Phenotypic variability and developmental rates affect the response of bean (Phaseolus vulgaris L.) plants to ozone

Tropospheric ozone is considered the most damaging gaseous air pollutant worldwide to which plants are exposed. Tissue injuries, reductions in plant growth and productivity, and changes in crop quality are some of the effects of ozone on plants. Ozone causes more damage to vegetation than all other air pollutants combined. The economic impacts of ozone on crop growth and productivity continue to be significant. Over the past several decades, researchers have focused on quantifying ozone-related damage on plants and establishing methods to explain plants\u27 reaction to ozone. Increasingly, however, it has been shown that plant species react to ozone in many different ways: some are excessively susceptible and their development suffers or is severely reduced; others adapt themselves to new environmental conditions and become more tolerant. In some cases, certain cultivars even show resistance. The studies presented here focus on the impacts of ozone injury on the development of plants with varying degrees of sensitivity to ozone exposure and how growth rate and morphological characteristics affect plant responses to ozone at various concentrations. The degree of plant sensitivity to ozone was determined by comparative field studies, or by using open top field chambers where plants were exposed to ozone at various concentrations. In addition to crop yield evaluations from plants with differences in response to ozone, stomatal conductance was measured as a method of determining potential physiological changes. Stomatal density and aperture size were also assessed. The present studies assess the relationship between morphological characteristics of ozone-sensitive and ozone-tolerant genotypes of bush bean (Phaseolus vulgaris L.) and ozone exposure under different environmental conditions. The results support the expectation that genotypes within same species may show differences in response to ozone. Morphological characteristics, especially that of leaves, seem to influence individual plant responses to various atmospheric treatments