Evaluation of Winter Hardiness in Pea (Pisum sativum L.).

Production of dry pea has increased in North Dakota and other states in the Great Plains due to their high protein content and ability to symbiotically fix atmospheric nitrogen. Pea production in southern states is typically a fall-sown crop while northern states traditionally grow spring-sown peas. Fall sowing allows the pea crop to avoid high summer temperatures during the bloom period and increase seed production. Inclusion of fall-sown pea in crop rotations would benefit northern states like North Dakota, however; the upper Midwest states experience extreme cold winter temperatures that limit the use of winter peas. This research aims to aid the development of winter hardy peas by developing improved screening methods to identify increased levels of winter hardiness. An RCBD with six and four replicates was used to evaluate 62 germplasm lines and 160 RILs, respectively. Two week old seedlings were given a four week acclimation period at 4°C and subjected to the freezing cycle. The freeze chamber ramped down from 3°C to -8°C at a rate of 1°C/hr and increased at the same rate after a one hour freeze at -8°C. Individual plants were given an injury score every three days during the 21 day recovery period. Injury scores were used to calculate an Area Under the Injury Curve value for each replicate plant. Phenotypic data for winter hardiness will be used to conduct QTL analysis using a SNP based map of the Shawnee/Melrose recombinant inbred line population. Statistically significant differences in injury among lines were detected (P<0.01) among the 62 germplasm lines. Results of the QTL analysis will be presented. Development of improved protocols and molecular tools to detect winter hardiness in controlled environment will increase the productivity of breeding programs focused on winter peas.