Genetic variation in the natural pollen cloud of pinus sylvestris: a study based on progeny testing

Seeds from open pollination of individual female stroboli on different days in June 1990 in a coastal clone archive of Pinus sylvestris (L.) in northern Sweden (latitude 63°39’ N) were used for a short‐term progeny experiment to study differences over time in the genetic composition of the background pollen. Analysis of progeny growth and cold acclimatization in artificial whole‐plant freezing tests suggested no genetic differences in the fertilizing pollen between pollination days. A clinal variation with the latitude of pollen origin was observed for reference progenies from fertilization with pollen of known geographical origin. Comparisons between open‐pollinated progenies and reference progenies indicate that the pollen cloud originated from approximately 1° latitude (based on height growth) or 1.5° latitude (based on freezing injury) north of the pollination site.