Location: Dairy Forage ResearchTitle: Environmental influences on the relationship between fall and spring vigor in hairy vetch (Vicia villosa Roth)
|PELZER, CHRIS - Cornell University - New York|
|SEEHAVER, SARAH - North Carolina State University|
|WAYMAN, SANDRA - Cornell University - New York|
|WIERING, NICHOLAS - University Of Minnesota|
|EHLKE, NANCY - University Of Minnesota|
|REBERG-HORTON, CHRIS - North Carolina State University|
|RYAN, MATTHEW - Cornell University - New York|
|POSKAITIS, MEGAN - University Of Maryland|
Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/12/2019
Publication Date: N/A
Interpretive Summary: Hairy vetch is an increasingly important cover crop in the United States to reduce erosion, improve soils, and supply nitrogen to subsequent cash crops. Little is known about the genetics of fall and spring vigor, the two prominent traits for cover crop performance. Researchers analyzed fall and spring vigor of diverse hairy vetch genotypes in six environments. Results show that the severity of winter conditions determines the focus and structure of breeding hairy vetch for cover crop use. In regions with low freezing degree days, breeding programs may save time by screening for only fall or spring vigor, as these traits are highly correlated. When nurseries experience more winterkill, however, identification of top-performing plants for both fall and spring vigor requires careful observation of each trait. Genotypic performance for spring vigor also varied across environment. Breeding programs should develop regionally-adapted lines based on winter severity. This analysis presents an extensive and rare analysis of genotype by environment interactions in hairy vetch. The results can help select better hairy vetch varieties to improve cover crop performance.
Technical Abstract: Hairy vetch (Vicia villosa Roth) is one of the most commonly grown legume cover crops in the United States. Critical breeding goals for the species include increasing early fall vigor and spring biomass production. To inform genetic improvement for these traits, we explored the relationship between fall and spring vigor. Moreover, we evaluated the variation in genotypic performance across multiple environments and assessed how weather variables impacted differential variety performance. The relationship between fall and spring vigor differed by winter weather conditions. In warmer locations, top performing genotypes in the fall were typically the top performers in the spring, allowing simultaneous selection for both traits of interest. Environments with more freezing degree-days, however, did not show linear relationships between fall and spring vigor. With exponential and quadratic relationships at cold sites, the most and least vigorous plants in the fall tended to underperform in the spring. Kolmogorov-Smirnov tests further indicated that the weakest individuals in the fall more frequently winterkilled. Results suggest that fall vigor is not a linear predictor of spring vigor in cold environments, and consequently, breeding programs should screen and select for both traits. Population by environment interaction (GE) heavily contributed to spring vigor performance. In our dataset, freezing and growing degree days explained the majority of the signal in the GE interaction. As a result, breeding programs would benefit from dividing selection sites between warmer and colder climates.