The results of studies on the influence of norms of mineral fertilizers and crop retardant protection on grain yield of malting spring barley are presented. It is established that the highest yield of spring barley of studied varieties was obtained at a norm of fertilization N₉₀P₉₀K₁₂₀ through the use of retardants Hlormekvat-chloride 750 and Terpal. For the growing of spring barley without retardants usage the most effective fertilization norm is N₆₀P₆₀K₈₀ kg a. s./ha.

Our research found that growing the investigated varieties of spring barley in the conditions of Right-bank Forest-steppe of Ukraine without the use of fertilizers and retardant protection provided yield at 2,96–3,45 t/ha, while on variants with norm of fertilization N₆₀P₆₀K₈₀ it was higher by 33,4–57,4 % (4,14–5,08 t/ha). During fertilization N₉₀P₉₀K₁₂₀ indicators of crop yield surpassed variant without fertilizers on 29,3–43,4 % and amounted to 4,04–4,63 t/ha depending on the variety. Slightly lower performance numbers of crop on the maximum variant of fertilization explained lodging of crops due to high nutrients availability, especially nitrogen.

According to the project of growing technology which included handling of crops with retardants Hlormekvat-chloride 750, yield on control plots (without fertilizer) was 3,08–3,39 t/ha, and on entering mineral fertilizers in norm N₆₀P₆₀K₈₀ it was increased to 55,5–71,1 % to 5,10–5,55 t/ha. The largest yield of this project technology had the variant of fertilization N₉₀P₉₀K₁₂₀ and it was 5,45–5,98 t/ha, that exceeded the control variant (without fertilization) to 66,2–84,2 %. Comparing growing technology project that involved handling of crops Hlormekvat-chloride 750 without the usage of retardants, we must say that its yield was higher by 17.1 % on average in varieties and fertilization norms.

Under conditions of spring barley treatment by Terpal, indicators of crop yield of the variant without fertilizers were 3,23–3,52 t/ha, while fertilizing at the rate of N₆₀P₆₀K₈₀ increased them by 58,5–74,7 % and compounded 5,30–5,82 t/ha. With the variant N₉₀P₉₀K₁₂₀, yield was highest in the experiment and was 5,82–6,29 t/ha, that exceeded the variant without fertilizers by 74,4–88,6 %. In other words, according to the processing conditions of the crop by Terpal, the yield at an average of varieties and fertilization norms was higher by 22.7 % compared with the control (without retardants). It should also be said that the highest rates of yield had Vodogray and Hladis varieties, and the smallest ones were Konserto and Kangu.

Having regard to the research, it is possible to draw the following conclusion. The priority principle of spring barley cultivation technology is establishment of rational amount of fertilizers, that is considered to be a framework for realizing crop productive potential. The usage of retardant crop protection promotes preservation of more plants per unit area by increasing their resistance to lodging and has a positive effect on yield formation due to biochemical changes in the plant organism. It should also be taken into account that the multi-method application of retardants with fertilization is effective during the quantitative enlargement of the last. Using only fertilizers in typical black soil humus Right-bank Forest-steppe of Ukraine the studied varieties of spring barley allow yield to be 4,14–5,08 t/ha (N₆₀P₆₀K₈₀), and providing increased rate of fertilization to N₉₀P₉₀K₁₂₀ yield reduces to the level of 4,04–4,63 t/ha due to crop lodging. Using of Hlormekvat-chloride 750 retardant drug in combination with the above fertilizer application norms spring barley provides yielding of grain right-on 5,45–5,98 t/ha, and the application of Terpal – 5,82–6,29 t/ha.

Key words: malting spring barley, fertilizer application norms, retardants, productivity.