Presentation at the March 2013 dialogue workshop of the Biosciences for Farming in Africa media fellowship programme in Accra, Ghana. Please see www.sti4d.com/b4fa for more information

1. F1 Hybrids
Claudia Canales

2. The need for more food
• F1 hybrids
• Fertilisers
• Mechanisation (tractors)
U.S. maize yields in the last 100 yearsU.S. population growth in the last 100 years
8-fold increase in maize yield thanks to:

3. What is a maize F1 hybrid?
The first generation (F1) of a cross between from two uniform
parent inbred lines
F1 Hybrid
Parent 1 Parent 2
X CROSS

4. Maize reproduction

5. Each kernel is a genetically unique individual

6. How do you make an F1
hybrid?

7. 3 steps
1: Development of parental inbred lines
By self-pollinations until a good degree of
uniformity is achieved. Selection for type and good
parent potential is done as the lines are inbred.
Inbreeding
depression

8. 2: Test crossing: sets of two inbred lines are
crossed (uniformly, with no selfing allowed)
How do you make an F1 hybrid? Cont.
Hybrid vigour

9. 3: Production crossing: commercial
production of F1 hybrid seed. Expensive and
labour-intensive.
How do you make an F1 hybrid? Cont.

10. What are the advantages of F1 hybrids?
• It is uniform in appearance and behaviour:
– enables farmer to treat and harvest crop at the same
time uniformity
– has marketing advantages when sold to buyers with
strict quality standards)
• It has hybrid vigour (makes them more
competitive with weeds)
• It is high yielding
• It is selected for improved grain quality
• A particular hybrid can be selected for specific
pest and disease resistance or drought tolerance

11. Maize F1 hybrids
P1 P2C B
14 days P1 P2C B
Maize
Parent 1 Parent 2 Parent 2Parent 1F1 Hybrids F1 Hybrids

12. Game introduction
• F2 generation of hybrid seed – variability and
consequences

13. • Hybrid seed is more expensive than open-
pollinated maize seed
• Farmers situated in a low potential environment
and who cannot afford extra inputs such as
fertilizer may not recover the costs of the hybrid
seed
• Fresh hybrid seed needs to be bought every
planting season (farmers cannot replant grain as
seed without major reductions in yield, which
might be a decrease of 30 % or more)
What are the disadvantages of F1
hybrids?

14. What are the disadvantages of F1
hybrids? Cont.
Parent 2
Parent 1
F1 Hybrid
F1 Hybrid seed selfed over several
generations
Inbreeding
depression
Hybrid vigour

15. F1 hybrid seeds vs landraces
• Genetic uniformity can be a problem if the
conditions are bad (such as extreme weather
conditions, new pest or disease)
• Traditional landraces are genetically very
variable, and hence more resilient, although
yields are lower
• Landraces are invaluable sources of genetic
diversity

16. Consequences of hybridisation
• Bought seed vs seed saving
• (Lack of) Ability of individuals or government
research institutions to produce in desired
quantity and quality
• F1 hybrid production closely linked to the
creation of private seed companies for
commercial seed production (public versus
private investment in plant breeding)

17. F1 hybrid seeds are not GM!!
Why? Because they are produced by crossing
two non-GM plants.
F1 Hybrid
Parent 1 Parent 2
X CROSS