural research and training organization with its headquarters in Los Baños, Laguna, in the Philippines, and offices in seventeen countries. IRRI is known for its wor ...
(IRRI) demonstrated in 1993 that an 87.5% reduction in pesticide use can lead to an overall drop in pest numbers. IRRI also conducted two campaigns in 1994 and 2003, respectively, which discouraged insecticide misuse and smarter pest management in Vietnam. Rice plants produce their own chemical defenses to protect themselves from pest attacks. Some synthetic chemicals, such as 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, can induce changes in the gene expression of the rice that cause the plant to become more susceptible to attacks by certain types of pests. 5-Alkylresorcinols are chemicals that can also be found in rice. Botanicals, so-called "natural pesticides", are used by some farmers in an attempt to control rice pests. Botanicals include extracts of leaves, or a mulch of the leaves themselves. Some upland rice farmers in Cambodia spread chopped leaves of the bitter bush (''Chromolaena odorata'') over the surface of fields after planting. This practice probably helps the soil retain moisture and thereby facilitates seed germination. Farmers also claim the leaves are a natural fertilizer and helps suppress weed and insect infestations. Among rice cultivars, there are differences in the responses to, and recovery from, pest damage. Many rice varieties have been selected for resistance to insect pests. Therefore, particular cultivars are recommended for areas prone to certain pest problems. The genetically based ability of a rice variety to withstand pest attacks is called resistance. Three main types of plant resistance to pests are recognized as nonpreference, antibiosis, and tolerance. Nonpreference (or antixenosis) describes host plants which insects prefer to avoid; antibiosis is where insect survival is reduced after the ingestion of host tissue; and tolerance is the capacity of a plant to produce high yield or retain high quality despite Home stored product entomology, insect infestation. Over time, the use of pest-resistant rice varieties selects for pests that are able to overcome these mechanisms of resistance. When a rice variety is no longer able to resist pest infestations, resistance is said to have broken down. Rice varieties that can be widely grown for many years in the presence of pests and retain their ability to withstand the pests are said to have durable resistance. Mutants of popular rice varieties are regularly screened by plant breeders to discover new sources of durable resistance.


Parasitic weeds

Rice is parasitized by the eudicot weed ''Striga hermonthica'', which is of local importance for this crop.


Ecotypes and cultivars

While most rice is bred for crop quality and productivity, there are varieties selected for characteristics such as texture, smell, and firmness. There are four major categories of rice worldwide: Indica rice, indica, japonica rice, japonica, Aromatic rice, aromatic and glutinous rice, glutinous. The different varieties of rice are not considered interchangeable, either in food preparation or agriculture, so as a result, each major variety is a completely separate market from other varieties. It is common for one variety of rice to rise in price while another one drops in price. Rice cultivars also fall into groups according to environmental conditions, season of planting, and season of harvest, called ecotypes. Some major groups are the Japan-type (grown in Japan), "buly" and "tjereh" types (Indonesia); ''sali'' (or ''aman''—main winter crop), ''ahu'' (also ''aush'' or ''ghariya'', summer), and ''boro'' (spring) (Bengal and Assam). Cultivars exist that are adapted to deep flooding, and these are generally called "floating rice". The largest collection of rice cultivars is at the
International Rice Research Institute The International Rice Research Institute (IRRI) is an international agricultural research and training organization with its headquarters in Los Baños, Laguna, in the Philippines, and offices in seventeen countries. IRRI is known for its wor ...
in the Philippines, with over 100,000 rice accessions held in the International Rice Genebank. Rice cultivars are often classified by their grain shapes and texture. For example, Thai
Jasmine rice Jasmine rice ( th, ข้าวหอมมะลิ; ; ) is a long-grain variety of fragrant rice (also known as aromatic rice). Its fragrance, reminiscent of ''pandan'' (''Pandanus amaryllifolius'') and popcorn, results from the rice plant's n ...
is long-grain and relatively less sticky, as some long-grain rice contains less
amylopectin Amylopectin is a water-insoluble polysaccharide and highly branched polymer of α-glucose units found in plants. It is one of the two components of starch, the other being amylose. Plants store starch within specialized organelles called amylopl ...
than short-grain cultivars. Chinese restaurants often serve long-grain as plain unseasoned steamed rice though short-grain rice is common as well. Japanese mochigome, mochi rice and Chinese sticky rice are short-grain. Chinese people use sticky rice which is properly known as "glutinous rice" (note: glutinous refer to the glue-like characteristic of rice; does not refer to "gluten") to make zongzi. The Japanese rice, Japanese table rice is a sticky, short-grain rice. Japanese sake rice is another kind as well. Indian rice cultivars include long-grained and aromatic
Basmati Basmati, , is a variety of long, slender-grained aromatic rice which is traditionally grown in India, Pakistan, and Nepal.
(ਬਾਸਮਤੀ) (grown in the North), long and medium-grained Patna rice, and in South India (Andhra Pradesh and Karnataka) short-grained Sona Masuri (also called as Bangaru theegalu). In the state of Tamil Nadu, the most prized cultivar is Ponni Rice, ''ponni'' which is primarily grown in the delta regions of the Kaveri River. Kaveri is also referred to as ponni in the South and the name reflects the geographic region where it is grown. In the Western Indian state of Maharashtra, a short grain variety called Ambemohar is very popular. This rice has a characteristic fragrance of Mango blossom. Aromatic rices have definite aromas and flavors; the most noted cultivars are Thai fragrant rice, Basmati, Patna rice, Vietnamese fragrant rice, and a Hybrid (biology), hybrid cultivar from America, sold under the trade name Texmati. Both Basmati and Texmati have a mild popcorn-like aroma and flavor. In Indonesia, there are also ''red'' and ''black'' cultivars. High-yield cultivars of rice suitable for cultivation in Africa and other dry ecosystems, called the New Rice for Africa, new rice for Africa (NERICA) cultivars, have been developed. It is hoped that their cultivation will improve food security in West Africa. Draft genomes for the two most common rice cultivars, ''indica'' and ''japonica'', were published in April 2002. Rice was chosen as a model organism for the biology of grasses because of its relatively small genome (~430 megabase pairs). Rice was the first crop with a complete genome sequence. On December 16, 2002, the UN General Assembly declared the year 2004 the International Year of Rice. The declaration was sponsored by more than 40 countries. Varietal development has ceremonial and historical significance for some cultures (see below). The King of Thailand, Thai kings have patronised rice breeding since at least the reign of Chulalongkorn, and his great-great-grandson Vajiralongkorn released five particular rice varieties to celebrate Coronation of Vajiralongkorn, his coronation.


