Response of Spring Barley to UV and γ-Irradiation

In two vegetation experiments on barley plants, the effect of separate and combined UV-B, UV-A, and γ-irradiation in different doses was studied for the varieties “Zazerskii 85” and “Vladimir.” The plants were assessed for flavonoid content, photosynthetic pigments, morphology parameters, and yield. The daily dose of chronic UV-B irradiation was 9 kJ/m2, that of chronic UV-A ranged from 45 to 72 kJ/m2, and single γ-irradiation was 2 and 4 Gy. It has been shown that the spring barley varieties “Zazerskii 85” and “Vladimir” differ in their sensitivity to chronic UV-B irradiation. When predicting the negative impact of UV-B radiation on plants, it is necessary to take into account the existing level of UVA radiation, since the effect is not additive. Stimulation of biomass growth under chronic UV irradiation may be accompanied by suppression of plant productivity. The response of barley plants to γ-irradiation can be significantly dependent on the level of UV-(A + B) radiation. In general, the dose-dependent effect of chronic UV and γ-irradiation can be considered as a transition from eustress to distress and its irreversible disruption. The data from this study may be relevant for programs to develop new varieties of spring barley that are resistant to elevated levels of solar UV radiation.