Lecture 20
Rice

Oryza sativa, Poaceae or Graminae, Tribe Oryzeae

 fig. 1

Rice is the most important world cereal.

It is a staple for over half of the human population and is eaten three times a day in Asia.

Unhusked rice is called paddy rice; (paddy also refers to the growing crop).

Husk is removed by milling (mortar & pestle) by primitive people.

However, unlike wheat where "flour" is used for baking bread and other products, rice grains are usually consumed whole.

History

  • An ancient crop, native to SE Asia.
  • Cultivated in China for 5000 years.
  • Originated from forms of Orzya perennis.
  • Plays an important part of ancient customs, religions, and magical rites.
  • Rice is a symbol of fecundity and plenty; the custom of throwing rice at newly-weds is borrowed from an ancient eastern fertility rite.

    • Uses

  • Food uses: boiled rice, rice flakes, puffed rice, rice pudding, risotto, ground rice for confectionery, glutenous rice for sweet meats.
  • Nonfood uses: rice powder, starch, sake (wine), Husks are used as a mix for concrete, rice oil for cooking, straw is used for thatch (poor for feeding), [Note: rice paper is not made from rice.]

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    Rice and curry on banana leaves, Ceylon

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    Types of Rice

  • Hill rice:
    Upland or dryland rice
    Need good rains for 3-4 months
  • Swamp rice:
    Lowland rice
    Grown in irrigated or flooded areas
  • Floating rice:
    Grown in areas of deep flooding (up to 5 m or more in height) keeping pace with flooding

    • Texture

  • Hard (vitreous): the main rice of commerce.
  • Soft (dextrinous): glutinous rice (does not contain gluten the protein that causes wheat to rise in bread making)
    Sticky and cloying in cooking, e.g. pearl rice grown in Japan.
    Used for sweetmeats in Japan, molded for sushi.
    Americans do not like sticky rice.
    (At one time the first cooking lesson of new American brides was to make each grain of rice abhor its neighbor.)
  • Instant rice: this rice is precooked, unsticky.

    		•  fig. 2b

    Grain Shape

    Extra long >7mm Asian rice
    Long 6–7 Asian rice
    Middling 5–6 Grown in US, softer than long grain
    Short <5  

    Season

  • Very early <110 days
  • Early 110–140 days
  • Late 150–170 days
  • Very late >180 days

    		•

    World Production 1000 MT Chief countries
    World 592,831  
    Africa 16,974 Egypt (5,700), Nigeria (3,298), Madagascar (2,300)
    North American 12,041 US (9,664), Dominican Rep (698), Cuba (350)
    South America 19,543 Brazil (10,207), Colombia (2,107), Peru (2,019)
    Asia 539,842 China (181,515), India (131,900), Indonesia (50,096)
    Europe 3,171 Italy (1,222), Spain (888), Russian Federation (497)
    Oceania 1,261 Australia (1,239), Fiji (16), Solomon (5)

    Botany

  • A diploid (2n = 24) but triploids and tetraploids also exist.
  • A freely tillering grass, usually 50–150 cm tall.
  • Normally self pollinate with outcrossing 0–4.5%.
  • Indica and photperiodic rices have a slow seed dormancy, require 1–3 months rest for maxim germination.
  • Optimum germination temperature is 30–35ºC (86–95ºF)

    		•

    Two Subspecies

  • Indica
  • Tall leafy
  • High tillering
  • Lodges easily
  • Low response to N
  • Photoperiod sensitive
    Short day plants (requires short days to flower)
    •
  • Japonica
  • Short stiff straw
  • Low tillering
  • Resistant to Lodging
  • High response to N
  • Photoperiod insensitive
  • Hardy
  • Disease resistant

    • Culture

    A tropical crop but grown extensively in subtropical and warm temperate climates.
    Requires 4–6 months of 68–77ºF (20–25ºC) and minimum of 50ºF (10ºC)

    Water Requirements

  • Lowland rice:
    Requires 800–2400 mm (72–96") of rain
    Requires 750 mm (30") over 3–4 months
    Cannot tolerate desiccation
  • Upland rice:
    Requires 500–1200 mm (24–48") of rain
    Typically short day plant but some photoperiod insensitive types ("Green Revolution" rices) are photperiodically insensitive
    Requires 8–10" inches of soil for root penetration
    Less important than paddy rice
    Popular in Brazil
    Typically is grown under shifting cultivation
    The seed is broadcast or dibbled in
  • Floating rice:
    Grown under deep flooding
    Can grow 53 cm in 4 days
    Crop requires 7 months or more
    In Bangladesh can be harvest from boats

    		•

    In paddy or swamp rice (wet rice) land is inundated; crop grown in water by flooding.

    Usually grown by small holders with 1–5 acres requiring 400 person hours per acre.

    Grown during the monsoon in Am climates; 2–3 crops can be grown, in some cases as a ratoon crop, that is, by repeat tillering.

    There is little fertilization in Asia because a blue-green algae fixes nitrogen with Azotobacter, thus wet rice can be grown continuously in a sustainable system.

    Soil structure is not a problem.

    Planting is usually by transplants which are directly seeded in a nursery.

