Air pollution effects on the leaf structure of some Fabaceae species

Abstract

Plants growing in the industrial areas and near the major roads absorb the pollutants at their foliar surface. In this paper, histological changes induced by air pollutants (from a cement factory combined with the pollution generated by human activities) in Lotus corniculatus L., Trifolium montanum L., T. pratense L. and T. repens L. leaves were followed. Some plant species have been identified to be able to absorb, detoxify and tolerate high levels of pollution. The tolerance degree is indirectly correlated with the intensity of injuries that occur in plant structure. Leaf thickness, the height of palisade cells, the diameter of the spongy cells, height and width of the upper epidermis cells, the thickness of the external wall of the upper epidermis cells, stomata length and stomatal index number of these species from highly polluted sites and lowly polluted sites were investigated by light microscopy. The stomata decrease in size and increase in density in leaves from high polluted sites. In the mesophyll cells (both in palisade and in spongy parenchyma) dark phenolic deposits could be observed.