To investigate the agronomy, yield and quality traits of 120 sweet and waxy maize inbred lines, and analyze the correlation between different traits and evaluate the breeding potential by using candidate inbred lines.

Investigating the general agronomic traits (flowering time, plant height, ear height), yield traits (fresh bud ear weight, fresh ear weight, fresh kernel weight, etc.) and quality traits (residue rate, brix, crude protein, crude starch, crude fat, etc.). The top 50% inbred lines with high yield and brix, and low residue rate were selected to determine the General Combining Ability (GCA) via diallel crossing. The same method was used to investigate the traits of the hybrid combinations, and the artificial score of taste was applied to six traits of smell, cheerful color, waxy/sweetness, flavor, tenderness and fineness, and the comprehensive score was obtained. The utilization value of the hybrid combinations was evaluated by comparing with the control varieties.

The coefficients of variation of residue rate, yield, and sugar content of the tested inbred lines reached 20%, 30%, and 10%, respectively, implying there is a large genetic variation. The generalized heritability of most traits such as residue rate, yield and sugar content are above 50%, indicating that these traits have high genetic stability. In the sweet corn population, flowering time is negatively correlated with sugar content, and positively correlated with yield and residue rate. Yield is positively correlated with residue rate, but has no significant correlation with sugar content. These results suggested that it is not easy to have both good taste and high yield in sweet corn breeding, and that moderate early flowering materials will be better in field. In the waxy corn population, residue rate is negatively correlated with flowering time and yield traits, while the sugar content has no significant correlation with flowering time and yield traits. These results suggested that good taste and high yield can be achieved simultaneously in waxy maize breeding, and that moderate late flowering will be better in field. In the candidate sweet corn inbred lines, there are 3 lines have been identified to have positive GCA value for yield traits, brix, and negative GCA value for the residue rate, respectively. In the candidate waxy corn inbred lines, there are 3, 3, and 4 lines have been identified to have positive GCA value for yield traits, brix, and negative GCA value for the residue rate, respectively. Six sweet corn hybrid combinations and six waxy corn hybrid combinations with great comprehensive breeding potential have been isolated. Four black sweet corn hybrid combinations with application potential, and one inbred line SICAU76 with great application value in black grain have been isolated.

The sweet and waxy corn inbred lines collected in this study have a large degree of genetic variation. The agronomic, yield, and quality traits of sweet and waxy corn have some intrinsic correlation. According to the correlation between flowering time and quality traits, moderate early flowering materials for sweet corn production, and moderate late flowering materials for waxy corn production will be better in field.