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Wheat Information Service
Number 83: 19-27 (1996)
Genetics and interrelationships of grain yield and
its related traits in bread wheat under irrigated and rainfed
conditions
S.S. Dhanda1 and G.S.
Sethi2
1Department of Plant Breeding, CCS Haryana
Agricultural University, Hisar, India
2Department of Plant Breeding and Genetics, H.P.
Agricultural University, Palampur (H.P.) India
Summary
Genetic control of yield and its related traits in nine
generations (Pl, P2, Fl,
F2, F3, Bl, B2,
B1s and B2s) under irrigated and rainfed
conditions were investigated in a cross of two contrasting wheat
varieties, CPAN 1992 and Kharchia 65. The mean performance of all the
characters was considerably lower under rainfed (E2)
conditions than under irrigated (El) conditions. Although
both the additive and dominance components were involved in the
expression of all the traits under both the environments, yet the
dominance component, in general, suffered more than the additive
component under rainfed conditions. Additive component appeared to be
the main source of genetic variance under both environments.
Dominance gene effects were also significant and more pronounced in
some characters, but these were not stable in controlling the
inheritance except grain yield, tillers/plant and days to maturity
only under rainfed conditions. Epistasis was observed for all these
traits under both the environments. Duplicate types of epistasis, in
general, prevailed for all the characters under both the
environments. The estimates of heritability and genetic advance were
higher under irrigated than under rainfed conditions which may be due
to better expression of genotypes under normal conditions. The
estimates of heritability, genetic advance and correlation
coefficients revealed that tillers/plant and biological yield were
important for yield improvement under El and
E2, respectively, whereas the harvest index was important
under both kinds of situations.
Introduction
Water supply is restricted in many parts of the world and
productivity in these areas can only be increased by the development
of crops that are well adapted to dry conditions. Since yield
potential has a net effect on yield performance under drought stress,
the ideotype must be drought resistant and of a reasonably high yield
potential. Development of cultivars for drought resistance thus
requires identification of potential drought resistant traits and
their transfer to agronomically acceptable varieties. Blum et al.
(1982) have also argued that a knowledge of influence of drought
>resistant character on yield is not essential. Rather if a
particular morphological or physiological character can be identified
and shown to improve the drought resistance of the crop, and if the
character and yield are separately inherited, incorporation of that
character into a high yielding variety should improve the performance
of the crop under drought stress.
Thus genetic improvement of wheat requires exploitation of genetic
variation for drought resistance and its utilization in breeding
programmes. The present investigations involving nine generations
(Pl P2, F1, F2,
F3, B1, B2, B1s and
B2s) were undertaken to study the gene action,
correlations, heritability and genetic advance under irrigated and
rainfed conditions.
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