Biotechnology


High-yielding varieties

The high-yielding varieties are a group of crops created intentionally during the Green Revolution to increase global food production. This project enabled labor markets in Asia to shift away from agriculture, and into industrial sectors. The first "Rice Car", IR8 was produced in 1966 at the
International Rice Research Institute The International Rice Research Institute (IRRI) is an international agricultural research and training organization with its headquarters in Los Baños, Laguna, in the Philippines, and offices in seventeen countries. IRRI is known for its wor ...
which is based in the Philippines at the University of the Philippines' Los Baños site. IR8 was created through a cross between an Indonesian variety named "Peta" and a Chinese variety named "Dee Geo Woo Gen.". IRRI Knowledge Bank. Scientists have identified and cloned many genes involved in the gibberellin signaling pathway, including GAI1 (Gibberellin Insensitive) and SLR1 (Slender Rice). Disruption of gibberellin signaling can lead to significantly reduced stem growth leading to a dwarf phenotype. Photosynthetic investment in the stem is reduced dramatically as the shorter plants are inherently more stable mechanically. Assimilates become redirected to grain production, amplifying in particular the effect of chemical fertilizers on commercial yield. In the presence of nitrogen fertilizers, and intensive crop management, these varieties increase their yield two to three times.


Future potential

As the UN Millennium Development project seeks to spread global economic development to Africa, the "Green Revolution" is cited as the model for economic development. With the intent of replicating the successful Asian boom in agronomic productivity, groups like the Earth Institute are doing research on African agricultural systems, hoping to increase productivity. An important way this can happen is the production of "New Rices for Africa" (NERICA). These rices, selected to tolerate the low input and harsh growing conditions of African agriculture, are produced by the African Rice Center, and billed as technology "from Africa, for Africa". The NERICA have appeared in ''The New York Times'' (October 10, 2007) and ''International Herald Tribune'' (October 9, 2007), trumpeted as miracle crops that will dramatically increase rice yield in Africa and enable an economic resurgence. Ongoing research in China to develop perennial rice could result in enhanced sustainability and food security.


Golden rice


Expression of human proteins

Ventria Bioscience has genetically modified rice to gene expression, express lactoferrin, lysozyme which are proteins usually found in breast milk, and human serum albumin, These proteins have Antiviral protein, antiviral, antibacterial, and Antifungal protein, antifungal effects. Rice containing these added proteins can be used as a component in oral rehydration solutions which are used to treat diarrheal diseases, thereby shortening their duration and reducing recurrence. Such supplements may also help reverse anemia.


