ANBAR JOURNAL OF AGRICULTURAL SCIENCES

Abstract

A field experiment was carrtied out in the city center of Euphates . Six inbred lines of corn were used in this studu by using half diallel crossing inspring season of 2012 to produce fifteen crosses . The parents and crosses were grown in autum season of 2012 using a randomized complete block design with three replication to determine general and specific combining ability effects ، heterosis and some genetic parameters. The results showed that significant differences among all genotypes .The line (zm7R) was the earlier in siliking date by 50.67 day , while inbred line (HS)was superior for number of grains and grains yield per plant (36.13 grain and 187.51 g.plant-1 ) respectively and gave the highest positive general combining ability effects (0.69 and 9.13) respectively. The cross S5xzm7R was the earlier in siliking date (51.67) day. The hybrid HSxs5 was superior for number of rows per ear 40.24 , The hybrid Hsxzm7R was superior for 300-grain weight (90.87 g.).The hybrid s6xzm19R was superior in grain yield per plant 261.82 and gave highest positive specific combining ability effects (54.42) and gave highest hybrid vigor (43.53) . the hybrid Hsxzm7R was highest for 300-grain weight 13.23 g. The ratio between ∂2gca ̸ ∂2Sca appeared less than one for all characters except relative growth ratewhich are controlled by dominance gene effects . The estimation of the broad sense heritability was highest for all characters . The estimation of the narrow sense heritability was low different . The estimation of the average of dominance degree (ā) was more than one for all studied traits .which is an indication of the effect of over dominance gene action .The results indicated that some inbred lines could be used in a breeding programs to develop an elite hybrids for high yield per plant and SCA ; and the most studied traits were under over dominance gene action .This showed that developing elite hybrids were the best method for improving grain yield.