Response of Beans to Simulated Ambient and Uniform Ozone Distributions with Equal Peak Concentration

Abstract

Response of Phaseolus vulgaris L. cv. California Dark Red Kidney to 2 different ozone concentration distributions was examined at 2 dose levels in controlled fumigations. When peak ozone concentrations were equal and total doses equivalent, there was no difference in injury, growth, or yield between a simulated ambient distribution with normal diurnal ozone fluctuations and a uniform distribution typical of laboratory fumigation at constant concentration. Plants fumigated with either ambient or uniform ozone distribution had oxidant stipple leaf necrosis and reduced growth and yield. There was significantly increased injury and reduced growth and yield at a high ozone dose for both types of distribution. The data indicate that with equal peak concentration and equivalent total dose, the constant square-wave, ozone concentration distributions in laboratory fumigations are adequate to describe mode of action and magnitude of response to ambient exposures.