The purpose of this investigation was to study the inheritance of grain yield and yield components in maize using generation mean analysis (GMA). Two inbred lines (B73 and MO 17), with different yield and other characters were crossed to produce the Fl generation. The resulting Fls were selfed and backcrossed to both parents to produce F2 and back cross generations. The experiment was conducted in Karaj using a randomised complete block design with three replications. GMA with joint scaleing test which simountiasly analysis all generation was performed. The mean squares of genetations were statistically significant for all the traits except for the kernel index and kernel thickness. The percentage of heterosis estimated for grain yield (GY), ear weight (EW), number of kernels per row (NKR), ear Icnght (EL), 300-kernel weight (KWT) were 111 %, 101 %, 55%, 22%, 17% and 6% , respectively. The
expected genetic advance as the percentage of mean was high for EW, GY, cob diameter (CD) and kernels row per ear (KR). Heritability in narrow sense
was estimated from intermediate to low for all the traits except for the EL, KR and ED. Different estimates of heritability in broad sense were observed for NKR, ear weight (EARW) . KR. ear circumference (EC), GY. Gene effects including mean effect (m), additive (d), dominance (h), additive. additive (I)" additive dominance (j) and dominance dominance (L) were obtained. However not all the interactions were significant in all traits. The dominance gene effects were most contributors to the inheritance of all the characteristics specially for GY and EW. Additive gene effect was significant but lower than dominant gene effects.. For all the traits studied inheritance of dominance .dominance (L) and addetive . addetive (I) were more important than that of addetive . dominance (J) effects.
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