Nitrogen oxides as a factor in the variability of chlorophyll content in leaf tissues of Salix kochiana Trautv. at different stages of vegetation

In this work, the variability of the content of chlorophylls in the tissues of the plant leaves of the introducedspecies Salix kochiana in response to the action of low doses of nitrogen oxides was determined. To set up the experiment,a fumigation chamber was used to simulate environmental pollution with nitrogen oxides, concentration 0.5; 1.0; 1.5 and2.0 units of the maximum one-time MPC. It was found that the relationship between the dose of the operating gas and thechlorophyll content is non-linear. At the beginning of the growing season, under the influence of nitrogen oxides with aconcentration of 0.5 and 1.0 MPC, the chlorophyll content increases sharply (1.3 times), a further increase in the dose ofthe operating gas to 1.5 and 2.0 MPC leads to a decrease in the value of this indicator to background level. At the end ofthe growing season, the effect of nitrogen oxides with a concentration of 0.5 and 1.0 MPC, on the contrary, is accompanied by a sharp decrease in the content of chlorophylls (1.7 times), and an increase in the dose of the active gas leads toan increase in the value of this indicator, but its level remains significantly lower than the background. The interpretationof the obtained data from the point of view of the theory of stress makes it possible to characterize the response of Salixkochiana plants at the beginning of the growing season as a stage of the primary stress reaction, at the end of the growingseason as a stage of resistance, which makes it possible to recommend the studied species for landscaping areas with a similar nature of atmospheric pollution.