Effect of tree cover on Scots pine pollination and seeds.
1994
Lindgren D.
The upper half of some Scots pine grafts growing in a seed orchard were covered to prevent pollen from reaching the grafts from above. Seeds were harvested from covered and uncovered control grafts. Frequency of selfing and frequency of non-orchard (alien) fathers were estimated using the embryo-macrogametophyte assay with allozymes. A group of clones with high pollen production and discriminating genotypes was identified. The frequency of aliens was estimated based on the frequency of seeds which could not have had any of these clones as father. It is suggested that some errors are avoided by this estimation technique. The frequency of alien fathers was estimated to be 53-58 % and the selfing rate was 4 %. The covers increased the fraction of empty seeds and reduced the number of filled seeds per cone. There were no systematic effects of cover on selfing or fertilization by alien pollen. This is interpreted to suggest alien pollen enter the orchard under conditions of hard and turbulent winds, capable of carrying pollen under the covers.
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