Germination and early seedling growth of Pinus densata Mast.provenances

摘要

We studied seed germination and early seedling growth of Pinus densata to explore the range of variability within the species and to inform afforestation practices.Phenotypes were evaluated at a forest tree nursery under conditions that support Pinus yunnanensis, one of the presumed parental species of P. densata. Seeds were collected from 20 open-pollinated trees within each of eight autochthonous populations representing the natural distribution of P. densata in China to assess variation in germination traits and early seedling growth, and to examine the relationships among these traits. Results showed that seeds from all populations germinated and seedlings established successfully. There were significant differences among populations in 13 of 14 traits evaluated. Seed germination and early seedling growth were strongly related to seed size and seed weight. Bigger seeds germinated earlier and faster than small seeds, and seedling size was positively correlated with seed size. Some germination traits were strongly and significantly correlated with climatic variables associated with the provenance of the studied populations. Based on these observations, we conclude there were large, significant, and biologically important differences among P. densata populations in seed germination and seedling growth traits. The observed variability probably reflects a high degree of adaptive differentiation among populations that is likely to be relevant for future afforestation.