Alexandra Skallas

Pisum sativum L. spp. arvense and related subspecies, which are known as ‘Austrian winter peas’, are annual plants categorized by their ability to overwinter. They are a common choice of winter cover crop, providing ecosystem services that enhance soil quality and prevent erosion. However, the genetic basis of their frost tolerance is not fully understood. Large-scale frost tolerance tests have taken place, and more are currently ongoing with the potential to determine quantitative trait loci (QTLs) associated with frost tolerance. Most of these studies have been performed in field conditions. Field tests are the benchmark for winter hardiness, but must contend with environmental variables, and numerous factors such as snow cover and soil water capacity that influence survival. Furthermore, they can be performed only once per year. This research posits that by comparing a controlled freeze chamber environment to 2022-2023 field data, it may be possible to assess the degree to which temperature affects winter survival, identify a lethal temperature for selected lines, and determine whether freeze chamber results correlate to and predict field results. 64 accessions from the USDA Winter Pea Germplasm Collection, representing a significant amount of genetic diversity found in winter peas, and 3 lines with known frost tolerance (low, moderate, high), were grown in -12ºC freeze chambers and evaluated on a scale of 1-5 for frost damage. Damage scores were converted to percent survival and compared to field percent survival for 2022 and 2023 winters. A bimodal distribution was found, suggesting that freeze chamber survival is indicative of field survival, but the inverse is not necessarily true. This may indicate multiple mechanisms determining winter survival that are separate from freezing tolerance. Furthermore, this provides identification of lines that can be used to increase efficiency of breeding programs for the upper Midwestern landscape.