Download How to Feed a Hungry World

How to Feed a Hungry World
World Population Levels
• 6 billion in 1999
• Will probably reach 8 billion by 2020,
this will add 2 billion in 20 years
• A population of 8 billion will present
major problems in the production and
distribution of sufficient food
Status of Hunger
• Approximately 1 billion people not
getting sufficient food today
• Marasmus and Kwashiorkor are
common in developing nations
• How can we adequately feed the
anticipated 2 billion that will be added
to the population?
Improvements in Agriculture
• Improvements in crop yields began
early in 20th century - as Mendel’s work
became known
• In past 50 yrs US yields continued to
increase - 3 fold increase since 1940s
– 1940s - corn yields 40 bushels/acre
– 1990s - corn yields 200 bushels/acre
• High yielding varieties at the center of
this accomplishment -- BUT not alone
High Yield Crops
• Also known as high impact crops and
high responding crops
• High Impact Crops Require
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Excellent growing conditions
Mechanization
Fertilizers --- may be the most important
Pesticides
Irrigation
Green Revolution
• After WWII, Rockefeller Foundation
and other agencies set up Agricultural
Research Stations in tropical areas
• Goal - improve crop production in
developing nations like those in US
• Most research initially focused on
wheat, rice, and corn but potatoes and
cassava research added later
Wheat - Principal Focus of
Green Revolution
• Father of Green Revolution - Dr.
Norman Borlaug
– Developed high yielding dwarf varieties
that take heavy fertilizer without lodging
– By late 1960s food production dramatically
increased in many developing nations
– 1970 - Borlaug awarded Nobel Peace Prize
“abolish hunger in a few years”
Disease and Pest Resistance
• Another aim of the Green Revolution
• 50% of the world’s crops destroyed in
field or in storage due to fungi, bacteria,
viruses, nematodes and insects
– Insects are chief competitors for human
food
– Fungi right behind
Ways to Produce Healthy Plants
• Chemicals
• Biological Controls
• Disease-Resistant Crops - cheapest and
most effective method
– Breeding for disease resistance must be
coupled to yield, quality, climate, taste
• Integrated Pest Management (IPM)
Problems with the Green
Revolution: What went wrong?
• Optimism of the 60s gave way to the
realities of 70s
– Cost associated with seeds, fertilizer,
pesticides, irrigation, farm equipment, fuel
– High energy costs - 2 barrels of oil/barrel
of fertilizer
– Environmental damage
– Loss of genetic diversity
– Whole premise wrong
Loss of Genetic Diversity
• Modern agriculture based on
monocultures -- disadvantages
• Share vulnerability to disease
• Loss of genetic diversity
• Native varieties are being replaced
• Tropical forests being cleared
• Will we have the resources to continue
developing new varieties?
• Seed banks may help but who owns the genes?
Solutions
• Continue along present course - some
researchers believe that we are near the
maximum potential yields for many
crops
• Alternative crops
• Biotechnology
Biotechnology
• Use of living organisms to provide
products for humanity
• Today term often implies the use of
genetic engineering to create plants
with new and useful characteristics
• Intent no different that traditional plant
breeding - differs in methods, speed,
and possible crosses
Cell and Tissue Culture
• Plant cells can be
cultured to get an
undifferentiated
mass of cells called a
callus
• When the right % of
hormones are added
to the culture, the
callus will develop
into a plant
Mutations in Cell Cultures
• Although all cells in culture are clones,
sometimes mutations occur
• During sexual reproduction, mutations
are rare - maybe 1 in 1 million
• In tissue culture mutation rate much
greater - called somaclonal mutants
• In one experiment with tomato plants
from culture 13 mutations in 230 plants
Applications of Cell Culture
• Somaclonal mutants may have useful
traits
• Expose tissue culture to certain toxins
or poisons to find resistant plants
– parasite toxins to look for resistance
– herbicides to look for resistance
Genetic Engineering
• Genetic Engineering uses the
techniques of recombinant DNA to
produce transgenic plants
– Recombinant DNA transfers segments of
DNA from one organisms to another
– Plants with foreign genes are called
transgenic plants
– This is possible because all organism use
the same genetic code
Gene Function
Gene Transfer
• Identify gene of interest
• Select a vector for transferring the gene
• Cut the gene from donor organism
• Transfer gene to vector
• Insert into host organism
Plasmids Used to Transfer Gene
Success of Genetic Engineering
• First successful genetically engineered
experiment on a plant in 1982
• First crop approved for sale in 1994 Flavr-Savr tomato
• Today dozens of genetically engineered
crops on the market
• Thousand of field tests
Genetically Engineered Plants
• Herbicide-resistant soybean, cotton,
corn, and canola
• Insect-resistant corn, cotton, potato
have genes for Bt (Bacillus thuringiensis)
toxins
• Tomatoes with delayed ripening
• Canola with high lauric acid production
Checks
• Lots of approval required before the
crops are released in environment
• Federal agency approving crops for
marketing
– FDA
– EPA
– USDA
Environmental Concerns
• Can the organism pass on traits in the
environment?
– Can herbicide resistance spread to weeds?
• Can insects become resistant to Bt
toxins?
• Can harmful traits be passed on
accidentally? Brazil nut allergen in soy