A Study On Impacts Of The Serotiny On The Fitness Of Pinus Yunnanensis Population

In most plants seeds fall down when ripe, but in some plants seeds are retained in the canopy after ripening, forming canopy seed banks. We measured the overground fresh weight, underground fresh weight, the biomass of overground and underground, plant height, root length and diameter, etc of seedlings from the seeds serotinous in different time of the population of Luliang and Wuding of Pinus yunnanensis at different growth time (100danys,300days), and analyzed the genetic diversity by a total of 90 individuals, and 8 microsatellite (SSR) markers to disguss the potential relationship between the serotinous time and seedling vigor, genetic diversity and reveal the influence of the fitness of the population with canopy seed bank. The results showed:(1)The germination rate of seeds of ripening of Pinus Yunnanensis is 51.67%, significantly higher than 1-year serotining (45%),2-year (36%) and 3- year (34%) in Luliang. In Wuding, the germination rate of seeds of ripening is 59%, significantly higher than 2-year (44%) serotining and 3-year (35%) serotining(P<0.05). With the serotinous time increacing, the germination rate of seeds gradually decreased.(2)At 100 days after germination, the overground and underground fresh weight, height, diameter, root length of seedling of ripening were more than the seedling of seed retenting in the canopy for 1 to 3 years. At 300 days after germination, the seedling of ripening was vigorous than 1-year serotining,2-year and 3-year. Serotinous time had a negative impact on seedling growth.(3)With the stored time increasing, the underground biomass and root length of seedlings of different serotinous time showed a downward trend, comparing with the seedlings of seeds of ripening. And the differences between the different serotinous time increased. It may decrease the capacity of drought resistance and competitiveness. The root was impacted more than another part by serotiny.(4)The average shannon index (0.767), the number of alleles (4) and expected heterozygosity (0.415) of cohort of ripening were higher than serotinous 1-year and 2-years. The genetic differentiation among cohorts of serotinous times of Pinus is smaller. The genetic variation is major in cohorts(100%),while among to 0%. The cohorts had high genetic similarity. The genetic diversity has any accumulation, while ripe seeds are retained in the canopy.