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We studied the influence of a natural plant growth regulator Ribav-Extra and ions of heavy metals (HM) Pb2+, Cu2+, Zn2+ and Ni2+ on the physiological and biochemical indices of the winter wheat (Triticum aestivum L. ) cultivar ‘Mironovskaya 808’. The seeds of wheat were treated with Ribav-Extra (10 ppm) and grown for 7 days on heavy metal salt solutions (10 μM or 1 mM). After that we recorded heavy metals accumulation, growth, generation of superoxide anion (•O2−), lipid peroxidation (LPO), and catalase (CAT) and ascorbate peroxidase (APOX) activity. It was found that 1 mM of HM in growth media increased heavy metals accumulation in wheat plants and inhibited the growth of roots and shoots. Both low and high concentrations of heavy metals stimulated •O2− production and oxidative damage in wheat seedlings. In most treatments, the toxic effect of heavy metals enhanced at higher concentration of metals. Pre-sowing treatment of seeds with Ribav-Extra decreased the negative impact of heavy metals by reducing oxidative stress which led to suppressed •O2− generation, lipid peroxidation intensity and catalase activity. This suggests that the wheat plants, whose seeds had been treated with Ribav-Extra, were more heavy metal-resistant than the untreated ones. [ABSTRACT FROM AUTHOR]

In the current study we investigated the effectiveness of synthetic Thidiazuron (TDZ), Cytodef (CTD), Epin-Extra® (24-EB) and natural Ribav-Extra® (RE) plant growth regulators (PGR) with a view to improving the heavy metal-tolerance in intact plants. To evaluate the effectiveness of PGR we chose the following parameters: the axial growth (as an integral indicator of the plant response to the environment), the superoxide generation (as an indicator of oxidative stress), the malondialdehyde (MDA) content (as an indicator of oxidative damage degree in plants), catalase (CAT) activity (as an indicator of the antioxidant defence systems activity) and the PGR capacity to change absorption and translocation of heavy metals in plants. The efficiency index was estimated on the basis of the results of winter wheat (Triticum aestivum L.) seedlings affected by 10 µM or 1 mM Zn2+, Cu2+ and Ni2+ or Pb2+ heavy metals. An empirical scale of the efficiency of PGR was developed. The study found that the efficiency of the PGR investigated with respect to tolerance of heavy metals increased as follows: TDZ