This document discusses hybrid breeding and its achievements. It describes the objectives, steps, and methods involved in hybrid seed production, including the development of inbred lines, evaluation of inbreds, and production of hybrid seeds. Various types of hybrids are mentioned, such as single cross, double cross, top cross, and population hybrids. The advantages of hybrids include increased yield, uniformity, and vigor. Examples are given of hybrids released in crops using male sterility systems. The document concludes with achievements of hybrids in various crops in India.
2. Hybrid - F1 from crosses b/w 2 Purelines, Inbreds, OPV, clones or other
population that are genetically dissimilar.
Hybridisation – Process of crossing two genetically different individuals
to result in a new individual with different traits.
Objectives:
To create genetic variation.
To combine desired characters into a
single individual.
Combination Breeding
Transgressive Breeding
Production of Hybrids
3. Steps involved in hybrid seed production
• Collection and evaluation of germplasm
• Development of inbreds
• Evaluation of inbreds
• Production of hybrid seed
4. Development of inbreds
Two methods:
» Selfing-heterozygous populations
» Doubling of haploids
Various population viz. open pollinated varieties, synthetic varieties
or any other heterozygous population can be used for selfing.
• Progeny of selected plants are grown separately from the selfed
seed in the next season.
• Again selection is made for the superior progeny and selfed.
• This processes is continue to get superior homozygous
inbred.
5.
6. Production of Doubled Haploids
• Production of doubled haploids leads to homozygosity in a single
generation after recombination of selected parents.
• Selection is more efficient for oligogenic or polygenic traits in DHs
because the genes are fixed in a homozygous background, limiting
dominance genetic variation and segregation.
• The DH method prevents losses of valuable genetic variations
better than the conventional selection method.
9. Phenotypic evaluation
• Based on the phenotypic performance of inbreds. Poor performance
inbreds are rejected.
• Highly effective for highly heritable characters.
• Effective in improving yielding ability of inbreds.
• Reliable measure of average performance of inbreds of all single
crosses.
• Genotypes after phenotypic evaluation are crossed to tester (OPV) with
wide genetic base.
• Performance of top cross progeny is evaluated in replicated yield trails.
Top cross test
10. Single cross method
• Used to measure SCA of those inbreds which are selected on the
basis of top cross performance.
• The selected lines are crossed in all possible combinations viz., n(n-
1)/2, where n is the number of inbred lines.
• These single crosses are evaluated in replicated yield trials over
several locations for yield performance.
• The best performing single crosses are identified for release as a
variety or for use in the production of double cross hybrids.
11. Production of Hybrid Seed
• After identification of superior line , hybrid seed is produced.
• Production of Hybrid seed on commercial scale requires-
a)Easy emasculation of female parent
b)Effective pollen dispersal from the male parent to ensure
satisfactory seed set in female parent.
Procedure of Hybridisation:
1. Selection of parents
3.Emasculation
13. Emasculation
Removal of stamens or anthers or killing the pollen of a flower
without the female reproductive organ.
Methods:
• Hand Emasculation
• Suction Method
• Hot Water Treatment
• Alcohol Treatment
• Cold Treatment
• Use of Gametocide
• Genetic Emasculation
• Self Incompatibility
• Male sterility
GMS (TGMS, PGMS)
CGMS
CMS
14. Types of hybrids:
Intraspecific Hybrid
Interspecific Hybrid
Intraspecific hybrid:
Single cross A*B
Double cross (A*B) *(C*D)
Three way cross (A*B)*C
Modified Single cross (A*A’)*B
Double Modified Single cross (A*A’)*(B*B’)
15. Varietal hybrid V1 *V2
Topcross hybrid V*A
Double top cross (A*B)*V
• A, B, C, D – Inbreds
• V – Open pollinated varieties
• A’, B’ – are sister inbreds of A and B.
• Hybrid varieties – first exploited in Maize.
16.
17. Single cross hybrids
• In cross pollinated species - cross between two inbreds (A x B),
• In self pollinated crops-between two homozygous varieties.
• Total number of single crosses is n (n-1) /2
• More common in some self –pollinated species than cross –
pollinated species.
• Used for the development of double cross and three way cross
hybrid.
