The objectives of this study are: (a) to estimate the level of
genetic diversity,
genetic distance (GD), heterotic groups, and the SSRs marker package that are effective to differentiate among 34 inbreds and relatively stable in their heterotic groups, (b) to correlate between the GD and seed weight per plant of single cross through testcrossed method, (c) to correlate between the GD and seed weight per plant of single cross hybrid through diallel method, and (d) to determine the hybrids that potential to develop as new hybrid varieties. Genetic diversity study characterizing 34 inbred lines by using 36 SSRs loci are distributed throughout the maize genome. SSRs marker package develops the data through simulation (data iteration) and Principal Component Analysis (PCA). Testcross method uses two testers (Mr4 and Mr14), crossed with 32 genotyped inbreds to get F1 single cross plus three cultivars for each set i.e. Bima1, Bisi2, and Semar10. Evaluation of the phenotypic performance of the two sets of F1 single cross is conducted at the Bajeng Experimental Station. The layout of the trials is alpha lattice 7 x 6 with two replications. Diallel method uses seven selected inbreds (from low to high average GD value), developing a set of 21 single cross hybrids. Evaluation of the phenotypic performance consists of 21 hybrids and four check cultivars (Bima1, Bima2, Bima3, and Semar10) conducted at the Bajeng Experimental Station, South Sulawesi and Muneng Experimental Station, East Java. The experiment uses Randomized Complete Block Design (RCBD) with four replications. The results shows that the observed GD between 34 inbreds ranging from 0.22 to 0.86, indicates the broad ranges of genetic variability of the inbreds. Construction of the dendrogram can differentiate among the inbreds, and also cluster the inbreds in five groups based on the genetic similarities (GS), and generally be consistent with the pedigree data. The limitation of using pedigree data showed up in this study where there are four inbreds having the same initial pedigree (SP007) scattered in the three groups or have unclear pedigree data. A set of twenty five SSRs markers package provides a high value of cophenetic correlation was 0.79; however, the correlation value is good enough to differentiate the inbreds. Heterotic groups that developed based on the 36, 30, and 25 SSRs markers do not assertively cluster the inbreds into five groups. There is a medium to high correlation between the genetic distance value and the seed weight per plant of F1 single cross using Mr4 and Mr14 testers i.e 0.81 and 0.76 respectively. The average correlation values of hybrids between GD and average seed weight per plant, GD and specific combining ability (SCA), GD and high parent heterosis (HPH), as well as GD and MPH are in the medium level i.e. 0.67, 0.59, 0.55, and 0.64 respectively. There are six hybrids showing potential to be developed as new hybrid varieties with seed weight ranging from 176.05 to 181.24 g/plant. These hybrids are Bisma-140-2×SP007-68, BM(S1)C0-172×Mr4, SP007-68×SP008-120, P5/GM26-22×SP008-120, Bisma-140-2×Mr14, and BM(S1)C0-172×Mr14. The intergroup inbreds placed by genotyping, generally produced hybrids with greater yield potential than the intragroup inbreds. This experiment indicates that the development of hybrids based on SSRs marker can reduce the number of crossing, and one or two cultivating seasons. The evaluation of phenotypic performance is sufficient by using one of the two methods of the process of hybrid development i.e. testcross or diallel methods. However, there is a need to add more primers in order to get the stable dendrogram. In the field experiment, there is also a need to find more locations and to add new hybrids specialty with medium to high GD value to have more oppotunities to obtain the best heterosis.