Pollen‐tube growth rate and seed‐siring success among <i>Betula pendula</i> clones

Abstract

The aim of this study was to investigate whether genetically different pollen donors ( Betula pendula clones) differed in pollen‐tube growth rate across 11 maternal plants and in vitro , and whether the differences between the donors were consistent across the recipients. To compare the seed‐siring success of competing pollen donors, a two‐donor hand‐pollination experiment with six donors and six recipients was conducted. The experiments were performed at a plastic‐house seed orchard. The donors showed significant variation in pollen‐tube growth rate on all the 11 recipients. The rankings of the pollen donors were statistically consistent across different maternal plants. A significant positive correlation between pollen tube growth in vivo and in vitro was found. The seed‐siring success of two competing pollen donors was unequal in 20 of 29 cases and there was a significant positive correlation between seed‐siring success and pollen‐tube growth rate in vivo and in vitro . The results show that fertilizations are not random and pollen competition operates in a B. pendula seed orchard population.