The response of etiolated seedlings of winter rye (Secale cereale), bread (Triticum aestivum) and durum (T. durum) wheats, as well as triticale (× Triticosecale) to the action of hyperthermia in relation to their resistance to oxidative stress was studied. Exposure of seedlings to 45°C for 4 hours led to a significant inhibition of the growth of T. aestivum, while the growth of T. durum and × Triticosecale seedlings was less sensitive to hyperthermia, and S. cereale seedlings showed the greatest resistance to heat stress. In bread wheat seedlings after heating, intensive development of oxidative stress. In durum wheat and triticale, such effects were less pronounced, and in rye, they were almost absent. In rye, triticale, and durum wheat seedlings, peroxidase activity increased under hyperthermia conditions, while in bread wheat, on the contrary, it decreased. In all four studied cereals, in response to the action of high temperature, the content of multifunctional stress metabolite proline increased, however, in rye, its absolute content significantly exceeded that in other species. The content of sugars during hyperthermia increased in S. cereale and T. durum, but did not change in the other two cereals. Triticale and especially rye have a high base content of anthocyanins and its increase in response to high temperature. A conclusion was made about the relationship between the ability of cereal seedlings to maintain growth under the action of hyperthermia and their resistance to oxidative stress, which is mainly due to the accumulation of metabolites with antioxidant activity.

The phenomenon of plant cross-tolerance to various stressors, particularly heat and drought, has been studied in considerable detail. However, there are no data on the relationship between resistance to these stressors in Triticum aestivum cultivars of different ecological and geographical origins at the stage of etiolated seedlings. At the same time, they are used for an accelerated assessment of the heat and drought resistance of breeding samples (separately for each factor). This work compared the response of seedlings of seven winter common wheat cultivars to heat stress (4-hour heating at 45°C) and a model drought (action of 12% PEG 6000). A correlation was found between the inhibition of seedling biomass accumulation as a whole (r=0.55) and separately for shoots (r=0.66) under heat and osmotic stress. A high correlation was shown between inhibition of shoot growth and accumulation of hydrogen peroxide and lipid peroxidation (LPO) products in shoots during heating (r=0.91 and 0.76, respectively) and a much lower correlation between the values of these markers of oxidative stress and inhibition of shoot growth during drought. A significant inverse correlation was found between the accumulation of sugars in the shoots and inhibition of shoot growth under drought (r=-0.85), and moderately high under heat stress (r=-0.60). At the same time, only a positive medium correlation (r=0.49) was observed between proline content and growth inhibition under both types of