Data from: Estimating agronomically relevant symbiotic N fixation in green manure breeding programs

Please cite as: Katherine Muller, Joseph Guinness, Matthew Hecking & Laurie Drinkwater. (2021) Data from: Estimating agronomically relevant symbiotic N fixation in green manure breeding programs. [Dataset] Cornell University eCommons Repository. https://doi.org/10.7298/vrd4-4k23

Widespread use of legume green manures is limited by a lack of reliable varieties that meet the needs of farmers. Improving symbiotic N fixation (SNF) in open-pollinated legume species poses a challenge because normal methods used for assessing SNF conflict with breeding practices such as seed production and removing low-quality sires. We investigated methods for measuring symbiotic N fixation that are compatible with breeding practice for two major legume cover crops: hairy vetch (Vicia villosa) and crimson clover (Trifolium incarnatum L.). We collected two non-destructive samples at the early-flowering stage (Meristem and Wedge) and a sample at seed harvest (Seed). Our objective was to determine which combination of measurements best predicted symbiotic N fixation (%Ndfa) and total N content at 50% flowering. Our statistical approach accommodated the problem that target traits and seed measurements cannot be measured in the same individuals. Overall, the Wedge sample provided the best prediction for Ndfa at 50% flowering. The best predictions for total N plant-1 came from combining vigor ratings with aboveground biomass at seed harvest. In addition to specific recommendations for legume cover crop breeding programs, we provide a flexible statistical method for studying relationships between traits that cannot be measured jointly.

This work was supported by USDA-NIFA grant #2015-51300-24192, with additional support from USDA-NIFA grant #2018-51106-28778. Guinness was supported by the National Science Foundation under grant No. 1916208 and the National Institutes of Health under grant No. R01ES027892.