Fruit set evaluation for self-compatibility selection in almond

Self-compatibility was assessed in 19 almond selections by genetic and physiological means, such as PCR with specific primers for the Sf allele, pollen tube growth, and fruit set after self-pollination and in bagged branches. Although all genotypes possessed the Sf allele and showed a similar pollen tube growth after self-pollination than after cross-pollination with cross-compatible pollen, fruit sets showed a different behaviour between years, ranging from 16.2 to 24.7%, as well as between treatments, with the highest after self-pollination. The differences between genotypes could be due to the genetic constitution of each genotype, where inbreeding may reduce set by the accumulation of deleterious genes in different members of a progeny. Flower morphology may also affect sets in bagged branches. Thus, in addition to bud density, flower sterility, pollination success and environmental conditions, other traits must be taken into account when evaluating yield in self-compatible almond cultivars, such as the inbreeding effect and the effective autonomous self-pollination.