The yield of plants is determined primarily by the size and performance of the photosynthesis, which must quickly achieve the optimal rate during plants growth and development. One of the factors determining the size of assimilation surface area is the mode of plants nutrition.

It is well known that one of the possibilities of spring wheat productivity increasing is the improvement of genetic potential of varieties which is closely related to technological measures, in particular, nutrition conditions.

Thus, the problem of increasing the productivity of photosynthesis of agrocenosis of Chado spring wheat variety on the basis of application of organic fertilizers, manufactured on the latest technologies, in conditions of Western forest-Steppe are topical nowadays.

In the USA, Western Europe, and in recent years in Ukraine the considerable attention is paid to studies on the use of trivalent chromium in the adaptive landscape technologies of crops growing.

Trivalent chromium is considered one of the essential elements for plants proper growth and development, human nutrition and animal feeding. To achieve this goal it is necessary to provide the human body with plant foods grown on the soil containing the required number of Cr⁺³ , and animal feeding should be provided with  these micronutrients.

Since scientific research on the production and use of organic fertilizers with a content of trivalent chromium in the technologies of cultivation of agricultural crops in Ukraine is unsufficient, and they have not been conducted in the Western Forest-Steppe, we developed a technology of production of organic fertilizers from wastes of tannery sludge and sewage by biological fermentation method with a balanced content of Cr³⁺ trace elements and the technology of production of liquid organic fertilizer "Biochrome" by cavitation method and studied their efficiency in cultivation technologies of agricultural crops.

The purpose of the study was to study the effect of organic fertilizers produced on the latest technologies, on photosynthetic activity of plants of spring wheat varieties Chado in terms of Western forest-Steppe.

Field and laboratory studies were performed during 2013-2016 in the experimental field of Podilskyi state agrarian-technical University.

The experimental plot soil was chernozem typical of heavy-grained granulometric composition which characterized by the following agrochemical parameters: pH 6.5-6.8, the content of humus – 4.12-4.34 %, easily hydrolyzed nitrogen provision– 116-124 mg/kg of mobile phosphorus – 86-91 mg/kg, exchange potassium – 127-168 mg/kg of soil. In the experiment we studied the effect of organic fertilizer “Bioproferm” (Cr⁺³ content  540 mg/kg) and plant growth regulator “Biochrome” (Cr⁺³ content 5.4 mg/l) obtained by the developed and patented technology on the productivity of photosynthesis of Chado spring wheat varieties.

Organic fertilizer “Bioproferm” and “Bioactive” and mineral fertilizer in the form of N₁₂₀P₈₀K₈₀, were introduced with the fall plowing of the soil, “Biochrome” – during the vegetation of Chado spring wheat variety. In researches were applied the technology of spring wheat cultivation conventional to the conditions of Western Forest-Steppe of Ukraine. Researches and observations were performed according to standard techniques.

Introduction of organic fertilizers, manufactured on the latest technologies, contributed to the increase in leaf area of spring wheat compared to the options without application. On average for 2013-2016 the crops formed the best leaf area in the variant of "Bioproferm" fertilization (10 t/ha) with a balanced content of trivalent chromium and spraying plants in the phase of tillering – early booting stage liquid organic fertilizer "Biochrome" (5 l/ha). In this variant, the leaf area of plants at the tillering stage was 10.8 thousand m²/ha more compared to the control, in the phase of stem elongation beginning – 8.1 thousand m²/ha in the phase of earing – by 10.4 thousand m²/ha.  An  intensive accumulation of plant dry weight was observed acccordingly.

The analysis of the photosynthetic potential of spring wheat plants showed that the maximum rate of photosynthetic productivity was obtained in the variant with  basic soil treatment with 10 t/ha "Bioproferm" organic fertilizer produced by the method of the accelerated biological fermentation, with a content of trivalent chromium (540 mg/kg) and spraying the plants during vegetation with liquid organic fertilizer "Biochrome" in a dose of 5 l/ha, produced by cavitations, and 3.2 million m²/ha days 1.3 million m²/ha days longer compared to the control and 1.0 million m²/ha days more compared to the variant with the introducing N₁₂₀P₈₀K₈₀.

Studies have found that organic fertilizers significantly influenced the formation of net productivity of durum spring wheat photosynthesis. Thus, on average for four years of the study, in the phase of tillering – booting, this figure ranged from 2.6 g/m² per day (in the variant without fertilizer application) to 4.9 g/m² per day (in the variant of application of  "Bioproferm" – 10 t/ha and "Biochrome" – 5 l/ha).

Key words: spring wheat, modern technology, "Bioactive", "Bioproferm", "Biochrome", trivalent chromium, photosynthesis productivity.