As a result of the conducted in 2016–2018 studies on the study of the features of photosynthetic activity of the Ratnik hybrid sunflower found that the indicators of the leaf area of one plant and one hectare changed under the influence of the use of mineral fertilizers and growth regulators and were large according to the classical system of basic tillage. The largest indices of the leaf surface area of one plant in all systems of basic tillage were noted with the introduction of full fertilizer N60P60K60. The use of growth regulators in all combinations resulted in an increase in leaf area per plant and per hectare. Large indices of net productivity of photosynthesis were noted in crops according to the classical system of basic tillage, which were, depending on the scheme of drug use: on the control (without fertilizers) – 5,95–6,16 g/m2 × day, in variants with the introduction of N40 – 6,31–6,56 g/m2 × day, in variants with the introduction of N40P60 – 6,25–6,47 g/m2 × day in the variants with the introduction of N60P60K60 – 6,29–6,42 g/m2 × day. The application of mineral fertilizers in various doses contributed to an increase in the net productivity of photosynthesis: according to the classical system by 0,31–0,44, according to the moldboard-free system by 0,02–0,24, at the minimum 0,01–0,08 g/m2 × day. The most favorable conditions for the formation of productivity by sunflower plants have developed according to the classical system of basic tillage with a yield depending on the dose of fertilizers and the option of using growth regulators 2,62–3,46 t/ha. The highest yields of the Ratnik hybrid sunflower – 3.46 and 3.45 t/ha, were obtained when growing according to the classical system of basic tillage, applying mineral fertilizers in a dose of N60P60K60 for pre-sowing cultivation of the second and fifth options for using growth regulators: 2. Rost-concentrate + Chelatin oilseeds (6–8 pairs of real leaves) 5.1 processing: Chelatin phosphorus-potassium + Chelatin мultimix + Chelatin mono boron (3–4 pairs of real leaves), 2 processing: Chelatin mono boron (6–8 pairs of real leaves). The formation of the crop was largely influenced by the system of basic tillage (r = -0.66) and the use of mineral fertilizers (r = 0.61) and the weak use of drugs (r = 0.17). It should be noted the close relationship between yield and leaf surface area (r = 0.78), CPF (r = 0.78), dry matter weight per plant (r = 0.99) and seed weight (r = 0.97 ).
Key words: sunflower, system of basic tillage, mineral fertilizer, growth regulator, leaf area, net productivity of photosynthesis, yield.
Influence of growth regulators on photosynthetic activity of spring barley crops