The top 20 crops: their ex situ collections in view of climate change

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The top 20 crops their ex situ collections in
view of climate change

• Bert Visser

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This presentation

• introduction
• production and consumption figures
• global distribution
• potential threats from climate change
• genebank holdings
• consequences for genetic resources management

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Introduction

• focus on 22 major and representative crops
• 6 cereals
• rice, wheat, maize, barely, sorghum, millets
• 3 pulses
• beans, cowpea, groundnut
• 8 starch and oil crops
• banana, cassava, potato, yam coconut, sugar
  cane, rape seed, oil palm
  
• 5 fruits and vegetables
• cabbage, apple, onion, tomato, pepper

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Crop statistics cereals (1)
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Crop statistics cereals (2)
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Crop statistics cereals (3)

• production figures different by order of
  magnitude
  
• millets 28,000 tonnes ? maize 725,000 tonnes
• maize mostly used as animal feed
• distribution of cereals across the globe varies
• millets in 64 countries ? maize in 125 countries
• smaller crops limited to specific climates

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Crop statistics pulses (1)
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Crop statistics pulses (2)

• production figures order of magnitude lower than
  for cereals
  
• less extremes
• different distribution patterns
• smaller crops limited to specific climates

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Crop statistics starch and oil crops (1)
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Crop statistics starch and oil crops (2)
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Crop statistics starch and oil crops (3)

• highly divergent production figures
• sugar cane, potato, cassava largest crops
• major calorie providers
• relatively more climate-confined major crops
• banana, cassava, coconut, oil palm, rapeseed

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Crop statistics vegetables (1)
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Crop statistics vegetables (2)

• as globally distributed as cereals
• production figures much lower than for cereals
  and some starch crops
  
• against a background of many local crops

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Production figures (106 tonnes 1990s) after
JHarlan
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Crop statistics general

• four types of crops
• truly global crops maize, potato, tomato, onion
• tropical/subtropical crops rice, sorghum,
  groundnut
  
• temperate/subtropical crops wheat, barley,
  cabbage
  
• tropical crops only banana, cassava, millets,
  coconut
  
• adapted to different ecosystems in their climate
  zones
  
• from drought tolerant to highly water-dependent
• 83 of major food crops from regions of long dry
  seasons (Mediterranean or tropical savanna)

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Threats and demands from climate change (1)

• changes in the following factors
• CO2 concentration
• higher
• temperature
• higher
• precipitation
• higher (temperate regions) or lower (tropical and
  subtropical regions)
  
• length of growing season
• shorter (linked to precipitation) or longer
  (linked to temperature)
  
• pests and diseases
• new combinations will occur

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Threats and demands from climate change (2)

• crops grown in confined zones
• may show less capacity to adapt in original
  growing areas
  
• may show less variability or variation in
  available genotypes to easily adopt in new
  growing areas
  
• some large crops may reach extremes
• e.g. day and night temperature and rice
  cultivation

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Desirable traits

• optimal CO2 response
• high temperature tolerance
• day and/or night temperature
• pest and disease resistances
• drought tolerance
• tolerance to water logging
• short day maturity
• long day maturity

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Genebank holdings cereals (1)
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Genebank holdings cereals (2)

• collection sizes of sorghum and millets much
  smaller
  
• collection size figures follow production
  figures
  
• variable number of source countries for CGIAR
  collections
  

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Genebank holdings pulses (1)
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Genebank holdings pulses (2)

• high number of source countries of CGIAR
  collections
  
• relative to size of CGIAR collections (cowpea and
  groundnut)
  
• important NARS collections
• relative to size of CGIAR collections
• no qualitative judgment

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Genebank holdings starch and oil crops (1)
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Genebank holdings starch and oil crops (2)
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Genebank holdings starch and oil crops (3)

• relatively small collections due to clonal
  propagation of most crops concerned
  
• clonal potato exception
• NARS collections dominate strongly
• cassava (and potato) exceptions
• few CGIAR mandate crops

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Genebank holdings vegetables (1)
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Genebank holdings vegetables (2)

• NARS collections dominate
• high number of NARS holdings reported
• CGIAR collections almost absent
• AVRDC collections on tomato and pepper with many
  source countries form execption
  

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Correlation production figures genebank
holdings

• a moderate correlation exists for seed-propagated
  crops, not for vegetatively propagated crops

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Preliminary conclusions (1)

• crops grown in confined zones
• may show less capacity to adapt in original
  growing areas
  
• may show less variability or variation in
  available genotypes to easily adopt in new
  growing areas
  
• have been less well conserved in ex situ
  holdings
  
• ? need for additional collecting to increase
  options for adaptation to climate change
  

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Preliminary conclusions (2)

• vegetatively propagated crops are less amenable
  to breeding of new (adapted) varieties
  
• more expensive, longer timelines
• vegetatively propagated crops are poorly
  represented in genebank collections
  
• no correlation between production figures and
  size of holdings
  
• ? collections for some vegetatively propagated
  crops should be particularly supported (e.g. yam
  and sweet potato)
  

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Traits for some major collections potato

• CIP
• pests and diseases, period from planting to
  harvest, percentage of dry matter
  
• GRIN
• pests and diseases, vigour, frost tolerance, heat
  tolerance
  
• ECDB
• pests and diseases, drought tolerance, dry matter
  content, dormancy, early harvest potential, frost
  tolerance, time to maturity,
  

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Some major collections wheat

• CIMMYT
• days to anthesis, days to maturity, growth habit,
  plant height
  
• GRIN
• disease resistances, plant height, plant habit,
  days to anthesis, days to flowering, drought
  tolerance, salt tolerance, winter hardiness
  
• ECDB
• diseases resistances, plant height, principal
  utilization, lodging intensity

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Some major collections rice

• IRRI
• days to maturity, panicle length, panicle
  shattering
  
• GRIN
• disease resistances, plant height, lodging, days
  to anthesis, days to flower, salt tolerance
  

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Some major collections cassava

• IITA and CIAT
• growth habit
• no CC-relevant traits

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Some major collections pepper

• AVRDC
• plant growth habit, plant size, days to
  flowering, days to fruiting
  
• GRIN
• disease resistances, plant growth habit, plant
  size, days to maturity
  
• CGN
• growth habit, plant height, vigour, time to
  flowering, time to harvest, diseases
  

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Preliminary conclusions (3)

• Some collections partly described for the traits
  indicated
  
• optimal CO2 response
• high temperature tolerance
• pest and disease resistances X
• drought tolerance X
• tolerance to water logging
• short day maturity X
• long day maturity (X)

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Preliminary conclusions (4)

• for many larger crops large collections stemming
  from many countries exist
  
• ? no need for additional collecting
• however, such collections are
• poorly described
• poorly evaluated, or
• poorly documented
• for desirable traits
• ? enhanced efforts to describe or document
  major collections on climate
  change relevant traits

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Summary

• share of individual crops in global food
  production shows asymptotic curve
  
• only quantitative statement, diversity in diet
  not taken into account
  
• crops growing in confined zones potentially more
  vulnerable and less well conserved
  
• targeted extra collecting may be warranted
• for most crops ample collections with wide
  geographic coverage available
  
• but not evaluated for climate change-relevant
  traits, or evaluation data not documented and
  accessible