Reduced fertilization capacity of SO2‐fumigated Picea omorika‐pollen

Dry pollen of Picea omorika was fumigated with 820 μg/m3 SO2 for 3, 4, or 5 days. Few or no adverse effects occurred during subsequent in vitro germination: germination percentage was not affected at all, and reduction of the pollen tube length was only 10% in pollen exposed for 5 days. Nevertheless pollination with fumigated pollen resulted in reduced seed production. 41% fewer seeds per cone were produced, and only 33% were filled seeds, compared to 70% filled seeds of the control. Seed‐weight was reduced from 3.6 g per thousand in the control to 3.0 g per thousand, when cones were pollinated with pollen fumigated for 5 days. Similar but less striking effects were found with pollen fumigated for 3 or 4 days.