The utilization of related Prunus species for almond variety improvement

Germplasm from a range of Prunus species in the subgenus Amygdalus, section s Euamygdalus, Spartoides, and Lyciodes has been evaluated fur potential va lue to almond (P. dulcis) breeding through an international, U.S.-Spain coo perative project. Species evaluated include Prunus; argentia, P. bucharica, Fl fenzliana, P. mira, P. persica, P. scoparia and P. webbii. The absence of severe crossing barriers in the initial hybridization and in subsequent backcrosses demonstrates a direct accessibility of this rich germplasm to a lmond breeding. The performance of interspecific hybrids, as well as their subsequent backcrosses to cultivated almond, further demonstrate valuable o pportunities for transferring useful traits including self-compatibility, r esistance to important pests and diseases, the improvement of seed nit qual ity tree growth architecture and bearing habit and tolerance to aberrant en vironments. The international collaboration has allowed a more thorough eva luation of related germplasm and avoids quarantine restrictions on the U.S. importation of new Prunus accessions.