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)

Abstract

Families and cultivars derived from three breeding strategies [the conventional 4x-4x (intra-Tuberosum), the interploid 4x (Tub)-2x (Phureja-haploid Tub), and 4x (Tub)-4x (diplandrous tetraploid-DTO)] were evaluated under short-day conditions in Brazil. Two 4x-4x (intra-Tub) cultivars (`Bintje' and `Delta') were used as standards. The 4x-2x (FDR) and 4x-4x (DTO) strategies were equivalent for all traits but they presented superior performance when compared to the 4x-4x (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 4x-2x (FDR) and 4x-4x (DTO) strategies were similar to the two standard cultivar for all traits but HM. However, eight families [six 4x-2x (FDR) and two 4x-4x (DTO)] had significantly superior performance for TTY when compared with the standard cultivars. For CY, the best 4x-4x (DTO) and the best 4x-2x (FDR) families outyielded `Bintje' by161% 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 4x female parent. However, superior families, based upon multi trait selection criteria, could be obtained only with the 2n-pollen-based strategies. It was possible to select high yielding 4x-2x (FDR) and 4x-4x (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-2x (FDR) and 4x-4x (DTO) schemes could be viable alternatives to the conventional 4x-4 × crosses also in tropical/subtropical areas of the world.