[Adaptive significance and possible origin of B-chromosomes in Picea Glauca (moench.) voss = P.canadensis B.S.P].

The karyotype (2n = 24 + 1B) was detected in 8 trees of Picea glauca (Moench.) Voss. = P. canadensis B.S.P., and the karyotype (2n = 24) was detected in 2 trees of spruce from the same stand in the centre of Voronezh. The majority of seeds, collected from these trees, were empty. From 150 selected seeds, which were full, four plantlets were obtained. One of them died, another one had no mitotic figures, and the third and fourth plantlets had karyotypes (2n = 24 + 1B, and 2n = 24, respectively). A possible mechanism of formation of B-chromosomes and their adaptive role are discussed.