Environmental Influences on the Relationship between Fall and Spring Vigor in Hairy Vetch

Abstract

Hairy vetch (Vicia villosa Roth) is a commonly grown legume cover crop in the United States. Critical breeding goals for the species include increasing early fall vigor and spring biomass production. To ascertain 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 affected germplasm performance. The relationship between fall and spring vigor differed by winter weather conditions. In warmer locations, top‐performing genotypes in the fall were the top performers in the spring, allowing simultaneous selection for both traits of interest. Environments with colder winter conditions, however, did not show linear relationships between fall and spring vigor. At cold sites, the most and least vigorous plants in the fall tended to underperform in the spring. 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 in cold climates. Genotype × environment interaction (GE) heavily contributed to spring vigor performance. In our dataset, days below freezing without snow cover, days below freezing, minimum daily temperature, and freezing degree days were related to the signal in GE. As a result, breeding programs would benefit from dividing selection sites according to the severity of winter conditions.

Estimating agronomically relevant symbiotic nitrogen fixation in green manure breeding programs

“…Our results confirm that a visual vigor rating serves as a good proxy for aboveground biomass, which has previously been demonstrated in red clover (Riday, 2009) but not in hairy vetch or crimson clover. This finding strengthens results from a recent study on hairy vetch that used vigor ratings as a proxy for fall and spring biomass (Kissing Kucek et al., 2019). We used the average of —five to seven vigor ratings.…”

“…The lack of genetic improvement in legume green manures means that their characteristics are uncertain. For new breeding programs aimed at improving legume green manures (Kissing Kucek et al., 2019; Kissing Kucek, Riday, et al., 2020; Moore et al., 2020), farmers identified symbiotic N fixation (SNF) as the most important trait of interest (Wayman et al., 2017). So far, new breeding programs for legume green manures have focused on removing undesirable traits like seed dormancy (Kissing Kucek, Azevedo, et al., 2020) and improving cover crop establishment, overwinter survival, and spring biomass production (Kissing Kucek et al., 2019; Wiering et al., 2018).…”

“…For new breeding programs aimed at improving legume green manures (Kissing Kucek et al., 2019; Kissing Kucek, Riday, et al., 2020; Moore et al., 2020), farmers identified symbiotic N fixation (SNF) as the most important trait of interest (Wayman et al., 2017). So far, new breeding programs for legume green manures have focused on removing undesirable traits like seed dormancy (Kissing Kucek, Azevedo, et al., 2020) and improving cover crop establishment, overwinter survival, and spring biomass production (Kissing Kucek et al., 2019; Wiering et al., 2018). Breeding for SNF is more complicated because the goals and strategies may differ depending on the crop species, its agronomic functions, and the environments where it is grown.…”

“…We include the vigor rating because it is a nondestructive proxy for aboveground biomass, which generally corresponds to aboveground N content. The vigor rating is also used to evaluate breeding goals of fall establishment and spring biomass production (Kissing Kucek et al., 2019) and to select which plants will contribute to the next generation in an open‐pollinated crossing block. We include flowering time because it is necessary to time SNF measurements so they coincide with a particular developmental stage of the plant.…”

Pod Dehiscence in Hairy Vetch (Vicia villosa Roth)

“…The germplasm for our genetic analysis of PD originated from an existing hairy vetch breeding program. For further details on source germplasm, nursery design, field data collection, and management see Kissing Kucek et al (2019). In the late summer and early fall of 2017, seven nursery environments (Clayton, NC; Goldsboro, NC; Beltsville, MD; Ithaca, NY; Varna, NY; Prairie Du Sac, WI; and St. Paul, MN) planted half-sib seed from 92 maternal plants selected in the summer of 2017, in addition to 12 check lines (Table S1).…”