Freezing injury in primary and secondary needles of Mediterranean pine species of contrasting ecological niches uri icon

abstract

  • Pine seedlings show a marked ontogenetic difference between primary and secondary needles, the latter prevailing with a different timing among species.
  • Primary needles were significantly more sensitive to freezing than secondary needles in Pinus halepensis, P. brutia, P. pinaster and P. nigra, whereas no differences were found in P. canariensis, P. pinea and P. radiata. LT50 was uncorrelated with needle sclerophylly but very highly correlated with the mean temperature of the coldest month at the seed source.
  • Results support an adaptive role of secondary needles in the mountain Mediterranean pines P. nigra, P. pinaster and P. brutia, while the more complex responses in coastal Mediterranean pines can be interpreted in the light of seedling ontogeny and species' ecological niches.
  • Using the electrolyte leakage method following an artificial freezing test, we aimed at (1) determining the differences in freezing tolerance between primary and secondary needles in eight pines of contrasting thermal habitats: P. canariensis, P. pinea, P. halepensis, P. brutia, P. pinaster, P. nigra, P. sylvestris and P. radiata, (2) evaluating the relation between freezing tolerance and sclerophylly and (3) relating freezing tolerance with the climate of origin.

publication date

  • 2009
  • 2009