Phenotypical and genetic breeding evaluation silver birch (Betula pendula ROTH) and downy birch (Betula pubescens EHRH.) ex situ and in vitro

Abstract

The results of a study of birch test cultures obtained by different methods of ex situ pollination and introduced into culture in vitro are presented. To identify the phenotypic, cultural and cytological characteristics of two birch species naturally growing in the Central Black Earth Region - silver birch (diploid) and downy birch (tetraploid), test cultures of seed origin F1 and F2 were specially created. The article presents data on phenotypic (growth in height in the juvenile and reproductive periods of ontogeny), genetic selection (seed propagation system) variability and some characteristics of the introduction of F1 seed progeny of breeding forms of local birch species into in vitro culture. To predict the growth characteristics of seed progeny of breeding forms of local birch species obtained by different methods of pollination - self-pollination and open pollination at different stages of ontogeny (at the age of 2 and 10 years), a statistical processing of the feature of growth in height of families was carried out using the rank Spearman's correlation coefficient ρ. Species specificity was shown in response to different pollination methods, morphogenic activity of self-fertile and self-sterile forms of these birch species on a nutrient medium ½ MC + 6-benzylaminopurine 1 mg/l, primary shoot formation of explants and regenerative capacity in these species, the nature of morphogenesis (formation of the main escape). For the polyploid species (downy birch), a higher level of self-fertility was established, as well as a more intensive growth of shoots in height than for drooping birch; primary explants in the former had a different character of morphogenesis (there was a joint initiation of the main shoot with adventitious ones) than in silver birch (formation of the main shoot), which indicates a greater adaptive potential for polyploid species and their greater opportunities for inclusion in genetic breeding experiments and obtaining valuable breeding forms.