Genetics of the polycross : 2. Male fertility variation in norway spruce, Picea abies (L.) Karst.

: Seeds from polycrosses with Norway spruce, in which the same sixteen male parents were crossed to a number of female parents in each of two years, were analysed electrophoretically to detect departures from male gamete frequencies expected assuming equal male fertilities, and to detect heterogeneity among female parents in male gamete frequencies in seeds. The data were also used to estimate the fertilities of the polycross trees used as male parents. Significant departures from male gamete frequencies expected assuming equal male fertilities were found in the seed pooled from all crosses. Male fertilities estimated from male gamete frequencies in seed from all crosses also departed significantly from expectation. The results are discussed with respect to assumptions made when estimating general combining abilities and expected response to selection in polycrosses.