Dynamics of growth and accumulation of heavy metals of Pisum Sativum L. grown on polluted soil (vegetative experience)

Abstract

The paper presents the results of studies of the effect of heavy metal salts (15 mg/kg CdCl₂ and/or 50 mg/kg CoCl₂) contamination of soddy-podzolic soil on the adaptive potential and phytoremediation activity of two pea genotypes contrasting in resistance: the cadmium-resistant mutant SGECDt and its wild line SGE. The experiment was carried out under laboratory conditions while maintaining a stable internal microclimate and an optimal degree of insolation in the room. The duration of the experiment was 85 days. A study of the dynamics of morphometric parameters, using the example of shoot and root biomass, showed that the SGECDt mutant demonstrated better resistance to toxicants: on average, the decrease in shoot biomass compared to control was 28.2%, and 5.5% for roots. Whereas on wild lines, the rates were 31.8% on shoots and 21.8% on roots, respectively. As expected, the tolerance of the mutant was best manifested in the variant with the introduction of cadmium ions. Thanks to mass spectrometric analysis, it was found that the content of cadmium in dry biomass of shoots increased with an increase in biomass in both genotypes. Moreover, in the mutant, it significantly exceeded the concentration of pollutant accumulation in the wild type, and practically did not change, starting from 30 days with separate or combined introduction of metals, and until the end of the growing season - 20-25 µg of dry biomass per gram of shoot. The content of cobalt, on the contrary, decreased in ontogenesis phases, with a slight superiority in metal fixation by the mutant, starting from 45 days after inoculation. With the simultaneous entry of both metals into the soil solution, synergism of action was not observed. The content of cobalt decreased even more in plants, while cadmium, on the contrary, increased. It can be concluded that the ion-exchange reactions between these pollutants differed in interactions in the "soil-plant" system by the type of antagonism. Among the optimal period for harvesting contaminated products for its further processing (phytomining), one can single out the budding phase - the beginning of flowering (45 days). During this period, the mutant plants simultaneously perform well detoxification (phytosanation) and active accumulation of atmospheric nitrogen in the soil.