LAUSR

*Corresponding author e-mail: [email protected] A b s t r a c t. The investigation of the effect of night chilling up to 4±2C, soil flooding at the optimal day and night temperature, and the combined effect of these stress factors on the adaptive potential of Amaranthus cruentus L. cv “Krepysh” containing amaranthine showed that changes in the intensity of the peroxide oxidation of lipids and superoxide dismutase activity, varied in antiphase to each other, both in the control and in experimental plants. Due to night chilling, unlike hypoxia, the content of amaranthine decreased shaply at the beginning of the stress period and then increased and significantly exceeded the control level until the end of the experiment. It has been suggested that lowering the temperature induces amaranthine synthesis, whereas with the development of hypoxic stress due to the reactions of reactive oxygen species neutralization, constitutive amaranthine is used. The suppression of plant growth during periods of hypothermia was more pronounced than it was due to soil hypoxia, this phenomenon may be associated with a decrease in the overall level of metabolism under conditions of hypothermia and is another example of the adaptive reactions of plants. It was found that the negative effects of the combined activity of soil hypothermia and soil hypoxia on plants, were greater than the negative effects of each stressor applied separately. K e y w o r d s: Amaranthus cruentus L., night hypothermia, oxidative stress, peroxide processes, soil flooding