Cytological and structural changes in Pinus pinea L. needles following the application of an anionic surfactant
In many coastal areas, synthetic surfactants are present as pollutants in the chemical composition of sea spray. Their phytotoxic action in synergism with sea salt is well known. This paper examines the early effects of an anionic surfactant (sodium alkylbenzene sulphonate = ABS) on the anatomy and ultrastructure of Pinus pinea L. needles. Three successive treatments in the open field on Pinus pinea trees about 2 m in height were carried out in the month of August. The crowns of the trees were sprayed with an aqueous solution containing 1000 g m−3, and subsequently the current-year needles were observed by light microscopy, as well as by scanning and transimission electron microscopy. A few days after the treatment the needles had turned yellow. The results of the microscopical analysis show that the surfactant is absorbed prevalently through the stomata and that it causes deterioration of the epistomatal wax structures and induces alterations in the stomatal guard cell walls. Lastly, it causes degeneration of the protoplasm in cells of the mesophyll, beginning with the cells closest to the stomatal openings. The efficiency of both photosynthesis and gaseous exchange processes may be affected.