UTILIZING FROST RESISTANCE OF DIPLOID SOLANUM SPECIES

Introductions of 13 frost-resistant diploid (2n=2x=24)Solanum species (2 non-tuberous) were inter-crossed to produce F1 hybrids involving two frost resistance sources. Successful F1 combinations were: (i) inter-crossed to produce hybrids involving 3 to 4 frost resistance sources, (F1×F1); and (ii) crossed with haploids (2n=24) of frost-susceptible tetraploid (2n=4x=48)S. tuberosum subsp. tuberosum, (F1×tbr). Thirty-five of the 75 crosses between the 13 species produced viable seed. The F1 and F1×F1 progenies segregated to yield plants more resistant to freezing temperatures than the parental species. All attempts to cross these hybrids with 24-chromosome tbr were successful. Although tuber production improved following the first cross to tbr, the frequency of resistant plants decreased approximately 50%. Thus far, all first back-cross attempts, (F1×tbr)×tbr, have succeeded. Utilizing hybrids synthesized from several sources of frost resistance as the donor parents, and clonal selections of 24-chromosome tbr as the recurring parents, may provide a high order of resistance throughout the backcrossing program and implement selection of frost-resistant, long-day tuberizing parental stocks acceptable to the potato breeder. © 1969 Springer.