The experiment was grown in a Randomized Complete Blocks
Design with three replications during two seasons. Generations
means analysis method was used to study the genetic parameters for number of days to heading, number of days to maturity, plant
height, number of spikes per plant, number of grains per spike and grain yield per plant of two bread wheat crosses Triticum aestivum L. (Gairwel7 x Douma4), (Azaz1 x Soued), Results have shown that
both additive and dominance genetic effects were high significant in most evaluated traits, with predominance of the dominance genetic effects’ values. Also, epistatic genetic effects have contributed to inheritance of most studied traits. The signs of dominance and dominance x dominance were opposite in most examined traits indicating duplicate epistasis for all studied traits of the first cross and for number of days to maturity, plant height and number of grains per spike of the second cross, that indicates that the selection for these traits should be delayed after several generations. High phenotypic variations were composed of high genotypic variations and less of environmental variations, indicating the presence of high genetic variability for different traits and less influence of environment. Highly significant heterosis relative to mid and better parents in F1 was recorded for most characters, accompanied with inbreeding depression for all traits in
F2. Narrow sense heritability and genetic advance were low in most cases due to the dominant of non-additive genetic action in controlling the genetic variation of the most studied traits.
During the three successive seasons of 2002, 2003, and 2004 six populations,
viz.,P1,P2,F1,F2,BC1, and BC2 of two single crosses of cotton (Aleppo40 x
Aleppo90) and (Aleppo33/1 x Line118) were established and evaluated to
explore heterosis, inbree
ding depression, heritability and genetic advance
under selection for reproductive branches number, number of bolls per plant,
boll weight, and ginning percentage. Significant positive heterotic effects were
found for all the studied traits in two crosses except ginning percentage (in the
second cross). Significant positive heterosis over mid-parent and higher parent
for yield components (number of bolls per plant and boll weight) may lead to a
positive heterosis for seed cotton yield/plant.
