1. Crop Plant Reproduction (p. 83-94 and chapter 4)
Flower Anatomy
Components
Terminology
Legume
Grass
Types
Different management requirements
Pollination
Fertilization
Yield Components
Flower growth crucial for maximum yield.
Harvest Index

2. Crop Flower Components
Wheat
Flowers = inflorescences
Components:
Sepals:
Protect flower bud
Petals:
Colorful attract insects
Stamens (male):
Anther: produces pollen
Filament: supports anther
Carpel (female):
Stigma: sticky - collects pollen
Style: connects stigma to ovary
Ovary: fruit, contains ovules
Ovule: seed, contains egg
Soybean

3. Flower Terminology Complete Flower: Incomplete Flower: Perfect Flower:
Sepals, petals, stamen, carpel.
Incomplete Flower:
Missing one of 4 components.
Perfect Flower:
Stamens and carpel (soybeans).
Imperfect Flower:
Male or female flower (corn).
Monoecious:
Male and female on same plant (most crops, corn, cucurbits, oak).
Dioecious:
Male or female plant (waterhemp, cannabis, ginko, holly).
Waterhemp

4. Flower Type and Farming
Flower type affects how a crop is grown and what is harvested.
Perfect flowers tend to be self-pollinated.
Soybeans, wheat, oats, barley, rye
Saving seed can be done according to seed trade laws.
Genetics of plant does not change.
Imperfect flowers require cross-pollination (wind, bees, etc.)
Corn
Seed can nor be saved – performance declines each generation.
Inbreeding reduces performance.

5. Legume (Dicot) Flower Complete and Perfect Flower parts in 5’s
Sepals (5):
Petals: (5)
1 standard
2 wings
2 fused into keel
Stamens (10):
1 free
9 fused (most)
Carpel/pistil (1):
Stigma:
Style:
Ovary:
Ovule:

6. Grass (Monocot) Flower Anatomy
Flower parts in 3’s
Incomplete (no sepals, petals)
Spikelet:
Florets:
Rachis: central axis
Rachilla: attaches florets to rachis
Glumes: protect spikelet
Lemma: modified sepals
Palea: modified sepals
Stamen:
Anthers (3):
Filaments (3):
Carpel/pistil (1):
Stigma (2): feathery
Style:
Ovary:
Ovule:

7. Flower and Inflorescence Types
Flower Type:
Spike:
Spikelet attached to rachis (Wheat)
Panicle:
Spikelets attached to branches attached to rachis (Oats)
Raceme:
Flowers attach at leaf axil to stem (Velvetleaf)
Head:
Flowers attach to receptacle (Sunflower)
Umbel:
Flowers attach to receptacle(Queen Anne’s Lace).
Inflorescence Type:
Determinant: meristem terminates inflorescence
Indeterminant: new inflorescences
continuously develop

8. Factors Affecting Flowering
Plant Nutrition:
>N2 > flowering delay
Light:
Photoperiodism:
Short-Day: respond to longer nights
Soybeans, corn, warm-season
Long-Day: respond to shorter nights
Small grains and cool-season
Day-Neutral: no response
alfalfa, cotton
Temperature:
Vernalization:
cold temps required
winter wheat, barley, rye
Cool temperature delays flowering

9. Asexual Reproduction
Reproduction and propagation from vegetative parts.
Types:
Apomixis: seed without fertilization
bluegrass, citrus, dandelions
Cuttings: sugarcane
Layering: develop plant while
attached
raspberry, blackberry
Division: parts divided
potato, bermudagrass,
pineapple, bluegrass
Grafting: joining plant parts
fruit trees

10. Sexual Reproduction Production of Pollen: Production of Embryo Sac:
Production of sperm cells.
Production of Embryo Sac:
Production of egg cell.
Pollination:
Transfer of pollen from anther to stigma.
Double Fertilization:
Egg + Sperm = Embryo
Sperm + Polar Nuclei = Endosperm

11. Male: Sperm Cell Development
Pollen Sac:
In anther
Microspores produced by meiosis
Pollen grain produced by mitosis
Tube cell
Generative cell
Produce 2 sperm by mitosis
Pollen
Anther
Filament
Within the anther, haploid microspores are produced by meiosis. They form pollen grain, which contain sperm.
Anther (2n)  pollen sac (2n microsporocyte)  meiosis  microspores (1n)  mitosis  pollen grain (1n male gametophyte)
Microspore Mother Cell (2n)
4 Microspores
Pollen Grain (Male Gametophyte)
1 Generative Cell 1 Tube Cell
2 Sperm Cells Pollen Tube
1 fertilizes egg
2 Prothallid Cells die

12. Female: Egg Cell Development
Megaspores produced by meiosis.
1 of 4 megaspores lives  2  4  8 nuclei of 7 celled embryo sac (female gametophyte).
3 antipodal cells
1 central cell with 2
polar nuclei
2 synergid cells
1 egg cell
Within the ovary, megaspores are produced by meiosis. One develops into embryo sac, which has an egg cell within it and the rest disintegrate.
Megaspore Mother Cell (Megasporocyte)
4 Megaspores
Embryo Sac (Female Gametophyte)
3 Antipodal Cells
2 Polar Nuclei
2 Synergids
1 Egg Cell

13. Flower Embryo Sac Double Fertilization Sperm 1 Sperm 2
Pollen Grain:
lands on stigma
germinates
forms pollen tube
grows between cells to the ovule.
Double Fertilization
Sperm 1
1 sperm + 2 polar nuclei = 3N endosperm cell
Sperm 2
Sperm enter embryo sac
1 sperm + egg = zygote (2N)

14. Pollination Transfer pollen from anther to stigma. Artificial:
Cross-pollination:
Pollen from different plant
By insects, wind
Corn, alfalfa, clover, sorghum
Self-pollination:
Pollen from same plant
Wheat, oats, soybeans, rice
Pollination: transfer of pollen from anther to stigma of pistil by wind or assisted by insects, bats etc.
Cross and self pollination.

15. Terminator Technology
Seed is unable to grow.
Genetically controlled.
Crops: corn
Uses:
Reduces volunteer the next year.
Seed can be stored for longer periods of time.
Reduce outcrossing – biotech traits
Patent Protection for developer.
Opposition

16. Yield Components Three components determine yield.
Plants Per Acre: planting time
Seeds Per Plant: floral initiation and pollination
Seed Weight: grain filling period
Yield = (ppa)(seeds/plant)(seed weight)
(28,000ppa)(586k/p)(.314g/k) = bu/A
Yield Compensation:
Components adjust for each other.
(33,000ppa)(500k/p)(.312g/k) = bu/A

17. Harvest Index
Crops differ in amount of photosynthate and nutrients diverted to yield vs growth.
Harvest Index = economic yield /
biological yield
Corn for grain = .50
Corn for silage = .80