Tropical Food Crops Lecture Notes

Most Produced Crops in the World

• The most produced crops in the world are:
  1. Corn
  2. Wheat
  3. Rice
  4. Soybean
  5. Oil Palm
  6. Sugarcane
  7. Barley
  8. Sorghum
  9. Canola
  10. Cassava
• These 10 crops account for 83% of harvested food calories and 63% of the global harvested area.

Important Crops of Costa Rica

• The most important crops of Costa Rica are:
  1. Coffee
  2. Rice
  3. Bananas
  4. Sugarcane
  5. Beans
  6. Oil palm
  7. Oranges
• These crops account for 82% of cropped land, with beef cattle being also important.

Columbian Exchange

• Moving plants around is called the Columbian Exchange.

Old World Crops

• Crops that were introduced to the New World from Europe include:
  1. Rice
  2. Wheat
  3. Rye, barley
  4. Lentil, chickpeas
  5. Soybeans, sugarcane
  6. Citrus, apples, bananas, mango
  7. Onions, garlic
  8. Yam
  9. Coffee
  10. Cattle, pigs, chickens, horses

New World Crops

• Crops that were introduced to Europe from the New World include:
  1. Corn
  2. Cassava
  3. Beans
  4. Tomatoes
  5. Hot peppers
  6. Rubber
  7. Tobacco
  8. Chocolate
  9. Vanilla
  10. Peanuts
  11. Squash
  12. Sweet potato

Other Exchanges in the Columbian Exchange

• Besides plants, diseases and ideas were also exchanged.

Importance of Crop Origin

• The origin of crops matters because:
  • Pollinators, predators, and plant diseases are more prevalent in their native regions.
  • Rubber trees, for example, are grown in Indonesia due to disease issues in their native Brazil.
  • Native regions are sources of genetic diversity, such as the numerous types of hot peppers developed by Mexican and American farmers.
• These regions contain wild relatives and genes that may be of interest for various varieties.

Plant Anatomy

• Above-ground part of a plant: shoot.
• Below ground part of plant: root system.
  • Rhizomes: below-ground stems.
  • Stolons: above-ground stems.
  • Stems have buds, roots, and varying arrangements of vascular tissues.

Root Crops

• Roots, rhizomes, and tubers are typically high in carbohydrates and used for starches.

Cassava (Yuca, Manioc)

• Cassava is treated as an annual crop.
• It ranks third in production, after rice and corn.
• Cassava can grow in poor soils.
• It yields a large amount of food per unit of land, providing more calories than rice, wheat, or corn.
• It can be boiled or turned into flour.

Types of Cassava

• Bitter varieties: Higher concentration of cyanogenic molecules.
  • They exhibit DIY pest control and are less susceptible to insects.
  • However, people have died of cyanide poisoning from consuming bitter cassava.
• Sweet varieties: Lower concentration of cyanogenic molecules, making them more susceptible to insects.
  • They are drought-tolerant.

Cassava Propagation

• Cassava is a woody plant propagated by planting pieces of stems that are 3 nodes long.
• During harvesting, stems are chopped up and put back into the ground for further propagation.

Tapioca

• Tapioca is cassava starch.

Sweet Potato

• Sweet potatoes have smooth skin.
• They are transgenic, containing and expressing DNA from Agrobacterium.
• Propagated vegetatively by planting roots again.
• Native to Ecuador and sensitive to water-logging.
• High levels of clay in the soil are problematic; well-drained soil is needed.
• They do not contain toxins in their tissues.
• Most susceptible of the tropical root crops to insect pests.

Yams

• Yams have rough, thick skins.
• 95% of yam crops are grown in Africa.
• They are vines that use trellises for support.
• Protected by toxins that break down when vines die back; some kinds must be cooked.
• Relatively few pests.
• Highly seasonal with a short shelf life.
• Harvested by hand and store worse if damaged.

Taro (Arum Family, Araceae)

• Taro is an Old World crop from the South Pacific.
• It is one of the earliest cultivated plants.
• Contains calcium oxalate, which is reduced by cooking.
• High moisture content makes it prone to rot and requires cool temperatures for storage.
• Tolerates saturated soils and can grow in waterlogged soil.

Potatoes

• Potatoes are a New World crop domesticated in Bolivia and Peru.
• They do not tolerate drought or poorly drained soils.
• Need cooler weather; in the tropics, they are grown at high elevations.
• Staple in the 1700s.
• All green tissue of potato contains toxin solanine.
• Once exposed to light or after sprouting, potato tubers become toxic and must be discarded.
• Higher protein content than many other vegetable/starch crops.

General Observations About Root Crops

• Many have toxins as a form of self-protection in the tropics.
• High water content leads to shorter storage life and high transportation costs.
• Vegetable propagation (asexual) leads to a lack of genetic diversity and easy propagation of diseases.

Land Race

• Land Race: Product of traditional cultivation. There has been selection, but it's not uniform.

Cultivar

• Cultivar: variation: Developed by modern crop breeders(more uniformed).