I hope it is useful to the students of B.Sc Agriculture and M.Sc Genetics and Plant Breeding.

1. Mr. Devkumar Arya
(Lecturer)
Department of Genetics and Plant Breeding
O.P. Agriculture College Budhwal, Behror, Alwar (Raj..),India
Affiliated to Sri Karan Narendra Agriculture University,
Jobner,(Rajsthan),India
Email:devkumararya59@gmail.com
PRODUCTION OF INBRED LINE
& HYBRID VARIETY

2. Outline
Inbred line
Introduction.
Production of inbred lines.
(A) Through inbreeding.
(B) Through haploid plants.
Evaluation of inbred lines.
Improving the characteristics.
Methods for genetic improvement.
Hybrid variety
Introduction.
History of Hybrid variety.
Types of hybrids.
Pollination control mechanism
Merits of hybrid varieties.
Demerits of hybrid varieties.
Achievements.
Future prospects and current status.

3. Introduction
A nearly homogygous line developed by continued inbreeding ,usually
selfing ,accompanied by selection.
Inbeeding is a mating of individuals more closely related by ancestor than
would be expected under random mating.
The source population generally an open pollinated variety but it may as well
be a synthetic,a single cross and a double cross.
In U.S.A. single crosses are the most commonly used source populations for
inbreds production.
Inbred isolated from open pollinated varieties,which is known as first cycle
inbreds.
When inbred isolated from hybrid varieties are termed as second,third or
fourth cycle inbreds.

4. Production of Inbred line through inbreeding
1st year-Selection of plants basis on the
phenotypes and according to purpose from
source population.
2nd year-(A)Plants are space planted for the
selfing.
(B)Selection of the superior plant or line
according to purpose.
6-7 generation repeat 2nd year steps .
Inbreds developed through half sib mating
were not superior to those produced through
selfing.
Source population
Selfing or some other close inbreeding
After 6-7 generations of self pollination,nearly
homozygous inbred lines are obtained

5. Production of inbred lines through haploid plant
Steps of anther culture
Culture vessels and their washing.
Selection and preparation of nutrient
medium.
Sterilization and storage of nutrient
medium.
Selection and sterilization of explants.
Transfer of sterilized explants on
nutrient medium.
Transfer of cultures in the culture room
for regeneration.
Rooting in regenerated shoots.
Transfer of plantlets in the field.

6. Haploid plant(AB)
n=10
Treatment with the
colchicine
Diploid plant (AABB)
ALL ARE HOMOZYGOUS INBREDS
Production of Diploid plant through haploid

7. Evaluation of inbred lines
Phenotypic evaluation-Phenotypic performance of the inbreds themselves.The
performance of inbreds is tested in a replicated yield trial in different location.
Topcross test-It is generally accepted that the performance of topcross progeny of
an inbred is a reliable measure of the average performance of all the single crosses
involves that inbred, and that topcross performance provides a reliable estimate of
GCA.
Single cross evaluation-It is believed that an important part of heterosis is due to
SCA.
Prediction of double cross performance-Prediction of double cross performance
from the performance data of single crosses was developed by Jenkins in 1934 by a
comparative evaluation of the predictions based on performance of inbred lines
single crosses and topcrosses.

8. Improving the characteristics of inbred lines
The productivity of inbred increasing for use in hybrid seed production.
To developed disease and insect resistance inbred lines.
The combining ability of inbreds to increase the yielding ability of their
hybrids. are improved.
Breeding methods
A-Pedigree selection. The choosing of breeding stock on the basis
of ancestral reproductive ability and quality is known as pedigree
selection.
Pedigree selection given by Love in 1927.

9. (B)Backcross method-The backcross method is most breeding method
for inbred improvement as like ,disease and insect resistance.

10. (C)Convergent improvement –The concept of convergent
improvement was put forth by Richey in 1927.
In this cross involving more than two parents.
It is a special case of backcross procedure, where a single cross is
backcrossed separately to the two parental inbreds.

11. (D)Gametic selection-When selection operates on gametes or the
haploid phase of life cycle,it is called gametic selection.Gametic
selection proposed by Stadler in 1944.

12. (E)Somatic hybridization-Somatic hybridization ,particularly
production of cybird and perasexual hybrid.
(F)Somaclonal variation-In vitro culture of plant cells
generates genetic variation. It is known as somaclonal variation.

13. (G)Genetic engineerimg –Genetic engineering offers an exciting tool to
improve specific traits of inbreds provided .For example,suitable versions of the cry
gene from Bt have been transferred into maize inbreds and insect resistance commercial
hybrid have been produced using such inbreds.

14. Introduction of hybrid variety
When F1 generation from a cross between two or more
purelines,inbreds,clones , strains or other genetically dissimilar populations/lines is
used for commercial cultivation,it is called hybrid variety.
Hybrid varieties were first time commercially exploited in maize.
In 1878,Beal reported that certain varietal crosses showed subatantial (up to
52%)heterosis .
In 1909,Shull suggested that inbreds should be developed from open pollinated
varieties by continued self fertilization.
The double cross scheme proposed by Jones in 1918.and first commercial double
cross hybrid variety proposed by Burr Leaming Dent was released in 1922.
The concept of topcross hybrids for preliminary screening of inbreds was
proposed by Davis in 1927.
 In 1934,Jenkins provided a reliable method for the prediction of double cross
performance.

