Somatic hybrids produced by protoplast fusion between S. tuberosum and S. brevidens: phenotypic variation under field conditions.

Phenotypic and flowering characteristics of hybrid plants generated by protoplast fusion between a tetraploid S. tuberosum line and diploid S. brevidens were assessed under field conditions. Hybrids were compared to both clonal parental material and protoplast-derived plants of each parent. Almost all of the hybrids were hexaploid. A wide range of variation in morphological characters was observed for hybrids and protoclones. Flowering was markedly reduced in protoclones. The majority of hybrids flowered, had viable pollen and set tubers. Tuber and pollen characteristics of hybrids produced from individual fusion calli also varied. The potential usefulness of fusion hybrids in potato improvement is discussed.