Histological Differentiation Among Abiotic Causes of Conifer Needle Necrosis

摘要

Symptoms induced by phytotoxic gases within conifer needles can be differentiated histological from those caused by other abiotic agents including winter drying, drought, and salt. However, it is not possible to differentiate among symptoms caused by hydrogen fluoride, sulfur dioxide, ethyl mercaptan, and hydrogen sulfide. Phytotoxic gases cause hypertrophy and hyperplasia of vascular parenchyma, endordermis collapse, and intense vascular staining. The other abiotic agents induce mesophyll collapse with little or no observable effects on vascular tissues. Histological analysis should be useful in diagnosis of air pollution-induced injury and damage in coniferous forests.