18. Double Cross Hybrid
Commonly used in maize and Sugarbeet
• The rows of female and male parent are planted in the ratio 4:1 in
maize.
• The number of all possible double crosses among selected inbred is
calculated by n ( n-1) ( n-2) (n-3) /8 where ‘n’ is number of inbreds
involved.
Double Top Cross Hybrid: used in maize
19. Top Cross:
• also known as inbred variety cross, and
• is used as testing the combining ability of inbreds and not for
commercial hybrid seed production
Multiple Crosses:
A cross involving more than four inbred line.
Polycross:
Open pollination of a group of selected genotypes in isolation from
other compatible genotype to promote random mating among
selected genotype.
20. Three Way Cross Hybrid:
These hybrids sometimes used in maize, in which single cross is used
as female and inbred as male and are planted in the ratio of 2:1.
These hybrids produced seed of normal shape and size but the main
drawback is the low pollen production efficiency of the male
inbred parent.
• In case of single and three way cross hybrids, the rows of female
and male parents are planted in 2:1 ratio.
• The tassels of female parent are removed and natural cross
pollination is allowed.
• In double cross hybrid , the rows of female and male parent are
planted in 3:1 or 4:1 ratio.
21.
22. Interspecific/ Intrageneric hybrids
• F1 progeny between two different species of the same genus
• rarely used for commercial cultivation, because such hybrids are
fertile only in few cases.
• In cotton, interspecific hybrids between
G. hirsutum x G. barbadense
G.arboretum x G.herbaceum are fully fertile. Several
interspecific hybrids at tetraploid level (Varalakshmi, Sruthi, HB224,
TCHB 213) and some hybrids at diploid level (DH7, DH9) have been
released for commercial cultivation in India.
23. Improving the characteristics of inbred lines
Various schemes suggested to improve the existing inbreds:
• Productivity, disease & insect resistance of inbreds
• Combining ability of inbreds.
The following methods are used-
a)Pedigree selection e)Somatic hybridization
b)Backcross method f)Somaclonal variation
c)Convergent improvement g)Genetic engineering
d)Gamete selection
27. Hybrids released crops using male sterility system
Name of crop Type of cross Name of hybrids
released
Pearlmillet Single cross MH 179, BK 560
Sunflower Single cross BSH 1, HSFH1
Castor Single cross GCH2, GCH3,GCH4
Sorghum Single Cross CSH1,CSH5,CSH6,C
SH9
Cotton Intraspecific H4, H6,H8
Interspecific Varalakshmi, Sruthi
Pigeonpea Single cross ICPH 8
28. • Largest number of hybrids – Pearl millet, Sorghum followed by
Maize, Cotton, Rice, Sunflower……
• Indian has pioneered in developing hybrid in both Desi and new
world cotton.
• In Maize, QPM opaque 2 gene, high starch (Histarch hybrid Makka),
baby corn hybrid HM4.
Recently released single cross hybrids are:
• HM10, Nithya Shree, Vivek Maize Hybrid 33, Vivek QPM 9
29. In Pearl millet:
• HB3, HB5 these were SCH from CMS line Tift 23A. And yeild upto 7
tonnes per hectare in National Demonstration trials
• Downy mildew resistant hybrids PHB 10, PHB 11,BJ104 and BK560
• Public sector hybrids:
Pusa 23, HHB50, and HHB 67.
30. TNAU Released Hybrids
Rice:
CORH 1 (MGR) – 1994, CORH 2, CORH 3, CORH 4, ADTRH 1 .
Maize:
COH 1 - 1982, COH 2 ,COH 3 ,COH 4, COH 5, COH 6,CO H (M)7, CO H
(M)8, CO H (M)9, CO H (M)10.
Redgram:
COH 1 – 1994, COPH 2.
Cumbu:
X 4, X 5, X 6, X 7, TNAU Cumbu hybrid CO 9, CO(Cu) H8…
31. Reference
• Plant Breeding Principles & Methods – B.D. SINGH.
• Development of Hybrid Varieties in Cross Pollinated Crops –
Vipin Kumar Pandey.
• Hybrid Breeding in Plants – JYOTI VERMA.
• TNAU AGRITECH PORTAL.
