INTERSPECIFIC HYBRIDIZATION PROGRAM AIMED AT OBTAINING DWARFING AND NON-SUCKERING ROOTSTOCKS FOR SWEET CHERRY

An interspecific hybridization program between the tetraploid Prunus fruticosa Pall. (2n=4x=32) and the diploid Prunus mahaleb Mill. (2n=2x=16) was undertaken in 1988 with a view to obtaining dwarfing and non-suckering rootstocks for sweet cherry. The program, performed by artificial cross-pollinations, revealed great interspecific incompatibility barriers between the parental species and a crossability rate of 0.67%. Out of 3000 cross-pollinated flowers of P. fruticosa, only 20 fruits were obtained, which produced 7 seedlings. A study of leaf blade morphology showed the apparent hybrid origin of the 7 offspring. The counting of the chromosome number has been assumed as definite proof; the first 4 tested seedlings were triploid (2n=3x=24), so they are to be considered true interspecific hybrids