effect of photoperiod on tuberisation in cultivated x wild potato species hybrids

Wild Solanum species offer a valuable source of genetic diversity for potato improvement. Most of these species are found in equatorial South and Central America and they do not tuberise under long-day photoperiods typical of those in the major potato production areas of North America, Europe and Asia. Crosses between two haploids of Solanum tuberosum Chilotanum Group as females and two wild Solanum species clones generated four hybrid families. The parents and progeny were subjected to two greenhouse trials to evaluate tuberisation at 20-, 14-, and 8-h photoperiods. Parents and offspring tuberised most readily at the 8-h photoperiod, and poorly or not at all at the 20-h photoperiod. Segregation for tuberisation in hybrids was apparent at the 14-h photoperiod and depended on the cultivated parent, but not the wild species parent. The data support previous studies and best fit a model in which tuber production under long photoperiods is controlled by two dominant genes in cultivated × wild species hybrids.