GENETIC DIVERSITY IN CUCUMBER (CUCUMIS-SATIVUS L) .2. AN EVALUATION OF SELECTED CULTIVARS RELEASED BETWEEN 1846 AND 1978

Genetic variation among 155 U.S. modern and heirloom cultivars was ass essed from assays of 21 polymorphic isozyme loci. Four loci (Fdp-1, Md h-1, Mpi-1 and Pgd-1) were monomorphic. Multivariate analyses partitio ned cultivars into two distinct groups: those released before 1968, an d those released after 1968. Cluster analysis produced a dendrogram wi th 14 nodes and 28 groups. Modern U.S. and European cultivars released after 1968 differed in isozyme frequencies. Isozymic profiles clearly discriminated some cultivars with unique attributes and/or pedigrees [e.g., 'Windermoor Wonder' (USA), 'Gergana' (The Netherlands), 'Seiram ' (The Netherlands), 'Fancy Pak' (USA), 'Dasher 2' (USA), and WI 2757 (USA)].