Dynamics of salt stress parameters in cultivated oat with different pH levels of root environment

Background. The development of the process of soil salinization can be accompanied by both a decrease and an increase in pH; at the same time, plants experience complex stress (salt + alkaline stress, salt + acid stress). The purpose of the research is to trace the dynamics of hydrogen peroxide content, peroxidase activity and proline content in oat leaves under the influence of NaCl against the background of acidic, neutral and alkaline reactions of the root environment. Materials and methods.The oat Avena sativa L. was used as the object of study. Plants were grown on vermiculite for 6 days, then stress factors were added, which were solutions combining NaCl salinity (200 mM) and different pH levels (pH 3, pH 6.5, pH ten). The alkaline medium was created with a glycine-KOH buffer, and the acidic medium was created with acetic acid. After stress exposure for 48 hours, peroxide content was determined in plant leaves by the ferrothiocyanate method, peroxidase function – by the Boyarkin method, proline – by the Bates method. Results. When exposed to NaCl salinity against the background of a neutral reaction of the environment, the height of the plants was lower than the control variant only after 48 hours of observation; in oat leaves, variability in the content of peroxide, an increase in the activity of peroxidases, and the accumulation of proline were observed. In the NaCl variant on an alkaline medium, the height of oats did not differ from the height of plants against the background of an alkaline reaction of the medium; in some periods of observation, an increase in the activity of peroxidases and the accumulation of proline were noted in oat leaves. Salinization against the background of an acid reaction of the environment contributed to a decrease in the height of oat plants; the activity of peroxidases did not increase in the leaves, and the accumulation of proline was noted only a day after the stress exposure. Conclusions. Against the background of neutral, alkaline and acid reactions of the environment, different degrees of manifestation of salt stress were noted. Increased inhibition and weak plant responses indicate the most negative effect of salts against the background of an acidic environment.