Aim. The adaptation of young corn plants (Zea mays L.) to the effect of chronic ultraviolet B (UV-B) irradiation during vegetative growth and formation of photosynthetic apparatus of leaves was studied. Methods. Corn plants hybrid Dostatok 300 MB in the phase of two developed leaves was irradiated with UV-B in dose of 2 kJ/m2 per day with a power of 1 W/m2 in long day conditions during 12 days. During this period, the growth of plants was measured, content of photosynthetic pigments and endogenous hydrogen peroxide (HP) was determined in the leaves. Results. It was established that the effect of chronic UV‑B irradiation caused the temporary inhibition of leaf growth, synthesis of photosynthetic pigments and increasing of HP content in them. Then the growth processes and pigment complex recovered to the level of no irradiated plants and exceed it, indicating the induction of adaptive reactions in young corn plants. Conclusions. It was shown that the effect of a low dose of chronic UV-B irradiation caused a delay in growth processes and the formation of a photosynthetic complex with subsequent adaptation to stress in young corn plants. Keywords: UV-B irradiation, Zea mays L., photosynthetic pigments, adaptation.

Aim. The comparation of photomorphogenetic response of pea plants in wide dose range of UV-C and UV-B irradiation was studied. Methods. Pea plants (Pisum sativum L.) cultivar Aronis were grown in water culture during 10 days and then were irradiated by UV-B and UV-C irradiation in doses 1, 2, 4, 8 and 15 kJ/m2. The length of shoots and roots and fresh weight of pea plants were measured. Results. It is established that UV-C irradiation caused strong inhibition effect on shoot growth against UV-B in the same doses. It is shown that the dose of 8 kJ/m2 was the threshold of the UV-B and UV-C effect. Dose above 8 kJ/m2 caused growth inhibition. The dose of 2 kJ/m2 caused the hormesis effect. Stem growth inhibition under the UV-C stimulated root growth. Conclusions. Comparative study of UV-B and UV-C irradiation demonstrated that the hormesis effect on plant growth was shown in the same dose of 2 kJ/m2. The inhibition effect of UV-C irradiation was stronger than UV-B in the same doses. Keywords: UV-B, UV-C, Pisum sativum L., hormesis.

One of the key tasks of modern pharmacology is complete and diverse use of natural raw materials -microorganisms and plants. So, different approaches of metabolism redirection were applied. Studying of plant protective reactions indicated a possibility to use various stress factors for the metabolism reorientation. One of the most effective approaches is to use ionizing and UV-C exposure. Thus, there is a shift in metabolic processes towards the formation of secondary metabolism substances with antioxidant, anticancer, immunomodulatory and anti-inflammatory effects. Biotechnological use of radiation exposure is based on the systemicity of radiobiological reactions, including protective and adaptive reactions in non-exposed organs («abscopal effect») and even in non-exposed organisms that are found in the same environment as exposed ones («by stander effect»). The products synthesized in these structures are some medicine materials and directly used by human. Radiation exposure affects developing, blocking of primary and secondary metabolism, so must be improved the selection of varieties with initial high productivity of medicinal raw materials, the choice of exposure and optimal doses inducing an increasing yield of the target metabolite and do not reduce the yield of medicinal raw materials. Effect of UV-C and X-ray pre-sowing exposure of seeds to the productivity of inflorescence formation of eight genotypes of Matricia chammomila L. was studied. There were indicated genotypes with increasing yield of inflorescence only under one or two exposure types and the variety with stimulation of flowering under UV-C exposure and absence of the marker under X-ray one.

Досліджено гормезисну дію УФ-С опромінення на пігменти, вміст ендогенного пероксиду водню та активність антиоксидантних ферментів листків гороху. Встановлено, що після опромінення рослин адаптуючою дозою УФ-С рівень ендогенного Н 2 О 2 знижується. Визначення активності аскорбатпероксидази і каталази виявило стимуляцію антиоксидантних ферментів після дії УФ-С. Вміст хлорофілів у листках після дії адаптуючого УФ-С опромінення стабілізується і надалі відновлюється. Показано, що УФ-С опромінення листків гороху в адаптуючих дозах підвищує стійкість рослин до повторної дії УФ-С опромінення.

Aim. The goal of this study was to study the interaction of chronic ultraviolet (UV-B) radiation and cytokinin 6-benzylaminopurine (BAP) in the adaptation of pea plants (Pisum sativum L.) to the effect of chronic UV-B irradiation. Methods. Pea plants cultivar Aronis were sprayed by BAP solution in concentration 10-5 M before the effect of chronic UV-B radiation at doses of 6 kJ/m2 per day with a power of 1 W/m2 for 12 days. During this time, the growth of plants and their mass were measured, the content of photosynthetic pigments and endogenous hydrogen peroxide (HP) were determined in the leaves. Results. It was established that the effect of chronic UV-B radiation at a dose of 6 kJ/m2 per day on pea plants caused a delay in plant mass accumulation, synthesis of photosynthetic pigments and increasing HP content in leaves. Treatment plants by BAP increased mass, stimulated synthesis of photosynthetic pigments, reduced the content of HP in the leaves of pea plants during the UV-B radiation. Conclusions. It was shown that treatment of pea plants by BAP caused the adaptation of pea plants at the beginning of UV-B radiation. Cytokinins are capable to detoxify reactive oxygen spices, stimulate formation of photosynthetic complex that promotes growth of pea plants under chronic UV-B radiation. Keywords: UV-B, BAP, Pisum sativum L., photosynthetic pigments, adaptation.