This document discusses different crossing methods used in plant breeding programs. It describes selection breeding, divergent breeding, and convergent breeding as the three main ways to produce genetic populations. Selection breeding involves selecting phenotypes from open-pollinated populations. Divergent breeding combines traits from genetically diverse parents using methods like single crosses, three-way crosses, and successive crosses. Convergent breeding aims to improve a single trait or few traits, using backcrossing to maintain other desirable traits from the recurrent parent. The document provides details on various specific crossing techniques and advises selecting parents with many positive traits to increase the likelihood of breeding success.

1. Importance of
crossing methods

2. Pemilihan tetua
• Tetua harus mengandung gen target
• Diketahui pola pewarisannya

3. Konsep pemilihan tetua:
• Konsep varietas
• Konsep sifat
• Konsep gen

4. Crossing methods
Enlargement of genetic variabillity
Success of breeding program

5. The choice of hybridization method
depend:
• Knowledge of whether the availbale
parents are capable of ensuring the
recombination of positive trait in new
cultivar
Three ways of methods of producing the
genetic population:
• Selection breeding
• Divergent breeding
• Convergent breeding

6. Selection
• Selection certain phenotypes from
population formed through open
pollination /random mating
• Selection from natural population (include
cytoplasmic male sterility)
• Phenotype selected=> intercrossed by
polycross => selected to develop
commercial varieties.

7. Divergent Breeding
• This method make use of genetically
diverse parent in order to combine their
desirable traits.
• Include gene interactions to obtain
cultivars with desirable trait.
• Ex. Single cross method, three-way cross,
successive crosses, double crosses,
diallel cross

8. Single cross-A x B
 The parents: possess the max positive traits and
min negative trait
 The progenies possessing positive trait of both
parent
 This method is reletively quick and reliable
 It has produced inumerable cultivare (wheat,
rice, barley)
• The method fo crossing two parents
• Tomato: Mutiara x G. Hijau
• Rice : Ir 36 x Rajalele
• Apple: Jonathan x Delecious

9. The weakness
• If one parent is an advanced and primitive
cultivars => it isn’t probable the line
superior better than parent.
• F2 and subsequent generation: most
plants will be intermediate and low
frequency of possessing desired gen of
both parent

10. Advise:
If a sufficient number of cultivars with
desireble traits is not available, => must
include primitive cultivar
Backcross to advanced cultivar

11. The method of three-way cross
• (A x B) x C
• When not all traits find in two parent
=>necessary to select a third parent
A Bx
F1 x C

12. Which is the better?
• A (advanced) x B (advanced) x C (less advanced)
• 25% 25% 50%
• (A x C) x B
• 25% 25% 50%
The first:
Advanced cultivar (A +B) incorparate 50% + less advanced 50%
The second:
advanced cultivars incorporate75% and less advanced 25%

13. The method of successive crosses
((AxB) x C) xD
• If all of trait intended cannot be found in
three parent => necessary introduce fourth
and even fifth parent
A x B
F1 x C
F1x D
selection
Portion of the germ plasm are:
[(A x B) x C] x D
12.5% 12.5% 25% 50%

14. Successive crosses:
• The last step of crossing a cultivar with the max
number of possitive trait.
• This method may be fairly successful
incombining gen from many parents.
• Take a long time to produce a desired genetic
population
• Used to improve existing cross combination
• To produce F1 may shortened by crossing in
greenhouse

15. Double crosses (AxB)x(CxD)
• All parent have equal possitive trait
• ( A x B) x ( C x D)
• 25% 25% 25% 25%
• Frequency of desirable gene in F2 of an
F1xF1 lower than in F2 generation of a
single cross if one/two parent possess a
large number of negative trait
• F1xF1 efficient for double-cross maize
hybrid production

16. The Method of diallel cross
• Full Diallel cross
• Partial diallel
Exlusively for genetic studies=> offers
information on the effect of number of gen,
combining ability, an gen interaction

17. Convergent breeding
• To improve of a single trait or a couple of
trait
• To maintain the other positive traits of that
cultivar
• Ex: The backcross method

18. BC cont.
• After 6 series of BC , progenies possess
98.4% of germplasm of the reccurent
parent (complete backcrossing)
• If a donor of a certain trait possesses a
number of other positive trait=>
incomplete BC is recommended
• Just one or two BC, to recombination for
other positive trait =>diverse line

19. Other methods of convergent crossing
1. Principle of maximum recombination
A x B C X D E X F G X
H
X X
X
25% A-type
12.5 % A-type

20. 2. Principle of transgresive recombination
A x B A X C A X D A X E
X X
X
50% A type
50% A type
50% A type

21. 3.Combined principle of transgressive
recombination and incomplete backcross
A x B A X D A X F A X H
X X
X
50% A-type
A AX A X A
X
X
75 % A-type
75 % A-type
75 % A-type

22. Conclude
The probability of success in breeding:
• is not increased by the used of complex
methods of crossing
• but a careful selection of parents which
should possess many possitive traits and
hence many desireable genes