Effect of polyploidy and pollination methods on capsule and seed set of pansies (Viola x wittrockiana Gams)

Pansy, Viola x wittrockiana, is a popular ornamental plant. Effects of polyploidy on phenotype and four pollination methods on capsule and seed set were studied using ten octoploid (2n = 8x) and two hexadecaploid (2n = 16x) genotypes, originating from induced mutagenesis. Principal component analysis, using 19 phenotypic, phenological and physiological characteristics, revealed that hexadecaploids showed larger differences to the corresponding standard cultivars than octoploids. Number of seed per capsule was similar among genotypes. Capsule set with open pollination was 32-64%, with self-pollination by hand 18-49% and with cross-pollination by hand 14-43%, while no plant successfully set capsules with seeds under isolators if not pollinated manually. Thus, Viola x wittrockiana is self-compatible but requires an agent-mediation for successful pollination. The induced phenotypes were found stable over four generations. Hexadecaploids had more attractive phenotypes but fewer seeds than octoploids. However, variation in seed set enabled selection of plants with high fertility, and average seed set increased over generations. Thus, new varieties, fulfilling aesthetic criteria as well as economic and agronomic traits, can be bred from induced mutagenesis.