rice plants

Rice is arguably the world’s No.1 most important food crop and dietary staple, ahead of wheat, corn and bananas. It is the chief source of food for about 3.5 billion people — about half of the world’s population — and accounts for 20 percent of all the calories that mankind consumes. In Asia, more than 2 billion people rely on rice for 60 to 70 percent of their calories. Rice consumption is expected to rise to 880 million tons in 2025, twice as much as in 1992. If consumption trends continue 4.6 billion people will consume rice in 2025 and production must increase 20 percent a year to keep up with demand.

Rice is a symbol in Asia and an important part of Asian culture. It is part of ceremonies and offerings. It is said the ancient Chinese removed the outer husks from the grains and sold them for polishing precious gems. Most Chinese and Japanese today prefer to eat white rice. Perhaps this originated from the importance of whiteness and purity in Confucian and Shintoism. In Japan there are thousands of shrines honoring Inari, their rice god.

According to the Thai government: “In an agricultural society, rice, as a cereal, is the stuff of life and the source of traditions and beliefs; it has played an important role in Thai society since time immemorial, providing a strong foundation for the evolution of all aspects of society and culture. Rice is regarded as a sacred plant with a breath (spirit), a life, and a soul of its own, just like that of human beings. To the Thai people, rice is guarded by the goddess Phosop, who acts as its tutelary deity, and rice itself is considered a "mother" keeping guard over the nation's young and watching over their growth into adulthood.[Source: Thailand Foreign Office, The Government Public Relations Department]

In the 2000s, China consumed 32 percent of the world’s rice. The figure is probably lower now as the Chinese have developed fondnesses for other kinds of food. But Asia is not the only part of the world that depends on rice. Many Latin Americans eat over a cup of rice a day. Europeans, Middle Easterners and North Americans eat a lot of it too.

World’s Top Producers of Rice, Paddy (2020): 1) China: 211860000 tonnes; 2) India: 178305000 tonnes; 3) Bangladesh: 54905891 tonnes; 4) Indonesia: 54649202 tonnes; 5) Vietnam: 42758897 tonnes; 6) Thailand: 30231025 tonnes; 7) Myanmar: 25100000 tonnes; 8) Philippines: 19294856 tonnes; 9) Brazil: 11091011 tonnes; 10) Cambodia: 10960000 tonnes; 11) United States: 10322990 tonnes; 12) Japan: 9706250 tonnes; 13) Pakistan: 8419276 tonnes; 14) Nigeria: 8172000 tonnes; 15) Nepal: 5550878 tonnes; 16) Sri Lanka: 5120924 tonnes; 17) Egypt: 4893507 tonnes; 18) South Korea: 4713162 tonnes; 19) Tanzania: 4528000 tonnes; 20) Madagascar: 4232000 tonnes. [Source: FAOSTAT, Food and Agriculture Organization (U.N.), fao.org]

Websites and Resources: USA Rice Federation usarice.com ; Rice Online riceonline.com ; International Rice research Institute irri.org ; Wikipedia article Wikipedia ; Types of Rice foodsubs.com/Rice ; Rice Knowledge Bank riceweb.org ;

Rice Plants

Rice is a cereal grain related to oats, rye and wheat. It is a member of a family of plants that also includes marijuana, grass and bamboo. There are over 120,000 different varieties of rice including black, amber and red strains as well as white and brown ones. Rice plants can grow to a height of ten feet and shoot up as much as eight inches in a single day. [Sources: John Reader, “Man on Earth” (Perennial Libraries, Harper and Row, [⊕]; Peter White, National Geographic, May 1994]

Rice grains can be either short or long, and thick or thin. Rice mainly grows in flooded fields. This variety is called lowland rice. In countries where there is plenty of rainfall, rice may be raised on hills. This s called upland rice. Rice grows almost anywhere where enough water can be supplied: the flooded plains of Bangladesh, the terraced countryside of northern Japan, the Himalayan foothills of Nepal and even the deserts of Egypt and Australia as long as irrigation is available. Rice straw was traditionally used make sandals, hats, ropes and patches for thatch roofs.

