Growth and ion uptake in maize plants exposed to Pb, Cd and Ni depend on NO3- /NH4+ ratio
2010
Mihailović, N., Institute for the Application of Nuclear Energy - INEP, Belgrade - Zemun (Serbia)
Maize (Zea mays L.) seedlings were grown in the presence of Pb, Cd or Ni under the treatment of two N ion forms: NO3-, and NO3-/NH4+ (2:1). Heavy metal accumulation, root growth and the concentrations of soluble proteins, proline, K, Ca and Mg were monitored. The results showed that the monitored parameters in maize were more susceptible to Cd and Ni than to Pb. Also, NO3-/NH4+ treatment made them significantly more susceptible to these metals. These results are in accordance with previous experiments demonstrating harmful effects of NH4+ on heavy metal tolerance. But, since there was no apparent connection between N form and heavy metal concentration in roots, we concluded that NO3- treatment probably contributed to organic ions (oxalate and citrate) accumulation and successful binding and inactivation of heavy metal ions. The results indicate that, apart from the specificity in maize response degree to different metals, there exists a wide genetic potential for increasing heavy metal tolerance that can be induced by properly selected N ion balance.
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