Cross-incompatibility of 'Ferragnes' and 'Ferralise' and pollination efficiency for self-compatibility transmission in almond

The decrease in the number of pollen tubes in the style was studied in several compatible and incompatible pollinations involving the almond ( Prunus amygdalus Batsch) cultivars 'Ferragnes' ( incompatibility genotype S1S3), 'Ferralise' (S1S3), 'Tuono' (S1Sf) and 'Marcona' (S11S12). After incompatible pollinations, the decrease of the number of pollen tubes was more pronounced and no pollen tubes reached the base of the style. No differences were observed among compatible pollinations, independently of the presence or not of a common S allele, thus confirming the full compatibility of half-compatible pollinations. The cross-incompatibility of 'Ferragnes' and 'Ferralise' suggested that their different behaviour in the transmission of self-compatibility from 'Tuono' to their offspring must be attributed to other genetic factors than the S alleles of pollen incompatibility.