Rice is a most versatile plant. Normally considered a tropical cereal grain, rice thrives in a variety of conditions and climates, including the temperate zones, for it can grow in lowland or upland environments and can withstand the hot sun and the cold equally well. No doubt its ability to adapt and its diversity played a parts in its embracement by humnas as a food source. [Source: Thailand Foreign Office, The Government Public Relations Department]

There are two principal kinds of domesticated rice: Oryza sativa, a species grown in Asia, and O. glaberrima, domesticated in West Africa, but the most prevalent rice varieties grown and sold in the world market come almost exclusively from Asia. By area of cultivation, rice may be classified into three subspecies: 1) The indica variety is characterized by a long, oval grain and is grown in the monsoon zones of Asia, primarily China, Vietnam, the Philippines, Thailand, Indonesia, India, and Sri Lanka; 2) The japonica variety is characterized by plump, oval grains and short stems, and it is grown in the temperate zones, such as Japan and Korea; and 3) The javanica variety is characterized by a large, plump grain, but it is planted much less than the other types because of its lower yields. It is grown in Indonesia and the Philippines.

Most rice — including two major sub-species “japonica” and “indica”, comes from the “Oryza sativa” plant. Oryza sativa japonica is short-grained and glutinous. Oryza sativa indica is long-grained and non-sticky.There are dry land varieties of rice and wet land varieties. Dry land varieties thrive on hillsides and in fields. Most of the world's rice is a wetland variety, which grows in irrigated paddies (55 percent of the world's rice supply) and rain-fed paddies (25 percent). Paddy (a Malay word that means "unmilled rice") is a small plot of land with a dike and a few inches of water in it.

History of Rice

Rice is believed to have been first cultivated in China or possibly somewhere else in eastern Asia around 10,000 years ago. The earliest concrete evidence of rice farming comes from a 7000-year-old archeological site near the lower Yangtze River village of Hemudu in Zheijiang province in China. When the rice grains unearthed there were found they were white but exposure to air turned them black in a matter minutes. These grains can now be seen at a museum in Hemudu.

20120525-rice Cambodiaricefarming2.jpg
rice farming in Cambodia
According to a Chinese legend rice came to China tied to a dogs tail, rescuing people from a famine that occurred after a severe flood. Evidence of rice dated to 7000 B.C. has been found near the village of Jiahu in Henan Province northern China near the Yellow River. It is not clear whether the rice was cultivated or simply collected. Rice gains dated to 6000 B.C. have been discovered Changsa in the Hunan Province. In the early 2000s, a team form South Korea’s Chungbuk National University announced that it had found the remains of rice grains in the Paleolithic site of Sorori dated to around 12,000 B.C.

For a long time the earliest evidence of rice farming in Japan was dated to around 300 B.C. which worked nicely into models that it was introduced when the Koreans, forced to migrate by upheaval in China n the Warring States Period (403-221 B.C.), arrived around the same time. Later a number of Korean objects, dated between 800 and 600 B.C., were found. These discoveries upset the neatness of the model. Then in the early 2000s, grains of wetland rice were found in pottery from northern Kyushu dated to 1000 B.C. This called into question the dating of the entire Yayoi period and caused some archeologist to speculate that maybe wet-land rice farming was introduced directly from China. This assertion is backed up somewhat by similarity in skeletal remains of 3000-year-old skeletons found in Quinghai province in China and Yayoi bodies unearthed in northern Kyushu and Yamaguchi prefecture.

Thailand is home to one of the world's oldest rice-based civilizations. Rice is believed to have first been being cultivated in there around 3,500 B.C. Evidence of ancient rice agriculture includes rice marking found on pottery fragments unearthed in graves unearthed at Non Noktha village in Khon Kaen province in northeast Thailand that have been dated to be 5,400 years old and rice husks found in pottery in the north, at Pung Hung Cave, Mae Hong Son dated to be around 5,000 years old. People that lived in a site called Khok Phanom Di in Thailand between 4,000 and 3,500 year ago practiced rice farming and buried their dead facing east in shrouds of bark and asbestos fibers.

