ACCUMULATION OF PHENOLIC-COMPOUNDS IN THE NECROTIC AREAS OF AUSTRIAN AND RED PINE NEEDLES DUE TO SALT SPRAY

Austrian pine (Pinus nigra) and red pine (P resinosa) were tested for needle damage caused by salt spray. Morphology and histology of newly grown needles were compared in 3- and 6-year-old plants growing in the greenhouse under controlled conditions. Potted plants covered with plastic bags were sprayed daily either with distilled H2O or saturated salt solution. Needle tips, mid-parts and bases were fixed after 1, 3 and 24 h, and 3, 7 and 30 d in glutaraldehyde+0·1 % caffeine for precipitation of phenolics. Histochemical reactions and electron microscope observations showed that the morphological damage is linked to increased phenolic compound deposition in mesophyll cells, beginning directly under the stomata. Disorganization of membranes leads to death of the mesophyll cells, even before morphological damage is recognizable as brown spots on the needle surface. Thus the histochemical reactions and observations of cell structure revealed damage earlier than macroscopic observations. © 1990 Annals of Botany Company.