POLLEN VIABILITY IN INTRODUCED SIBERIAN STONE PINE
Pollen viability in Siberian stone pine (Pinus sibirica Du Tour) under conditions of introduction in Bashkir Cis- Urals (Ufa city) is characterised in the paper. The most pollen viability is determined in the variants of agar media with 5 % and 10 % sacсharosa - 58,4 and 65,6 % correspondingly. Pollen of 37-76-year trees is superior of the same for more young (22-23-year) trees just reached the generative age. Viability value varies in different years from 50 to 66 % averaging about 57 %. In the period from 2014 to 2016, the certain decrease of pollen material quality, though not strong, took place. In 2016 it could be due to the unfavorable regime of heat and moisture - dry and hot weather, established since the beginning of the growing season. The portion of atypical pollen grains which has 2 pollen tube is 5,2 to 8,8 % without much difference between the age groups of trees. Pollen collected in 2014 which were keeping during the year retained germination, however its viability reduced by almost 6 times (up to 10,9 %). The comparison with available data shows that quality of pollen material in the region under investigation is lower than in natural populations of the species but it nears to the values determined in artificial stands in natural species range and in some other introduction regions in Russia. In general, the quality of the forming pollen in introduced Siberian stone pine under conditions of urbanised environment can be described as satisfactory.