The effects of lead and zinc metals on Hordeum vulgare L. cv. "Tarm" (Barley) and Raphanus sativus L. (White radish) seed germination and leaves' some anatomical, morphological and physiological properties on seedling stage

In this work, the effects of various concentrations of zinc [Zn(NO3)2.4H2O] and lead[Pb(NO3)2] on the germination of barley (Hordeum vulgare L. cv. "Tarm") and whiteradish (Raphanus sativus L.) seeds and on the various anatomical particularities of leaves and some growth parameters of the seedlings grown for 21 days in growth chamber under conditions of 25±1ºC constant temperature, continuous fluorescent light (8.000 lux) and 60%±5 moisture were studied.Zinc and lead, particularly lead, delayed germination and inhibit growth of the both species. These effects, mainly delayed germination, were remarkable on R.sativus L.. When the the percentages of atypical germination was compared; H. vulgare L. was more sensitive than R. sativus L.. Atypical germination of H. vulgare L. seeds increased markedly, especially at treatment of lead, even at low levels of heavy metals. The heavy metals prevented radicle output more than plumule (coleoptile/hypocotyl) output and decreased fresh weight in seedlings of both species. The effect of heavy metal decreased fresh weight values in both species but no statistically significant difference was observed in dry weights. Due to the fresh weights were decreased, the water content values of the both species were decreased. H. vulgare L. seeds were sensitive to the heavy metal than R. sativus L. seeds. At the end of growth period of 21 days after transfer of the seedlings from germinated seeds to the growth chamber; zinc decreased fresh weights in H. vulgare L. seedling compared to the control, lead led to increase the fresh weights in some concentrations. The fresh weights in R. sativus L. were decreased by the both heavy metal. Zinc led to decreased dry weights of H. vulgare L. seedlings on the contrarylead led to an increase of H. vulgare L. seedlings? dry weight in all of lead concentrations. It was fluctated on dry weights of R. sativus L. compared to the control by the effect of both heavy metals. The percentage of water content in H.vulgare L. seedlings were decreased compared to the control, in R. sativus L. seedlings were fluctuated increases/decreases was observed in the heavy metal medium. Heavy metals reduced significantly root and stem elongation of the both species, these effects were shown more apparent in R. sativus L.. In general the heavy metals led to decrease of leaf area in the both species. The fresh and dry weights of leaves and the percentages of leaf water content were decreased generally by the heavy metal effect in the both species. The percentages of water content of R.sativus L. leaves were more sensitive than H. vulgare L. to the both heavy metals. As some anatomical investigations of leaf anatomy; the number of stomata, stomatal index, the width and length of stomata parameters of H. vulgare L. seedlings often gave similar responses to heavy metals. The numbers of stomata almost all the leafsurfaces in zinc and lead medium, except the lower surface of leaf in zinc media, was usually followed fluctuating compared to the control. Both heavy metal caused a decrease on stomatal index in both upper and lower surfaces. The width and length of the stoma, except leaf stomata length in zinc media, excluding the lower surface, remaining leaf surfaces under the effect of zinc and lead led to fluctuations compared to the control. Mentioned parameters of R. sativus L. seedlings had different reactions than H. vulgare L. in zinc and lead medium: while the number of stomata,in the presence of zinc and lead, descreased in general in the lower surfaces, fluctuated in the upper surfaces in zinc media and increased upwards from 4 mM in lead media. While both surface?s stomatal index decreased in zinc medium, fluctuated in lead medium. The width of stoma; generally decreased in zinc medium, fluctuated in the presence of lead in the both surfaces. While the lenght of stoma inzinc medium; fluctuated in the upper surface, usually increased in the lower surface. The lenght of stoma in the presence of lead, reduction in upper surface, fluctuating in lower surface was observed. The only common effect of zinc that reduced stomatal index of both species in the both lower and upper surface. The numbers?, widths and lengths of the epidermis cells, leaf thickness and distance between vascular bundles gave similar responses to zinc and lead mediums in the both species: While heavy metals led to increase of the epidermis cells on the upper surfaces of the both species,caused an increase on H. vulgare L. and a decrease on R. sativus L.?s lower surface. The lengths of epidermis cells were decreased on the both surfaces of both species by effect of the heavy metals. While decreases of epidermis cell?s length was observed in the both species in zinc medium, fluctuations were observed in lead medium, except the lenght of epidermis cell on H. vulgare L.?s upper surface. While the both heavy metals caused a decrease in leaf thickness of H. vulgare L., they generally led fluctuating results in the R. sativus L. leaves. The both species? distance betweenvascular bundles gave similar responses to zinc and lead and they decreased.