ANBAR JOURNAL OF AGRICULTURAL SCIENCES

Abstract

Full – diallel cross was carried out among four inbred lines of corn (Zea mays L.) in Spring season (2006). In autumn season (2006) a comparison experiment was carried out at Al– Madain Field in randomized complete block design with four replicates. Study was conducted to identify and select superior maize inbred lines based on their performance parse, as to evaluate their single– cross hybrids performance based on results of analysis of combining ability and the first method with fixed model . Significant differences were found between genotypes in all studied characters and most of hybrids gave significant heterosis. Results of diallel analysis showed that heterosis in diallel hybrids which was greater than reciprocal hybrids for most characters except for plant height and ear height . Diallel hybrids (1×4) , (2×4) gave higher positive hybrid vigor for weight of grain and grain yield (13.5% , 17.6%) respectively .
Some parents showed preferred GCA effect in characters consecutively with preferred SCA effect for grain yield and many other characters .The ratio of variance of general combing ability (б2gca) to the specific combining ability (б2sca) and of the reciprocal (б2rca) was less than 1.0 in most studied characters , expect for plant height and ear length in reciprocal hybrids which was greater than 1.0 . The value of dominance degree was less than 1.0 for most studied characters in both diallel and reciprocal hybrids. As for broad and narrow sense heritability , it was low for all studied characters in both diallel and reciprocal hybrids . Genetic variance dominance values (б2D) was higher than genetic variance additive values (б2A) for most of other studied characters important grain yield was (154.8) in diallel hybrids, (66.3) in reciprocal hybrid this was indicating the importance of both additive and non additive gene actions in the control of these characters .