The Possibility of Using Decaploid Interspecific Hybrids (Fragaria × ananassa × F. nilgerrensis) as a Parent for a New Strawberry

The leaf shape, leaf area, and fruit size of six crossings between a decaploid cultivar 'Kurume IH No. 1' and three new decaploid interspecific hybrids ('Kurume No. 58' × Fragaria nilgerrensis) were evaluated. 'Kurume IH No. 1' was a normal type with one crown. The three new decaploids were fasciculate types with many shoots. In all crossings between the different decaploid interspecific hybrids, normal and fasciculate types coexisted. The uniformity of leaf shape in normal-type seedlings was good, and these seedlings were vigorous. They exhibited heterosis for leaf area that exceeded that of their parents and the leading cultivar, 'Toyonoka'. The apical fruits of normal-type seedlings were very large but soft. The taste is superior because the fruit sugar content is the same as in cultivated strawberries and the F 1 seedlings have a peach-like sweet fragrance. Thus, fruit appearance could be improved by crossing the superior parent because fruit shape and color differed according to the combination used. From the results of these crossings between decaploid interspecific hybrids in this research, the raising of a seed-propagated strawberry is impossible because fasciculate plants coexist in the F 1 seedling generation. However, the decaploid interspecific hybrids have high potential as a parent for vegetatively propagated strawberries that make efficient use of heterosis.