The paper presents an estimation of ¹³⁷Cs and ⁹⁰Sr effects on the plant testorganism Lepidium sativum L. seed germination, root and shoot growth as well as on the change of parenchyma cell parameters under experimental laboratory conditions.

All the ¹³⁷Cs activity concentrations studied (4·10²–4·10⁵ Bq/l) have been found to induce a statistically significant slight stimulation of L. sativum root growth. From all ⁹⁰Sr activity concentrations studied (1·10³ – 2·10⁵ Bq/l), only the highest activity concentration statistically significantly increased L. sativum root growth. All the other ⁹⁰Sr activity concentrations statistically significantly slightly inhibited root growth. The effect of 4·10⁴ Bq/l was most pronounced.

All ¹³⁷Cs activity concentrations studied demonstrated an insignificant stimulation of L. sativum shoot growth. The highest statistically significant stimulation level was observed at the ¹³⁷Cs activity concentration of 4·10⁴ Bq/l.

Aqueous solutions containing separate ⁹⁰Sr activity concentrations (1·10³ – 3·10⁴ Bq/l) also statistically significantly stimulated shoot growth, the stimulation being much more significant than in ¹³⁷Cs aqueous solutions. The different effect of ¹³⁷Cs and ⁹⁰Sr on the growth of plant vegetative organs (roots and shoots) can be explained by the different metabolism of ¹³⁷Cs and ⁹⁰Sr as stable chemical analogues of K and Ca, respectively, in plant cells. This predetermines their variable accumulation in separate plant organs and their different distribution in plant cells and tissues.

Keywords: technogenic radionuclides, concentration activity, plant test-organism, seeds, roots, seedlings, parenchyma cells