Breeding Plums in Florida

Abstract

Two plum species account for a majority of the commercial plums in the world, Prunus domestica and P. salicina. The former is hexaploid (6X) and in general has a higher requirement for exposure to winter cold to terminate dormancy. Because of its more complex genetics and higher chilling requirement, it has not been used in breeding in the Southeastern United States. P. salicina (Japanese plum) is diploid (2X) and requires less winter chilling for satisfactory adaptation and growth. However, these plums have too high a winter cold need to set good crops at Gainesville, and they bear irregularly, even in northwest Florida (4).

Japanese plums were introduced into this country about 1870 (1). Burbank began importing seeds and varieties of the species extensively about 1885 (2); and he is given most of the credit for the variety improvement upon which the California plum industry was established. Immediate selection was made for annual production by escape from late spring frost (5). This type of selection would favor genes for a high chilling requirement. Because this characteristic is quantitatively inherited, there may be genes for low chilling types present in Japanese plums in a masked condition.