Permalink : http://hdl.handle.net/2115/33064

KEYWORDS : Abies sibirica Ledeb.;Chromosomes;Microsporogenesis;Meiosis;Meiotic irregularities

Meiosis in Siberian fir is characterized by asynchrony (prophase I and tetrads in the same microsporangium simultaneously). Up to 4 nucleoli (in natural stands) and 5 (in an arboretum) are observed at prophase I. The shortest meiotic stages are telophase 1 and 2. Each of them is observed in 0.2% (in an arboretum) and 0.05% (in natural stands) of cells. In natural stands meiosis elapses quickly (within 2 days). In an arboretum it can continue for more than two weeks. Mainly meiosis is regular. Meiotic irregularities are, though, also encountered at different stages (fragments, bridges, etc.). In trees growing in an arboretum the total number of irregular cells can reach 17.9%. In natural populations only 11.7-13.3% of cells are irregular. The spectrum of meiotic irregularities in an arboretum is wider than in natural stands.