15. In 1944 about 80 percent of the area covered by maize was under hybrid
variety.
By 1960 single crosses had become widely accepted in USA. and today only
single cross hybrids are grown.
In india intensive research for the development of hybrid maize began in
1952,when the coordinated maize improvement project was initiated in
collaboration with the Rockefelter foundation.
A large no. of inbreds and other germplasm were introduced from USA in india.
In 1961 ,four maize hybrids viz.,Ganga 1,Ganga 101 Ranjit and Deccan were
released which is double cross hybrid.
In 1961 ,based on CGMS of combine Kafir 60 (Sorghum) and Tift 23A
(pearlmillet)

16. Type of hybrids
Single cross hybrid(AXB).
Modified single cross hybrid(AXA1)XB.
Double cross hybrid(AXB)X(CXD).
Three way cross hybrid(AXB)XC.
Modified three way cross hybrid(AXB)X(CXC1).
Top cross hybrid(A inbred X open pollinated
variety).

17. Double cross hybrid
Single cross hybrid
In case of hybrid
certified seed production
female and male line
planting ratio 1:1 or 3:1.
In case of hybrid
certified seed production
female and male line
planting ratio 8:2 or
10:2.

18. Three way cross hybrid
Under certified seed
production female and
male line planted in
the field 3:1 or 4:1.

19. Topcross hybrid
A open
pollinate
d variety
F1(hybrid)
Cross between an inbred and open pollinated variety.
Inbred lines

20. Pollination control mechanism
(A)Male sterility
 Genetic male sterility
 Cytoplasmic male sterility
 Cytoplasmic genetic male sterility.
 Environmental male sterility /Pistillate lines
 Chemically induced male sterility(MG1 and MG2)
(B)Manual emasculation and or pollination
(C)Self incompatibility
(D)Mechanical control-This is depend on plant
structure.

21. Isolation –Separation of two or more plants,strains or populations to prevent
mating among them. Usually distance, planting time or physical barries.
Inbred lines(M) Foundation Seed(M) Certified
Seed(M)
Roguing-Removal of off type plants of the same species.

22. Merits of hybrid variety
Hybrid varieties exploit both GCA and SCA components of
heterosis.
The produce from particularly single cross veriety is more
uniform as compared to that from open pollinated.
They can be produced both in cross and self pollinated crops
species.
Hybrid are maintained in the form of their parental inbreds,which
are grown in isolation and subjected to selfing or sib-mating.
In many self pollinated crops hybrid varieties yield 25-30% more
than the pureline varieties.

23. Demerits of hybrid varieties
Farmers have to purchase new hybrid seed every year. since they cannot use the next
generation of a hybrid crop as a seed.
Hybrid seed production requires considerable technical skill.
The exploitation of full potential of hybrid varieties requires an adequate supply of
irrigation water and fertilizer, and control of weeds diseases and insects.
The large scale production of hybrid seed depends on easy emasculation of the
female parent,and on an adequate pollen dispersal from the male parent.
In most cross pollinated species, the requirement of isolation are rigid and,ordinarily
difficult to fulfil,except on large farms.
The amount of hybrid seed required to cover the entire area under any crop appears
to be impossible to produce with our present seed production set up.
If the parents of a hybrid variety differ appreciably for grain quality, the produce of
the variety will not be of uniform quality.

24. Achievements of hybrid varieties
The hybrid varieties have been commercially exploited in mosty of the cross
pollinated crops,especially in maize.
Hybrid varieties have been successful in some self pollinated crops as like Cotton
in india.
Tomato,chillies,rice in china and india and wheat in U.S.A.
In india hybrid varieties have been released for commercial cultivation in 12 field
crops.
The first hybrid varieties in maize were released in 1961,when four double cross
hybrid as like Ganga 1,101,Ranjit and Deccan were released for cultivation.
In pealmillet HB1 hybrid variety released in 1965 PAU,Ludhiana. and PHB
10,11,BJ 104,BK506 these are downy mildew resistant.
 The first hybrid variety of cotton was H4; it was developed by the Gujarat
Agriculture University and released for commercial cultivation in 1970.

25. Future prospects and current status
Improvement of crop genotypes to increase stress resistance and productivity in a
future climate(CIMMYT).
To reduce poverty, hunger.
To develope heat tolerant varieties.
In ICRISAT (hyderabad) Dr.Rajiv Kumar Varshney Sir.

26. References
 Singh B.D.2009,Plant Breeding, Kalyani Publications, Ludhiana.
 Prasad B.K. 2006,Plant Breeding, Kalyani Publications, Ludhiana.
 Singhal N.C.2003,Hybrid seed production in field crops, Kalyani
Publications, Ludhiana.
 Mukharjee B.K.1995,Heterosis Phenomenon, Kalyani Publications,
Ludhiana.
 Singh R.K. 2006,Plant Breeding, Kalyani Publications, Ludhiana.
 Singh Phundan.2005,Plant Breeding,Kalyani Publications, Ludhiana.
 By Google.

27. Any query ?
Thank you for listening