Two crosses of soybeaٌ (Crawford x Clark) and ( Crawford xCalland), each with six populahons (Pj, P2, F1, F,, BC1, and BC,) were tested
for yield, some of yield components and some growth attributes.
Significant negative heterosis were detected for flowering date, maturity
date; filling period, plant height, first pod height and 100-seed weight in the
first cross. Significant positive heterotic êffects were detected for other
traits. Over dominance towards the higher parent was found for number of
pods per plant, number of seeds per plant and ڑeed weight per plant in both
crosses, number of branches and plant height ،n the second cross and first
pod height ،n the first cross.
Significant positive values of inbreeding depression were detected for plant
height, number of pods per plant, number of seeds per plant and seed weight
per plant ،n both crosses, number of branches per plant and first pod height
in the second cross, and 100-seed weight in the first cross. However,
significant negative value was found for first pod height in the first cross, In
• the remaining traits, the values of inbreeding depression were not
significant. Significant E1 and E, were detected for most traits. Additive gene
effects were significantly exhibited in all traits, except seedAveight per plant
and number of seeds per plant in the first and second crosses, respectively.
Dominance and additive x additive types of geae action were found to be
significant for all traits. Also, additive x dominance and dominance x
dominance types of gene effects were significant for most traits. Heritability
estimates In broad sense were high to moderate in magnitude with values
between 51.73% for filling period to 93.00% يor number of pods per planL
The predicted genetic advance was rather moderate for number of branches
per plant ،n both crosses and first pod height In the second cross, and low
for the remaining traits. .