Seed Germination and Composition of Double and Triple Endosperm Mutants of Tropical Sweet Corn under Different Harvest and Storage Conditions

Abstract

The development of inbred sweet corn lines that combine multiple endosperm mutants is an important aspect of breeding for eating quality. This study aimed to investigate the impact of different endosperm mutants, harvest times, and storage durations on traits related to seed quality and kernel carbohydrates. Sweet corn genotypes with specific gene combinations were carefully selected using single-nucleotide polymorphism (SNP) marker-assisted selection. Sixteen corn genotypes underwent germination assays through two tests: the standard between-paper test (BP test) and sand test (S test). The genotypes in each group were further refined based on germination and then evaluated for kernel carbohydrate dynamics during milk stages and postharvest storage. Each corn genotype exhibited distinct kernel carbohydrate dynamics during postharvest at each storage period. Out of 16 genotypes, four genotypes (K99, K30, 101L, and C13) were tolerant to degradation with slow rates [<0.27 mg·g−1 fresh weight (FW) per hour] for sucrose and total sugar. Three corn genotypes K118 (bt2bt2sese), K116 (bt2bt2sh2sh2sese), and K127 (bt2bt2sh2sh2sese) exhibited the highest germination percentage and germination speed in both tests. The optimal harvest date to achieve maximum sucrose, total sugar, and phytoglycogen was 22 days after pollination in the dry season of tropical savanna. When corn kernels have an increased shelf life, the amount of sucrose decreases, but the accumulation of fructose, glucose, and phytoglycogen increases. Two genotypes, K108 (bt2bt2sese) and K30 (bt2bt2sh2sh2sese), were identified as interesting alternatives for testers in sweet corn breeding programs. Genotype K108 showed moderate seed quality, tenderness, and high creaminess, and genotype K30 had low seed quality and tenderness, but high sweetness. This information is important for enhancing the efficiency of producing synergistic and augmented sweet corn F1 hybrids.

Keywords

• hybrid seed production
• kernel sugar
• seed vigor
• sugary enhancer
• super sweet corn