Changes in some physiological and biochemical parameters of Avena sativa L. in conditions of salinity and soil acidity

Background. The accumulation of salts in soils is often accompanied by a change in pH to the alkaline side, technogenic salinization can be accompanied by an acidic reaction of the soil. Under conditions of salinization and acidic reaction of the environment, plants experience osmotic and oxidative stresses. The purpose of the research was to study the reactions of oat plants to the combined effects of NaCl salinity and acidic soil reaction according to some physiological and biochemical parameters. Materials and methods. Avena sativa L. oats of the Steyer variety were used as the object of the study. The plants were grown in a model experiment on a background sod-podzolic soil with various combinations of pH (pH 4.9 and pH 7.3) and salinity (0.5 % NaCl). A neutral medium (pH 7.3) was created by the addition of CaCO3. Salinity was created in % relation to the dry weight of the soil. The control was a saline–free variant with a pH of 7.3. 4 and 8 days after the appearance of seedlings in the leaves of plants, hydrogen peroxide was determined by the ferrothiocyanate method, catalase activity was determined permangatometrically, and peroxidase function was determined by the method of A.N. Boyarkin. Morphometric parameters were recorded within 8 days after the emergence of seedlings. Results. Compared with the control, growth processes slowed down more strongly in the variants of the experiment with salinity and were arranged in the following order: pH 4.9 + NaCl > pH 7.3 + NaCl > pH 4.9. The H2O2 content in oat leaves in the experimental variants did not differ or minimally differed from the control during the first observation period, but in the second period it was 1.6–1.7 times higher in all experimental variants. Catalase activity in both observation periods was higher than the control in the variants with salinity by 10–30 %. In the second follow-up period, catalase activity was generally one-third lower compared to the first in all studied variants. The activity of peroxidases in oat leaves in all experimental variants was significantly higher than in the control variant in both experimental periods. In the second follow-up period, peroxidase function was higher in comparison with the first in all studied variants (by 16–81 %). Conclusions. The greatest depression of oat plants, judging by morphometric indicators, was observed at the initial stages of the experiment (the first 4 days), especially in the experimental version combining salinization and acidic soil reaction. Catalase was actively involved in the adaptation of plants to the conditions of salinity and soil acidity at this stage, and peroxidase by the 8th day of the experiment.