Influence of Cadmium on Chlorophyll Content of Beans (Phaseolus Vulgaris) Use of Plant as Bio-Indicator of Pollution (in Vivo Experimentation)

摘要

Studies carried out in different plant species have revealed that Cd is strongly phytotoxic and causes growth inhibition and even plant death, although the mechanisms involved in its toxicity are still not completely understood. The present investigation is aimed at highlighting some of the problems related to Cd and trying to answer some of the questions that have arisen as a consequence of Cd behavior and its toxic nature t o plant species. The culture experiment of beans Phaseolus vulgaris was carried out in a hydroponic solution with variable Cd concentrations to determine the effects of different concentrations of Cd on photosynthesis and chlorophyll content. Chlorosis was the primary symptom caused by Cd toxic levels and this led to the study of its causes by investigating the effect of Cd on Chlorophyll formation and its content in plants. In that respect, one question appeared to be important about the nature of the effect of Cd on chlorophyll and Mg concentration was the first conclusion obtained on the basis of evidence achieved from analysis of the chlorophyll content by atomic absorption and ultra violet spectroscopy. Although some results were obtained indicating the formation of free-Mg chlorophyll suggesting the disturbance of the pigment and probably the removal of Mg caused by the increase of Cd concentrations in the chlorophyll. But more still to be achieved to suggest a possible displacement of Mg by Cd. Meanwhile a speculative view was considered to explain the matter by suggesting that Cd was rather interfering with other divalent elements such Fe and Cu which are known to be involved in the chlorophyll synthesis than Mg directly.