A, B and C scaling test as well as 6-parameters model were used in order to
assess the nature of gene effects for seven traits in three crosses of bread wheat viz.
plant height, number of days to heading. number of days to maturity, number of
spikes/plant, number of kernels lspike, 1000 kernel weight and grain yield lplant in
three bread wheat crosses (Tritlcum aestivum, L) Analysis of variance indicated
significant differences existed among generations for all studied traits Non-allelic
interactions were observed for all traits and crosses except in few cases in which the
values did not reach the significant levels . In the 6—parameters model, the additive
component (a) as well as dominance component (d) were significant In most cases.
Additive X additive tea) was significant for all cases except for plant height in cross
lll Additive X dominance (ad) component was significant for plant height in cross II
and days to maturity and spikasfplant in cross 1. The dominance X dominance (dd)
component was significant for all cases except
for days to maturity in cross ll, and spikeslpiant in cross l and cross ill
Significant values of heterosis based on mid- parent values were obtained Negative
inbreeding depression was detected for some traits in some crosses whereas no
inbreeding depression was observed for spikeslplant in cross I. High heritability values
1n broad sense were observed for all studied trails for all crosses. Narrow sense
heritability ranged from 42.05 for kernelslspike to 74.30 for plant height in cross lll.
Genetic advance values were higher for spikesipiant in all crosses whereas those
values were found to be very low for days to maturity in all crosses under study