Globally, about 30 % of all soils are damaged by salinity. Salinity leads to lower productivity of agro- and biocenosis, a decline in biodiversity and, as a result, significant economic losses. For the most important oil culture – sunflower (Helianthus annuus L.), primary reactions to salt stress are almost unexplored. This paper analyzes the impact of a wide range of NaCl concentrations on the growth of the main root of sunflower sprouts and the development of programmed cell death processes in trichoblasts. Experiments have shown that sunflower plants are relatively resistant to salinity (NaCl). They were able to grow at the level up to NaCl 250 mmol/L in the environment. Significant symptoms of programmed cell death were detected only at high concentrations of NaCl 250 –500 mmol/L. Previously undescribed in the literature, the reaction of reducing the number of symptoms of programmed cell death under150 mmol/L NaCl treatment (medium salt stress level for sunflower) was determined. An inhibitory analysis of the NaCl-induced potassium flux showed that it was only 15 % inhibited by specific potassium channel antagonists (Ba2+ ). This indicates a low proportion of potassium channels and the dominant role of non-selective cation channels in providing NaCl-induced potassium loss in Helianthus annuus L. plants.

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Nickel (Ni2+) performs a number of vital functions in plants, but at high concentrations it causes toxic effects and inhibits their growth and development. The problem of nickel contamination has a special place in environmental physiology, since the refuse to use nickel alloys and therefore the reduction of Ni2+ release into the biosphere are practically impossible today. In nature one of the mechanisms of adaptation to the excessive nickel content in the medium is increased synthesis of histidine, which forms chelates with Ni2+. In the present work, for the first time, a detailed analysis of the effects of nickel and nickel-histidine complexes on the growth and development of sunflower roots (Helianthus annuus L.) of Belarusian selection (variety Orion) was carried out. It was established that Ni2+, starting from its level in the medium of 0.3 mmol/L, caused a significant growth inhibition of this agricultural plant. At a nickel concentration in the medium above 3 mmol/L, the growth of sunflower stopped completely. Histidine, introduced together with Ni2+, caused a decrease in the toxicity of this metal for the root system, in some cases shifting by single-order nickel concentrations, causing the same effect. Nickel treatment caused a significant increase in the percentage of cells with programmed cell death symptoms, while histidine inhibited the development of these symptoms. Thus, the concentration dependences of nickel and nickel-histidine complexes effects on root growth and the processes of programmed cell death in the sunflower root were first demonstrated.