Response of Pinto Bean to Simultaneous Exposure to Ozone and PAN

Abstract

Ten day old pinto bean [Phaseolus vulgaris] plants were exposed for 4 h to either 588 .mu.g/m3 (0.30 ppm) ozone, 247 .mu.g/m3 (0.05 ppm) PAN [peroxyacetylnitrate], or the 2 pollutants combined at these concentrations. Ozone induced adaxial fleck whereas PAN produced mainly abaxial bronzing on the 1st trifoliolate leaf. Plant response to the combined pollutants was either additive or synergistic on the adaxial leaf surface and antagonistic on the abaxial leaf surface. The antagonistic abaxial response resulted in a nearly complete suppression of symptoms. The percentage injury for the combined leaf surfaces indicated an overall antagonistic response to the pollutants.