The six populations i.e., P1, P2, F1, F2, BCI and BCII of the three
crosses (Sids 4 x Sids 1) (Sids 1x Giza 168) and (Giza 168x Gemmeiza
9) were used to estimate genetic variance, gene action, heterosis,
inbreeding depression, heritability and genetic advance for the days to
heading, days to maturity and plant height as well as yield and its
components traits. The experiment was conducted at Sids Agric. Res.
Stan. (Beni suef governorate) during the three successive growing
seasons 2003 / 2004, 2004 / 2005 and 2005 / 2006.Significant positive
heterosis effects relative to mid parent values were obtained for number
of spikelets / spike, number of kernels / spike, grain yield / spike and
grain yield / plant in the three crosses and for 1000-kernel weight in the
2nd and 3rd cross. Significant negative heterosis effects were found for
days to heading, days to maturity and plant height in the three crosses,
and for number of spikes / plant in the 2nd cross. Significant negative
inbreeding depression were detected for days to heading, days to
maturity and number of spikes / plant in the three crosses, for plant
height in the 2nd and 3rd crosses and for1000-kernel weight in the 1st and
3rd crosses. Significant positive inbreeding depression were obtained for
number of spikelets /spike, number of kernels / spike and grain yield /
spike in the three crosses, for 1000-kernel weight in the 2nd cross and
for grain yield / plant in the 2nd and 3rd cross. The additive type of gene
action was significant either positive or negative for all traits except days
to heading, days to maturity and1000-kernel weight in the 3rd cross, plant
height, number of spikelets/ spike and grain yield / spike in the 2nd and
3rd crosses and grain yield / plant in the 2nd cross. Dominance effects
were significant either positive or negative for all traits except plant
height, number of spikelets / spike and 1000-kernel weight in the 3rd
cross, number of spikes / plant in the 2nd cross and grain yield / spike in
the 1st cross. The additive x additive gene effects were significant for all
studied traits except plant height in the 1st and 3rd crosses, number of
spikes / plant in the 1st cross as well as number of spikelets / spike and
1000- kernel weight in the 3rd cross. The additive x dominance gene
effects exhibited significant for the majority traits except days to heading
in the 2nd cross, plant height and number of spikelets / spike and 1000-
kernel weight in the 3rd crosses and grain yield / spike in the 2nd and 3rd
crosses. The dominance x dominance gene effects were found to be
significant either positive or negative for all traits expect plant height in the 3rd cross. High to moderate heritability values in broad sense were
detected for most studied traits. Moderate heritability values in narrow
sense were detected for most studied traits except tw cases. These results
ascertained that both additive and non–additive genetic variance were
important in the existence of variability in these traits.