COMPARISON OF 2 TECHNIQUES FOR INTROGRESSION OF UNADAPTED ANDIGENA GERM PLASM INTO TEMPERATE GERM PLASM

The South American tetraploid potatoes Solanum tuberosum ssp andigena have been used to increase the genetic variability of the temperate potato S. tuberosum ssp tuberosum. One technique that has been practiced for Andigena-based germ plasm enhancement has been to select within Andigena for adaptation to temperate conditions then to hybridize these selections with Tuberosum. This technique which is called pre-selection in this paper reduces the number of original accessions during selection resulting in loss of diversity of the enhanced germ plasm. This technique was compared to an alternative one called early hybridization, which consisted of hybridizing the Andigena introductions with Tuberosum, then practicing the same type of selection for adaptation on the hybrid population. Both techniques improved the yielding ability of the base population in subsequent selections. Even though the early hybridization technique maintained the higher mean yield in every cycle of selection, the rate of improvement was greater in the pre-selection technique. The early hybridization technique did not appear to favor the recovery of the Tuberosum genome in subsequent selections, and preserved a higher proportion of the original accessions. The most advanced population, the hybrid formed at the end of the pre-selection technique, produced greater yield and larger tuber size than the most advanced hybrid population formed in the early hybridization technique.