A few inbred grain-sorghum varieties, developed and grown in Korea, have low productivity. Several hybrid cultivars have been demonstrated to be more productive and resistant to unfavorable environmental conditions than pure line varieties. However, very limited studies have been conducted on hybrid sorghum in Korea. Information on combining ability of Korean landraces based on parental materials is of great importance for increasing the productivity of sorghum through hybrid breeding programs. This study was conducted to determine the combining abilities of Korean sorghum landraces and cultivars. Two cytoplasmic male-sterile lines (A.Arg-1 and A03017) were crossed with 13 male-fertile lines to generate 26 experimental grain-sorghum hybrids. The hybrids were evaluated at two locations (Daegu and Miryang) in Korea in 2018. They were planted in three replications and standard agronomic practices were followed at both sites. There were significant (p=0.001) variations among genotypes for yield and secondary traits. For each trait, general combining ability (GCA) and specific combining ability (SCA) effects were estimated using the line-tester method. A positive heterosis for grain yield was observed in several hybrids. The A03017×Sodamchal hybrids exhibited considerable heterosis of up to 54.1%. The lines 18AYT-S04 and Sodamchal displayed positive significant GCA effects for grain yield, and A03017×Sodamchal crosses showed the highest positive SCA effects. The crosses, A.Arg-1×18OYT-S17, A.Arg-1×Sodamchal and A.Arg-1×18OYT-S01 had high grain yields with waxy endosperms, and could be recommended for grain-sorghum breeding programs in Korea.

This study was carried out to select waxy corn inbreds with good general combining ability through a diallel analysis of 10 half diallel crosses among five inbreds developed from Korean maize landraces. Total of 21 agronomic and palatability traits were investigated over two locations in 2016. There was a significant hybrid by location interaction found in plant height, ear height, number of tillers/plant, per ear weight, ear tip filling, ear commercial value and sweetness when four additional check cultivars were included in the analyses. A significant general combining ability by location interaction was found in ear height, number of tillers/plant, per ear weight, ear length and sweetness while ear width, ear commercial value and sweetness were significant for specific combining ability by location interaction. Sweetness was found significant for both interactions. The first and fourth inbred lines had the most number of traits with good estimate of general combining ability. The first inbred is expected to improve days to tasseling, anthesis silking interval, ear width, ear circumference and sweetness while decreasing husk cover in a hybrid combination. The fourth inbred line would improve days to tasseling, days to silking, plant height, ear height, per ear weight and ear length but ears would be a bit tougher than the average. A total of 19 traits had higher variance of general combining ability than that of specific combining ability. Husk cover was 12.1 times higher. Plant height and number of tillers/plant had higher variance of specific combining ability.