Crops And People Flashcards
1
Q
10 crop use catergories
A
- human food (including beverages and additives)
- vertebrate food (forage and fodder)
- invertebrate food (e.g. plants feeding honeybees and silkworms)
- materials (e.g. wood, fibre)
- fuels (e.g. charcoal, ethanol)
- social uses (e.g. narcotics, ritual, religious uses)
- poisons (for vertebrates and invertebrates)
- medicines (human and veterinary)
- environmental (e.g. intercrops, wind breaks, ornamentals)
- gene sources (e.g. wild crop relatives
2
Q
World population growth
A
- very slow population growth 10,000 BCE to 1700 (0.04% annually)
- exponential growth from 1bn in 1800 to over 8bn today
- increase in crop production and yield but not significant increase in land usage
- from improvements in crop characteristics and management and use of synthetic fertilisers and pesticides
3
Q
Crop statistics
A
- majority of production and global production is ‘big three’
- wheat, maize, rice
- monocot
- Poacea (grass) family
4
Q
Current investment in agriculture
A
- global agricultural exports very small as a percentage of GDP
- not many large companies
- not much investment in research, reliant on declining government funding
5
Q
Neolithic revolution
A
- 13,000ya, humans slowly abandoned hunter-gatherer way of life (seasonal movement to follow food sources) to become settled farmers
- start of settled life, development of villages with permanent structures to support farming
- multiple theories proposed for change in behaviour
- possibly related to environmental change, plant domestication followed the end of the most recent glacial period
- populations maybe noticed the concentration of grains and fruit plants in past human waste deposits
6
Q
Fertile crescent
A
- first origin of agriculture
- middle East/ South west Asia
- provided higher level of nutrition which could support much higher population densities than hunter gatherers could
- complete system through domestication of cereals (Emmer and einkorn wheat, barley), pulses (peas, lentils, chickpeas), fibre (flax), animals (sheep, goats)
- spread to other populations
7
Q
Evolution of cereals
A
- progenitors of modern wheat and barley evolved independently of man
- evolved in an environment with cold winters and hot dry summers
- evolved qualities beneficial to humans including large carbohydrate rich seed, short growing season, storable seeds
- a few small mutations such as non-shattering and uniform germination domesticated them
8
Q
Domestication of cereals
A
- evolution of uniform domestication created reliability, most plants are non-uniform to increase chance of success through dormancy
- increase in grain size
- single gene change meant grain no longer shattered from ear to initiate dispersal, grains remain in ear until harvest and are then ‘threshed’ to break apart
9
Q
Spread of agriculture
A
- spread very quickly
- food storage and surpluses
- population growth
- less time collecting and processing food
- political organisation
- writing (records of agricultural production
- conflict (larger societies, ships)
- epidemic diseases (closer proximity to animals, migration)
10
Q
Genetic modification
A
- arose as a consequence of cultivation
- identification of plants with good crop qualities from natural variation and store and plant those seeds
- increased representation of those qualities in subsequent generations
11
Q
Genetic modification of maize
A
- Teosinte = maize ancestor
- highly branched, very small cobs
- genetic modification decreased branching and increased grain and cob size
- increased yield of most useful part of plant
12
Q
Domestication of wheat
A
- arose from human influence
- Einkorn wheat (AA) (early cultivated what vulnerable to disease) hybridised with goatgrass (BB)(hardy weed) to form Emmer wheat (AABB), tetraploid, genome size increased cell size and therefore grain size and hardiness
- Emmer hybridised with Tausch’s goatgrass (stress tolerant weed) to create spelt and bread wheat (hexaploid, AABBDD)
- further increased hardiness and grain size
13
Q
Origins of house mouse
A
- first found in Fertile Crescent 12,000ya
- passively spread to Western Europe through migration if farmers
- possibly from threshing debris and stored grain
14
Q
The green revolution
A
- 1950s-60s, period of agricultural research and technological advancements that dramatically increased crop yields
- development of high yielding varieties of cereals
- expansion of irrigation infrastructure
- modernisation of management techniques
- distribution of hybridised seeds
- synthetic fertilisers and pesticides
- mechanisation linked to WW2
- raised concerns about environmental impacts
15
Q
Impact of semi-dwarf genotypes
A
- cereal crops historically tall, current crops less tall, much higher yields
- 1946, Americans in Japan noticed short wheat crops
- introduced to US and international breeding
- pioneering work in the International Maize and Wheat Improvement Centre (CIMMYT), Mexico
- Normal Borlaug (1970 Nobel Peace prize) introduced dwarf genes worldwide
16
Q
Semi dwarf genotypes, India
A
- 1963, large famine as Indian food production hits limit, fertilisers just made crops overgrow and collapse
- Borlaug’s high-yielding disease resistant semi-dwarf strains introduced in mid 1960s
- rescued Indian food production, yields rose from 12m to 20m tonnes from 1965-1970
- India went from having chronic food deficits and famines in 1960s to becoming self sufficient by early 1970s
- Borlaug helped train a generation of Indian agriculturalists and scientists
17
Q
Semi-dwarf wheat varieties, Rht
A
- Rht = reduced height genes
- Rht-B1 and Rht-D1 loci of B and D genomes of hexaploid wheat
- semi-dwarf is Rht-B1b and Rht-D1b
- extreme dwarf varieties too severe
18
Q
Parallel ‘green revolution’ in Asian rice
A
- 1966, semi-dwarf IR8 rice bred at International Rice Research Institute (IRRI) in Philippines
- Philippine rice production increased from 3.7-7.7m tonnes in 2 decades
