Root crops

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Root crops
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David S. Seigler Department of Plant
BiologyUniversity of IllinoisUrbana, Illinois
61801 USAseigler_at_life.illinois.eduhttp//www.l
ife.illinois.edu/seigler
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Root Crops - Outline

• Botanical
• o roots, rhizomes, corms, etc.
• Domestication
• o mostly asexual reproduction
• o reduced toxicity
• o increased size
• Properties
• Nutritional
• Water
• Starch
• Minerals, vitamins
• Preservation

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Reading

• CHAPTER 7 IN THE TEXT

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Introduction

• Root crops are underground parts of plants and
  include rhizomes, tubers, roots, stems, and
  leaves.
• Other than in the U.S., Western Europe and Japan,
  root crops are usually hand harvested.

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• Possibly domesticated before seed crops. Used by
  most hunter-gatherer societies.
• Domestication has not affected many of them
  significantly. Usually larger size. Sometimes
  lower toxicity.

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• Used in all cultures, but only major in a few
  e.g., the potato in Europe, minor root crops in
  the Andes, and cassava in the lowland tropics.
• About as much grown in terms of tonnage as cereal
  grains, but much less nutritional value.
• The most important root crops are cassava,
  potato and sweet potato.

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Crops from tubers and rhizomes

• Difficult to estimate production of many of these
  as they are consumed locally.
• Storage structures of plants.
• Often reproduced vegetatively. Mostly water. Some
  minerals. Starch.
• Used in most pre-agricultural cultures.
• Only in a few cultures have these become major
  food crops, mostly at high elevations in the
  tropics or in the wet lowland tropics.

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Root crops in market in Peru
Courtesy Nancy Hikes
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• Mostly water and starch.
• Shipping involves shipment of water.
• Little protein or fats.
• Most root crops spoil easily when harvested.

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Potatoes (Solanum tuberosum)

• Potatoes (Solanaceae) and other related species
  were domesticated in Andean South America.
• Cultivated at least 4000 years ago.
• Potatoes will grow at elevations where few other
  crops can be cultivated.
• The early Spanish found potatoes from Colombia to
  Chile.

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Potatoes in market in Wolfenbuettel, Germany
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Potato field near Toluca, Mexico
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Potato, Solanum tuberosum, Solanaceae
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• Either Sir Frances Drake or Sir Walter Raleigh
  brought back potatoes to England.
• The potato was enthusiastically received into
  Ireland. The climate was particularly suited to
  growing potatoes. By the 1840's the Irish ate
  unbelievable quantities of potatoes.
• In 1845, the potato blight (Phytophthora
  infestans) struck and wiped out the potato crop.
  Perhaps 1-2 million people died. At least another
  million came to the U.S.
• People obviously began to realize the hazard of
  depending too heavily on one crop.

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• Today potatoes are grown everywhere in upland
  tropical and in temperate parts of the world.
• Reproduced vegetatively. Burbank produced many
  new lines. Seeds often sterile.
• Solanum tuberosum cultivars are usually
  tetraploids.
• In the U.S. most of crop goes into potato chips
  and freeze dried instant mashed potatoes.
• These processes solve much of shipping weight
  problem.

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• Tuber about 80 water, about 20 starch, 2
  protein.
• Toxicity of potatoes. Lenape line of chipping
  potatoes. Greened tubers can produce
  teratogenicity. In some areas of Bolivia, people
  practice geophagy to absorb the toxic materials
  from primitive lines of cultivated potatoes.
• Potatoes are often treated to prevent sprouting.
  Harvested potatoes are washed and stored cool.
  Sugar is converted to starch on storage.

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• Russia, Belarus, Ukraine, and Poland are major
  producers.
• In the U.S., Florida and California (winter) and
  Maine, California, Idaho (summer) are major
  producing areas.
• Newfoundland, Maritime Provinces, and Vancouver
  Island, B.C., in Canada.

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Sweet potatoes (Ipomoea batatas, Convolvulaceae)

• Sweet potatoes are native to northwestern South
  America.
• They were taken very early to the South Pacific
  area and many considered them native there.
• Some postulated that sweet potatoes were taken
  from South America to the South Pacific by
  pre-Columbian voyagers.

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Sweet potatoes, Ipomoea batatas, Convolvulaceae
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• Sweet potatoes have been found in South America
  as far back as 8000-10000 years. They were
  cultivated by 2000 B.C. Some feel that they go
  back in the South Pacific as far as 1200 A.D.
• A hexaploid.
• Wild forms are not known with certainty. Origin
  complex.

