Inbreeding, coancestry, and founding clones of sweet cherries from North America

Inbreeding and coancestry coefficients were calculated for 66 sweet cherry (Prunus avium L.) selections released from four breeding programs in North America (HRIO, Vineland, Ont., IAREC, Prosser, Wash., NYSAES, Geneva, N.Y., and PARC, Summerland, B.C.). Highly used founding clones were 'Black Heart', 'Emperor Francis', 'Empress Eugenie', 'Napoleon' and 'Windsor'. Coefficients of coancestry between all selections and these clones averaged 0.038, 0.045, 0.060, 0.091, and 0.033, respectively. In these five founding clones, coefficients of coancestry in self-compatible selections were over twice as much as those in self-incompatible selections except 'Windsor'. In the analysis of coefficients of coancestry between self-incompatible and self-compatible sweet cherry, almost 20% of self-incompatible selections represent more than a half-sib relationship (0.125) to self-compatibles. Increasing and maintaining genetic diversity is needed in sweet cherry breeding program in North America for continued breeding progress.