The Journal of Research ANGRAU

Research Notes
J.Res. ANGRAU 41(1) 88-92, 2013
CONSTRUCTION OF SELECTION INDICES FOR F 2
POPULATION
DERIVED FROM CROSSES BETWEEN
GRAIN SORGHUM × SWEET SORGHUM [Sorghum bicolor (L.) Moench]
VEMANNA IRADDI, T. DAYAKAR REDDY, A. V. UMAKANTH, CH. RANI,
D. VISHNU VARDHAN REDDY and M. H. V. BHAVE
Department of Genetics and Plant Breeding
Acharya N.G. Ranga Agricultural University, Hyderabad – 500 030
Date of Receipt : 06.11.2012 Date of Acceptance : 12.12.2012
The selection indices by discriminant
function analysis were constructed based on the data
of a population of 800 F 2
plants developed by
crossing three grain sorghum genotypes viz., 27 B,
ICSB 38 and 296 B as a female parent and four sweet
sorghum genotypes viz., SSV 84, SSV 74, URJA
and NSSV 13 as a male parent. Majority of selection
indices were found to be more efficient than straight
selection based on sugar yield alone. The selection
index consisting of six character combination viz.,
sugar yield, total biomass, fresh stalk yield, brix per
cent, juice yield and total soluble sugars was more
effective with higher relative efficiency. While,
selection based on five characters combinations viz.,
sugar yield, total biomass, fresh stalk yield, brix per
cent and juice yield as well as four character
combination viz., total biomass, fresh stalk yield, brix
per cent and juice yield were also equally effective
in selection of plants for maximum sugar yield.
However, selection index comprising six and five
character combinations are of little importance in
selection process as it includes derived parameters
such as sugar yield and total soluble sugars. In this
regard it is suggested to go for four character
combination which also manifested maximum relative
efficiency coupled with higher genetic advance.
The practical or economic value of a plant is
affected by several traits. Since, majority of the
economic traits are polygenically inherited and their
expression is subjected to varying degrees of
fluctuations due to environmental factors, eventually
direct selection may not be useful for such characters.
Efficiency of selection under such circumstances can
sometimes be improved by taking into consideration
simultaneously the phenotypic values of a number
of plant attributes which are correlated with the
genotypic values (high heritability) of the characters
under consideration.
The material for the present study comprised
of 800 F 2
population of sweet sorghum crosses
derived from parents having low and high sugar
content developed at Directorate of Sorghum
Research, Rajendranagar, Hyderabad. These
populations were developed by crossing the
contrasting parents (27 B with SSV 84, ICSB 38 with
SSV 74, 296 B with URJA and 27 B with NSSV 13)
through hand emasculation and pollination during
kharif 2010 and the F 1
plants of the two crosses were
grown during rabi 2010 - 11 and selfed to produce the
F 2
seeds, which were evaluated during summer 2012.
The technique of discriminant function
developed by Fisher (1936) was adopted to know the
true genotypic worth of yield and its components and
to have computational formulae for construction of
selection indices which when applied to select plants
can bring about effective improvement in yield
compared to straight selection for yield. Smith (1936)
has illustrated the use of discriminant function in plant
selection.
Formulation of selection indices through
discriminant function analysis Selection indices
were formulated in F 2
populations of sweet sorghum
considering sugar yield and its five component
characters which had high correlation with sugar yield.
Among six characters, sugar yield (X 1
) was
considered as dependent character, while other
characters viz., total biomass (X 2
), fresh stalk yield
(X 3
), brix per cent (X 4
), juice yield (X 5
) and total soluble
sugars (X 6
) were considered as independent
variables. In order to select plants with high sugar
yield, discriminant functions were computed with
email: vemanraddi@gmail.com
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