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• The sweet potato is a true root. They are usually
  reproduced vegetatively using portions of the
  aerial stem.
• The roots contain about 2 protein. Lots of
  vitamin A.

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• In Japan, (especially) sweet potatoes are a major
  crop. They are used there to prepare starch, wine
  and alcohol. They are also widely fed to animals.
  China is easily the world's leading producer.
• Widely eaten in the southern U.S. Not eaten
  particularly in Europe.

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Cassava (Manihot esculenta)

• Cassava (also known as manioc, mandioca, or yuca)
  is widely eaten. This plant is the major starchy
  food for more than 500 million people.
• Cassava is native to central South America and
  has been cultivated for thousands of years.

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Cassava or yuca, Manihot esculenta, Euphorbiaceae
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Peeling and washing cassava
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Grinding and pressing cassava
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Seiving the catevia and removal of nepe
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Cooking the tortas
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Tortas
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Drying tortas and tortas in market
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• Griddles for cooking cassava go back at least
  2000 years.
• However, since the crop developed in the lowland
  tropics where preservation is poor, it may go
  back much farther.
• Cassava contributes over 37 of the total
  calories consumed in Africa and 11 in Latin
  America.
• Little nutritional value other than starch. About
  30 starch. Little protein. Doesn't keep well
  when harvested.

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• Cassava is toxic if not processed properly.
• The natives of South America had developed
  technology to remove the cyanide generating
  compounds.
• Sweet and bitter cultivars.
• Highly productive and little labor involved.
• Will keep for several months if left in ground.
• Reproduced vegetatively from stem cuttings.

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• Sweet types often boiled and fried.
• Bitter types often made into "tortas" or
  "farinha".
• Tapioca made from partially gelatinized cassava
  starch.

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Yams or Ñame

• Not to be confused with the sweet potato
  (Convolvulaceae).
• Ignaime (French) or ñame (Spanish) ... but
  probably originally from an African language.
• Yams are Dioscorea species and members of the
  Dioscoreaceae.
• Different species cultivated in Africa (where
  they were especially important), Asia, and the
  Americas.
• Probably tubers.

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Dioscorea spp., true yams, Dioscoreaceae, female
flowers
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A yam, Dioscorea sp., Dioscoreaceae
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• Reproduction asexual.
• Many are poisonous and must be peeled and/or
  cooked to remove toxic principles.
• Yams relatively high in protein for root crops.
• In most places where yams were formerly
  cultivated, they have been replaced by sweet
  potatoes or cassava.

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Taro and its relatives

• These are plants of the Araceae. Taro is
  Colocasia esculenta. Members of this family
  domesticated as root crops in both the Old and
  New World. Colocasia is native to Asia.
• A corm.
• About 30 starch, 3 sugar. Must be boiled to be
  eaten.
• A staple in the Polynesian area. In Hawaii, they
  use taro to make poi. Hawaiians used to eat 10-20
  lbs. per day.

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Taro, Calocasia esculenta, Araceae, field in
Madagascar
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Taro, Calocasia esculenta, Araceae
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Jicama, Pachyrrhizus erosus, Fabaceae
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Minor Andean root crops

• A large number of these were domesticated in the
  Andes. Few (other than the potato) were used
  outside of the area.
• añu Tropaeolum tuberosum
• arracacia Arracacia xanthorrhiza
• oca Oxalis tuberosa
• melloco Ullucus tuberosus, Basellaceae, second
  only to potatoes in upland Peru.
• maca Lepidium meyenii, Brassicaceae or
  Cruciferae.
• llacón Polymnia sonchifolia, Asteraceae or
  Compositae.

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Añu, Tropaeolum tuberosum, Tropaeolaceae
Courtesy R. Norton
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Añu, Tropaeolum tuberosum, Tropaeolaceae
Courtesy Dr. Tim Johns
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Arracacia, Arracacia xanthorhiza, Apiaceae
Courtesy Nancy Hikes
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Oca and quinoa in a Bolivian garden
Courtesy Dr. Tim Johns
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Oca, Oxalis tuberosa, Oxalidaceae
Courtesy Dr. Tim Johns
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Melloco, Ullucus tuberosus, Basellaceae
Courtesy R. Norton
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Maca, Lepidium meyenii, Brassicaceae or
Cruciferae.
Courtesy Dr. Tim Johns
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Harvesting maca in Bolivia
Courtesy Dr. Tim Johns
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Llacón, Polymnia sonchifolia, Asteraceae or
Compositae
Courtesy Dr. Tim Johns
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