This correlation is not present in the plants of any of the test groups with that of the control plants. As mentioned before, visual observation of the control and test plants was made on the same day that the plants were cut for dry weight activities. Color photos of the plants taken on that day are shown on pages 9 and 10. The six control plants plants whose soils were laced with metal concentrations of zinc look healthy and similar in size. The similarity of growth magnitude of these 2 groups of plants is also apparent with stem growths and dry weights.
Visual observation indicates cadmium and lead concentrations are toxic to the plants.
Zinc concentrations do not show any toxicity to the plants. The information from the stem growth and dry weight data also indicates the same. Visual observation seems to indicate a correlation between toxic effects in the plant and the concentration of cadmium. The plants look progressively more healthy with decreasing concentrations of cadmium. This progressive magnitude of toxic affect is also indicated in the stem growth data for cadmium.