Mating system in a clonal Douglas fir (Pseudotsuga menziesii (Mirb) (Franco) seed orchard. II. Effective pollen dispersal

Abstract

Genetic variation of effective pollen received by individual ramets in a Douglas fir clonal seed orchard was not representative of the genetic variation of this clonal seed orchard. This deviation was not due to selfing rate. Effective pollen dispersal might be responsible for this deviation. It was then assessed around 3 individual ramets by comparing genotypes of effective pollen with those of pollinator and surrounding trees located in a circle or in an ellipse focused on the receptor tree. The best prediction of genetic diversity of effective pollen was obtained considering a maximum pollination distance of about 20-30 m and an elliptical pollen dispersal. Effective pollen dispersal took place preferentially along rows of trees and probably depended on the wind. As the flowering period was short and particularly synchronous in the year of seed collection, reproductive phenology probably did not favour some peculiar crosses. Matings between a few neighbour trees was probably the major cause of the homozygosity level in seed crop. © 1995 Elsevier/INRA.