Foliary alterations suggest effects of vehicle pollution in myrtaceae gender plants in urban areas

Abstract

Alteration in leaf size as well as fluctuating asymmetry, i.e. variations in the symmetry of bilateral leaf characters, have been used to assess the impacts of vehicular pollution on plants. Some parameters indicate instability in the development of plants according to their environment, therefore an effective tool in environmental biomonitoring. In this study, we verified whether there is variation in size and floating asymmetry in leaves of three species of Myrtaceae (Eugenia uniflora, Plinia cauliflora and Psidium guajava) under three environmental conditions: i) central urban areas (with high-intensity vehicle traffic); ii) peripheral urban areas (with low vehicular traffic); iii) natural areas, without urbanization, presumed to be free of vehicular traffic, therefore without polluting gases emitted by combustion (control). The foliar measurements, length and width and asymmetry were obtained using a digital caliper. To determine floating asymmetry, the leaf's central vein was used as a reference to measure three points on the left and right sides: leaf base (near the petiole insertion), intermediate area (leaf half) and tip area (leaf apex). The asymmetry values were transformed into logarithms and recalculated on new values (d = log x - log x) and Box - Cox, d * = (| d | + 0.00005^0,33). There was variation in leaf dimensions and fluctuating asymmetry for E. uniflora, P. guajava and P. cauliflora (ANOVA; p <0.05). There is evidence of instability in the development and ontogeny of the leaves of E. uniflora, P. guajava and P. cauliflora, potentially in response to an environmental stress promoted by vehicular pollution. These species can therefore be bioindicators of air pollution promoted by vehicular combustion in the urbanized area.