Formation of Nonspecific Resistance in Winter Wheat Plants by the Hydrogen Peroxide Treatment

Aim. The aim of the investigation was to study the effect of hydrogen peroxide on the activity of antioxidant enzymes, pigments' content and productivity of winter wheat in order to determine the biochemical mechanisms of induced winter wheat plant resistance during ontogenesis in the field. Methods. The study of physiological and biochemical parameters were carried out on winter wheat varieties of the wooded steppe (Poliska 90) and steppe (Skala) ecotypes at the tillering and flowering phases. The experimental plants were foliar treated with hydrogen peroxide (H2O2) in concentration of 1.10(-1) M twice, with a 3-day-interval, while the control ones - with distilled water. Spraying of plants was performed at spring (tillering phase). Lipid peroxidation (LPO) was determined as the formation of a peroxidation end product - malondialdehyde, which content was determined as the extinction of its condensation product with thiobarbituric acid. The activity of superoxide dismutase (SOD) was determined by a method based on the ability of SOD to inhibit nitroblue tetrazolium recovery by superoxide radicals in the light in the presence of riboflavin and methionine. The activity of catalase was calculated using the extinction coefficient of - 39.4 mM(-1) cm(-1). Results. It was established that after 24 h of hydrogen peroxide treatment the processes of lipid peroxidation were intensified and antioxidant enzymes' activity was decreased in two varieties. In the next phase of ontogenesis (flowering) antioxidant enzymes' activity increased in both varieties: Poliska 90 and Skala, which suppressed the LPO growth. Conclusion. Treatment of plants with hydrogen peroxide promoted the formation of non-specific plant resistance and increased grain productivity of winter wheat varieties investigated.