Effects of Atmospheric Fluorides and Various Types of Injury on the Respiration of Leaf Tissue.

Abstract

Seven plants species were grown under various atmospheric hydrogen fluoride treatments for several weeks, and measurements were made of the respiration rate of lead discs and the fluoride content of the leaf tissue. No direct effect of the fluoride on respiration was detected, even when very high fluoride concentrations were used. An increase in oxygen uptake which appeared to be related directly to the development of leaf necrosis, was found in 2 varieties of gladioli. Injury of gladiolus leaves by scalding, crushing, and burning with a hot iron caused an increase in the respiration rate of the adjacent tissue comparable to that found when leaf scorch was produced by hydrogen fluoride in the atmosphere. Removal of part of a leaf by cutting did not affect the respiration of the remaining leaf tissue. The increase in respiration was greatest near the injured tissue and was somewhat proportional to the amount of injury produced. An explanation is offered for the apparent disagreement of the results with the reported inhibitions of respiration and enolase activity by fluoride solutions. The data indicate that it is very unlikely that fluorides in the atmosphere of urban or industrial areas ever affect the respiration of vegetation, atmore » least not without first producing much more obvious effects such as the development of severe leaf necrosis.« less