Abstract:

Aims The earlier second generation seed orchards of Pinus massoniana have been going to normal blossom stage in China. Our objective was to study the pollen dispersal and constitution of the male parents of open-pollination progenies to provide a theoretical basis for the design and genetic management of advanced generation seed orchards.
Methods We identified 320 open-pollination progenies from 8 clone individuals and 48 clones as candidate male parent using 11 polymorphic SSR loci. CERVUS was used to assign the paternity of each progeny based on maximum likelihood analysis.
Important findings We detected 61 alleles at 11 loci, and the number of alleles ranged from 2 to 11 (average of 5.55). The average observed and expected heterozygosity (H_o and H_e) were 0.428 and 0.433, respectively, and the average polymorphic information content (PIC) was 0.387. Among 320 progenies, 232 progenies (75.50%) could be assigned paternity at a confidence level of 80%. Progenies were produced by each mother tree with 19 male trees. The self-crossing rate reached 1.72% in open-pollination condition, and outcrossing was the primary mating mode. The reproduction contribution varied from 1.00 to 4.00% for most male parents, with an average of 2.17% (produced 5 progenies). Strong negative correlation existed between pollination distance and reproductive success of male parents with the same mating distance. In accord with a normal distribution, the main pollination distance ranged from 0 to 100 m; maximum dispersal distance was 192 m. The pollen contamination ratio was 4.06%. Compared with the north progenies of crown, there was an increasing trend of the mating distance of parents in the south progenies of crown, while there was no obvious trend in the male parent numbers of the south and north progenies of crown.

Key words: male reproductive success, paternity analysis, Pinus massoniana, pollen dispersal, second generation clonal seed orchard