Freezing tolerance and tuber production in selfed and backcross progenies derived from somatic hybrids between Solanum tuberosum L. and S-commersoniiDun.

Selfed and backcross progenies developed from tetraploid somatic hybrids be tween Solanum tuberosum (tbr) and S. commersonii (cmm) were characterized f or nonacclimated freezing tolerance (NA) and acclimation capacity (ACC) (tw o independent genetic components of freezing tolerance) under controlled en vironments. The segregation covered 28% and 71% of the parental range for N A and ACC, respectively, with the distribution skewed toward the tbr parent . Therefore, ACC appeared to be relatively easier to recover in the segrega ting generation. Some first backcross progeny had greater freezing toleranc e than the cultivated parent primarily through the increase in ACC. When gr own in the field, the improved freezing tolerance observed in the selfed pr ogeny under controlled conditions was confirmed. Among NA, ACC, and freezin g tolerance after acclimation (AA, which is the cumulative performance of N A and ACC), AA exhibited the highest correlation coefficient with field fro st tolerance. In addition to freezing tolerance, vine maturity and tuber tr aits including tuber yield, tuber number per plant, mean tuber weight, and specific gravity were also segregating. No significant correlation between undesirable tuber traits and freezing tolerance was detected. Vine maturity and freezing tolerance were significantly correlated, so more careful sele ction for earliness was necessary in incorporating freezing tolerance. Yiel d comparable or superior to the backcross parent Wis AG 231 and an early Ca nadian cultivar, 'Sable', was found in many backcross progeny and some self ed progeny. The observed high yield can be attributed to the increase in me an tuber weight as well as tuber number. Moreover, a high portion of progen y had a specific gravity higher than 1.085, and some greater than 1.1. The implications derived from this study in breeding for freezing tolerance and further use of these materials are discussed.