Abstract.
The aim of this work was to test our hypothesis that pine needles protect themselves against UV-B radiation via anatomical changes in the epidermal layer. This could lead to needle growth reductions if large quantities of assimilates are allocated for the epidermal protective mechanisms at the expense of photosynthetic area. Effects of enhanced UV-B radiation on the needle ontogeny of mature Scots pines (Pinus sylvestris L.) were studied during the second season of a field experiment. Depending on the season and the time of the year (1996–1997), the enhanced UV-B irradiance varied from 0.92 to 5.09 kJ m–2 day–1 UV-BBE compared to 0.54–2.44 kJ m–2 day–1 UV-BBE of ambient radiation. It was found that UV-B treatment accelerated the early development of needles. In 6-day-old enhanced UV-B-treated needles, mesophyll and hypodermic cells were fully differentiated, whereas in ambient-treated needles, no lobate mesophyll cells were seen and hypodermic cells had not yet developed. In fully grown needles, no accelerated differentiation was seen, except that the epidermal cross-sectional area was smaller. The continuation of the experiment will show if such a significant difference only occurs irregularly and incidentally or if it is of consistent significance for needles.
Similar content being viewed by others
Author information
Authors and Affiliations
Additional information
Electronic Publication
Rights and permissions
About this article
Cite this article
Latola, K., Kinnunen, H. & Huttunen, S. Needle ontogeny of mature Scots pines under enhanced UV-B radiation. Trees 15, 346–352 (2001). https://doi.org/10.1007/s004680100107
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/s004680100107