Abstract:

A total 61 clone parents and 320 open-pollination progenies from 8 clone individuals were identified by 12 polymorphic SSR loci. The result showed that the level of genetic diversity in progeny population was the same as in maternal population, progeny population had all alleles detected in maternal population, and there were not obvious surplus phenomenon of homozygotes in progeny population(F=0.046). The south crown had more strobili than the north crown, however the genetic diversity of the north crown strobili was not substantially reduced. The progeny of neutral trees had the same level of genetic diversity as in the progeny of partial female trees, with the fixation index tended to be zero, which was accorded with Hardy-Weinberg equilibrium. The multilocus outcrossing rate in the seed orchard was 1.097, and there was no significant inbreeding between parents (t_m-t_s=-0.031). The multilocus outcrossing rate and singlelocus outcrossing rate in the south crown were higher than that in the north crown. The multilocus outcrossing rate of partial female trees was the same as in neutral trees, and the neutral tree had no obvious declining outcrossing rate with reduced proportion of female and male strobilus compared with partial female tree, with the fixation index tended to be zero. The progeny of the second generation clonal seed orchard still had rich genetic diversity, gene exchange among clones was relatively sufficient, and biparental inbreeding was not significant.

Key words: Pinus massoniana, the second generation seed orchard, SSR, genetic diversity, outcrossing rate, inbreeding index