Heterosis and Specific Combining Ability in Sweet Corn and Its Correlation with Genetic Similarity of Inbred Lines

The heterosis phenomena has been exploited in hybrid maize field production. Theoretically, heterosis was depending on genetic distance of inbred lines. Meanwhile, different from field corn breeding, sweet corn does not have well defined heterotic group. The objective of this study was to determine genetic similarity (GS) of eight selected inbred lines of sweet corn based on morphological traits and its correlation with specific combining ability (SCA) and heterosis. The eight inbred lines were characterized and crossed in full diallel design. Then, the lines, F1 and its reciprocal, were evaluated by using the Randomized Complete Block Design in three replications. The result showed positive heterosis and SCA effect in most of the hybrids which indicated the heterosis effect in the hybrids performance. Based on the morphological traits, the genetic similarity between the inbred lines was 62.2-82.4%. The inbred lines with 70% similarity coefficient were grouped into three. There was significant correlation between the genetic similarity and heterosis in all traits, except in the plant height. Meanwhile, only SCA of days to maturity and TSS showed significant correlation to genetic similarity. This indicated the usefullness of genetic similarity to identify the potential inbred lines for parental hybrid.