The factors of the formation of the yield-capacity of early ripening potato on the black sod-podzol soil, being created during the processing of the tubers and aboveground mass with the plant growth regulators were investigated.

The application of plant growth regulators is one of the modern directions of yield-capacity and increasing quality of potato. Under their influence the yield-capacity of vegetable plants increases and the quality of the product improves. The application of growth regulators allows us to fully realize the potential opportunities of the plants, given by nature and breeding.

Nowadays the early ripening potatoes should be fertilized carefully, therefore, we applied new plant growth regulators to increase the yield-capacity. So, these questions require more detailed investigations in the conditions of the Forest-Steppe area of Ukraine.

The methods of investigation. The results are obtained by using the accepted field and laboratory methods on the basis of the field experiment and biochemical laboratory analysis using mathematical methods of analysis of variance, which confirm the accuracy of the results of the investigation.

The investigation was conducted on the experimental field of the Department of vegetable growing, which is situated in the Educational and Scientific Department of Uman National University of Horticulture. The investigated area is 40 m², including accounted one – 20 m². The soil of the investigated field is black sod-podzol loamy soil with well-developed humus horizon, thickness is 40 – 45cm.

A variety of the early ripen potato Latona was used in the investigation. We used such growth regulators as Emistim C, Gumi+, Gumifield, Azotofit, Fitozyd, Potejtin and Biocomplex to process potatoes before planting.

In the investigation we conducted biometric observation, namely: defined in the dynamics the area of the leaf using the method «die-cutting» in cm2 and area of leaf surface in thousand m2/ha; defined the weight of potatoes using «weight for area» method, evaluated the quality of the products according to the State Standard of Ukraine ISO 2165-2002.

The results of the investigation and their discussion. In our investigation, we sought to account for the factors of influence on potato plants and identify plant growth regulators, which could lead to greater growth and accelerate the development of plants in the conditions of open ground, and, consequently, give higher yield-capacity. The indicators of plant growth were the subject of thorough study in our investigation. These indicators are mainly quantitative – the leaf area, the quantity of the leaves, and the total area of the leaves. We defined the leaf area and the total area of the leaves in the period of intensive growth of the plants in the beginning of flowering. According to these indicators we estimated the productivity of plants.

The height of the plants plays an important role in evaluating of growth parameters. The measurement of the height of the plants in the period of intensive growth in the first decade of June showed that the plants were higher when Gumifield, Gumi + and Azotofit were used. Their height reached the size of 30,4 – 34,6 cm, that had probable difference to the controlled indicators 8,6 – 12,8 cm (in 2011 НІР05 = 5,3 cm, in 2012 – 6,4 cm, in 2013 – 5,8 cm). When the growth regulators Emistim C, Biocomplex, Potejtin and Fitozyd were used the height of the plants was on the level of 23,5 – 28,7 cm, that made the difference to the control 1,7 –6,9 cm.

Stem per unit of area consists of the number of potato bushes and stalks in each of them.

The investigations have shown that a significantly larger number of shoots at a bush had potato plants processed before planting with growth regulators Emistim C, Gumi +, Gumifield and Azotofit – from 6,0 to 6,4 pcs./plant. The lowest indicator was in control – 5,5 pcs/plant. Accordingly the plants of the variants, where the tubers were processed with Potejtin and Biocomplex had the average number of stalks per unit of area – 5,9 pcs/plant.

The improvement of the cultivation conditions of potato, even under adverse weather conditions in the years of investigation, allowed to receive more vegetative mass and accordingly higher yield-capacity. So, the variants where Gumi + and Azotofit were used had the area of the leaves on one hectare significantly higher than the controlled variant – 34,3–34,6 thousand m2/ha. The processing of the tubers with the growth regulators Biocomplex, Gumifield and Emistim C helped to get the total area of the leaves on a level of 33,2 – 33,8 thousand m²/ha.

When the growth regulators Fitozyd and Potejtin were used the total area of the leaves reached 31,9 – 32,5 thousand m2/ha and exceeded the controlled variant 0,8 – 1,4 thousand m²/ha.

The increase of the yield-capacity was obtained in the variants where the tubers were processed with Azotofit and Gumi +. It was 5,1 – 5,8 tons/ha. The usage of the growth regulators Biocomplex, Gumifield, Emistim C when processing the potato plants also gave us positive results. In this case, the yield-capacity significantly increased by 3,5 – 4,6 tons/ha. The variant where the tubers were processed with the solution of Fitozyd and Potejtin gave the lowest yield-capacity – 32,4 – 34,06 tons/ha.

Conclusions. Relying on the results of the investigations in the conditions of the Forest Steppe area of Ukraine we recommend to grow potatoes processing the tubers with the plant growth regulators Gumi + and Azotofit. These measures give an opportunity to get 5,1 – 5,8 tons/ha additionally.

Key words: potato early ripening, plant growth regulators, the height of the plants, stem, yield-capacity.