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ESTIMATION OF SELECTION INDICES IN BRASSICA JUNCEA L. AND
BRASSICA NAPUS L.
A.S. LARIK AND L.S. RAJPUT
Abstract: Genetic selection indices were studied for six productive traits in
two varieties (S-9 and S-95) of Brassica juncea and four varieties
(Canola-l,II,III and Canola standard) of B. napus. Correlation
analysis indicated that seed yield/plant had strong positive association
with plant height, branches/plant, siliqua/ plant, seeds/siliqua and
dry matter yield/plant. Path analysis and selection indices also confirmed
that all the traits contributed significantly towards seed yield/plant.
The direct and indirect effects were found to be regulating the character
association in all the traits. Magnitude of genetic and phenotypic variance
ranged between 0.555 (seed yield/plant) to 960.63 (siliqua/plant), respectively.
Heritability (b.s) showed high estimates (ranging from 97.70% to 60.24%)
for all the traits, indicating the involvement of additive gene action.
Dry matter yield/plant, seeds/siliqua and plant height exhibited low
genetic advance irrespective of their high heritability estimates, probably
due to non-additive gene (dominance and epistasis) effects. On the basis
of selection indices, it is concluded that branches/plant and siliqua/plant
are the most important yield components, therefore, selection based
on these traits could be exploited for the improvement of yeild in present
genotypes.
Department of Plant Breeding & Genetics, Faculty of Crop Production,
Sindh Agriculture University,
Tandojam-70060, Pakistan.
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