Flood-tolerant rice

Due to the varying levels that water can reach in regions of cultivation, Deepwater rice, flood tolerant varieties have long been developed and used. Flooding is an issue that many rice growers face, especially in South and South East Asia where flooding annually affects . Standard rice varieties cannot withstand stagnant flooding of more than about a week, mainly as it disallows the plant access to necessary requirements such as sunlight and essential gas exchanges, inevitably leading to plants being unable to recover. In the past, this has led to massive losses in yields, such as in the Philippines, where in 2006, rice crops worth $65 million were lost to flooding." Recently developed cultivars seek to improve flood tolerance.


Drought-tolerant rice

Drought represents a significant environmental stress for rice production, with of rainfed rice production in South and South East Asia often at risk." Under drought conditions, without sufficient water to afford them the ability to obtain the required levels of nutrients from the soil, conventional commercial rice varieties can be severely affected—for example, yield losses as high as 40% have affected some parts of India, with resulting losses of around US$800 million annually. The
International Rice Research Institute The International Rice Research Institute (IRRI) is an international agricultural research and training organization with its headquarters in Los Baños, Laguna, in the Philippines, and offices in seventeen countries. IRRI is known for its wor ...
conducts research into developing drought-tolerant rice varieties, including the varieties 5411 and Sookha dhan, currently being employed by farmers in the Philippines and Nepal respectively. In addition, in 2013 the Japanese National Institute for Agrobiological Sciences led a team which successfully inserted the DEEPER ROOTING 1 (DRO1) gene, from the Philippine Upland and lowland (freshwater ecology), upland rice variety Kinandang Patong, into the popular commercial rice variety IR64, giving rise to a far deeper root system in the resulting plants. This facilitates an improved ability for the rice plant to derive its required nutrients in times of drought via accessing deeper layers of soil, a feature demonstrated by trials which saw the IR64 + DRO1 rice yields drop by 10% under moderate drought conditions, compared to 60% for the unmodified IR64 variety.


Salt-tolerant rice

Soil salinity poses a major threat to rice crop productivity, particularly along low-lying coastal areas during the dry season. For example, roughly of the coastal areas of
Bangladesh Bangladesh (}, ), officially the People's Republic of Bangladesh, is a country in South Asia. It is the eighth-most populous country in the world, with a population exceeding 165 million people in an area of . Bangladesh is among the mos ...
are affected by saline soils. These high concentrations of salt can severely affect rice plants' normal physiology, especially during early stages of growth, and as such farmers are often forced to abandon these otherwise potentially usable areas." Progress has been made, however, in developing rice varieties capable of tolerating such conditions; the hybrid created from the cross between the commercial rice variety IR56 and the wild rice species ''Oryza coarctata'' is one example." ''O. coarctata'' is capable of successful growth in soils with double the limit of salinity of normal varieties, but lacks the ability to produce edible rice. Developed by the
International Rice Research Institute The International Rice Research Institute (IRRI) is an international agricultural research and training organization with its headquarters in Los Baños, Laguna, in the Philippines, and offices in seventeen countries. IRRI is known for its wor ...
, the Hybrid (biology), hybrid variety can utilise specialised leaf glands that allow for the removal of salt into the atmosphere. It was initially produced from one successful embryo out of 34,000 crosses between the two species; this was then Backcrossing, backcrossed to IR56 with the aim of preserving the genes responsible for salt tolerance that were inherited from ''O. coarctata''. Extensive trials are planned prior to the new variety being available to farmers by approximately 2017–18. When the problem of soil salinity arises it will be opportune to select salt tolerant varieties (IRRI or to resort to soil salinity control. Soil salinity is often measured as the electric conductivity (EC) of the extract of a saturated soil paste (ECe). The EC units are usually expressed in decisiemens per metre or dS/m. The critical ECe value of 5.5 dS/m in the figure, obtained from measurements in farmers' fields, indicates that the rice crop is slightly salt sensitive.


Environment-friendly rice

Producing rice in Paddy field, paddies is harmful for the environment due to the release of methane by Methanogen, methanogenic bacteria. These bacteria live in the anaerobic waterlogged soil, and live off nutrients released by rice roots. Researchers have recently reported in ''Nature'' that putting the barley gene SUSIBA2 into rice creates a shift in biomass production from root to shoot (above ground tissue becomes larger, while below ground tissue is reduced), decreasing the methanogen population, and resulting in a reduction of methane emissions of up to 97%. Apart from this environmental benefit, the modification also increases the amount of rice grains by 43%, which makes it a useful tool in feeding a growing world population.


