Cytological and structural changes on 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 Sulfonate = 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. Their crowns were sprayed with an aqueous solution containing 1,000 g m-3 and, later, 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 the deterioration of the epistomatal wax structures and induces alterations in the stomatal guard cell walls. Lastly, it causes the degeneration of the protoplasm in cells of the mesophyll, beginning with the ones closest to the stomatal openings. The efficiency of both photosynthesis and gaseous exchange processes may be affected.