Stomatal Clogging by Aerosol Particles in Necrotised Pinus thunbergii Needles

Fine structures were investigated on Pinus thunbergii needles in the coastal area of Seocheon, Korea. Both asymptomatic and necrotised needles were collected and subjected to electron microscopy and X-ray microanalysis. Particles of varying sizes and shapes covered both the asymptomatic and necrotised needles. The ratio of clogged stomata to open stomata was significantly higher in necrotised needles. X-ray microanalysis revealed particles composed of aluminium, calcium and silicon. However, sodium chloride crystals were rarely observed. These results suggest that needle necrosis in pine species may be associated with stomatal clogging by aerosol particles.