RESPONSE OF TRITICUM AESTIVUM SEEDLINGS OF DIFFERENT ECOLOGICAL AND GEOGRAPHICAL ORIGIN TO HEAT AND DROUGHT: RELATIONSHIP WITH RESISTANCE TO OXIDATIVE STRESS AND OSMOLYTE ACCUMULATION

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

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