Genetic study of yield traits in normal and quality protein maize genotypes (Zea mays L.) using line X tester analysis
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Date
2009
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Publisher
CCSHAU
Abstract
Seventy one maize genotypes were evaluated for the nature and magnitude of
variability, heritability and genetic advance for yield, yield components, and quality
parameters in Uchani, Karnal, Haryana during Kharif 2008-09. Analysis of variance
revealed significant differences among the genotypes for all the characters studied. The
highest genotypic and phenotypic coefficient of variation was observed for carotene
content followed by grain yield per plant, lysine content, tryptophan content, and number
of grains per row. Heritability was highest for carotene content followed by tryptophan
content, lysine content, oil content, sugar content, specific gravity, protein content, grain
yield per plant, plant height, and number of grains per row. Genetic advance as percent of
mean was highest for carotene content followed by grain yield per plant, lysine content,
tryptophan content, and number of grains per row. The high heritability and high genetic
advance estimates suggested that there is ample scope of improvement in the traits
studied.
Analysis of variance for combining ability revealed that mean squares due to
hybrids, and parents vs. hybrids were significant, which in turn exhibited significant
genotypic differences for all characters under study. The significant differences for
parents vs. hybrids indicated the presence of heterosis. This warranted further estimation
of GCA and SCA effects for characters being studied. Combining ability of yield and
yield traits indicated the importance of both additive and non-additive gene action, with
the magnitude of non-additive component being higher for most of the traits except for
tasseling, silking, cob placement, cob girth, rows/cob, tryptophan and lysine content. In
the present study good combiners were identified on the basis of high and significant gca
effects towards the desired direction. The inbred line L5 (1332) was the best combiner
for early male and female flowering, this line was also best seed parent for sugar and oil
content as it had significant gca effect in the desired direction. Best testers for male and
female flowering were T1 (295) and T2 (193-2), these testers were also best combiners
for maturity as they possessed negative and significant gca effects.
For an efficient utilization of cross combinations heterosis for large number of
traits is more desirable. Cross 13 x 4 was most promising having high standard heterosis
for six traits. Crosses 5 x 1, 6 x 2, 13 x 1, 11 x 3, and 9 x 3 were also good combinations
followed by 10 x 3, 4 x 1, and 3 x 1for five and four traits respectively. Knowledge of
interrelationships between grain yield and its contributing components can improve the
efficiency of breeding programs through the use of appropriate selection indices. Grain
yield exhibited positive and significant association with carotene content but showed
negative association with oil content. Further it exhibited positive non-significant
association with protein, tryptophan, lysine, and starch content, and also negative
non-significant relationship with specific gravity and sugar content. Correlation
coefficients at the genotypic level were greater than their corresponding phenotypic level
correlations; this indicated the presence of a strong inherent association between various
traits studied.
Crosses like 10 x 3,2 x 1,12 x 3,13 x 4 depicting high sca, per se performance
and heterosis (10 x 3, 2 x 1,4 x 1) for yield and its components as well as quality traits
should be tested in multi-location trials and if found stable should be considered for their
testing in all India coordinated project on maize.
Description
Keywords
Maize, Genotypes, Heritability, Combining ability, Heterosis, Correlation