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Lecture 12

ENSC 315 Lecture 12: Seeds

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Department
Environmental Studies
Course
ENSC 315
Professor
Susan Belyea
Semester
Winter

Description
Seeds Wednesday, February 8, 2017 11:06 AM Anatomy of a Seed • Embryo (embryonic plant) • Food Supply (endosperm, cotyledon) • Covering (seed coat) What is 'natural' about seeds? • Humans have been manipulating plant genetics for 10 000 years Debates about Seeds • Genetic modification of seeds • Intellectual property Rights Teosinte and Corn • Teosinte: grass from central America • Corn developed from the central grass - (maize) Why do we manipulate Seeds? • Higher yield • Drought tolerant • Pest resistant • Fungus / blight resistant; • Ease of cultivation- ideal form /size from mechanical harvesting, etc. processing • Shorter time to maturity • ** Nutritional value- adding micronutrients, proteins • Control allergens • Herbicide residents- round up ready • Durability for distribution • Appearance, novel traits How do we manipulate seeds? Techniques have included: • Careful seed saving from plants that fare well in open pollinated fields (farmers and science) How do we manipulate seeds? Techniques have included: • Careful seed saving from plants that fare well in open pollinated fields (farmers and science) • Deliberate crossing and scientific manipulation of varieties of the attributes we desire (science and farmers) • Genetic modification (science) Plant Breeding Open Pollination • What is it? ○ Natural pollination -based propagation - birds, bees, insects, winds ○ (Often called Heirloom or heritage, though there are many open pollinated seeds that are not heirloom seeds) • Pros: ○ Adapted to conditions naturally so should be best grown in local conditions § Local seeds- local foods- local movements ○ Maintain cultural and historical connection ○ Tends to biodiversity ○ Taste? Cultural and nostalgic value • Cons: ○ Yields? Will not be the same as a plant bred for yield production ○ Inadvertent crossing ○ New varieties -market and consumer demands ○ Cant quickly develop tolerance to rapidly changing conditions (evolution takes time -at least 8-10 generation of careful seed saving) Example of Open Pollination Domestication of maize • Farmers selected teosinte crops which were larger, had more kernels, were resistant to drought & pests • Select and replant seed from best plants • In the early 1940s the average farmer in the US could grown about 24 bushels of corn per acre per year = 1.5 tonnes/hectar "Classical" scientific Plant Breeding • Creating hybrids through deliberate interbreeding of relatvarietiesto produce new crop varieties with desirable properties. Related plants are crossbred to introduce traits from one variety or line into a new genetic corn per acre per year = 1.5 tonnes/hectar "Classical" scientific Plant Breeding • Creating hybrids through deliberate interbreeding of relatvarietiesto produce new crop varieties with desirable properties. Related plants are crossbred to introduce traits from one variety or line into a new genetic background • Technolo
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