Creating high polyploidy pink-flowered strawberries with improved cold tolerance

The reciprocal crosses of octoploid pink-flowered strawberry cv. ‘Pink Princess’ (2 n = 8 x = 56) and synthetic white-flowered dodecaploid individual ‘YH15-10’ (2 n = 12 x = 84) were performed to create high polyploidy pink-flowered strawberries with improved cold tolerance. Among the 246 hybrids derived from the cross of Pink Princess (8 x ) × YH15-10 (12 x ), 30 randomly selected hybrids were examined in aspects of morphological characters, chromosome numbers and cold tolerance. Most of the morphological characters were widely separated in F 1 hybrids with high broad sense heritability, indicating that these variations were mainly caused by the genetic effect. In terms of flower color, the progeny was separated into deeper pink flowers than ‘Pink Princess’, white flowers as in ‘YH15-10’ and intermediate types ranged from extremely light pink to pink. Excellent fruit quality and strong musky flavor were found in some hybrids. Most hybrids were confirmed to be decaploids (2 n = 10 x = 70), and several octoploid (2 n = 8 x = 56), enneaploid (2 n = 9 x = 63), undecaploid (2 n = 11 x = 77), dodecaploid (2 n = 12 x = 84), and 13-ploid (2 n = 13 x = 91) individuals were also observed. The cold tolerance of about 76.4 % hybrids was significantly superior to that of ‘Pink Princess’ at P