Wild rice grows in forest clearings but was adapted to grow in shallow flooded fields. The introduction of paddy agriculture dramatically changed the landscape and ecology of entire regions. DNA analysis shows that these early forms of rice were different from varieties eaten today. Africans cultivated another species of rice around 1500 B.C. People in the Amazon ate a species grown there around 2000 B.C. Rice arrived in Egypt in the 4th century B.C. Around that time India was exporting it to Greece. The Moors introduced rice to greater Europe via Spain in early medieval times.

For centuries, rice was a standard of wealth and was often used in place of money. Japanese peasants paid their landlords in bags of rice. When Japan occupied China, Chinese “coolies” were paid in rice. [Source: goodness .co.uk]

Rice as Food

The seeds in rice are contained in branching heads called panicles. Rice seeds, or grains, are 80 percent starch. The remainder is mostly water and small amounts of phosphorus, potassium, calcium and B vitamins.

Freshly harvested rice grains include a kernel made of an embryo (the heart of the seed), the endosperm that nourishes the embryo, a hull and several layers of bran which surround kernel. White rice consumed by most people is made up exclusively of kernels. Brown rice is rice that retains a few nutritious layers of bran.

The bran and hull are removed in the milling process. In most places this residue is fed to livestock, but in Japan the bran is made into salad and cooking oil believed to prolong life. In Egypt and India it is made into soap. Eating unpolished rice prevents beriberi.

The texture of rice is determined by a component in the starch called amylose. If the amylose content is low (10 to 18 percent) the rice is soft and slightly sticky. If it is high (25 to 30 percent) the rice is harder and fluffy. Chinese, Koreans and Japanese prefer their rice on the sticky side. People in India, Bangladesh and Pakistan like theirs fluffy, while people in Southeast Asia, Indonesia, Europe and the United States like theirs in between. Laotians like their rice gluey (2 percent amylose).

Rice as a Food Crop

a tray of rice seedlings
About 97 percent of the world's rice is eaten within the country in which it is grown and most of this is cultivated with three miles of the people that eat it. About 92 percent of the world crop is raised and consumed in Asia — a third in China and a fifth in India. Where irrigated paddy rice is grown one can find the densest populations. Rice supports 770 people per square kilometer in Yangtze and Yellow river basins in China and 310 per square kilometer in Java and Bangladesh.

Over 520 million tons of rice is harvested every year and about one tenth of all cultivated acreage in the world is devoted to rice. More corn and wheat is produced than rice but over 20 percent of all wheat and 65 percent of all corn is used for feeding livestock. Almost all rice is eaten by people not animals.

The Balinese eat about a pound of rice a day. The Burmese consume a little more than a pound; Thais and Vietnamese about three quarters of a pound; and the Japanese about a third of a pound. In contrast, the average America eats about 22 pounds a year. A tenth of rice grown in the United States is used in making beer. It provides a "lighter color and more refreshing taste," an Anheuser-Busch brewmaster told National Geographic.

Rice Agriculture

Rice is one of the world's most labor intensive foods. In Japan the planting and harvesting is done mostly with machines, but in much of the world these chores — along with weeding, and maintaining the paddies and irrigation canals — are still largely done by hand, with water buffalo helping with the plowing and preparing of the fields. Traditionally rice has been harvested with a scythe, left to dry on the ground for a couple of days, and bundled into sheaves. Between 1000 to 2000 man or women hours are required to raise a crop on 2.5 acres of land. The fact that rice is so labor intensive tends to keep a lot of the population on the land.

Rice is also a water thirsty crop, requiring lots of rain or irrigation water The wet rice grown in most Asia, needs hot weather after a period of rain, conditions provided by the monsoons that affected many of the places where rice is grown. Rice farmers can often produce multiple crops a year often by adding no or little fertilizer. Water provides a home for the nutrients and bacteria that enrich the soil. Often the remains or previous crops or the burned the remains or previous crops are added to the soil to increase its fertility.

