Diallel analysis of grain yield, number of kernel rows per ear and number of kernels per row in early maturity maize hybrids

To determine the general (GA) and specific (SCA) combining abilities 36 hybrids developed in 9 × 9 diallel crossing design were grown and evaluated in three locations (Karaj، Isfahan and Mashhad) of Iran in 2004 and 2005. Grain yield، number of kernel rows per ear and number of kernels per row were measured and recorded. All crosses were made in 2003، based on Griffing''s method 4، mixed model B. diallel hybrids were evaluated in randomized complete block design with three replications in each environment. Genotypic differences، among the hybrids، were significant for all of the traits، therefore، the genetic parameters related to the diallel method were estimated. The GCA and SCA were significant for all of the traits. The degree of dominance ranged from 0. 24 for the number of kernel rows per ear to 4. 07 for the grain yield. The values for broad-sense heritability were high (0. 98 to 0. 99) indicating that environmental variance was relatively low compared to genetic variance. As expected، the narrow- sense heritability for grain yield was very low (0. 06). This was due to relatively higher non-additive variance compared to additive variance. Among the nine parental lines only two lines KE 75039 (P2) and OH 43/1-42 (P5) had high GCA for grain yield. Only one combination (P4×P9) showed high and significant SCA for grain yield، and four hybrids demonstrated relatively high SCA for grain yield. P4 produced suitable hybrid combinations with P5، P6، P7 and P8. The five best single-cross combinations to produce early maturity maize hybrids were (P2×P9)، (P4×P7)، (P4×P8)، P4×P6) and (P4×P5). Parental lines P2، P5 and P4 can be used to develop synthetic varieties in early maturity maize breeding programs.