Quantifying winter survival of alfalfa (Medicago sativa L.)

Authors: POUDEL, KABITA - University Of Minnesota; SHEAFFER, CRAIG - University Of Minnesota; JUNGERS, JACOB - University Of Minnesota; Weihs, Brandon; LAMB, JOANNE F.S. - Retired ARS Employee; BAUDER, SARAH - South Dakota State University; PISCASSO, VALENTINE - University Of Wisconsin; Heuschele, Deborah - Jo; Xu, Zhanyou

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/24/2023
Publication Date: 10/1/2023
Citation: Poudel, K., Sheaffer, C., Jungers, J., Weihs, B.J., Lamb, J., Bauder, S., Piscasso, V., Heuschele, D.J., Xu, Z. 2023. Quantifying winter survival of alfalfa (Medicago sativa L.). Agronomy Journal. 116(1):170-179. https://doi.org/10.1002/agj2.21487.
DOI: https://doi.org/10.1002/agj2.21487

Interpretive Summary: Alfalfa is the most critical forage crop used in ruminant animal production in North America. But winter injury and winterkill of alfalfa in the northern regions of the United States decrease its economic and ecosystem benefits. Therefore, continued improvement in alfalfa cultivar winter survival (WS) is crucial for sustaining the productivity of the perennial crop. The currently used individual plant based WS estimation system does not reflect the way alfalfa is grown by farmers. A new method to assess the WS of alfalfa grown in sward plots was developed that more accurately reflects the WS of alfalfa when grown in production fields, has a higher correlation with biomass yield, and thus, can replace the individual plant based WS scoring system. Adopting the sward plot WS measurement method of alfalfa cultivars will enhance decision-making for breeders and alfalfa farmers.

Technical Abstract: Winter injury of alfalfa in the northern regions of the United States decreases its economic and ecosystem benefits. Therefore, continued improvement in alfalfa cultivar winter survival (WS) is crucial for sustaining the productivity of the perennial crop. The North American Alfalfa Improvement Conference (NAAIC) standard test for WS recommends measuring the winter survival of spaced plants grown in rows. Measurement of WS of alfalfa grown in sward plots used by plant breeders would increase data collection and better reflect potential for WS when grown in production fields. We conducted trials at seven location-year environments spanning from Wisconsin to South Dakota in the northern US. These trials involved six check cultivars from the NAAIC standard test. The objectives were (1) to determine if WS and biomass yield assessment from sward plots were similar to those from the standard spaced planted row ratings, and (2) determine if location-dependent environmental conditions affected the usefulness of alternative approaches to measuring WS. Estimation of WS using spaced plants and sward measurements were highly correlated, while correlations between the WS of the spaced planted rows and biomass yields were less. The number of locations required for spaced and sward plantings to determine cultivar differences was at least two, with four replications per location. Measuring WS from swards can increase data collection and relate better to the production of alfalfa on-farm. Increased availability of sward-plot WS descriptions of alfalfa cultivars will enhance decision making by producers.