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

Abstract

Dalbato A.L., Kobza F., Karlsson L.M., 2013. Eff ect of polyploidy and pollination methods on capsule and seed set of pansies (Viola × wittrockiana Gams). Hort. Sci. (Prague), 40: 22-30.Pansy, Viola × wittrockiana, is a popular ornamental plant. Eff ects 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 diff erences 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. Th us, Viola × wittrockiana is self-compatible but requires an agent-mediation for successful pollination. Th e 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. Th us, new varieties, fulfi lling aesthetic criteria as well as economic and agronomic traits, can be bred from induced mutagenesis. Pansies (Viola × wittrockiana Gams) are popular bedding plants. Whilst perennial by nature they are usually grown as an annual or biennial in garden beds, pots, borders, in hanging baskets or in landscapes (Horn 1996;Bailey 1998). Th ere is a seemingly unlimited need for new varieties. Th e planned pansy breeding through purposeful hybridization began in 1862 (Horn 1956). Breeding goals focused on selecting plants for unusual fl ower colours and increased fl ower size from the initial cross made between the small fl owered heartsease (V. tricolor L.) and yellow large fl owered V. lutea Huds. (Wittrock 1895). Hybridization between an alpine perennial, V. cornuta L., and V. altaica (Ker-Gwal) Pall. -a perennial with large and varied fl ower colours gave hundreds of pansy cultivars (Wittrock 1895;Horn 1956). Garden pansy (V. × wittrockiana Gams) is an octoploid (n = 6, 8x = 48) which is thought to be derived from cross combinations among V. tricolor (2n = 26), V. lutea (2n = 48), V. cornuta (2n = 22) and V. altaica (Clausen 1927;Horn 1956;Yockteng et al. 2003). Garden pansy is larger than its ancestors in plant height and fl ower size (Wittrock 1895).

Pomological Traits and Genome Size of Prunus armeniaca L. Considering to Geographical Origin

“…Over the years, different methods have been used to estimate genome sizes in plants (e.g., Feulgen densitometry, reassociation kinetics, chemical extraction). However, flow cytometry has become the method of choice because of the ease of sample preparation, low cost, possibility to quickly analyze high numbers of particles and high accuracy and resolution [22][23][24][25][26]. The method enables the analysis of the optical properties of individual particles in suspension while they move in a narrow liquid stream through a beam of light.…”

Evaluation of genetic diversity in pansy accessions (Viola spp.) using growth and flowering traits

“…The flowers are of various colours with attractive patterns, beautiful forms and variable colour combination. The flowers have a wide range of colours, including different shades of blue, purple, yellow, pink and beautiful marked stripes or penciled blotches.The blooms have sporophytic self-incompatibility and require human pollination to set seed (Dalbato et al, 2013). The flowers are mildly sweet scented, particularly early in the morning.…”

Garden pansy (Viola × wittrockiana Gams.) - a good candidate for the revitalisation of polluted areas

“…Increasing ploidy levels of garden pansy could be useful for the creation of new genotypes characterised by new desirable ornamental traits e.g. larger flowers, flower colours or tolerance to biotic or abiotic stresses (Dalbato et al 2005(Dalbato et al , 2013. Little is known about their physiological and developmental responses to environmental factors.…”