On-Farm Plant Breeding - I

Michael Mazourek Cornell University

Northern Organic Vegetable Improvement Collaborative

Addressing Grower Needs

Addressing Grower Needs“Breeding, Research, and Education Needs Assessment for Organic Vegetable Growers in the Northeast”Hultengren, Glos and Mazourek 2016 https://ecommons.cornell.edu/handle/1813/44636

210 growers responded to a survey sent to over 1,000 growers in the Northeast.

Working group of researchers, students, growers, extension, and seed companies reviewed responses.

Crops Prioritized by Growers for Cultivar DevelopmentA

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Certified Organic Grower Responses

Responses from growers

Challenges

Define Seed Resources• Learn what others are growing in your area

• Ask at conferences like this!

• Call seed suppliers for recommendations• Organic variety trial database www.eorganic.info• www.pickacarrot.com – like google for seeds• Seed Savers Exchange• Regional seed groups

Know Your Crop’s Genus

Search for “Cucurbita Gene List”

“Capsicum Gene List” Search

Requesting PI Accessions from NPGS (GRIN)

• Cultivar – distinct plant germplasm grown in agriculture

• Line – true breeding plant germplasm that may be appropriate for use as a cultivar

• Accession – a sample of seed that was collected, can include mixture

Requesting PI Accessions from NPGS (GRIN)

• Accession – a sample of seed that was collected, can include mixture

• Potential for disease• Not all individuals will have trait you seek• Balance benefit of request with erosion of

genetic diversity collected from nature

Seed Borne Disease• www.vegetablemdonline.ppath.cornell.edu• www.agdia.com

Immunostrip Test

Flowers Can Hint toward Best Pollination and Breeding Approaches

• Plant that tend to self-pollinate tend to have perfect flowers (pollen and pistil on each flower)

• These can often be self-pollinated with little to no inbreeding depression

• There are exceptions• Plants that tend to outcross tend to have separate

male and female flowers tend to outcross• These can often show inbreeding depression• There are exceptions

Peppers• Perfect flowers• Self-pollinate readily• In the field outcross at about 20%

depending on pollinators present• Emasculated bud serves as female• Pollinated by open flower shedding pollen

Broccoli- an exception• Perfect flowers but

• Will not self-pollinate• Exhibits inbreeding depression

• Self-incompatibility common in brassica• Reject pollen similar to themselves• Promotes outcrossing• Circumvent by pollinating like a pepper (bud pollination)

• Cytoplasmic male sterility introduced• Controversial• Facilitates hybrid seed production

Cucumbers• Monoecious, Gynoecious and more• No real inbreeding depression• Although separate male and female flowers

require vector• Hybrids easily generated by planting

gynoecious alongside monoecious plants • Seed increase of gynoecious plants by use

of silver or hormones

Mendel• Alleles – different forms for a gene that control a trait

• Dominant allele – written in CAPITAL LETTERS• Recesive allele – written in smalls

• True Breeding = Homozygous

• Cross dominant plant x recessive plant • Heterozygous offspring• AA x aa => Aa F1

Breeding with HybridsDominant traits• only needs to be inherited from one parent to appear in

progeny – see it in the F1• visible if presentRecessive traits • needs to be inherited from both parents to appear in progeny• plant can be an invisible carrier Hybrid with dominant trait• may or may not be true breeding• Common for disease resistanceHybrid with recessive trait • progeny will be true breeding• Common for domestication traits