In order to develop a core set and new corn variety in Korea, we evaluated the morphological characteristics of 194 maize accessions by examining eight quantitative characteristics. On the evaluation of quantitative traits for 194 maize accessions, they showed the morphological variations in tassel length (35.1±5.0 cm), plant height (226.1±33.7 cm), ear height (86.3±22.6 cm), stem diameter (2.3±0.6 cm), leaf width (9.3±1.1 cm), ear length (14.5±2.4 cm), ear row number (14.1±1.9 row), and 100 kernel weight (24.9±4.4 g). The results of principal component analysis (PCA) indicated that the tassel length, plant height, and ear height greatly contributed to positive direction on the first principal component axis. One-hundred kernel weight contributed to negative direction on the second principal component axis. Thus these morphological characteristics, which contributed greatly in the first and second principal components, might be useful for discrimination among 194 maize accessions. In our study, seven accessions, such as IT026357, IT026441, IT027321, IT033271, IT033591, IT033597 and IT124273, particularly were measured high on yield-related traits. Consequently, the 194 maize accessions used in this study could be used as promising materials for maize breeding programs such as development of new hybrid in Korea.

Grain yield, agronomic traits, and correlation between genetic distance of 36 F₁ hybrids produced by half-diallel crosses using nine maize inbred lines were analyzed. In the analyses of F₁ hybrids and their mid-parent heterosis (MPH) for agronomic traits, grain yield showed highest MPH value of 156%. One-hundred kernel weight showed the lowest value of 7%. In addition, when genetic distance based on agronomic traits was estimated, parental inbred lines did not agree with their own pedigree. Therefore it had the limitation to estimate genetic distance using agronomic traits. In this study, 92 SSR markers were used to calculate genetic distance at DNA level. However we did not confirm their own pedigree of nine parental inbred lines. There was no correlation between grain yield and SSR markers. Therefore molecular marker selection was conducted in relation with grain yield by the step-by-step method using 92 SSR markers. The selected nine SSR markers showed a significant positive correlation (r²=0.703**) between grain yield and SSR markers. The correlations between the selected SSR markers and agronomic traits of ear length, ear width, plant height, and ear height were particularly showed positively correlated. The nine SSR markers selected in this study would help predicting heterosis and planning crosses for hybrids in maize breeding programs.