Meiosis and DNA repair

Rice is used as a model organism for investigating the molecular mechanisms of meiosis and DNA repair in higher plants. Meiosis is a key stage of the sexual cycle in which diploid cells in the ovule (female structure) and the Stamen, anther (male structure) produce haploid cells that develop further into gametophytes and Gamete#Plants, gametes. So far, 28 meiotic genes of rice have been characterized. Studies of rice gene OsRAD51C showed that this gene is necessary for Homologous recombination, homologous recombinational repair of DNA, particularly the accurate repair of DNA double-strand breaks during meiosis. Rice gene OsDMC1 was found to be essential for pairing of homologous chromosomes during meiosis, and rice gene OsMRE11 was found to be required for both synapsis of homologous chromosomes and repair of double-strand breaks during meiosis.


Cultural roles of rice

Rice plays an important role in certain religions and popular beliefs. In many cultures relatives will scatter rice during or towards the end of a wedding ceremony in front of the bride and groom. The pounded rice ritual is conducted during weddings in Nepal. The bride gives a leafplate full of pounded rice to the groom after he requests it politely from her. In the Philippines rice wine, popularly known as ''tapuy'', is used for important occasions such as weddings, rice harvesting ceremonies and other celebrations. Dewi Sri is the traditional rice goddess of the Javanese people, Javanese, Sundanese people, Sundanese, and Balinese people in
Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania between the Indian and Pacific oceans. It consists of over 17,000 islands, including Sumatra, Java, Sulawesi, and parts of Borneo and New Guine ...
. Most rituals involving Dewi Sri are associated with the mythical origin attributed to the rice plant, the staple food of the region. In Thailand, a similar rice deity is known as ''Phosop''; she is a deity more related to ancient local folklore than a goddess of a structured, mainstream religion. The same female rice deity is known as ''Po Ino Nogar'' in
Cambodia Cambodia (; also Kampuchea ; km, កម្ពុជា, UNGEGN: ), officially the Kingdom of Cambodia, is a country located in the southern portion of the Indochinese Peninsula in Southeast Asia, spanning an area of , bordered by Thailand t ...
and as ''Nang Khosop'' in
Laos Laos (, ''Lāo'' )), officially the Lao People's Democratic Republic ( Lao: ສາທາລະນະລັດ ປະຊາທິປະໄຕ ປະຊາຊົນລາວ, French: République démocratique populaire lao), is a socialist ...
. Ritual offerings are made during the different stages of rice production to propitiate the Rice Goddess in the corresponding cultures. A 2014 study of Han Chinese communities found that a history of farming rice makes cultures more psychologically interdependent, whereas a history of farming wheat makes cultures more independent. A Royal Ploughing Ceremony is held in certain Asian countries to mark the beginning of the rice planting season. It is still honored in the kingdoms of
Cambodia Cambodia (; also Kampuchea ; km, កម្ពុជា, UNGEGN: ), officially the Kingdom of Cambodia, is a country located in the southern portion of the Indochinese Peninsula in Southeast Asia, spanning an area of , bordered by Thailand t ...
and Thailand. The 2,600-year-old tradition begun by Śuddhodana in Kapilavastu (ancient city), Kapilavastu was revived in the republic of Nepal in 2017 after a lapse of a few years. Thai king Vajiralongkorn released five particular rice varieties to celebrate Coronation of Vajiralongkorn, his coronation.


See also

* Artificial rice * Glutinous rice * List of dried foods * List of rice cultivars * List of rice dishes * Maratelli rice * Fungiculture#Substrates, Mushroom production on rice straw * Leaf Color Chart * Post-harvest losses (grains), Post-harvest losses * Puffed rice * Rice Belt * Rice bran oil * Rice bread * Rice wine * Rice writing * Rijsttafel * Risotto * Straw *
System of Rice Intensification A system is a group of interacting or interrelated elements that act according to a set of rules to form a unified whole. A system, surrounded and influenced by its environment, is described by its boundaries, structure and purpose and expressed ...
* Texas rice production *
Upland rice Upland rice is a type of rice grown on dry soil rather than flooded paddy field, rice paddies. It is sometimes also called dry rice. Introduction Today nearly 100 million people depend on upland rice as their daily staple food. Almost two-thi ...
* Wild rice


Notes


References


Further reading

* * *


External links


International Rice Research Institute
{{Authority control Rice, Crops originating from China Grasses of Asia Plant models Types of food Tropical agriculture