Elemental Interactions and Comparisons

In soil and soil solutions, plants are exposed to many elements simultaneously and to other factors, which could interact in different ways. Thus, the integrated effects may be quite different from those obtained when any of the elements or factors is acting alone. 

Interactions both positive and negative may be species-, and conditions specific, for example, in a series of pot experiments to investigate the effects and interactions of Zn, Cu and Ni, present at toxic or near toxic levels, Davies (1980) showed that the crops had differing sensitivities to the three heavy metals. At the levels tested the toxic effect on each metal was increased by the others on clover, lettuce and red beet. Positive interactions between Cu and Zn were shown by barley and between Ni and Zn by French beans. 

Hassett et al. (1976) reported that the elongation of soil-grown maize seedlings was depressed more by Pb and Cd in combination than by Pb alone. Webber (1980) found that Cd reduced the uptake of Zn in lettuce and there was a tendency for the reverse effect also. 

---