Review of agronomic and kernel quality traits of 273 almond cultivars

Abstract Almond stands out as one of the best-adapted temperate tree species globally. Its adaptability facilitated a widespread distribution from Central Asia to regions such as the Mediterranean, the United States, and Australia, enabling the adaptation of different genotypes to specific edaphoclimatic conditions. Throughout this spreading process, diverse almond landraces were selected in each growing area, resulting in a collection with varying agronomic and kernel quality properties well adapted to each origin. In addition to these native cultivars, various almond breeding programs, both public and private, released new cultivars to address key issues related to the production and kernel quality of traditional cultivars. This collective effort has resulted in a wide range of cultivars with diverse phenotypic characteristics, available for cultivation and breeding purposes. In this review, we summarize the main agronomic and kernel quality characteristics of globally available cultivated almond germplasm. This germplasm comprises genotypes from Asia, Africa, North America, South America, Australia, and Europe, either locally cultivated or released from breeding programs. For each cultivar, we provide information (if known) on the origin, parentage, year of introduction, self-(in)compatibility, S alleles, blooming time, chilling, and heat requirements, bearing habits, kernel and shell characteristics, harvesting time, tree characteristic, and disease susceptibility/resistance. In conclusion, the global diversity of cultivated almond germplasm presented in this review provides a valuable repository of phenotypic traits and genetic resources to continue advancements in almond cultivation and breeding worldwide.