Abstract
Inbreeding is a great concern for breeding of vegetatively propagated crops because of the repeated crossings among a limited number of breeding material. Coefficients of inbreeding (CI) in recently developed cultivars of sweet potato, potato and strawberry were calculated using a personal computer and a programming language, Prolog. The CI in sweet potato cultivars, Beniazuma, Shiroyutaka, Satsumahikari and Joy White was 0.017, 0.073, 0.140 and 0.009, respectively; that in potato cultivars, Toyoshiro, Nishiyutaka, Konafubuki and Beniakari was 0.043, 0.072, 0.028 and 0.018, respectively; and that in strawberry cultivars, Nyoho, Tochiotome and Akihime was 0.172, 0.262 and 0.223, respectively. These values of potato were smaller than those of sweet potato and strawberry. It had been reported that the plants with a CI less than 0.1 showed no inbreeding depression, but those with a CI more than 0.2 showed significant inbreeding depression in sweet potato. CI values in sweet potato obtained in this study were lower than the critical value for inbreeding depression, but that in strawberry was higher. The records of old ancestors might be inaccurate, but estimated CI values of recently bred cultivars may be reliable because the discrepancy of old ancestors had little effect on the CI values.
