FLOWERING AND FRUIT CHARACTERISTICS OF BLACK WALNUT CULTIVARS AT THE UNIVERSITY OF MISSOURI REPOSITORY

Abstract

Black walnuts (Juglans nigra L.) are valued for their uniquely fruity flavor and are often used as an ingredient in baked goods and ice cream, or are eaten as a snack food. Although black walnuts can be harvested from wild trees, several cultivars have been selected for such characteristics as ease of cracking, size of kernel, and thickness of husks and shells. Other characteristics, such as date of bud break, time of flowering, length of season and date of harvest, are also important adaptive traits as there is considerable variation within the species. The University of Missouri Horticulture and Agroforestry Research Center (HARC) maintains a repository of more than 65 named cultivars of black walnut valued for their kernels. The identities of each of these cultivars have been confirmed by fingerprinting, using a series of ten single sequence repeat microsatellite markers. A subset of cultivars maintained in the repository is used in an applied breeding program focusing on nut improvement. Average date of bud break, flower type, bloom period, pollination date, nut season length, and harvest date of cultivars were recorded from 2002 to 2006 at HARC. Such information offers a valuable resource to other breeders and producers in the identification of specific black walnut traits.