Lowland rice, known as wet rice, is the most common species in Southeast Asia which can be planted in two or three crops a year. Seedlings are raised in nursery beds and transplanted after 25-50 days to flooded fields surrounded by soil-raised border. The paddy stem is submerged in two to six inches of water and the seedlings placed in rows approximately a foot apart. When the leaves of the rice stalks start to turn yellow the paddies are drained and dried in preparation for the harvest. Vietnamese farmers reap rice by using sickles to cut the stalks. Then they tie the stalks together and dry them. [Source: Vietnam-culture.com vietnam-culture.com

Rice Paddies

rice planting in Japan
Wet rice is grown in paddies in lowlands and terraces on the slopes of hills and mountains. Most rice paddies and terraces are irrigated with water that originates above where the rice is grown. In most cases water from one paddy drains into another paddy. Rice has to be harvested when the soil is dry and consequently the water must be emptied from the paddy before the harvest and filled up again when the new crop is ready to plant.⊕

A typical paddy system consists of a holding pond and a network of canals, ditches and wooden or bamboo conduits to transport water to and from the paddies. The holding pond is usually at the head of a valley and collects water that seeps naturally from the surrounding hillsides. From the holding pond the water is carried down slopes in narrow ditches to run alongside the paddies. These ditches are always kept at a level slightly higher than the paddies.

Dikes are built around the fields to keep water in the paddy. Simple sluice gates, often comprised of a thick board and a few sandbags are set up at intervals along the ditchs. The amount of water entering a paddy can be regulated by opening and closing these gates. A drainage canal usually runs down the center of the valley. New innovations include concrete-sided canals, water pumped from underground sources and abandonment of holding ponds.

Maintaining a rice paddy is also very labor intensive. Shoring up the dikes and cleaning out the irrigation systems has traditionally been men’s work while planting and weeding has traditionally a job for women. Some knowledge of hydrodynamics is necessary to make sure the water is directed where it needs to go.

Rice Planting

mechanized planter in Japan
Fields are prepared before the rainy season with some plowing, often using water buffalo, and flooding. About a week or before planting so the paddy is partially drained, leaving behind a thick, muddy soup. Rice seedlings are grown in nursery plots, transplanted by hand or with a machine. Seedling are planted instead of seeds because the young plants are less vulnerable to disease and weeds than the seeds. Farmers that can afford pesticides and fertilizers sometimes plant seeds.

Rice planting in much of the world is still done by hand, using methods that for the most part have remained unchanged for the last three of four thousand years. The foot-long seedlings are planted a couple at a time by bent-over planters who use their thumb and middle fingers to push the seedlings in the mud.

Good planters average about one insertion a second in a process that the travel writer Paul Theroux once said was more like needlepoint than farming. The sticky, black mud in the paddy is usually ankle deep, but sometime knee deep, and rice planter generally go barefoot instead of wearing boots because the mud sucks the boots off.

Growing and Harvesting Rice

The water depth in the paddy is increased as the rice seedlings grow and then gradually lowered in increments until the field is dry when the rice is ready to be harvested. Sometimes the water is drained during the growing season so the field can be weeded and the soil aerated and then water is put back in.

Rice is harvested when it is a golden-yellow color several weeks after water has been completely drained from the paddy and the soil around the rice is dry. In many places rice is still harvested with a sickle and bundled into sheaves and then threshed by cutting the top inch or so of the stalks with a knife and removing the grains by slapping the stalks over propped up boards. The rice is placed on large sheets and left to dry on the ground for a couple of days before being taken to the mill to be processed. In many villages around the world, farmers usually help each other to harvest their crops.

After the rice harvest the stubble is often burned along with waste products from the harvest and the ashes are plowed back into the field to fertilize it. Hot summers often translate to meager rice harvests and lower quality rice. Shortages of high-quality rices often result in bags of blended rice in which it isn’t always clear what is in the mix. Some of the blends are created by “rice masters” who are skilled at getting the best taste at the lowest cost from their blends.

