INHERITANCE OF SEXUAL INCOMPATIBILITY IN APRICOT

The study was carried out with 3- to 6-year-old apricot progenies from the breeding programmes of ARS in Fresno, California, USA and of CEBA S in Murcia, Spain. Progenies from 19 different crosses were studied t o determine the inheritance of the genetic incompatibility trait. The 19 crosses included those where both parents were self-compatible or b oth self-incompatible, and also those where a self-compatible parent a nd another self-incompatible were crossed. Segregating progenies were studied either by bagging a sufficiently high number of flowers in bal loon stage and determining the percentage of fruit set several weeks l ater or by following pollen tube growth with fluorescence microscopy. Results indicated that a monofactorial system with a multiallelic seri es appears to control the trait. Alleles for self-compatibility would allow the pollen tubes to grow in any style and reach the ovules. Alle les for self-incompatibility would stop the pollen tube growth if the same allele is present in the pollen grain and in the pistil.