A half diallel set of crosses involving
the five parental lines was evaluated in
both 1983/84 and 1984/85 seasons.
Significant seasons mean squares were
detected for all traits except pods
shedding percent. Mean squares for
genotypes as well as their components
reached the significance level of
probability for all traits. Mean squares
associated with general and specific
combining abilities (GCA and SCA)
were significant for all traits. Also, high
GCA/SCA ratios exceeding unity were
obtained for all traits, indicating that the
largest part of the total genetic variability
associated with these traits was a result of
additive and additive by additive types of
gene action. These fixable types of gene
action proved to be the most prevalent
when rither component or graphical
analysis was applied. Both additive and
non-additive types of gene action were
affected by environmental changes with
the additive ones seemed to be less
affected. The parental line NA 112
seemed to be the best combiner for low
total shedding percent. The parental line
1.54 exhibited a significant positive GCA
effects for number of flowers, meanwhile,
it was average of the shedding.
Studies on the nature and degree of
dominance revealed the existence of
overdominance for shedding of pods and
partial dominance for the other traits.
The negative and positive alleles were
unequally distributed among parental
populations for most cases. High
heritability values were detected for most
traits. The correlation between parental
mean performances and their order of
dominance revealed that increaser genes
were dominant over decreasers for
shedding of flowers and total shedding in
both seasons; meanwhile, decreasers
behaved as dominant ones for largest
number of dominant genes responsible
for expression of total shedding % and |