Mechanized Rice Planting and Harvesting

In Japan, Korea and other countries, farmers now use small diesel-powered rototiller-tractors to plow the rice paddies and refrigerator-size mechanical rice transplanters to plant the rice seedlings. In the old days it took 25 to 30 people to transplant the seedlings of one rice paddy. Now a single mechanical rice transplanter can do the job in a couple dozen paddies in one day. The seedling come on perforated plastic trays, which are placed directly on the transplanter. which uses a hook-like device to pluck the seedlings from the trays and plant them in the ground. The trays cost anywhere from $1 to $10. About ten pallets contain enough seedlings for a small paddy.

There are also harvesting machines. Some diesel-powered rototiller-tractors and mechanical rice transplanters are available with harvesting attachments. Large machines are not used to harvest rice because they can not maneuver around the paddy without messing them up. Plus, most rice paddies are small and divided by dikes. Large machines need long tracts of uniform land to do their job efficiently.

Kevin Short wrote in the Daily Yomiuri, “The tractors used in the harvest are tiny, but nonetheless very well-designed. A typical ride-on-top machine cuts several rows of rice at a time. The rice grains are automatically separated from the stalks, which can be either tied into bundles or chopped into pieces and scattered back into the paddy. On some models the rice grains are automatically loaded into bags, while on others they are temporarily stored in an onboard bin, then transferred to a waiting truck via a suction-powered boom.”[Source: Kevin Short, Yomiuri Shimbun. September 15, 2011]

harvesting rice in Japan
Kubota is major manufacturer of rice transplanters and harvesters. According to the company’s website their machines “have helped the mechanization of rice transplanting and harvesting, the most labor-intensive processes in rice farming, thereby reducing labor and increasing efficiency. According to the paper “Impact of Modern Rice Harvesting Practices over Traditional Ones” (2020) by Kamrul Hasan, Takashi S. T. Tanaka, Monjurul Alam, Rostom Ali, Chayan Kumer Saha: Mechanized agriculture entails the utilization of farm power and machinery in farming operations to increase productivity and profitability of farming enterprises through minimum inputs...Jones et al. (2019) mentioned that technologies/mechanization can improve the timing of tasks, reduce drudgery, make labor more efficient; and improve the quality and quantity of food. Timely harvesting is a crucial and important process to ensure yield, quality and production cost of rice.

The time required for completing the operation of harvesting and threshing with traditional practice (manual harvesting and threshing with mechanical thresher by manual labor) was about 20 hours whereas with combine harvester and straw reaper was 3.5 hours (Anonymous, 2014). Zhang et al. (2012) reported that the working efficiency of combined harvester was 50 times higher than that of manual harvesting in rapeseed crop. Bora and Hansen (2007) examined field performance of a portable reaper for rice harvesting and the result showed that harvest duration was 7.8 times less than manual harvesting. The cost could be saved 52% and 37% for using a mini-combine harvester and reaper, respectively over manual harvesting system (Hasan et al., 2019). Hassena et al. (2000) reported that the cost per quintal of manual harvesting and threshing was 21 % and 25% higher than the cost of combiner harvesting, respectively. The net benefit of combiner harvesting was about 38% and 16% higher in Asasa and Etheya regions of Ethiopia, respectively, compared to manual harvesting and threshing. Jones et al. (2019) mentioned that mini-combine harvester on an average can save 97.50% of time, 61.5% of costs and 4.9% of grain losses over manual harvesting.

