PhD

The present study, "Genetic basis of seed yield and seed quality in sesame
(Sesamum indicum L.)" was carried out at the Department of Plant Breeding and
Genetics, College of Agriculture, Vellayani during 1 Y97-2000. The objective of
the study were:
. To assess the genetic basis of seed yield and seed quality attributes, to
study the interrelationship and direct influence of different characters on yield.
To assess the general combining ability of parents and specific combining
ability of the hybrids to identified good parental' combinations and to estimate
the extent of heterosis expressed in the hybrids for the different characters.
Fifty genotypes of sesame (Sesamum indicum L.) maintained at RARS
for Onattukara region were used for the study. The genotypes were planted in
an RBD with two replications. Analysis of variance showed significant
difference among genotypes with respect to all the characters studied viz.,
plant height, height upto fir~t capsule, number of branches, capsules on main
axis, number of capsules per plant, length of capsule, number of seeds per
capsule, seed yield per plant, weight of capsule per plant, 1000 seed weight,
number of days taken for first flowering, number of days taken for harvest,
seed oil percentage and seed protein percentage. The characters viz., number
of branches, number of capsules per plant, seed yield per plant and weight of
capsules per plant registered high coefficient of variation at phenotypic and
genotypic level revealing the scope for selection.

.t.


High heritability and high genetic advance were observed for plant
height only. High heritability and moderate genetic advance were observed
for number of capsules per plant and number of seeds per capsule and these
characters can be improved through selection. All other characters showed
high heritability and low genetic advance and these characters can be
improved by heterosi ~ .breeding or recombination breeding.
Seed yield had high positive genotypic correlation with plant height,
number of branches, capsules on main axis, number of capsules per plant,
number of seeds per capsule and weight of capsules per plant. So selection
for these characters will improve the yield. Plant height had high positive
genotypic correlation with capsules on main axis and weight of capsules per
plant. Number of branches had high positive genotypic correlation with
number of capsules per plant and weight of capsules per plant. Capsules on
main axis had high genotypic correlation with number of capsules per plant
and weight of capsules per plant. Length of capsule had high genotypic
correlation with number of seeds per capsule. Number of days taken for first
flowering and harvest recorded high genotypic correlation.
Path coefficient analysis showed that number of capsules per plant,
number of seeds per capsule had high direct effect on seed yield and 1000
seed weight had moderate direct effect on seed yield. Selection for these
characters will automatically improve yield.
Genetic divergence analysis was done based on Mahalanobis' 02 and
the genotypes were clustered using Tocher's method. Fifty genotypes were
clustered into nine clusters with maximum in cluster I with 19, cluster 11 with
three, cluster III with 10. cluster IV with three, cluster V with six, cluster VI
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with five, cluster VII with two and VIII and IX with 1 each genotypes.
Maximum average intracluster distance was observed for cluster I and
maximum intercluster distance between cluster VII and cluster VIII. Based on
D2 analysis, six divergent parents with high yield viz., IVTS-5, A VTS-8,
AVTS-16, Si-255-2, Si-266 and Si-722 from six divergent clusters viz., V, Ill,
IV, I, II and VII respectively were selected. They.w a'e crossed in half diallel
fashion. These parents, their direct F I S and one standard variety were raised in
RBD with 3 replications. In addition to the observations taken for the
evaluation of the parents, quality aspects viz., acid value, saponification
value, iodine value, peroxide value, total nitrogen, amino acid profile and
fatty acid profile were estimated. Analysis of variance showed significant
difference among genotypes for all the characters, except, number of days
taken for first flowering and harvest. The GCA and SCA variances for number
of branches, length of capsule, 1000 seed weight, acid value, peroxide value
and total nitrogen were non-significant. Hence, gene action could not be



worked out for these traits.


Seed yield per plant; seed protein and



saponification value had non-significant SCA showing significance of only
additive gene action. For plant height, height upto first capsule, capsule on
main axis, number of capsules pet plant, number of seeds per capsule, capsule
yield per plant, seed oil percentage and iodine value both gca and sea effects
were significant. Both additive and non-additive gene action were significant.
Plant height, height upto first capsule, capsule on main axis, number of
capsules per plant, number of seeds per capsule, seed oil percentage and
iodine value showed a preponderance of non-additive gene action. Seed yield
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per plant, weight of capsules per plant and saponification value showed
predominance of additive gene action.
Significant heterobeltiosis and standard heterosis were observed for
different characters in different hybrids.
The parents IVTS-5 and AVTS-16, the good general combiners can be
utrlised for further crop improvement programmes.
The two hybrids viz., IVTS-5 x A VTS-8 and IVTS-5 x A VTS-16 showed
significant superiority for the most important economic characters viz., seed yield
per plant, seed oil percentage, number of capsules per plant, number of seeds per
capsule, protein percentage and iodine value. So these hybrids can be considered for
further crop improvement programme.