In the conditions of the field experiments conducted during the 2015–2016 vegetation seasons retardants Medax Top, 1.0 l/ha (prohexadione-Са and mepiquat-chloride), appeared more effective than Terpal, 1.5 l/ha (mepiquat-chloride and ethephon), on field plots with high-yield varieties. Foliar application of Megafol promoted the productivity of winter wheat varieties Smuglyanka and Podolyanka and reduced the negative influence of retardants on the wheat plants in the vegetation seasons which were characterized by moisture deficit. The influence of modern retardants – prohexadione-Ca + mepiquat-chloride (Medax Top) and mepiquat-chloride + etefone (Terpal, both BASF, Germany) on the accumulation of some macro- and micronutrients in winter wheat plants was determined. The assays were performed on an ICP-MS Agilent 7700x mass spectrometer (Agilent Technologies, USA) with ICP-MS Mass Hunter WorkStation. Samples of winter wheat plants were taken in the phase of flowering and grain ripening. The samples were dried, homogenized, 0.400 gof weight was dissolved in ICP-grade nitric acid in the Milestone Start D (Milestone Inc., USA). All solutions were prepared on 1st class water (18 MΩ cm–1) obtained on the Scholar-UV Nex Up 1000 (Human Corporation, Korea) water purification system. The ICP-MS Complete Standard IV-ICPMS-71A was used as the external standard, and the internal standard was Sc, both of Inorganic Ventures, USA. According to the ICP-MS results of plant samples of winter wheat of Smuglylanka and Podolanka, it has been shown that, in conditions of wheat growing on light soils of Polissya, modern compositional retardants affect the ionome of plants during vegetation, as well as change the content of inorganic elements in the grain. It was found that winter wheat of middle-stem Podolyanka type, of the intensive type, reacted more responsively to retardant treatment than the short-stem-type highly intensive Smuglyanka type. At the same time, there was an increase in the content of nutrients in winter wheat of the Podolyanka variety. It should be noted that wheat grain of the Smuglyanka variety contained a significantly higher pool of macro- and trace elements than the Podolyanka variety. It was established that the treatment of winter wheat Podolyanka varieties by mepiquat-chloride and ethephon (Terpal, 1.5 l/ha) positively influenced the accumulation of potassium, magnesium and calcium and manganese, copper and zinc in the grain. We found that foliar application of compositions of amino acids simultaneously with retardants can reduce the negative action of PGR’s on formation of the harvest in conditions of drought and influence the maintenance of composition of inorganic elements in the plants and in the grain. The composition of retardants with the content of cyclohexadione derivative (Medax Top) also significantly influenced the changes in the content of inorganic elements in plants and grains. We note the significant increase in the content of magnesium in the leaves and in grain due to the action of Medax Top. These differences in reaction of winter wheat varieties to the action of retardants of the class of cyclohexadione are important for clarifying the systems of nutrition of crops in intensive growing technologies, especially in the conditions of drought and high temperatures. Reduction in the pools of a number of inorganic elements in plants, for example iron, by the action of retardants may be due to the constraints on the entry of these elements from the poor soils of the Polissya zone and should be compensated via foliar nutrition. Also, the peculiarities of the activity of plant growth regulators have been shown to indicate a close relationship between signal systems of plants and changes in ionome.
ASSESSMENT OF WINTER WHEAT VARIETIES BY THEIR ASSOCIATIVE NITROGEN FIXATION ABILITY