Ecological Advantages of Rice Cultivation

Unlike slash and burn agriculture, which can sustainably support only 130 people per square mile, often seriously damaging the soil and filling the air with smoke, rice cultivation can support 1,000 people and not deplete the soil.⊕

Rice is unique as a crop in that it can grow in flooded conditions that would drown other plants (some rice species grow in water 16 feet deep). What makes this possible is an efficient air-gathering system consisting of passages in the upper leaves of rice plants that draw in enough oxygen and carbon dioxide to nourish the entire plant. ⊕

Nitrogen is the most important plant nutrient and fortunately for rice growers blue-green algae, one of two organism on earth that can transform oxygen from the air into nitrogen, thrives in the stagnant rice paddy water. The decayed algae as well as old rice stalks and other decomposed plants and animals provide nearly all the nutrients for growing rice plants, plus they leave behind enough nutrients for future crops.⊕

The constant supply of nutrients means that the paddy soils are resilient and don't become worn out like other soils. In flooded rice paddies few nutrients are leached (carried away by rain water deep into the soil where plants can't get them) and the nutrients dissolved in the murky water are easy for the plant to absorb. In tropical climates two, sometimes three, rice crops can be raised every year.⊕

Rice paddies create a lovely landscape and have their own rich ecosystem. Fish such as minnows, loaches and bitterling can survive in the paddies and the canals as can aquatic snails, worms, frogs, crawfish beetles, fireflies and other insects and even some crabs. Egrets, kingfishers, snakes and other birds and predators feed on feed on these creatures. Ducks have been brought into rice paddies to eat weeds and insects and eliminate the need for herbicides and pesticides. Innovations such as concrete-sided canals have damaged the rice paddy ecosystem by depriving plants and animals of places they can live.

Problems with Rice Cultivation

nets protect fields from birds
in Japan
Bacterial leaf blight, plant hoppers, rodents and stem borders are the major rice destroying pests. These days the biggest threat to the world rice crops is the leaf blight, a disease which wipes out as much as half the rice crop in some parts of Africa and Asia, and annually destroys between 5 and 10 percent of the world's total rice harvest. In 1995, scientist cloned a gene that protects rice plants from leaf blight and developed a genetically-engineered and cloned rice plant that resists the disease.

The trend towards reliance on only a few strains of highly-productive rice plants worldwide has the potential of causing a disaster. If these strains suddenly become vulnerable to a disease or pests, huge amounts of crops could be destroyed, causing severe food shortages or even a famine. If many strains are used and some of them are destroyed by disease or pests, there are still many remaining stains producing rice and overall food supply is not jeopardized.

While demands for food increase, land used to grow rice is being lost to urbanization and industry and the demands of a growing population. Demographers estimate that production of rice must increase by 70 percent over the next 30 years to keep up with a population that is supposed to grow by 58 percent before the year 2025.

Much of the rice grown in coastal plains and river deltas is vulnerable to sea-level rises caused by global warming. Sometimes fertilizers and pesticides leak out of the paddies and damage the environment.

Based on the Council for Partnership on Rice Research in Asia (CORRA) 2007 country report, the following are the challenges that need to be addressed in Vietnam: 1) Pest and diseases: brown plant hopper (BPH) and virus disease transmitted by BPH; as well as bacterial blast 2 )Grain quality: improving rice quality through rice breeding and post-harvest technologies. 3) Stresses: drought, salinity, acid sulfate toxicity become more severe due to climate change, [Source: Vietnam-culture.com vietnam-culture.com

Rice is often dried in the roads because valuable farmland can't be used for sun drying. As a result, imported bags of Vietnamese rice are increasingly sullied with debris from passing trucks and motorbikes, and bird and dog droppings. Rice is often still harvested by hand with a scythe, left to dry on the ground for a couple of days, and bundled into sheaves. Rice is dried in the roads because valuable farmland can't be used for sun drying. As a result, imported bags of Thai rice sometimes have passing trucks and motorbikes in them.

Image Source: Wikimedia Commons; Ray Kinnane, Jun from Goods in Japan, MIT, University of Washington, Nolls China website

Text Sources: National Geographic, New York Times, Washington Post, Los Angeles Times, Smithsonian magazine, Natural History magazine, Discover magazine, Times of London, The New Yorker, Time, Newsweek, Reuters, AP, AFP, Lonely Planet Guides, Compton’s Encyclopedia and various books and other publications.

Last updated March 2022

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