General and Specific Combining Ability and Genetic Parameters (Zea mays L.) of Single Crosses in Corn

Six inbred lines of maize namely; A (1), B (2), C (3), D (4), E (5) and F (6) were used in half diallel cross. The seeds of inbred lines and its single cross hybrids were cultivated in an experiment using randomized completely block design (RCBD) with three replicates, at Twaitha Research Station, Plant Breeding Improvement Center, Iraq, during autumn season (2016). The parents and F1 were significantly differed at 5% for number of days to tasseling and silking, plant height (cm), ear diameter (cm) and yield per plant. Some hybrids showed a significant desirable heterosis for studied traits such as days to tasseling and silking. While plant height and yield per plant for all hybrids showed a significant desirable heterosis (deviation of F1 from mid parents). The mean squares of general and specific combining ability were highly significant for all traits. The additive and dominance variances were differed from zero for all studied traits. The broad sense heritability values were high for all studied traits. Narrow sense heritability was moderate for number of days to tasseling, plant height and ear diameter, but it was low for number of days to silking and yield per plant. The average degree of dominance was higher than one for all traits.