New early 27 yellow three-way crosses of maize were evaluated at two planting
dates (early and late). Genotypic and phenotypic variation, correlation coefficients,
heritability in the broad sense and heterosis were estimated for six economic traits.
Mean squares due to planting dates were highly significant for a" attributes except for
number of rows/ear. The means were higher under the early planting date compared
with the late planting date for a" the traits. The genetic variance of genotypes was
significant for all traits at each of the two planting dates and across planting dates.
While, the interaction between genetic variance and planting dates was not significant
for a" the studied traits.
Phenotypic and genotypic variances were increased under early planting date
(non- stress environment) for silking date, ear length and ear diameter, while the
phenotypic and genotypic variances were increased under late planting date (stress
environment) for grain yield, number of rows/ear and number of kernels/row.
Heritability was higher under non stress environment for silking date, grain yield and
ear length, while it was higher under stress environment for ear diameter, number of
rows/ear and number of kernels/row. The highest_value of heritability was obtained for
silking date (91.43%).
Phenotypic and genotypic correlations were high between grain yield and each
of ear length, ear diameter, number of rows/ear and number of kernels/row showing
that these traits have a major contribution towards yield.
Genotypic correlation coefficient was higher than phenotypic correlation
coefficient, meaning that there was a strong association between any studied trait and
grain yield which is due to linkage of genes, hence the indirect selection for linked
traits with vield would be useful and effective for improving grain yield. The highest
three- way crosses for heterotic effects for grain yield relative to the commercial hybrid
TWC 352 Here SC Sk52 x Sk 6015/31, SC Sk11 x Sk U10 and SC Sk11 x Sk U14 by
27.64% 27.03% and 22.03% , respectively.