Coastal Douglas-fir seed orchards, exposed to contaminate pollen from local stands, can result in a substantial reduction in the orchard seed lot?s genetic worth (GW) and lower adaptive potential of seed orchard progeny. Since 50% of the gamete contribution is from pollen, a seed lot rated at a genetic worth of 20%, with a contamination level of 50% (assuming a breeding value of 0) would result in a GW of 15% and a loss of 5% wood volume at rotation. This loss could even be higher if the planting stock is also poorly adapted or the breeding value of the contaminate pollen was lower. Since a seed lot?s GW is now incorporated into Timber Supply Analyses, errors associated with calculating GW will be carried through every stage of wood production. Because this project is linked to Timber Supply Analyses, the FIA-FSP program and priority theme that fits best with this project is Timber Growth and Value?Growth and Yield Modelling/Predictions. The current protocol for assessing pollen contamination uses pollen monitoring technique. Seed orchard contamination is estimated by comparing the extent and duration of pollen catch from pollen monitoring stations from within the orchard (ORC) to regional stations located at a distance from the orchard (CON). The level of contamination for the receptivity period of any specific seed orchard parent tree is then calculated as the ratio of regional values to orchard values. We believe these procedures can provide reasonable estimates of the magnitude of contamination but they are not being applied consistently across all orchards. Furthermore, the protocol for calculating the reduction in GW from pollen contamination requires a breeding values be assigned to pollen contamination. Initially we assigned a negative 15 value to contaminate pollen but this value may not be justified. Assigning a more realistic breeding value to pollen contamination is not part of this project?s objectives but it is linked to our overall objective of assessing the actual impact of pollen contamination on GW. In year one, we focused on the inconsistencies in how pollen is trapped and expressed as pollen cloud density (both for estimating orchard and contaminate pollen cloud densities). While the overall approach to estimating pollen contamination in the two selected orchards follows required protocol, there are several adjustments we can make in the monitoring, counting and reporting steps to improve the accuracy of estimating pollen contamination. Any modifications we make to our pollen monitoring procedures will be validated with our more robust molecular technique (paternity analyses). Our objective for year two will be to refine the monitoring and counting procedures used by the two orchards so that results are more accurate and consistent. Furthermore, we expect that next year?s pollen flight will be heavier than this year?s because of the long hot summer experienced in 2004. We will assess the heavier pollen load from contaminate pollen as we did for 2004 but with some refinements for counting and calculating percent contamination in selected seed orchard parent trees within each of the same two Douglas-fir seed orchards. Levels of contamination will be confirmed with paternity analyses (DNA analyses).
Webber, Joe E., Stoehr, Michael U.. 2007. Evaluating the protocol for quantifying pollen contamination on the genetic worth of conifer seed orchards. Forest Investment Account (FIA) - Forest Science Program. Forest Investment Account Report
Topic: FLNRORD Research Program
Keywords: Forest, Investment, Account, (FIA), Conifers, Propagation, Genetics, British, Columbia
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