Sweet Corn (Zea mays var. rugosa)

1
Sweet Corn (Zea mays var. rugosa)

• Key points
• Difference from other corns
• 3 categories of sweet corn
• Wind pollination and its implications
• Succession
• Problems

2
Sweet Corn is unlike other corns

• _________________
• Produces and retains large amounts of sugar in
  the kernels, rather than starch
• Pericarp
• The skin of __________ is thinner, making them
  tender
• Seed is wrinkled when _______________

Sweet corn seed
3
Types of Sweet Corn

• ____________ cultivars
• Contain the sugary gene (su)
• Have less initial kernel sugar than other sweet
  corn types
• Sugary enhancer
• Contain the ___________________ (se) gene
• Significantly raises the sugar content above
  standard cultivars
• Taste, tenderness, and texture are outstanding

4
Types of Sweet Corn

• Supersweet cultivars
• Contain the shrunken-2 gene (sh2)
• Much initial R D was done at University of
  Illinois in 1950s
• Hold sweetness longer than su or se types
• Kernels have a crispy, tough-skinned texture
• Require ______________ soils for germination than
  others
• Must be isolated from other types of corn
  tasseling at same time

5
Sweet Corn Planting

• To have sweet corn throughout the summer must
  have succession plantings
• Use both __________________ timing (temporal) and
  cultivars with different maturity
  (___________________)
• Example of a planting regime
• First planting (varietal succession)
• _________________ crop cultivar
• Main crop cultivar
• Second planting (temporal succession)
• Same cultivar when three to four leaves have
  appeared on the seedlings in the previous planting

6
Sweet Corn Reproduction

• Flowers
• Separate male and female flowers on each plant
• Which is which?

7
Sweet Corn Reproduction

• Male flowers are tassels
• Spikelets contain ____________ , which produce
  pollen

Branch of tassel
8
Sweet Corn Reproduction

• Female flowers are ______________
• Each potential kernel produces a silk, on which
  the pollen lands for fertilization

9
Sweet Corn Development

• Plants have a tendency to produce
  ________________ or tillers
• Dont really need to be removed cant compete
  with main stalk

10
Sweet Corn Pollination

• _______________ pollinated
• Plant sweet corn in blocks of at least four rows
  to ensure good pollination
• Cross-pollination
• Prevent from cross pollination by field corn,
  __________________ corn, or popcorn
• Especially supersweet cultivars because if
  pollinated by other corns they will not develop
  high sugar content
• Cross pollination between ___________ and white
  cultivars will affect appearance of white corn

11
Sweet Corn Harvesting

• Ears should be picked during _______ phase
• Juice of the kernel appears milky, not thick
• Occurs 20 days after appearance of first silks
• Harvest time indicators
• Drying and ___________ of the silks
• Fullness of the ________
• Firmness of the unhusked ears

12
Sweet Corn Problems

• Corn ______________
• Once caterpillar is inside husk, there is no
  effective control
• Bt or mineral oil on young silks may help prevent
  entry
• Can insert _____________ gene for Bt protein into
  sweet corn

13
Genetically modified vegetables (GMOs)

• Has a _____________ gene inserted using
  molecular biology techniques
• Difference from cultivars developed with
  traditional plant breeding
• Gene inserted from __________________ organisms
• Single or a few genes inserted in GMO
• Selectable markers in GMO

14
Genetically modified vegetables

• Pest _______________ has generally been the
  target
• Consumer acceptance has been an issue
• Flavr-Saver Tomato
• No longer available
• __________ containing sweet corn and potato
• No longer available
• Glyphosate-resistant lettuce
• Not marketed

15
GMOs The Issues

• Pest resistance will develop
• Genes may move into related _______ species
• Superweeds
• Adverse health effects
• Allergic reactions to food
• Ethical issues
• Who benefits from GMOs?

16
Sweet Corn Problems

• ___________ beetle
• Carry Stewarts _________
• Yellow streaking of leaves, ___________, plant
  death
• More severe in southern IL

17
Sweet Corn Problems

• Smut
• Caused by a ________ that invades kernels or
  tassels
• More severe in hot,_____ conditions and with
  white cultivars
• Culinary delicacy, especially in __________
• Called cuitlacoche
• Can cause contractions in pregnant women

18
Sweet Corn Problems

• Raccoons
• Raccoons eat sweet corn when it is in the early
  ____________ phase, just before the ears are
  ready to harvest
• Hard to control
• ____________ can be necessary
• Watch for tracks