Assessment under short-day conditions of genetic materials derived from three potato breeding strategies:: 4x-4x (intra-Tuberosum), 4x-2x (FDR 2n-pollen), and 4x-4x (diplandrous tetraploid)

Families and cultivars derived from three breeding strategies [the conventional 4 x-4 x (intra-Tuberosum), the interploid 4x (Tub)-2 x (Phureja-haploid Tub), and 4 x (Tub)-4x (diplandrous tetraploid-DTO)] were evaluated under short-day conditions in Brazil. Two 4 x-4 x (intra-Tub) cultivars (`Bintje' and `Delta') were used as standards. The 4 x-2 x (FDR) and 4 x-4x (DTO) strategies were equivalent for all traits but they presented superior performance when compared to the 4 x-4 x (intra Tub) scheme (as a group) for total tuber yield (TTY), commercial yield (CY), and plant vigor (PV). No differences among breeding schemes were observed for three other traits: eye depth (ED), plant uniformity (PU), and haulm maturity (HM). As a group, the 4 x-2 x (FDR) and 4 x-4x (DTO) strategies were similar to the two standard cultivar for all traits but HM. However, eight families [six 4 x-2 x (FDR) and two 4x-4 x (DTO)] had significantly superior performance for TTY when compared with the standard cultivars. For CY, the best 4x-4x (DTO) and the best 4 x-2 x (FDR) families outyielded `Bintje' by 161% and 128%, respectively. No major differences were observed between breeding schemes for TTY and CY when comparing families derived from one single cultivar (`Chiquita') as 4 x female parent. However, superior families, based upon multitrait selection criteria, could be obtained only with the 2n-pollen-based strategies. It was possible to select high yielding 4 x-2 x (FDR) and 4 x-4 x (DTO) families with favorable trait combinations (e.g., high yielding with ED scores similar to the standards). Individual DTO clones selected within these families may represent outstanding parental materials for crosses with tropical-adapted commercial cultivars. This initial comparison of progenies and cultivars derived from these breeding strategies suggests that 4x-2 x (FDR) and 4 x-4 x (DTO) schemes could be viable alternatives to the conventional 4 x-4 x crosses also in tropical/subtropical areas of the world.