o:7414 VIŠEGODIŠNJA OPAŽANJA GRADE CVASTI GINANDRIČNOG STABLA MALJAVE BREZE SEVERAL-YEAR OBSERVATIONS OF THE CLUSTERS OF A GINANDRIC TREE OF TUBESCENT BIRCH sr In the article was described the occurrence of four types of two-pole clusters on one from eleven analized trees of pubescent birch (Betula pubescens E h r h.). The occurrence of two-pole clusters an only one from eleven trees might be explained by different sensibility of the genetical and physiological mechanism which had determined the pole of the abnormal tree in competition with envinronmental conditions. While one ginandric tree, grown under the equal ecologic conditions, reacted by forming male, female and four types of two-pole clusters, the other trees had formed only male and female clusters. There is no doubt that a study of the abnormal clusters in pubescent birch is of interest not only for the explanation of the evolution of the reproductive organs of anemogaus species, or for amelioration of the techniques of controlled hybridization, but also from the aspect of a closer explanation of the inheritance of the pole in birch species. It will benecessary to establish, by experimental way, i. e. on the vegetative copies of this tree, the conditions for a more abundant development of the two-pole clusters. The experiments cf D e l i n g s h a u s e n and S t e r n (1958) with the vegetative copies in the green-house and in the field have confirmed the need of such experiments for more detailed studies of the mechanism of pole inheritance in birches. During the emasculation in controlled hybridization of birches it is necessary to remoce two-pole clusters as well, since in the male zone the viable pollen-grains are usually formed, which might provoke the auto-fecundation of one part of female flowers, having influence in that way on the quality of hybridization works. 2025-04-07T10:24:08.887Z 44 yes 46 Aleksandar Tucović 46 Milutin Jovanović application/pdf 3081356 https://unilib.phaidrabg.rs/o:7414 no yes 1 70 92000001 1976 71A07 Zbornik radova Instituta za šumarstvo 13-14 5 13 Institut za šumarstvo 1976