Hormesis in barley (Hordeum vulgare L.) plants derived from -irradiated seeds under contrasting weather conditions

Identification of mechanisms of adaptive response to weak external exposure is one of the most complex and urgent problems of the modern biology. Such reactions include the effect of hormesis which is the stimulating effect of moderate doses of stressors (e.g. the low doses of various physical and chemical agents) repeatedly confirmed at all levels of the organization of living matter. The dynamics of the growth and development of the plants, grown from γ-irradiated barley ( Hordeum vulgare L.) seeds of Nur variety, which combines high productivity potential (up to 80 c/ha), resistance to drought, good forage and brewing qualities of grain, high resistance to lodging and serious diseases, was studied in a field trial. It was shown that irradiation of seeds significantly influenced the development of plants throughout the vegetative period. The duration of the initial stages of ontogenesis was shortened, and the phase of full ripeness came on 5-7 days earlier than in the control. The length of the stems, the weight of 1000 grains, the number of grains per ear, the number of productive stems, the weight of straw and ears increased. The dependence of economically valuable traits on the dose of γ-irradiation of seeds was statistically significantly better described by models that take into account the effect of hormesis. The manifestation of the effect of presowing γ-irradiation was different in the years with contrasting weather conditions. In the dry year of 2014, the increase in yield was determined by the increase in the number of productive stems, and under optimal conditions in 2015, this was due to the increase in the number of grains per ear. In 2016, an increase in the amount of precipitation by 2.5 times relative to the climatic norm leveled the stimulating effects. The results obtained in this study indicate that presowing g-irradiation of seeds notably affects the development of barley plants throughout the growing season, significantly changing the structure of the crop. In the plants from the seeds irradiated at stimulating doses, the manifestation of economically valuable traits was statistically significantly increased when vegetation seasons were contrasting in weather conditions. Realization of the effect of hormesis specifically depends on the conditions in which the plants developed.