Today, with the globalization of heavy metal pollution, most plants cannot escape this polluted environment. Whether the existing plants can adapt and how to adapt the polluted environment is very important for continuing reproduction and survival of the species. Therefore, research of plants adaptation characteristics for many generations under the pollution conditions is extremely significant, and understandings of the ecological adaptation processes of existing plants to ever-lasting anthropogenic pollution are undoubtedly needed. The past investigation has showed that plants growing on lead (Pb) and cadmium (Cd) polluted soils would reduce shoot growth, biomass and inhibit root growth, but how it may change after a long-timed toxic metal pollution has not reported. We designed field experiments about Pb and Cd contaminated soils with different concentration gradients and continuously cultivated 15 years of maize (Zea mays), the seeds were collected from each plot every year then continued to be planted on the same plot at the next year. The plant height, stem diameter, tassel length, root length and the dry weight of roots, stems, leaves, tassels and seeds per plant, biomass and dry weight of 50 seeds of generation 1st, 2nd, 4th, 5th, 10th, 12th, 13th, 15th were observed.
Results/Conclusions
The results showed that under the influence of Pb and Cd pollution, the response of these quantitative traits to contamination were fluctuated at different generations, the values of some generations were significantly increased, some generations were not significantly different and some generations were significantly decreased compared with control check. In addition, at the 15th generation, seed set rates in the plots which the concentrations of Cd were 10 mg/kg and 60 mg/kg were all decreased by 16.67% compared with the control check, one-sixth of the plants were sterile and could not produce seeds. However, the germination rate of all the obtained maize seeds ranged from 84.34% to 96.67%, but it was not significantly different from that of the control group. A change trend as to a specific trait seemed not be observed clearly, but an adaptative network among quantitative traits could be developed. It should be strengthened on a long-term scale study for many generations in future.