MITOTIC ACTIVITY OF THE APICAL MERISTEM OF <i>ZEA MAYS</i> L. ROOTS UNDER INFLUENCE OF ZIRCON PREPARATION UNDER CHLORIDE STRESS
Despite the favorable conditions for the cultivation of many crops, Crimea belongs to the risky zone of agriculture. Significant impact on the natural environment of Prisivashia was made by the introduction of the North Crimean Canal. As a result, the groundwater level rose, soil was flooded, and soil salinity increased. The factor has a negative impact on all cultivated plant species, and its level is higher, the greater the degree of salinity. The negative effect of salinization is expressed in the deterioration of many properties and functions of plants, which as a result leads to a decrease in their productivity. Maize ( Zea mays L.) takes the third place in the world in sowing areas, and the first place - in productivity. A significant range of its application is associated with high productivity, which is due to S4-type of photosynthesis and active growth processes. In this case, maize is demanding for the water regime, because with intensive growth and the formation of a significant volume of vegetative mass, a large number of micro- and macroelements are consumed in a short period of time. In the practice of agriculture, various plant growth regulators are used to increase the yield and enhance the resistance of plants to extreme environmental actions, including salt stress. These regulators include a new generation Zircon growth stimulant, whose active ingredient is a mixture of hydroxycinnamic acids (HCA) extracted from the plant material Echinacea purpurea (L.) Moench. Zircon performs in plants the functions of growth stimulant, immunomodulator and adaptogen to stress. The effect of this growth regulator on plants has often been studied under optimal non-stress conditions, and data on the use of Zircon to improve the salt tolerance of plants and to study its effect on mitotic activity under such conditions have not been observed. Therefore, the aim of our work was to investigate the mitotic activity of the apical meristem of the roots of Zea mays L. sprouts under the influence of Zircon in condition of chloride stress. As an object of study, we used maize plants Zea mays L., CV / TAP 349 MB. Sampled on average size and etched in a weak solution of potassium permanganate, the seeds were pre-soaked for 4 hours in the solutions under study. After soaking, the seeds, 30 in number, were placed in cuvettes on a filter paper. To simulate salt stress, 300 ml of a solution with various concentrations of NaCl salts (50 mM, 100 mM, 150 mM, 200 mM; control 1 - distilled water) were poured into the cuvettes. To study the effect of the Zircon preparation on the germination of maize seeds in chloride salinity, the above concentrations of NaCl were used with the addition of 0.05% growth regulator (control 2 - 0.05% Zircon). Seeds were germinated in a thermostat according to GOST 12038-84. On day 4, rootlets (5-7 mm) were cut off from corn seedlings and immersed in a fixation solution (acetic alcohol) per day, then the fixed root tips were transferred to a solution of 70° ethyl alcohol and thus stored in a refrigerator. Staining was performed with acetocarmine for 72 hours, after that temporary preparations were made. The control of the preparation was carried out under the magnification of the ×100 microscope, and its investigation - under the increase ×400. Each experiment was carried out in triplicate. For each variant of the experiment, the root tips of 3 seedlings were analyzed, at least 1000 cells in each root tip. The mitotic and phase indices were calculated by Prokhorova's formulas. Morphometric parameters of plants were determined by standard methods in plant physiology. Statistical processing of experimental data was carried out by calculating the arithmetic mean and standard error of the arithmetic mean. To determine the reliable differences in the distribution of biometric data, Student's t-test was used. As our studies have shown, in the cells of the apical meristem of the roots of maize seedlings, the Zircon praparati