Parents for spring frost tolerance in apricot

Apricot (Prunus armeniaca L.) is particularly sensitive to spring frosts, which can cause irreversible damage to the flower buds or to the just-set fruits. In order to evaluate if the differences in frost tolerance, observed under field conditions, could be confirmed, cold-stress tests under artificial sub-zero temperatures were conducted, eliminating the multiple variables of the field. The results showed a different degree of cold tolerance according to the genotype and the phenological stage. After the break of endo-dormancy and at the pre-flowering stage, when flower buds are generally more susceptible, some genotypes ('Haggith', 11/48/2, 7C/20/3, 2/29/11) were hardy, not only at -4 degrees C, but also at -8 degrees C. The frost-hardy genotypes, identified in natural conditions by satisfactory yields, showed an elevated tolerance to freeze damage after artificial cold treatments too