Seed size has a major impact on fall seedling vigor in the cover crop hairy vetch (Vicia villosa Roth)

Abstract

Seedling vigor is a critical trait for successful cover crop varieties. Selection for seed size can impact fall seedling vigor in the cover crop hairy vetch (Vicia villosa Roth). Fall vigor and seed size measurements from 1239 plants and fall vigor measurements from 13,923 progeny across 25 different growing environments were used to calculate narrow sense heritabilities and identify relationships between variance components of fall vigor and seed size. Standardized parent–progeny heritabilities were estimated across multiple years and environments and used to determine the impact of seed size on offspring fall vigor. A genome-wide association study for seed size (n = 853, m = 1,010,403, two environments) was conducted to explore genetic determinants associated with this trait. Seed size was influenced by parent genetics and parent growing environments and had a significant impact on the fall vigor of the offspring. The narrow sense heritability of seed size was greater than visual fall vigor scores (0.580 and 0.111, respectively) and was less influenced by genotype-by-environment variance. Finally, parental seed size had a strong and consistent genetic correlation to offspring fall vigor relative to direct parental measurements of fall vigor (standardized parent–progeny heritability 0.17 for parent seed size-progeny fall vigor compared to nearly zero for parent fall vigor_offspring fall vigor). The genome-wide association study did not find significant loci controlling seed size. The strong correlation between seed size and fall vigor highlights an important consideration for growers since larger seed size may increase fall vigor, thus impacting profitability for producers.