    Two Systems of Wet Rice Cultivation

    Traditional Systems

  • Traditional wet rice is completely grown with hand labor.
  • Seed (50–60 kg/ha) is sown in small nursery.
  • Seedlings are transplanted by hand in 30 cm rows when 2 months old in paddies separated by dikes in which water flows by gravity in sluggish current.
  • Dikes are usually permanent and can be planted in fruit trees to hold earth in place (China).
  • Harvest by hand, panicle by panicle.
    •

    Mechanized Systems

  • Seeded by airplane, or transplanted by machine.
  • Weeded by chemicals, harvested by combine.
  • Presoaked seed is planted in fields flooded 2.4 to 5 cm (1 to 2") and maintained until plant is 15–20 cm.
  • Water level is then raised to bring depth to 10–15 cm.
  • Fields are drained a week before grain is ripe, approximately 3 weeks after flowers.
  • High fertilization is carried out and good weed control is essential.
  • Many weeds will not sprout if the field is kept flooded.

    		•

    Processing (Milling)

  • Husk must be separated from the seed.
  • This can be done in a mortar and pestle type apparatus or by machinery.
  • Grain consists of seed coat and aleurone layers (= bran) and embryo and starchy endosperm.
  • Vitamin B1, thiamin is found in the aleurone layers.
  • Lack of vitamin B1 leads to the beri-beri disease.
  • Unpolished rice is called brown rice; does not store as well as white polished rice.
  • Polishing removes last of the bran and the embryo and thus eliminates all of vitamins.
  • White polished rice contains starch and little else.
  • Parboiling is a system to boil the rice in the husk (paddy rice).
  • This gelatinizes the outer layers of starch and allow it to absorb part of vitamins.
  • Stores better than unpolished rice.

    		•

    Storage

    White polished rice stores the best
    Polished > parboiled rice > milled unpolished.

    Rice Improvement

  • Main agency is the International Rice Research Institute (IRRI), Los Banos, Philippines.
  • IR8 = miracle rice (indica x japonica), fertilizer responsive, lodging resistant, photoperiodically insensitive.
  • Similar varieties developed in Tawain by Japnaese between 1900–1930.

    • fig. 5

    Rice Paddies, Bangkok, Thailand

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    Rice Paddies, Thailand, near Bangkok

    fig. 7

    Rice Paddies, Bangkok, Thailand

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    Plowing paddy by hand, Ceylon

    fig. 9

    Plowing rice paddy with water buffalo, Ceylon

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    Leveling rice field with water buffalo, Ceylon

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    Cooperation in plowing, Ceylon

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    Plowing rice with water buffalo, Ceylon

    fig. 13

    "Land Master" rotivator replaces water buffalo, Ceylon

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    Plowing & leveling with tractor, Ceylon

    fig. 15

    Hand leveling of rice paddy, Ceylon

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    Hand weeding rice, Ceylon

    fig. 17

    Peace Corps workers cleaning paddy ridge, Ceylon

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    Dusting rice with malathion for paddy bugs, Ceylon

    fig. 19

    Dusting rice with malathion, Ceylon

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    Harvesting rice with sickle, Ceylon

    fig. 21

    Harvesting rice with sickle, Ceylon

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    Hauling rice, Ceylon

    fig. 23

    Carrying rice to threshing floor, Ceylon

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    Threshing rice, Ceylon

    fig. 25

    Threshing rice, Ceylon

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    Farmer in Ceylon hills

    fig. 27

    Cleaning paddy burm for forage, Ceylon

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    Harvesting grass for water buffalo, Ceylon

    fig. 29

    Feeding grass to water buffalo, Ceylon

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    Drying cooked rice, Ceylon

    fig. 31

    Hauling dried rice, Ceylon

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    Rice farming near Bandung

    fig. 33

    Rice farming near Bandung, West Java

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    Rice paddy, Bali, Indonesia

    fig. 35

    Rice paddy near Bandung, West Java, Indonesia

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    Wet rice, rice culture, Bali, Indonesia

    fig. 37

    Rice culture, Bali

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    Rice terraces, Bali

    fig. 39

    Harvesting rice, West Java

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    Carrying harvested rice to dry, West Java

    fig. 41

    Carrying harvested rice to dry, West Java

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    Carrying rice to dry after harvest, West Java

    fig. 43

    Drying rice, Sumatra

    		 fig. 44

    Mechanical rice planting, Korea

    fig. 45

    Korea

    		 fig. 46

    Korea

    fig. 47

    Korea

    		 fig. 48

    Korea

    Dryland Rice

    fig. 49

    Upland rice, dry land plowing, Ceylon

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    Upland rice clearing in forest for rice, Maranhao

    fig. 51

    Rice cultivation, Mariana, Minas Gerais, Brazil

    		 fig. 52

    Hand threshing of dry land rice, Minas Gerais triangle, Brazil

    fig. 53

    Hand threshing of rice, Minas Gerais triangle, Brazil

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    De-husking rice, Ze-Doca, Moranhao

    fig. 55

    Separating rice & chaff, Ze-Doca, Maranhao

    		 fig. 56

    Cleaning rice, Ceylon

    fig. 57

    Carrying rice

    		 fig. 58

    Carrying rice harvest, Maranhao

    fig. 59

    Moving cleaned rice on Rio Pundere, Maranhao

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    Germinating rice, Ceylon

    fig. 61

    Seed cleaning, Ceylon

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    Seed separation, Ceylon

    fig. 63

    Rice plots, Ceylon

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    Short stemmed rice & lodging long-stem rice, Ceylon

    fig. 65

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