Reaction of Barley Varieties on the Content of Polyphenols on Stress Soil Backgrounds

Abstract

To assess the stress resistance of genotypes, the authors studied the influence of soil stressors on the content of polyphenolic compounds in grain, straw, and roots of barley (Hordeum vulgare L.) of various varieties with differentiation by origin (domestic and foreign selection), and methods of production (hybridization and cell selection). The plants were grown in vegetative tanks with sod-podzolic soil in natural conditions until the seeds ripened. The experimental design included the following options: with excessive cadmium (Cd²⁺ 6.4 mg/kg); increased acidity (pH_KCl = 4.8); simulated drought in the interphase period, emergence into the tube-earing; without stress load at pH_KCl = 6.5 (control). The content of polyphenols in terms of gallic acid was determined by the spectrophotometric method. The total accumulation of polyphenols in grain under drought conditions (9.18–11.13 mg/g) and in the presence of excessive Cd²⁺ in the soil (9.07–9.10 mg/g) exceeded the control by 2.5–14.8 and 2.8–8.5%, respectively. On acidic soil, compared with the control, the amount of polyphenols in grain significantly decreased in all domestically bred barley varieties that underwent selection on acidic soils or selection on acidic selective media in vitro, by 16.1% in Vitrum and 11.8% in Rodnik Prikamye. In varieties of foreign selection (Zazersky 85, Triumph, and Tallon), under acidic conditions, the value of this indicator, on the contrary, increased by 2.2–4.8%. Most of the polyphenols were in a bound state. The free fraction of polyphenols was distributed among organs (% of the total amount in the plant): straw (41.4–49.1) > roots (32.4–42.5) > grain (15.6–22.6). Among the stressors studied, increased acidity contributed to a greater extent to the increase in the relative accumulation of free polyphenols. The most significant increase of accumulation was noted in the roots: in varieties and regenerants of the selection of the Federal Agrarian Research Center of the North-East, the increase was 19.0%; in varieties of foreign selection, it comprised 35.7%.