Comparative Analysis of Triticum aestivum L. (Poaceae, Poales) and Pisum sativum L. (Fabaceae, Fabales) Resistance to Heavy Metals

Abstract—Heavy metals are widespread soil pollutants frequently identified in agricultural lands. In many cases, their pollution levels significantly exceed the maximum permissible concentrations. Pea (Pisum sativum L.) and wheat (Triticum aestivum L.) plants are among the most important agricultural crops. However, no comparative analyses of their resistance to high concentrations of heavy metals has been performed before. Therefore, an experiment was conducted with the purpose to assess the resistance of T. aestivum and P. sativum seedlings to chronic effects of lead and copper salts in concentrations lethal for T. aestivum (copper sulfate: 0.15, 0.30, and 0.60 g/L; lead nitrate: 0.5, 1.0, and 1.5 g/L). All studied toxicant concentrations reduce the germination capacity of T. aestivum seeds in comparison with the control variant: lead nitrate, by 19–38%, and copper sulfate, by 23–58%. The decrease in the germination capacity is a direct manifestation of the lethal effects exercised by these heavy metals. All studied toxicant concentrations reduce the root system length (from 69% to 25 times) and shoot height (by 25–76%) in T. aestivum seedlings in comparison with the control variant. In addition, heavy metals intensify lipid peroxidation in seedling shoots, which indicates the development of a stress reaction. By contrast, heavy metal salts in concentrations lethal for T. aestivum have virtually no effect on the parameters of P. sativum (except for the root system: exposure to lead nitrate reduces its length). Overall, P. sativum is significantly more resistant to effects caused by the concentrations of lead nitrate and copper sulfate studied than T. aestivum; this applies to parameters such as the seed germination capacity, growth processes in the root system and shoot, and peroxide homeostasis.