Potential Breeding Applications of 39 Early-maturing Sweet Corn Lines

Objective Agronomy and quality of early generation progenies of 39 early-maturing sweet corn lines were evaluated for breeding high-yield, high-quality fresh-eating varieties.

Methods From 192 sweet corn cultivars, 39 were selected based upon visual judgement at the ear-bearing stage for an incomplete diallel crossing with 3 test lines. A total of 117 hybrid combinations were developed with their early generation progenies evaluated on quality and combining ability through phenotypic identification, statistical analysis, and principal component analysis (PCA) to determine potential applications for breeding.

Results The 39 germplasms were clustered into clearly distinguishable categories. The key traits, including plant height, ear position on stalk, growth period, and kernel sugar content, of the early generation progenies followed the normal distribution pattern. Desirable qualities tended to exist in same selected hybrids. Separately, the three PCA principal components of the agronomic traits reflected yield, quality, and physical structure of the hybrids, indicating a trade-off in choosing corn yield and sugar content for breeding. On combining ability, the high GCA/SCA ratios of the progenies suggested additive genetic effects to be predominant in the hybridization process. Hence, hybrids A233 and A74 could potentially be applied as the candidates targeting for high yield, while A859 and A837 for high quality, in breeding.

Conclusion By comprehensively analyzing the distribution, principal components, and combining ability on agronomic traits of the early generation progenies of 39 early-maturing sweet corn lines, a trade-off between yield and quality seemed existed for the breeding program. A233 and A859 appeared to be the choice candidates for breeding desirable new varieties.