Transmittance of Winterhardiness in Segregated Populations of Peas 1

Winterhardiness in Pisum sativum (L.) was evaluated in segregated populations derived from crossing the cultivars ‘Melrose’ (hardy) and ‘Romack’ (intermediate) to ‘Garfield’ (nonhardy). The reciprocal backcrosses and the F 2 generations were advanced by single seed descent to derive F 5 lines. The F 5 lines derived from these six populations and the parental lines were evaluated for winter survival and winter injury at Moscow, Idaho, during the winter of 1982—1983 on a Palouse silt loam (finesilty, mixed, mesic pachic Ultic Haploxeroll). The three populations derived from the cross between Melrose and Garfield were also evaluated for survival and freezing injury in the laboratory. Increasing the dosage of the more hardy parent increased the number of winter‐hardy lines recovered. In populations with 75% of their genetic background from the more hardy parent, approximately half the F 5 lines had greater than 70% survival in the field. Percent survival and injury score in the field were significantly correlated (r = 0.80 and r = 0.82; both at the 0.01 level) for both crosses. Screening in the laboratory at −7°C was more closely correlated with the field evaluation than results obtained at either −4° or −10°C. Recovery of lines with the same level of winterhardiness as either parent from populations with less than 50 lines suggests that as few as three or four genes or linkage groups could be responsible for winterhardiness in the pea lines evaluated. Winter survival in Pisum was found to be associated with the genes which produce pigmented hilum (P l ) on Chromosome VI and pigmented seed coat (A) on Chromosome I, suggesting that genes which condition winterhardiness are linked to these genes.