POLLEN VIABILITY AND SEED SET OF SILVER FIR (ABIES-ALBA MILL) IN POLLUTED AREAS OF SLOVAKIA

Viability parameters of pollen grains collected from 16 trees of silve r fir (Abies alba MILL.) growing in 3 locations in Slovakia under vary ing degrees of air pollution were compared. In vitro pollen germinatio n tests were compared with controlled crossing experiments. The percen tage of germinating pollen grains and pollen tube length varied consid erably between individual trees. Both these characteristics were highe st in samples from a relatively unpolluted locality (Jedlove Kostolany ). Germination of pollen samples from a moderately polluted locality ( Repiste) was reduced by 20 %, and in samples from highly polluted habi tats (Mociar and Kamenec) germination was reduced by 76 % and 84 %, re spectively. In 3 samples of 9 trees from the highly polluted locations , the pollen completely failed to germinate in vitro. Pollen tube leng th was reduced by 21 %, 15 % and 33 % of the control mean pollen tubes length in samples from the unpolluted site. Except for 2 maternal tre es of silver fir which exhibited an inverse relationship, a positive c orrelation was observed between the in vitro viability parameters of p ollen grains and the amount of filled seeds in trees used in artificia l crossing experiments.