The study of combining ability early maturity maize inbred line by using diallel crosses.

Nine inbred lines of early maturity corn were used in a 9x9 diallel cross to determine the general and specific combining abilities (GCA and SCA) in 2004-2004 in Karaj, Esfahan and Mashhad, IRAN. The characters studied included grain yield, kernel rows per ear, kernel per row, plant height and ear height, All crosses were mode between the inbred lines in 2003, following Griffing's method 4, mined model B. In 2004 and 2004 (during two years) 36 hybrids were planted in complete block design in three replications in Karaj, Masshhad and Esfahan, Genotypic differences among the hybrids was significant for the traits under study. Therefore, the statistical calculations were followed to estimate the genetic parameters related to the diallel method. The GCA and SCA were significant for all the characters studied. The degree of dominance ranged from 0.24 for the kernel rows to 4.07 for the yield. The values for broad-sense heritability were high (0.98 to 0.99) indicating that environmental variation was relatively low compared to genetic variation. As expected, the narrow- since heritability for grain yield was very low (0.06) and this was due to relatively higher no additive variance compared to additive variance. Among the nine parental lines only two lines KE 75039 (P2) and OH 43/1-42 (P5) exhibited igh GCA for grain yield. Only one out of 36 combination (P4xP9) exhibited high and significant SCA for grain yield, and four out of 36 hybrids exhibited high SCA for grain yield, in general , P4 mude interesting combinations with P5, P6, P7 and P8.The simple correlation coefficients calculated used on hybrids data indicated that grain yield was positively associated with kernel. Per row, ear hight and plant hight. The kernel rows had positive but no significant correlation with grain yield. The five best single-cross combinations to produce early maturity corn hybrids were (P2xP9), (P4xP7) (P4xP8, P4xP6, P4xP5) in the present study, the parental lines P2,P5 and P4 could be used to develop synthetic varieties.