Winter wheat relates to the leading grain-forage crops in Ukraine and occupies about 60% of sown area at steppe region. The water deficit has negative impact on winter wheat growth, development and productivity. Significant phisiological and biochemical changes occur in a plant in the course of its adaptation to water stress. The solving of the problem of plants resistance to stress and increasing their productivity is a priority research area in agriculture.

One of the possible ways to activate growth processes and raise the genetic potential of plants is using biostimulants and complex fertilizers. The silicum-potassium fertilizers have been widely introduced lately due to their multifunctional properties. However, the agrobiological effect of this fertilizers on crops  has not been studied properly.

Positive effect of silicic fertilizers was revealed on wheat, barley, rice, sorgum, corn, sunflower, beans, vegetables and citrus crops. Silicum can stimulate plant natural protection reactions through participating in the methabolism. It is proved, that silicum nutriets optimization  results in the roots weight and volume increase and improves root’s respiration. The assimilation of micro- and macronutrients raises under the silicon effect. The soluble forms of silicum-potassium fertilizers increase leaf surface of grain crop, activate photosynthetic apparatus, increase the number of productive spikes under drought.

The study aim was to determine the influence of silicum-potassium fertilizer «Agroglass Stimul» on germination of the winter wheat under condition of water deficiency.

Seeds of Antonovka variety winter wheat were used for the laboratory study.  The control variant seeds were soaked in distillated water for 4-6 hours. The experimental variants seeds were soaked in solutions of silicum-potassium fertilizer «Agroglass Stimul» (5, 15, 30, 60, 100 ml/l) at 22±2 ^оС. Silicum-potassium fertilizer «Agroglass Stimul» was prodused by “PCC Ukrsilikat” (Zaporizhzhia city) with content of SiO₂-21,3 % and K₂O-8,3 %. Seeds were germinated for 8 days according to the international protocols.  Seeds were grown at 5 % solution of PEG-6000 for water deficiency stress induction. The laboratory germination, length and weight of seedlings and roots of wheat were determined in the course of the experiment. The results were processed statistically.

Germination of wheat seeds on 5 % solution of osmotic compound polyetheleneglycol (PEG-6000) create the condition of  water deficiency and caused germination decrease of by 9 %.

Seed pre-sowing treatment with «Agroglass Stimul»  solutions (5-15 ml/l) leveled the negative effect of water depression which indicates germination energy increase by 3.8–5.3 % and laboratory germination of wheat seeds increase by 3.8–6.0 % to the control index. However, high concentration of fertilizer (60ml/l) inhibited germination of wheat seeds under the condition of  water deficiency.

The incubation of wheat plants on PEG 6000 solution for 8 days resulted in the essential decrease of both seedlings raw weight by 1.7 times and roots – by 1.43 times compared with the crops grown  in water medium. Silicum-potassium fertilizer «Agroglass Stimul» raise the raw weight of wheat seedlings by 5.7 %-26.6 % and root by 17.5 %-27.4 %, respectively, in comparison with untreated seeds.

When determining the dry mass it was established that «Agroglass Stimul» fertilizer provided the accumulation of mineral part of the biomass under water stress condition. Similar results were obtained on winter wheat seedlings under condition of salt stress model. The dry weight of seedlings exceeded the control by 12.6 %–16.5 % and roots dry weight by 34.5–69.1 % under the influence of fertilizer in concentration of 5 ml/l-30 ml/l. It is necessary to mention, that even maximum concentration of «Agroglass Stimul» (60 ml/l) didn’t show negative affect under water deficiency conditions, but, on the contrary, it stimulated the accumulation of wheat biomass on the early stage of development.

Inadequate water supply is known to inhibit the processes of cells elongation are inhibited which causes stunted plant. Nevertheless, «Agroglass Stimul» promoted seedlings elongation by 13-14 % and roots elongation by 16–30 % compared with the control plants and in a case of pre-sowing seeds treatment. The fertilizer concentration of 5-30 ml/l increased the length of wheat seedlings the most effectively under water deficiency condition.

Thus,  silicum-potassium fertilizer «Agroglass Stimul» indirectly influences crop water balance normalization through regulating cells osmotic penetration.

Seeds pre-sowing treatment with «Agroglass Stimul» (5-15 ml/l) levels the negative effect of water depression, which indicates wheat’s seeds energy growth and laboratory germination by 5-6 %. It was established that silicum-potassium fertilizer, being as a regulator of osmotic pressure of plant tissues, enhanced growth processes in water stress condition under all studied concentration range (5-60 ml/l).

Key words: winter wheat, water stress, silicum-potassium fertilizer, growth, development, germination.