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Chapter 3 - Growing Plants for Human Use
Nutrition
• Plants are the only terrestrial organisms that convert
inorganic carbon, oxygen, hydrogen, nitrogen, and
sulfur to organic forms, via photosynthesis.
– They are called autotrophs (meaning “self-feeder”).
• Humans, and just about everything else that live on
land are heterotrophs (or “other feeders”).
– Because they feed off autotrophs or other heterotrophs.
tab
Practical Horticulture 5th edition
By Margaret J. McMahon, Anton M. Kofranek and Vincent E. Rubatsky
© 2011, 2007, 2002, 1988 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
Chapter 3 - Growing Plants for Human Use
Nutrition
• Only a small percentage of all the plant species in
existence feed the world’s people:
– Cereal crops—wheat, maize (corn), rice, barley, oats,
sorghum, rye, millet.
• Over half the world’s food supply come from these crops.
– Roots & tubers—potatoes, sweet potatoes, cassavas.
– Oil crops—soybeans, corn, peanuts, palm, coconuts,
sunflowers, olive, safflower.
– Sugar—sugar cane & sugar beets.
– Fruit crops—bananas, oranges, apples, pears, etc.
– Vegetable crops—tomatoes, lettuce, carrots, melons,
asparagus, etc.
tab
Practical Horticulture 5th edition
By Margaret J. McMahon, Anton M. Kofranek and Vincent E. Rubatsky
© 2011, 2007, 2002, 1988 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
Chapter 3 - Growing Plants for Human Use
Nutrition
Common crops ranked in relation to the calories
and proteins produced per unit of land area.
Not all of the total production
of food materials is available
for human consumption.
Much is lost during harvesting,
transportation, and marketing.
Some of the production is
saved to be used as seed
for future plantings.
tab
Practical Horticulture 5th edition
By Margaret J. McMahon, Anton M. Kofranek and Vincent E. Rubatsky
© 2011, 2007, 2002, 1988 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
Chapter 3 - Growing Plants for Human Use
Nutrition
Adults need 2000 to 3000 kcal of energy per day,
depending on their size and level of activity.
This energy can be provided by carbohydrates,
typically found in plant foods.
Twenty-four
to energy
thirty-six
Lipids
provide
in
slicescondensed
of bread isform.
one
more
way to get our daily
energy requirement.
tab
Practical Horticulture 5th edition
By Margaret J. McMahon, Anton M. Kofranek and Vincent E. Rubatsky
© 2011, 2007, 2002, 1988 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
Chapter 3 - Growing Plants for Human Use
Nutrition
• Animal fats tend to be saturated fats, which lack
double bonds in their fatty acids.
• Plant energy carbohydrate sources are healthy as
they are associated with indigestible fiber, which
protects from colon disorders.
– Purified carbohydrates such as refined sugar or starch
are not as beneficial, and carry their own health risks.
tab
Practical Horticulture 5th edition
By Margaret J. McMahon, Anton M. Kofranek and Vincent E. Rubatsky
© 2011, 2007, 2002, 1988 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
Chapter 3 - Growing Plants for Human Use
Nutrition
An adult needs about 70 grams of protein in a day.
Plant foods, especially cereal grains and pulses (peas & beans),
often provide enough protein along with the energy they supply.
tab
Practical Horticulture 5th edition
By Margaret J. McMahon, Anton M. Kofranek and Vincent E. Rubatsky
© 2011, 2007, 2002, 1988 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
Chapter 3 - Growing Plants for Human Use
Nutrition
• A plant diet may not satisfy protein requirements,
as it may be deficient in one or more amino acids.
– Plant proteins often have a low proportion of essential
amino acids
– An exception is quinoa (Chenopodium quinoa).
– Animals generally provide better-quality protein.
• Eggs are generally regarded as providing perfect protein.
• Deficiencies of individual plant foods can be
remedied to a large extent by combining them.
• A balance can also be achieved on a plant diet
with a small amount of meat or other animal food.
tab
Practical Horticulture 5th edition
By Margaret J. McMahon, Anton M. Kofranek and Vincent E. Rubatsky
© 2011, 2007, 2002, 1988 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
Chapter 3 - Growing Plants for Human Use
Nutrition
• Carbohydrates, lipids (fats), and proteins are the
bulk constituents of our diet.
– We also need small amounts organic molecules—vitamins.
• Most can be obtained from fruits, vegetables, or grains.
tab
Practical Horticulture 5th edition
By Margaret J. McMahon, Anton M. Kofranek and Vincent E. Rubatsky
© 2011, 2007, 2002, 1988 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
Chapter 3 - Growing Plants for Human Use
Nutrition
• Vitamin C is found only in fresh fruits and
vegetables.
• Vitamin A is derived from carotene, found in green,
yellow, orange, or red fruits, vegetables, and grains.
• Vitamin B12 is not provided by plants.
– Cyanocobalamin is manufactured by bacteria, especially
in ruminant organisms, is available in meat & dairy foods.
• We require six major inorganic nutrients—calcium,
phosphorus, magnesium, sodium, potassium,
chloride—and seven micronutrients.
– All can be obtained from plant foods, although
often more abundant in animal foods.
tab
Practical Horticulture 5th edition
By Margaret J. McMahon, Anton M. Kofranek and Vincent E. Rubatsky
© 2011, 2007, 2002, 1988 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
Chapter 3 - Growing Plants for Human Use
Nutrition
• Worldwide there are about 0.25 hectares (0.6 acres)
of cropland for each person.
– With realistic inputs/yields, this is about enough to provide
everyone with a vegetarian diet.
• In addition to land required to grow crops, we should
count area needed to provide inputs of energy and
chemicals, and absorb the wastes generated.
tab
Practical Horticulture 5th edition
By Margaret J. McMahon, Anton M. Kofranek and Vincent E. Rubatsky
© 2011, 2007, 2002, 1988 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
Chapter 3 - Growing Plants for Human Use
Nutrition
• Crop production has become concentrated and
specialized in regions & countries around the world.
– California and Florida produce more than 60% of U.S.
grown fruits and vegetables.
• Crops can move thousands of miles from producer to consumer.
tab
Practical Horticulture 5th edition
By Margaret J. McMahon, Anton M. Kofranek and Vincent E. Rubatsky
© 2011, 2007, 2002, 1988 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
Chapter 3 - Growing Plants for Human Use
Nutrition
• Some argue—from an ecological perspective—that
we should consume local produce.
– However, energy costs of transport are much lower
than for out-of-season production in a greenhouse.
• Nutrient flow from food transport presents problems.
– The nutrients in the produce are removed from the area
where the crop was grown.
tab
Practical Horticulture 5th edition
By Margaret J. McMahon, Anton M. Kofranek and Vincent E. Rubatsky
© 2011, 2007, 2002, 1988 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
Chapter 3 - Growing Plants for Human Use
Nutrition
• In moist, temperate parts of the world, it is easy to
forget how much water is needed to produce crops.
– It can take a ton of water to produce a kilogram of grain.
• In dry areas, a large land surface may be needed to
collect water to be used for irrigation to grow crops.
– Water needs in arid locations cause political problems.
tab
Practical Horticulture 5th edition
By Margaret J. McMahon, Anton M. Kofranek and Vincent E. Rubatsky
© 2011, 2007, 2002, 1988 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458