Іnfluence of multicomponent growth regulators on winter resistance forming and productivity of winter wheat.

The growth of gross grain may be obtained only with growth of agrotechnical methods. Therefore there is a need for further investigation of the complex influence of the main technical means on plant growth and development. It is necessary to define an influence of multicomponent drugs on the wheat win- ter resistance and productivity. To solve this task, field investigations were held for conditions of northern Steppe aiming to define regularities of growth and development, winter resistance forming, and productivity of the hard winter wheat depending on growth regulating drugs, different levels of mineral nutrition, and different predecessors. The investigation (2013–2017) was held on the training field “Samarskiy” of Dneprovskiy National Agrarian-economical University (Dnipropetrovsk oblast) on common chernozem soil with low contains of humus medium loam. The square of the field 30 sq. m., three times frequency, allocation is systematic. In general, the weather conditions for years of the investigation were specific for the Steppe zone. It was defined that depending on the presence of the main factors of life sustenance, the influence of studied drugs (which contain different organic and non-organic elements) varies a lot but there are some regularities. At the worst conditions (after a stubble predecessor and with low level of nutrition) the drugs have shown minimal influence on wintering of the hard winter wheat. So, the maximum increase of nutrition the drugs can give (drugs “Mars ELBi” and “AKM”) only at 2.6 % higher than at the control, which is not so significant. Minor increase or even decrease of wintering caused by usage of the studied drugs was noticed also at the best background (fallow land, N30Р60K40). The best cryoprotection was obtained with the drug “Vympel”, which increased the plant survival at 8.6 % comparing with the control. The same regularities of the influence of complex drugs depending on the background are found at the productivity forming as well. At follow land in conditions of sufficient nutrition the effect of the most studied drugs hasn’t increased or was insignificant. Chlormequat-chloride 750, as opposed to multicomponent drugs, has shown consistent and positive effect in conditions of high background. Among studied drugs the best sustainability in increasing grain productivity of the hard winter wheat has shown drug “Mars ELBi” used in spring after the vegetation renewal (daily-average temperature +10 оС) with norm 750 ml per ha. Key words: hard winter wheat, growth regulator, winter resistance, productivity, grain quality, cost efficiency.