Advances in pollination techniques for large-scale seed production in Eucalyptus globulus

Abstract

The effectiveness of supplementary pollination techniques for large-scale production of elite Eucalyptus globulus seed was tested using pollen fixed for a rare allozyme. We assayed the paternity of 1954 seedlings derived from 1089 flowers on 14 trees with no emasculation or style isolation. We first compared the success of pollinating the transversely cut style surface to direct stigma pollination. For flowers pollinated up to six days after operculum shed, style cutting resulted in a 15-fold increase in the number of seed with the marker allozyme (intended pollination) compared to stigma pollination. There was no difference between either pollination treatments and open pollination in 7-14 day-old flowers. We subsequently pollinated 13 trees using the cut style technique that resulted in 86.9% of progeny having the marker allozyme. Microsatellite analysis showed that only 4.8% of the progeny were selfs. Thus, we show that it is possible to obtain seed with low level of contamination and little selfing, without the costly steps of flower emasculation, isolation and labelling, by simply cutting the style, just prior to pollination, and pollinating all suitable flowers on a tree on a weekly cycle. By using this approach, elite full-sib families can be generated for deployment into plantations to exploit both additive and non-additive effects.