The effect of heavy metal-containing wastewater sediment on the microanatomical characteristics of the leaves and stem of Salix viminalis L.

Abstract

A comparative microanatomical study of Salix viminalis L. shoots was performed in order to get an idea of the effect of toxic elements stress on the microanatomical parameters of the shoot (leaves, stem). The examined Salix viminalis L. shoots originated from the Lovász-zug suburban area of Debrecen city, where a sewage settling pond was formerly operated as a secondary biological purification unit. The control Salix triandra x viminalis L. 'Inger' samples originated from the Nyíregyháza experiment with uncontaminated soil. As a result of our research, we can state the following in the case of the leaf samples grown on contaminated soil: the leaf lamina thickness decreased; the extent of the palisade parenchyma decreased; the extent of the intercellular spaced increased inside the spongy parenchyma; the width and the height of the main veins increased; the extent of the collenchyma bordering the main vein increased; the stomatal density increased both in the case of the adaxial and abaxial epidermis; the size of the stomas decreased. In the case of the stem samples, we observed the following: in the case of the samples grown on contaminated soil the extent of the primer cortex increased; the cell wall of the cells building the sclerenchimatic fibers thickened; the number of Ca-oxalate crystal rosettes and sclereids increased; the extent of secondary phloem increased; the lumen of the tracheas in the secondary xylem increased; the average width of the annual rings decreased; the extent of the central stele of the stem increased.