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Characteristics of commercial Torenia cultivars

Laojunta, T., Narumi-Kawasaki, T., Fukai, S.
Acta horticulturae 2017 no.1167 pp. 205-212
Scrophulariaceae, Torenia fournieri, color, corolla, cultivars, diploidy, genotype, greenhouses, hybrids, leaves, parents, scanning electron microscopy, shade, summer, tetraploidy, triploidy
Torenia is a popular summer bedding plant belonging to the family Scrophulariaceae. Recently, the number of commercially available cultivars, including both seed-propagated and vegetatively-propagated genotypes, has increased. Twenty-five Torenia cultivars were grown in a greenhouse under 50% shading. A wide range of petal colors was observed: deep to light blue, deep to light reddish purple, yellow and white. Cultivars could be divided into two groups: with or without yellow blotch on the abaxial (lower) petal. SEM observations revealed that the shape of the petal surface cells was different depending on cultivars. Torenia concolor had a lower conical, T. fournieri had a conical shape and T. baillonii had a sharp conical shape. Interspecific hybrids had the intermediate cell shape of the putative parents. Torenia fournieri showed erect growth type, and both T. concolor and T. baillonii were creeping types. Interspecific hybrids showed semi-erect to creeping types. Leaf size and shape also varied depending on the cultivars. The vegetatively-propagated cultivars are assumed to be interspecific hybrids derived from crossing among T. fournieri, T. concolor and T. baillonii. The vegetatively-propagated cultivars included diploids, triploids and tetraploids. Cultivars with higher ploidy level produced larger flowers.